WO2021062048A2

WO2021062048A2 - Methods and systems for modulating hepatic gaba production or release to alter food intake in monogastric species

Info

Publication number: WO2021062048A2
Application number: PCT/US2020/052571
Authority: WO
Inventors: Benjamin J. RENQUIST; Caroline E. GEISLER
Original assignee: Arizona Board Of Regents On Behalf Of The University Of Arizona
Priority date: 2019-09-24
Filing date: 2020-09-24
Publication date: 2021-04-01
Also published as: WO2021062048A3

Abstract

Methods and compositions (such as compounds, drugs, molecules, etc,) for modulating food intake, e.g., increasing food intake or reducing food intake, in a monogastric animal species. Certain methods herein feature administering to the animal a composition that depresses hepatic GABA production, depresses GABA release, inhibits expression or activity of GABA transaminase, inhibits expression or activity of particular GABA transporters associated with export of GABA, increases expression or activity of particular GABA transporters associated with GABA re- uptake, etc. The methods may help decrease food intake and subsequently improve weight loss. Certain methods herein may feature administering to the animal a composition that activates hepatic GABA production, activates GABA release, increases expression or activity of GABA transaminase, increases expression or activity of particular GABA transporters associated with export of GABA, decreases expression or activity of particular GABA transporters associated with GABA re-uptake, etc. The methods may help increase food intake, and subsequently help promote weight gain.

Description

METHODS AND SYSTEMS FOR MODULATING HEPATIC GABA PRODUCTION OR

RELEASE TO ALTER FOOD INTAKE IN MONOGASTRIC SPECIES

BACKGROUND OF THE INVENTION Field of the Invention

[0001] The present invention is related to methods and systems for modulating hepatic GABA production or release, more particularly to modulating hepatic GABA production or release for the purpose of altering food intake in particular animal species, e.g., monogastric animal species and humans. Altering food intake in said animal species may help enhance weight gain or weight loss.

Background Art

[0002] The present invention describes hepatic GABA production as a signal that stimulates food/feed intake in monogastric species. The present invention features methods and systems for modulating hepatic GABA production and release or hepatic vagal afferent nerve signaling to alter food intake and/or body weight. For example, the present invention describes depressing either hepatic GABA production or release to help reduce food intake, thereby enhancing weight loss. The present invention also describes enhancing hepatic GABA production or release to help increase food intake, thereby enhancing weight gain.

[0003] Non-limiting examples of compounds that may be considered for weight loss and a reduction in food intake include vigabatrin and ethanolamine-O-sulfate (EOS). This finding was surprising, since those in the field believe that vigabatrin is associated with weight gain (Ben- Menachem, 2007, Epilepsia 48 Suppl 9:42-5; Lambert and Bird, 1997, Seizure 6:233-235).

BRIEF SUMMARY OF THE INVENTION

[0004] The present invention features methods and systems for modulating hepatic GABA production or release for the purpose of altering food intake in particular animal species, e.g., monogastric animal species, humans. Increasing hepatic GABA production/release will increase food intake in said animal species or human and encourage weight gain, while decreasing hepatic GABA production/release will decrease food intake and encourage weight loss.

[0005] The present invention features methods of reducing food intake in a monogastric animal (e.g., pig, chicken, dog, cat, horse, rodent, e.g., mouse, rat, etc.) or a human. In some embodiments, the method comprises administering to the monogastric animal or human an effective amount of a composition that depresses hepatic GABA production or release, wherein depressing hepatic GABA production or release causes the monogastric animal or human to reduce its food intake as compared to its food intake prior to being administered the composition. The method may be applied for weight loss purposes. [0006] In certain embodiments, the composition is a drug, a compound, or a molecule (such as but not limited to an antisense oligonucleotide).

[0007] In certain embodiments, the composition inhibits GABA signaling on the hepatic vagal afferent nerve.

[0008] In certain embodiments, the composition inhibits expression of or activity of GABA transaminase (GABA T) or inhibits GABA production. In certain embodiments, the composition that inhibits expression of or activity of GABA transaminase, or inhibits GABA production comprises valproic acid, vigabatrin, phenylethylidenehydrazine (PEH), ethanolamine-O-sulfate (EOS), L-cycloserine, aminooxyacetic acid, gabaculine, phenelzine, rosmarinic acid, branched chain fatty acid, 2-methyl, 2-ethylcaproic acid, 2,2-dimethylvaleric acid, S-vigabatrin, [3- (aminomethyl)phenyl]acetic acid, [2-(aminomethyl)phenyl]acetic acid, ursolic acid, succinic semialdehyde, succinate, Sr2+, SH-group reagent, pyruvate, propionic acid, pimelic acid, phenylhydrazine, oxalacetate, ornithine, oleanolic acid, Ni2+, muscimol, monoiodoacetate, Mn2+, Mg2+, methanol, maleate, lysyl reagents, KCN, imperatorin, hydroxylamine, hydrazine, HgCI2, glyoxylate, glycine, glutarate, glutamic acid, GDP, gastrodigenin, gamma-vinyl 4- aminobutanoate, gabaculine, falcarindiol, ethylamine-2-sulfonic acid, ethanol, trimethylcitryl- beta-D-galactopyranoside, tetrazole-5-(alpha-vinyl-propanamine), propan-2-one N-(2,4- dimethylphenyl)semicarbazone, p-chloromercuribenzoate, N-(4-bromophenyl)-3-(4- fluorophenyl)-6,7-dimethoxy-3a,4-dihydroindeno[1,2-c]pyrazole-2(3H)-carboxamide, N-(4- bromophenyl)-3-(4-chlorophenyl)-6,7-dimethoxy-3a,4-dihydroindeno[1 ,2-c]pyrazole-2(3H)- carboxamide, DL-cysteine, divalent metal ions, dioxan, D-penicillamine, D-cycloserine, cycloserine, Cu2+, Co2+, Cd2+, Ca2+, carbonyl reagents, butyric acid, beta-alanine, beta- cypermethrin, baclofen, Ba2+, ATP, aminooxyacetate, alpha-alanine, ADP, adipic acid, acetic acid, 6-Azauracil, 6-Azathymine, 5-thiouracil, 5-nitrouracil, DL-3-amino-1-cyclopentene-1- carboxylic acid, DL-trans-4-amino-2-cyclopentene-1 -carboxylic acid, cis-3-aminocyclohex-4-ene- 1 -carboxylic acid, 5-iodouracil, 5-diazouracil, (+/-)-(1S,2R,4S,5S)-4-amino-6,6- difluorobicyclo[3.1 0]hexane-2-carboxylic acid, (+/-)-(1S,2S,4S,5S)-4-amino-6,6- difluorobicyclo[3.1.0]hexane-2-carboxylic acid, (+/-)piperidine-3-sulfonic acid, (1R,3S,4S)-3- amino-4-fluorocyclopentane-1 -carboxylic acid, (1 R,4S)-4-amino-2-cyclopentene-1 -carboxylic acid, (1R,4S)-4-amino-3-fluorocyclopent-2-enecarboxylic acid, (1R,4S)-4-amino-3- pentafluoroethylcyclopent-2-enecarboxylic acid, (1 R,4S)-4-amino-3-trifluoromethylcyclopent-2- enecarboxylic acid, (1S,2S,3E)-2-amino-3-(fluoromethylidene)cyclopentanecarboxylic acid, (1 S,2S,3Z)-2-amino-3-(fluoromethylidene)cyclopentanecarboxylic acid, (1 S,3S)-(Z)-3-amino-4- (2,2,2-trifluoroethylidene)cyclopentanecarboxylic acid, (1S,3S)-3-amino-4-(2,2,2-trifluoro-1- trifluoromethylethylidene)-cyclopentanecarboxylic acid, (1S,3S)-3-amino-4- difluoromethylenecyclopentanecarboxylic acid, (1S,4R)-4-amino-2-cyclopentene-1 -carboxylic acid, (1S,4S)-2-(difluoromethylidene)-4-(1H-tetrazol-5-yl)cyclopentanamine, (2E)-4- methylpentan-2-one N-(2,4-dimethylphenyl)semicarbazone, (2E)-butan-2-one N-(2,4- dimethylphenyl)semicarbazone, (4R)-4-amino-1-cyclopentene-1 -carboxylic acid, (4S)-4-amino-

1-cyclopentene-1 -carboxylic acid, (R,S)-4-amino-3-fluorobutanoic acid, (S)-4-amino-4,5-dihydro-

2-thiophenecarboxylic acid, (Z)-4-amino-2-butenoic acid, 1-(4-acetylphenyl)-3-(4- bromophenyloxy)-pyrrolidine-2,5-dione, 1-(4-acetylphenyl)-3-(salicyldehydoxy)-pyrrolidine-2,5- dione, 1H-tetrazole-5-(alpha-vinyl-propanamine), 2,4-diaminobutanoate, 2,4-dimethylphenyl semicarbazide hydrochloride, 2-Aminobenzenesulfonate, 2-aminobutanoate, 2-aminoethane phosphonic acid, 2-N-(acetylamino)cyclohexane sulfonic acid, 2-oxoadipic acid, 2-oxoglutarate, 2-Thiouracil, 3-(aminomethyl)benzoic acid, 3-aminocyclohexanecarboxylic acid, 3-chloro-1-(4- hydroxyphenyl)propan-1-one, 3-Chloro-4-aminobutanoate, 3-Mercaptopropionic acid, 3-Methyl- 2-benzothiazolone hydrazone hydrochloride, 3-Phenyl-4-aminobutanoate, 4-(aminomethyl)-1H- pyrrole-2-carboxylic acid, 4-(aminomethyl)furan-2-carboxylic acid, 4-(aminomethyl)furan-3- carboxylic acid, 4-(aminomethyl)thiophene-2-carboxylic acid, 4-(aminomethyl)thiophene-3- carboxylic acid, 4-acryloylphenol, 4-amino-2-fluorobutanoate, 4-amino-5-fluoropentanoic acid, 4- Amino-hex-5-enoic acid, 4-aminohex-5-enoic acid, 4-Aminohex-5-ynoic acid, 4-ethynyl-4- aminobutanoate, 4-hydroxybenzaldehyde, 4-hydroxybenzylamine, 5,5'-dithiobis-2-nitrobenzoic acid, 5-(aminomethyl)-1H-pyrrole-2-carboxylic acid, 5-(aminomethyl)furan-2-carboxylic acid, 5- (aminomethyl)thiophene-2-carboxylic acid, L-tyrosine, L-DOPA, desipramine, timonacic, amicar, orindyl, pemirolast, mesalazine, glutathione, gly-gly, 5-ALA, Vit. U, methionine, glutamine, pyridoxalphosphate, acivicin, GABOB, 3-ABA, 5-AVA, glycine, carnitine, amitriptyline, pregabalin, erythromycin, cyclosporin A, rifampicin, EF1502, betaine, and NNC 05-2090 hydrochloride, 5-amino-1,3-cyclohexadienylcarboxylate, and metformin. In certain embodiments, the composition that inhibits expression of or activity of GABA transaminase or inhibits GABA production is an AMPK activator.

[0009] In certain embodiments, the composition inhibits GABA release. In certain embodiments, the composition inhibits expression or activity of GABA transporters that export hepatic GABA. In certain embodiments, the composition that inhibits GABA release inhibits mRNA or protein expression of the Solute Carrier Family 6 Member 6 (SLC6A6) gene or the Solute Carrier Family 6 Member 8 ( SLC6A8 ) gene. In certain embodiments, the composition inhibits mRNA or protein expression of or activity of TauT, a GABA transporter protein encoded by the SLC6A6 gene. In certain embodiments, the composition inhibits mRNA or protein expression of or activity of creatine transporter (CRT), a GABA transporter protein encoded by SLC6A8 gene. In certain embodiments, the composition that inhibits mRNA or protein expression or activity of SCL6A6 or TauT is vigabatrin, d-ALA, guvacine, taurine, Beta-alanine, Guanidinoacetate, b-Guanidinopropionate, g-Guanidinobutyrate, Guanidinoethansulfonate, and taurine. In certain embodiments, the composition that inhibits expression or activity of SCL6A8 or CRT is an AMPK activator, Guanidinoacetate, b-Guanidinopropionate, y-Guanidinobutyrate, Guanidinoethansulfonate, creatinine, methylguanidine, l-arginine, RGX-202, 2,4-dinitro-1- fluorobenzene, tetraethylammonium, guanidine, creatine, arginine, lysine, DTBM, DNFB, or NEM.

[0010] In certain embodiments, the composition improves GABA re-uptake. In certain embodiments, the composition increases mRNA or protein expression of the Solute Carrier Family 6 Member 12 ( SLC6A12 ) gene or the Solute Carrier Family 6 Member 13 ( SLC6A13 ) gene. In certain embodiments, the composition increases mRNA or protein expression of or activity of BGT1, a GABA transporter protein encoded by the SLC6A12 gene. In certain embodiments, the composition increases mRNA or protein expression of or activity of GAT2, a GABA transporter protein encoded by the SLC6A13 gene. In certain embodiments, the composition that increases expression of SLC6A12 and/or SLC6A13 is an AMPK activator.

[0011] In certain embodiments, the composition inhibits expression or activity of succinate semialdehyde dehydrogenase. In certain embodiments, the composition that inhibits expression or activity of succinate semialdehyde dehydrogenase comprises 2-methyl, 2-ethylcaproic acid; 2,2-dimethylvaleric acid, 2-oxoglutaric semialdehyde, 4-dimethylaminoazobenzene-4- iodoacetamide, 4-hydroxy-trans-2-nonenal, 4-hydroxybenzaldehyde, 4-methoxybenzaldehyde, 4-tolualdehyde, 5,5'-dithiobis(2-nitrobenzoic acid), Acetaldehyde, Acrolein, ADP, AMP, Arsenite, ATP, Benzaldehyde, Ca2+, Cd2+, Chloral hydrate, Cu2+, Disulfiram, Dithionitrobenzoate, Fe3+, Glyoxylate, Hg2+, lodoacetamide, m-hydroxybenzaldehyde, Mg2+, Mn2+, N-ethylmaleimide, N- formylglycine, NAD+, NADH, NEM, Ni2+, o-phthalaldehyde, p-bromobenzaldehyde, p- chlorobenzaldehyde, p-chloromercuriphenyl sulfonate, p-ethoxybenzaldehyde, p- ethylbenzaldehyde, p-fluorobenzaldehyde, p-hydroxymercuribenzoate, p-iodobenzaldehyde,p- isopropylbenzaldehyde, p-Methoxybenzaldehyde, p-methylbenzaldehyde, p-nitrobenzaldehyde, Pb2+, PCMB, pyridoxal 5'-phosphate, succinate semialdehyde, Valeraldehyde, and Zn2+. In certain embodiments, the composition that inhibits expression or activity of succinate semialdehyde dehydrogenase is an AMPK activator.

[0012] In certain embodiments, the AMPK activator is a biguanide, a thiazolidinedione, a ginsenoside, or a polyphenol. In certain embodiments, the AMPK activator is A-769662, metformin, resveratrol, troglitazone, pioglitazone, rosiglitazone, quercetin, genistein, epigallocatechin gallate, berberine, curcumin, ginsenoside Rb1, alpha-lipoic acid, cryptotanshinone, 5-aminoimidazole-4-carboxaminde ribonucleoside (AICAR), benzimidazole, salicylate, compound-13, PT-1, MT63-78, and APC. [0013] In certain embodiments, the composition comprises an inhibitor of sodium potassium ATPase. In certain embodiments, the composition reduces hepatic mitochondrial uncoupling.

[0014] The present invention features methods of increasing food intake in a monogastric animal. In some embodiments, the method comprises administering to the monogastric animal an effective amount of a composition that increases hepatic GABA production or release, wherein increasing hepatic GABA production or release causes the monogastric animal to increase its food intake as compared to its food intake prior to being administered the composition. The method may be applied for improving weight gain. In certain embodiments, the composition is a drug, a compound, or a molecule (such as but not limited to an anti-sense oligonucleotide). In certain embodiments, the composition activates GABA signaling on the hepatic vagal afferent nerve. In certain embodiments, the composition increases expression of or activity of GABA transaminase (GABA T) or increases GABA production.

[0015] In certain embodiments, the composition increases or activates GABA release. In certain embodiments, the composition increases expression or activity of GABA transporters that export of hepatic GABA. In certain embodiments, the composition that increases GABA release increases expression of the Solute Carrier Family 6 Member 6 ( SLC6A6 ) gene or the Solute Carrier Family 6 Member 8 ( SLC6A8 ) gene. In certain embodiments, the composition increases expression of or activity of TauT, a GABA transporter protein encoded by the SLC6A6 gene. In certain embodiments, the composition increases expression of or activity of creatine transporter (CRT), a GABA transporter protein encoded by SLC6A8 gene.

[0016] In certain embodiments, the composition decreases GABA re-uptake. In certain embodiments, the composition decreases expression of the Solute Carrier Family 6 Member 12 ( SLC6A12 ) gene or the Solute Carrier Family 6 Member 13 ( SLC6A13 ) gene. In certain embodiments, the composition decreases expression of or activity of BGT1 , a GABA transporter protein encoded by the SLC6A12 gene. In certain embodiments, the composition decreases expression of or activity of GAT2, a GABA transporter protein encoded by the SLC6A13 gene.

[0017] In certain embodiments, the composition increases expression or activity of succinate semialdehyde dehydrogenase. In certain embodiments, the composition comprises an activator of sodium potassium ATPase. In certain embodiments, the composition increases hepatic mitochondrial uncoupling.

[0018] While the methods related to increasing food intake may be directed to animals, e.g., monogastric animals, the present invention is not limited to the application of said method to non-human animals. For example, there may be instances wherein the method is applied to humans in order to help increase food intake and/or gain weight. [0019] Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one of ordinary skill in the art. Additional advantages and aspects of the present invention are apparent in the following detailed description and claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING (S)

[0020] The features and advantages of the present invention will become apparent from a consideration of the following detailed description presented in connection with the accompanying drawings in which:

[0021] FIG. 1 shows weight gain (g) in high fat diet fed mice after vagotomy (or sham), which shows that hepatic vagotomy limits weight gain.

[0022] FIG. 2 shows light cycle food intake (g) in mice following vagotomy (or sham). Hepatic vagotomy decreases light cycle food intake and 24-hour food intake.

[0023] FIG. 3A shows GABA release after viral induced expression of a hyperpolarizing channel, which limits obesity-induced hepatic GABA release.

[0024] FIG. 3B shows weight gain on a high fat diet after viral induced expression of a hyperpolarizing channel, which limits body weight gain on a high fat diet (60% of calories from fat).

[0025] FIG. 4A shows double immunohistochemical labeling of the vagal afferent marker calretinin (green) and GABAA receptors (red) (arrows indicate co-staining; BV = blood vessel). [0026] FIG. 4B is an enlarged view of the white box in FIG. 4A (white arrows indicate costaining, yellow arrows indicate GABA_A positive staining immediately adjacent to calretinin positive fibers).

[0027] FIG. 4C shows double labeling for the alternative vagal afferent marker calcitonin gene- related peptide (CGRP; green) and GABA_A receptors (red) (arrows indicate co-staining; BV = blood vessel).

[0028] FIG. 4D shows an enlarged view of the white box in FIG. 4C (white arrows indicate co- staining, yellow arrows indicate GABA_A positive staining immediately adjacent to CGRP positive fibers).

[0029] FIG. 4E shows a schematic view of the proposed regulation of hepatic GABA release by intracellular and extracellular ion concentrations.

[0030] FIG. 5 shows GABA release in an ex vivo liver slice. Treatment with the GABA- transaminase inhibitor, ethanolamine-O-sulfate (EOS), limits liver slice GABA release.

[0031] FIG. 6A shows food intake (g) after various days of treatment with control (PBS), ethanolamine-O-sulfate (EOS), or vigabatrin. Both EOS and vigabatrin decrease food intake within 5 days of initiating treatment.

[0032] FIG. 6B shows weight loss (g) after various days of treatment with control (PBS), ethanolamine-O-sulfate (EOS), or Vigabatrin. Both EOS and vigabatrin induce body weight loss within 5 days of initiating treatment.

[0033] FIG. 6C shows food intake (g) in group housed mice after various days of treatment with control (PBS) or ethanolamine-O-sulfate (EOS). EOS decreases daily food intake.

[0034] FIG. 6D shows weight loss (g) in group housed mice after various days of treatment with control (PBS) or ethanolamine-O-sulfate (EOS). EOS causes weight loss.

[0035] FIG. 6E shows weight loss (g) in high fat diet (60% of calories from fat) fed mice after long term oral ethanolamine-O-sulfate (EOS) treatment (3 g/L), showing chronic treatment with EOS caused body weight loss.

[0036] FIG. 7 shows the AMPK activators A-769662 and metformin decrease expression of GABA-transaminase (ABAT).

[0037] FIG. 7A shows the AMPK activator A-769662 decreases expression of ABAT mRNA. ABAT is a gene encoding GABA transaminase.

[0038] FIG. 7B shows the AMPK activators A-769662 and metformin decrease expression of ALDH5a1 mRNA. ALDH5a1 is a gene encoding succinate semialdehyde dehydrogenase.

[0039] FIG. 7C shows the AMPK activators A-769662 and metformin increase the expression of SLC6A12 mRNA. SCL6A12 encodes a liver GABA re-uptake transporter.

[0040] FIG. 7D shows the AMPK activators A-769662 and metformin increase the expression of SLC6A13 mRNA. SLC6A13 encodes a liver GABA re-uptake transporter.

[0041] FIG. 7E shows the AMPK activators A-769662 and metformin decrease expression of SLC6A8, a gene encoding a creatine transporter (GABA exporter).

[0042] FIG. 8A shows multivariate regressions including intrahepatic triglyceride % (IHTG%) and the mRNA for the hepatic GABA transporters (Slc6A6, Slc6A8, Slc6A12, and Scl6A12) and hepatic ABAT (GABA-T) as explanatory variables for variations in glucose infusion rate during a hyperinsulinemic euglycemic clamp (mMoI/kg fat free mass/min). mRNA (FPKM; Fragments Per Kilobase of transcript per Million mapped reads) was quantified by RNA-Seq from liver tissue. Data are presented as mean ± SEM.

[0043] FIG. 8B shows the glucose disposal rate calculated during a hyperinsulinemic- euglycemic clamp (Glucose Rd, % increase). mRNA (FPKM; Fragments Per Kilobase of transcript per Million mapped reads) was quantified by RNA-Seq from liver tissue. Data are presented as mean ± SEM.

[0044] FIG. 8C shows the basal serum insulin. mRNA (FPKM; Fragments Per Kilobase of transcript per Million mapped reads) was quantified by RNA-Seq from liver tissue. Data are presented as mean ± SEM. [0045] FIG. 8D shows the basal hepatic insulin sensitivity index (HISI). mRNA (FPKM; Fragments Per Kilobase of transcript per Million mapped reads) was quantified by RNA-Seq from liver tissue. Data are presented as mean ± SEM.

[0046] FIG. 8E shows single nucleotide polymorphisms (SNPs) that cause missense mutations in Slc6A12 or Slc6A13 are associated with an increased incidence of type 2 diabetes (T2D) adjusted for body mass index (BMI). Data are presented as mean ± SEM.

[0047] FIG. 8F shows SNPs in the ABAT promoter are associated with a decreased risk of type 2 diabetes (T2D). Data are presented as mean ± SEM.

[0048] FIG. 9A shows immunohistochemical evidence of GABAA receptor expressing vagal afferent innervation in the liver. Double labeling for the vagal afferent marker calretinin (green) and GABA_A receptors (red) (arrows indicate co-staining). Blue = DAPI (nucleus). Images at 10X magnification. BV = blood vessel.

[0049] FIG. 9B shows an enlarged view of area within the white box in FIG. 9A (white arrows indicate co-staining, yellow arrows indicate GABA_A positive staining immediately adjacent to calretinin positive fibers). Blue = DAPI (nucleus). Images at 10X magnification.

[0050] FIG. 9C shows immunohistochemical staining for the alternative vagal afferent marker calcitonin gene- related peptide (CGRP, green) and GABA_A receptors (red) (arrows indicate co- staining). Blue = DAPI (nucleus). Images at 10X magnification. BV = blood vessel.

[0051] FIG. 9D shows an enlarged view of area within the white box in FIG. 9C (white arrows indicate co-staining, yellow arrows indicate GABA_A positive staining immediately adjacent to CGRP positive fibers). Blue = DAPI (nucleus). Images at 10X magnification.

TERMS

[0052] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which a disclosed invention belongs. The singular terms “a,” “an," and “the” include plural referents unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise. The term "comprising" means that other elements can also be present in addition to the defined elements presented. The use of "comprising" indicates inclusion rather than limitation. Stated another way, the term "comprising" means "including principally, but not necessary solely". Furthermore, variation of the word "comprising", such as "comprise" and "comprises", have correspondingly the same meanings. In one respect, the technology described herein related to the herein described compositions, methods, and respective component(s) thereof, as essential to the invention, yet open to the inclusion of unspecified elements, essential or not ("comprising").

[0053] All embodiments disclosed herein can be combined with other embodiments unless the context clearly dictates otherwise. Suitable methods and materials for the practice and/or testing of embodiments of the disclosure are described below. Such methods and materials are illustrative only and are not intended to be limiting. Other methods and materials similar or equivalent to those described herein can be used. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety for all purposes. In case of conflict, the present specification, including explanations of terms, will control. Although methods and materials similar or equivalent to those described herein can be used to practice or test the disclosed technology, suitable methods and materials are described below. The materials, methods, and examples are illustrative only and not intended to be limiting. In order to facilitate review of the various embodiments of the disclosure, the following explanations of specific terms are provided.

[0054] Animal: As used herein, the term “animal” includes but is not limited to a human, mouse, rat, rabbit, dog, cat, pig, chicken, non-human primates, etc.

[0055] Antisense oligonucleotide: As used herein, the term “antisense oligonucleotide” refers to a single-stranded oligonucleotide having a nucleobase sequence that permits hybridization to a corresponding region or segment of a target nucleic acid. Antisense technology is emerging as an effective means for reducing the expression of specific gene products.

[0056] Effective Amount: The term “effective amount," as used herein, refers to a dosage of a compound or a composition effective for eliciting a desired effect. This term as used herein may also refer to an amount effective at bringing about a desired in vivo effect in an animal, mammal, human, etc. Effective amount may vary depending upon body mass of the individual to be treated, the health and physical condition of the individual to be treated, the taxonomic group of individual to be treated, the formulation of the composition, depending on the evaluation, and other relevant factors of a medical condition of an individual varies between individuals obtain.

[0057] Treatment: As used herein, the terms "treat" or ’treatment" or ’treating" refers to both therapeutic treatment and prophylactic or preventative measures, wherein the object is to prevent or slow the development of a disease or condition, such as slow down the development of obesity, or reducing at least one adverse effect or symptom of a condition, disease or disorder, e.g., any disorder characterized by insufficient or undesired function. Treatment is generally "effective" if one or more symptoms or clinical markers are reduced as that term is defined herein. Alternatively, a treatment is "effective" if the progression of a disease is reduced or halted. That is, "treatment" includes not just the improvement of symptoms or decrease of markers of the disease, but also a cessation or slowing of progress or worsening of a symptom that would be expected in absence of treatment. Beneficial or desired clinical results include, but are not limited to, alleviation of one or more symptom(s), diminishment of extent of disease, stabilized (e.g., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. "Treatment" can also mean prolonging survival as compared to expected survival if not receiving treatment. Those in need of treatment include those already diagnosed with a condition, as well as those likely to develop a condition due to genetic susceptibility or other factors such as weight, diet and health.

DESCRIPTION OF THE INVENTION

[0058] The present invention describes hepatic GABA production as a signal that stimulates food/feed intake in monogastric species, including humans. The present invention features methods and systems for modulating hepatic GABA production and release or hepatic vagal afferent nerve signaling to alter food intake and/or body weight. For example, the present invention describes depressing either hepatic GABA production or release to help reduce food intake, thereby enhancing weight loss. The present invention also describes enhancing hepatic GABA production or release to help increase food intake, thereby enhancing weight gain.

[0059] For example, FIG. 1 shows weight gain in mice over 9 weeks following a vagotomy or sham procedure. From 6 weeks and beyond of a high fat diet (60% of calories from fat), weight gain in mice with vagotomy is significantly reduced compared to mice with the sham procedure, showing that hepatic vagotomy limits weight gain on a high fat diet, supporting the hypothesis that the hepatic vagal nerve is involved in the control of food intake. Likewise, when light cycle food intake, dark cycle food intake, and 24-hour food intake was observed in mice following vagotomy or sham procedure (see FIG. 2), a significant decrease in 24-hour food intake and light cycle food intake was observed in mice with vagotomy compared to the control group. This data also indicates hepatic vagotomy is involved in the control of food intake.

[0060] Viral induced expression of the hyperpolarizing Kir2.1 channel was tested in lean and obese mice. As shown in FIG. 3A, induced expression of Kir2.1 limits obesity-induced hepatic GABA release. FIG. 3B shows weight gain on a high fat diet after viral induced expression of a hyperpolarizing channel, which limits body weight gain on a high fat diet (60% of calories from fat). Mice expressing the Kir2.1 hyperpolarizing channel also displayed significantly reduced body weight when fed a high fat diet for 9 weeks.

[0061] FIG. 4A and FIG. 4B show double labeling of the vagal afferent marker calretinin (green) and GABA_A receptors (red) (white arrows indicate co-staining, yellow arrows indicate GABA_A positive staining immediately adjacent to calretinin positive fibers). FIG. 4C and FIG. 4D show double labeling for the alternative vagal afferent marker calcitonin gene-related peptide (CGRP; green) and GABA_A receptors (red) (white arrows indicate co-staining, yellow arrows indicate GABA_A positive staining immediately adjacent to CGRP positive fibers). FIG. 4E shows a schematic view of the proposed regulation of hepatic GABA release by intracellular and extracellular ion concentrations.

[0062] GABA release can be modified using drugs, such as but not limited to vigabatrin and ethanolamine-O-sulfate (EOS). FIG. 5 shows GABA release in an ex vivo liver slice. Treatment with the GABA-transaminase inhibitor, ethanolamine-O-sulfate (EOS), limits liver slice GABA release. FIG. 6A, FIG. 6B, FIG. 6C, FIG. 6D, and FIG. 6E show food intake and weight changes in mice treated with EOS or vigabatrin. For example, FIG. 6A shows food intake after various days of treatment with ethanolamine-O-sulfate (EOS) or vigabatrin. Both EOS and vigabatrin decrease food intake within 5 days of initiating treatment compared to controls. FIG. 6B shows weight loss after days of treatment with ethanolamine-O-sulfate (EOS) or vigabatrin. Both EOS and vigabatrin induce body weight loss within 5 days of initiating treatment. FIG. 6C shows food intake in group housed mice after days of treatment with ethanolamine-O-sulfate (EOS). EOS decreases daily food intake compared to controls. FIG. 6D shows weight loss in group housed mice after days of treatment with ethanolamine-O-sulfate (EOS), showing EOS causes weight loss compared to controls. FIG. 6E shows weight loss in high fat diet (60% of calories from fat) fed mice after long term oral ethanolamine-O-sulfate (EOS) treatment (3 g/L), showing chronic treatment with EOS caused body weight loss.

[0063] FIG. 7 A, FIG. 7B, and FIG. 7E show the AMPK activators metformin and A-769662 decrease expression of ABAT mRNA (GABA transaminase), ALDH5a1 mRNA (succinate semialdehyde dehydrogenase), and SLC6A8 (a creatine transporter/GABA exporter). FIG. 7C and FIG. 7D show the AMPK activators metformin and A-769662 increase expression of SLC6A12 mRNA (a liver GABA re-uptake transporter) and SLC6A13 mRNA (a liver GABA reuptake transporter).

[0064] FIG. 8A, FIG. 8B, and FIG. 8C shows associations between hepatic GABA system and glucoregulatory markers in obese humans. FIG. 8A shows multivariate regressions including intrahepatic triglyceride % (IHTG%) and the mRNA for the hepatic GABA transporters (Slc6A6, Slc6A8, Slc6A12, and Scl6A12) and hepatic ABAT (GABA-T) as explanatory variables for variations in glucose infusion rate during a hyperinsulinemic euglycemic clamp (mMoI/kg fat free mass/min). FIG. 8B shows the glucose disposal rate calculated during a hyperinsulinemic- euglycemic clamp (Glucose Rd, % increase). FIG. 8C shows the basal serum insulin, and FIG. 8D shows the basal hepatic insulin sensitivity index. FIG. 8E shows single nucleotide polymorphisms (SNPs) that cause missense mutations in Slc6A12 or Slc6A13 are associated with an increased incidence of type 2 diabetes (T2D) adjusted for body mass index (BMI). FIG. 8F shows SNPs in the ABAT promoter are associated with a decreased risk of T2D.

[0065] Referring to FIG. 8A, FIG. 8B, FIG. 8C, FIG. 8D, FIG. 8E, and FIG. 8F, hepatic GABA system measures were correlated with glucoregulatory markers in the basal state and during a HECP. A multivariate regression showed that during a clamp, IHTG % was negatively associated with both glucose infusion rate (FIG. 8A) and the percent increase in glucose rate of disposal from the basal state to the hyperinsulinemic clamp (FIG. 8B, Table 1). Table 1 shows regression coefficient estimates showing the association between hepatic mRNA expression of genes involved in GABA production ( ABAT) and GABA transport ( SLC6A6 , SLC6A8, SLC6A12, and SLC6A13 ) and glucose infusion rate (mMoI/Kg Fat Free Mass/min) and Glucose Rd (rate of disposal; % increase) during a hyperinsulinemic-euglycemic clamp.

TABLE 1

[0066] There was a trend toward a positive correlation between IHTG % and basal plasma insulin concentration (P=0.06; FIG. 8C) and a negative correlation between IHTG % and hepatic insulin sensitivity index (HISI, a product of the basal endogenous glucose production rate and plasma insulin concentration, P=0.07; FIG. 8D, Table 2). Table 2 shows regression coefficient estimates showing the association between hepatic mRNA expression of genes involved in GABA production (ABAT) and GABA transport (SLC6A6, SLC6A8, SLC6A12, and SLC6A13) and basal plasma insulin concentration (mU/mL) or hepatic insulin sensitivity index (HISI).

TABLE 2

[0067] Examining these relationships with hepatic GABA transporter mRNA, it was found that glucose infusion rate and insulin-induced percent increase in glucose disposal during a clamp were negatively correlated to hepatic SLC6A6 (Tau-T) and SLC6A8 (CRT) mRNA expression, and by contrast were positively correlated to hepatic SLC6A12 (BGT1) and SLC6A13 (GAT2) mRNA expression (FIG. 8A, FIG. 8B). Furthermore, it was shown that hepatic SLC6A12 (BGT1) mRNA was negatively associated with basal plasma insulin concentrations and positively associated with HISI (FIG. 8C, FIG. 8D). In turn, it was hypothesized that BGT1 and GAT2 are primarily acting as GABA re-uptake transporters, which limit GABA signaling onto the HVAN, and that Tau-T and CRT are acting to export GABA, which encourages metabolic dysfunction. This hypothesized role of BGT 1 and GAT2 in hepatic GABA re-uptake is supported by explant data. Of note, the summed expression of SLC6A6 and SLC6A8 was positively associated with IHTG %, suggesting that their expression increases with steatosis (P = 0.04).

[0068] The Accelerating Medicines Partnership Type 2 Diabetes Knowledge Portal was used to understand the effect of missense mutations in genes encoding the hepatic GABA transporters ( SLC6A6 , SLC6A8, SLC6A12, and SLC6A13). Missense mutations in the

SLC6A12 and SLC6A13 genes are significantly associated with an increased incidence of T2D (FIG. 8E and Table 3). Table 3 shows single nucleotide polymorphisms (SNPs) that result in missense mutations in GABA transporters are associated with an increased incidence (OR; odds ratio) of type 2 diabetes (T2D; source: knowledge portal diabetes database). MAF - minor allele frequency.

TABLE 3

[0069] Of note a missense mutation inducing a pre-mature stop codon in the SLC6A12 gene increases the odds ratio forT2D 15.8 times (dbSNP ID rs199521597), establishing its key role in limiting the incidence of diabetes. Although, not specific to the liver, this GWAS data does support the hypothesis that GABA transporters encoded by SLC6A12 and SLC6A13 act to preventing the development of T2D. Since it has been established that GABA-T knockdown and inhibition reduces food intake and body weight, mutations associated with BMI were identified. It was found that missense mutations in SLC6A12 (6), SLC6A6 (3), and SLC6A13 (4) that were associated with increased BMI (Table 4). Table 4 shows single Nucleotide Polymorphisms (SNPs) that result in missense mutations in GABA transporters are associated with BMI (Source: knowledge portal diabetes database). MAF - minor allele frequency.

TABLE 4

[0070] Hepatic GABA-T expression was correlated with basal glucoregulatory markers. Hepatic ABAT mRNA expression was positively associated with plasma insulin and negatively with HISI (FIG. 8C, FIG. 8D). Using the Diabetes Knowledge Portal database, single nucleotide polymorphisms (SNPs) in the reporter region of ABAT were identified to be associated with decreased risk of T2D (FIG. 8F, Table 5). Table 5 shows single Nucleotide Polymorphisms (SNPs) in the promoter of the ABAT gene, which encodes for GABA transaminase, are associated with a decreased odds ratio (OR) for type 2 diabetes (T2D; Source: knowledge portal diabetes database). MAF - minor allele frequency.

TABLE 5

[0071] Importantly, no promoter region SNPs were found that were significantly associated with an increased odds ratio for T2D. Moreover, given the key role of GABA-T in the central nervous system it is not surprising that SNPs in the ABAT gene were not identified. These data support the notion that GABA-T is a driver of insulin resistance in people. Taken together, the data obtained from the studies conducted in people support the potential clinical translation of findings in the mouse.

[0072] FIG. 9A, FIG. 9B, FIG. 9, and FIG. 9D shows immunohistochemical evidence of GABA_A receptor expressing vagal afferent innervation in the liver. Double labeling for the vagal afferent marker shows calretinin (green) and GABAA receptors (red) (see FIG. 9A; arrows indicate costaining). FIG. 9B shows an enlarged view of area within the white box in FIG. 9A (white arrows indicate co-staining, yellow arrows indicate GABA_A positive staining immediately adjacent to calretinin positive fibers). FIG. 9C shows immunohistochemical staining for the alternative vagal afferent marker for calcitonin gene-related peptide (CGRP, green) and GABA_A receptors (red) (arrows indicate co-staining). FIG. 9D shows an enlarged view of area within the white box in FIG. 9C (white arrows indicate co-staining, yellow arrows indicate GABAA positive staining immediately adjacent to CGRP positive fibers).

[0073] Given the above, the present invention describes methods for reducing food intake in a subject, e.g., monogastric animals (e.g., mice, humans, etc.). In some embodiments, the method comprises administering to the animal an effective amount of a composition that depresses hepatic GABA production or release. Depressing hepatic GABA production or release causes the animal to reduce its food intake as compared to its food intake prior to being administered the composition. The composition may inhibit GABA signaling on the hepatic vagal afferent nerve. The purpose of reducing the animal’s food intake may be for weight loss purposes, for example.

[0074] In some embodiments, the composition is a drug, a compound, or a molecule (e.g., anti-sense oligonucleotides). In some embodiments, the composition is an inhibitor of GABA-T, TauT (SLC6A6), CRT (SLC6A8), sodium potassium ATPase, hepatic succinate semialdehyde dehydrogenase, or hepatic gluconeogenesis etc. The composition may comprise ethanolamine- O-sulfate (EOS). The composition may comprise vigabatrin. In some embodiments, the composition does not cross the blood-brain barrier. For example, in some embodiments, the composition comprises a derivative of vigabatrin or EOS that does not cross the blood-brain barrier.

[0075] The present invention also describes methods of increasing food intake in a subject, e.g., a monogastric animal (e.g., mouse, human, etc.). The method comprises administering to the animal an effective amount of a composition that increases hepatic GABA production or release. Increasing hepatic GABA production or release causes the animal to increase its food intake as compared to its food intake prior to being administered the composition. In some embodiments, the composition is an inhibitor of BGT1 (SLC6A12) or GAT2 (SLC6A13), Nonlimiting examples of GAT2 inhibitors include homotaurine, baclofen, gabapentin, lorazepam, pyridoxal phosphate, ZAPA, L-tyrosine, L-DOPA, desipramine, timonacic, amicar, orindyl, pemirolast, mesalazine, glutathione, gly-gly,5-ALA, Vit. U, methionine, glutamine, pyridoxalphosphate, acivicin, vigabatrin, GABOB, 3-ABA, 5-AVA, glycine, beta-alanine, creatinine, carnitine, amitriptyline, pregabalin, erythromycin, cyclosporin A, and rifampicin (Schlessinger et al., 2012, JBC 287:37745-37756). Non-limiting examples of inhibitors of BGT1 include EF1502, betaine, and NNC 05-2090 hydrochloride. BGT1 inhibitors may also include certain compounds containing the 4,4-bis(3-methyl-2-thienyl)-3-butenyl side chain of tiagabine (Vogensen et al., 2013, J Med. Chem. 56:2160-2164).

[0076] The composition may activate GABA signaling on the hepatic vagal afferent nerve. The purpose of increasing the animal’s food intake may be for weight gain purposes, for example.

[0077] In some embodiments, the composition is a drug, a compound, or a molecule (e.g., anti-sense oligonucleotide). In some embodiments, the composition is an activator of GABA-T, TauT, CRT, sodium potassium ATPase, hepatic succinate semialdehyde dehydrogenase etc. In some embodiments, the composition activates succinate dehydrogenase In some embodiments that compound activates hepatic vagal GABA-A receptors.

[0078] Although there has been shown and described the preferred embodiment of the present invention, it will be readily apparent to those skilled in the art that modifications may be made thereto which do not exceed the scope of the appended claims. Therefore, the scope of the invention is only to be limited by the following claims. In some embodiments, the figures presented in this patent application are drawn to scale, including the angles, ratios of dimensions, etc. In some embodiments, the figures are representative only and the claims are not limited by the dimensions of the figures. In some embodiments, descriptions of the inventions described herein using the phrase “comprising” includes embodiments that could be described as “consisting essentially of’ or “consisting of’, and as such the written description requirement for claiming one or more embodiments of the present invention using the phrase “consisting essentially of’ or “consisting of’ is met.

[0079] The reference numbers recited in the below claims are solely for ease of examination of this patent application, and are exemplary, and are not intended in any way to limit the scope of the claims to the particular features having the corresponding reference numbers in the drawings.

Claims

WHAT IS CLAIMED IS:

1. A method of reducing food intake in a monogastric animal or a human, said method comprising: administering to the monogastric animal or the human an effective amount of a composition that effectively depresses hepatic gamma-aminobutyric acid (GABA) production or release, wherein depressing hepatic GABA production or release causes the monogastric animal or human to reduce its food intake as compared to its food intake prior to being administered the composition.

2. The method of claim 1, wherein the monogastric animal is a pig, a chicken, a dog, a cat, a horse, or a rodent.

3. The method of claim 2, wherein the rodent is a mouse or a rat.

4. The method of claim 1 , wherein the method is for weight loss.

5. The method of claim 1 , wherein the composition is a drug, a compound, or a molecule.

6. The method of claim 5, wherein the molecule is an anti-sense oligonucleotide.

7. The method of claim 1, wherein the composition inhibits GABA signaling on the hepatic vagal afferent nerve.

8. The method of claim 1 , wherein the composition inhibits expression of or activity of GABA transaminase (GABA T) or inhibits GABA production.

9. The method of claim 8, wherein the composition that inhibits expression of or activity of GABA transaminase, or inhibits GABA production comprises valproic acid, vigabatrin, phenylethylidenehydrazine (PEH), ethanolamine-O-sulfate (EOS), L-cycloserine, aminooxyacetic acid, gabaculine, phenelzine, rosmarinic acid, branched chain fatty acid, 2- methyl, 2-ethylcaproic acid, 2,2-dimethylvaleric acid, S-vigabatrin, [3- (aminomethyl)phenyl]acetic acid, [2-(aminomethyl)phenyl]acetic acid, ursolic acid, succinic semialdehyde, succinate, Sr2+, SH-group reagent, pyruvate, propionic acid, pimelic acid, phenylhydrazine, oxalacetate, ornithine, oleanolic acid, Ni2+, muscimol, monoiodoacetate, Mn2+, Mg2+, methanol, maleate, lysyl reagents, KCN, imperatorin, hydroxylamine, hydrazine, HgCI2, glyoxylate, glycine, glutarate, glutamic acid, GDP, gastrodigenin, gamma- vinyl 4-aminobutanoate, gabaculine, falcarindiol, ethylamine-2-sulfonic acid, ethanol, trimethylcitryl-beta-D-galactopyranoside, tetrazole-5-(alpha-vinyl-propanamine), propan-2- one N-(2,4-dimethylphenyl)semicarbazone, p-chloromercuribenzoate, N-(4-bromophenyl)-3- (4-fluorophenyl)-6,7-dimethoxy-3a,4-dihydroindeno[1,2-c]pyrazole-2(3H)-carboxamide, N-(4- bromophenyl)-3-(4-chlorophenyl)-6,7-dimethoxy-3a,4-dihydroindeno[1,2-c]pyrazole-2(3H)- carboxamide, DL-cysteine, divalent metal ions, dioxan, D-penicillamine, D-cycloserine, cycloserine, Cu2+, Co2+, Cd2+, Ca2+, carbonyl reagents, butyric acid, beta-alanine, beta- cypermethrin, baclofen, Ba2+, ATP, aminooxyacetate, alpha-alanine, ADP, adipic acid, acetic acid, 6-Azauracil, 6-Azathymine, 5-thiouracil, 5-nitrouracil, DL-3-amino-1- cyclopentene-1 -carboxylic acid, DL-trans-4-amino-2-cyclopentene-1-carboxylic acid, cis-3- aminocyclohex-4-ene-1-carboxylic acid, 5-iodouracil, 5-diazouracil, (+/-)-(1S,2R,4S,5S)-4- amino-6,6-difluorobicyclo[3.1 0]hexane-2-carboxylic acid, (+/-)-(1S,2S,4S,5S)-4-amino-6,6- difluorobicyclo[3.1.0]hexane-2-carboxylic acid, (+/-)piperidine-3-sulfonic acid, (1R,3S,4S)-3- amino-4-fluorocyclopentane-1 -carboxylic acid, (1 R,4S)-4-amino-2-cyclopentene-1 -carboxylic acid, (1R,4S)-4-amino-3-fluorocyclopent-2-enecarboxylic acid, (1 R,4S)-4-amino-3- pentafluoroethylcyclopent-2-enecarboxylic acid, (1 R,4S)-4-amino-3-trifluoromethylcyclopent- 2-enecarboxylic acid, (1S,2S,3E)-2-amino-3-(fluoromethylidene)cyclopentanecarboxylic acid, (1 S,2S,3Z)-2-amino-3-(fluoromethylidene)cyclopentanecarboxylic acid, (1 S,3S)-(Z)-3-amino- 4-(2,2,2-trifluoroethylidene)cyclopentanecarboxylic acid, (1S,3S)-3-amino-4-(2,2,2-trifluoro-1- trifluoromethylethylidene)-cyclopentanecarboxylic acid, (1S,3S)-3-amino-4- difluoromethylenecyclopentanecarboxylic acid, (1S,4R)-4-amino-2-cyclopentene-1- carboxylic acid, (1S,4S)-2-(difluoromethylidene)-4-(1H-tetrazol-5-yl)cyclopentanamine, (2E)- 4-methylpentan-2-one N-(2,4-dimethylphenyl)semicarbazone, (2E)-butan-2-one N-(2,4- dimethylphenyl)semicarbazone, (4R)-4-amino-1-cyclopentene-1-carboxylic acid, (4S)-4- amino-1-cyclopentene-1 -carboxylic acid, (R,S)-4-amino-3-fluorobutanoic acid, (S)-4-amino- 4,5-dihydro-2-thiophenecarboxylic acid, (Z)-4-amino-2-butenoic acid, 1-(4-acetylphenyl)-3- (4-bromophenyloxy)-pyrrolidine-2,5-dione, 1-(4-acetylphenyl)-3-(salicyldehydoxy)- pyrrolidine-2, 5-dione, 1H-tetrazole-5-(alpha-vinyl-propanamine), 2,4-diaminobutanoate, 2,4- dimethylphenyl semicarbazide hydrochloride, 2-Aminobenzenesulfonate, 2-aminobutanoate, 2-aminoethane phosphonic acid, 2-N-(acetylamino)cyclohexane sulfonic acid, 2-oxoadipic acid, 2-oxoglutarate, 2-Thiouracil, 3-(aminomethyl) benzoic acid, 3- aminocyclohexanecarboxylic acid, 3-chloro-1-(4-hydroxyphenyl)propan-1-one, 3-Chloro-4- aminobutanoate, 3-Mercaptopropionic acid, 3-Methyl-2-benzothiazolone hydrazone hydrochloride, 3-Phenyl-4-aminobutanoate, 4-(aminomethyl)-1H-pyrrole-2-carboxylic acid, 4- (aminomethyl)furan-2-carboxylic acid, 4-(aminomethyl)furan-3-carboxylic acid, 4- (aminomethyl)thiophene-2-carboxylic acid, 4-(aminomethyl)thiophene-3-carboxylic acid, 4- acryloylphenol, 4-amino-2-fluorobutanoate, 4-amino-5-fluoropentanoic acid, 4-Amino-hex-5- enoic acid, 4-aminohex-5-enoic acid, 4-Aminohex-5-ynoic acid, 4-ethynyl-4-aminobutanoate, 4-hydroxybenzaldehyde, 4-hydroxybenzylamine, 5,5'-dithiobis-2-nitrobenzoic acid, 5- (aminomethyl)-1H-pyrrole-2-carboxylic acid, 5-(aminomethyl)furan-2-carboxylic acid, 5- (aminomethyl)thiophene-2-carboxylic acid, L-tyrosine, L-DOPA, desipramine, timonacic, amicar, orindyl, pemirolast, mesalazine, glutathione, gly-gly, 5-ALA, Vit. U, methionine, glutamine, pyridoxalphosphate, acivicin, GABOB, 3-ABA, 5-AVA, glycine, carnitine, amitriptyline, pregabalin, erythromycin, cyclosporin A, rifampicin, EF1502, betaine, and NNC 05-2090 hydrochloride, 5-amino-1,3-cyclohexadienylcarboxylate, and metformin.

10. The method of claim 8, wherein the composition that inhibits expression of GABA transaminase is an AMPK activator.

11. The method of claim 1 , wherein the composition inhibits GABA release.

12. The method of claim 11, wherein the composition inhibits expression or activity of GABA transporters that export hepatic GABA.

13. The method of claim 11, wherein the composition that inhibits GABA release inhibits expression of the Solute Carrier Family 6 Member 6 (SLC6A6) mRNA or the Solute Carrier Family 6 Member 8 ( SLC6A8 ) mRNA.

14. The method of claim 11 , wherein the composition inhibits expression of or activity of TauT, a GABA transporter protein encoded by the SLC6A6 gene.

15. The method of claim 11, wherein the composition inhibits expression of or activity of creatine transporter (CRT), a GABA transporter protein encoded by SLC6A8 gene.

16. The method of claim 14, wherein the composition that inhibits expression or activity of SCL6A6 or TauT is d-ALA, guvacine, taurine, Beta-alanine, Guanidinoacetate, b- Guanidinopropionate, g-Guanidinobutyrate, Guanidinoethansulfonate, and taurine.

17. The method of claim 15, wherein the composition that inhibits expression or activity of SCL6A8 or CRT is an AMPK activator, Guanidinoacetate, b-Guanidinopropionate, g- Guanidinobutyrate, Guanidinoethansulfonate, creatinine, methylguanidine, l-arginine, RGX- 202, 2,4-dinitro-1-fluorobenzene, tetraethylammonium, guanidine, creatine, arginine, lysine, DTBM, DNFB, or NEM.

18. The method of claim 1, wherein the composition improves GABA re-uptake.

19. The method of claim 18, wherein the composition increases mRNA or protein expression of the Solute Carrier Family 6 Member 12 ( SLC6A12 ) gene or the Solute Carrier Family 6 Member 13 (SLC6A13) gene.

20. The method of claim 18, wherein the composition increases expression of or activity of BGT 1 , a GABA transporter protein encoded by the SLC6A12 gene.

21. The method of claim 18, wherein the composition increases expression of or activity of GAT2, a GABA transporter protein encoded by the SLC6A13 gene.

22. The method of claim 20 or 21, wherein the composition that increases mRNA expression of SLC6A12 and/or SLC6A13 is an AMPK activator.

23. The method of claim 1 , wherein the composition inhibits expression or activity of succinate semialdehyde dehydrogenase.

24. The method of claim 23, wherein the composition that inhibits expression or activity of succinate semialdehyde dehydrogenase comprises 2-methyl, 2-ethylcaproic acid; 2,2- dimethylvaleric acid, 2-oxoglutaric semialdehyde, 4-dimethylaminoazobenzene-4- iodoacetamide, 4-hydroxy-trans-2-nonenal, 4-hydroxybenzaldehyde, 4- methoxybenzaldehyde, 4-tolualdehyde, 5,5'-dithiobis(2-nitrobenzoic acid), Acetaldehyde, Acrolein, ADP, AMP, Arsenite, ATP, Benzaldehyde, Ca2+, Cd2+, Chloral hydrate, Cu2+, Disulfiram, Dithionitrobenzoate, Fe3+, Glyoxylate, Hg2+, Iodoacetamide, m- hydroxybenzaldehyde, Mg2+, Mn2+, N-ethylmaleimide, N-formylglycine, NAD+, NADH, NEM, Ni2+, o-phthalaldehyde, p-bromobenzaldehyde, p-chlorobenzaldehyde, p- chloromercuriphenyl sulfonate, p-ethoxybenzaldehyde, p-ethylbenzaldehyde, p- fluorobenzaldehyde, p-hydroxymercuribenzoate, p-iodobenzaldehyde,p- isopropylbenzaldehyde, p-Methoxybenzaldehyde, p-methylbenzaldehyde, p- nitrobenzaldehyde, Pb2+, PCMB, pyridoxal 5'-phosphate, succinate semialdehyde, Valeraldehyde, and Zn2+.

25. The method of claim 23, wherein the composition that inhibits expression of succinate semialdehyde dehydrogenase is an AMPK activator.

26. The method of any of claims 10, 17, 22, or 25, wherein the AMPK activator is a biguanide, a thiazolidinedione, a ginsenoside, or a polyphenol.

27. The method of any of claims 10, 17, 22, or 25, wherein the AMPK activator is A-769662, metformin, resveratrol, troglitazone, pioglitazone, rosiglitazone, quercetin, genistein, epigallocatechin gallate, berberine, curcumin, ginsenoside Rb1, alpha-lipoic acid, cryptotanshinone, 5-aminoimidazole-4-carboxaminde ribonucleoside (AICAR), benzimidazole, salicylate, compound-13, PT-1, MT63-78, and APC.

28. The method of claim 1 , wherein the composition comprises an inhibitor of sodium potassium ATPase.

29. The method of claim 1, wherein the composition reduces hepatic mitochondrial uncoupling.

30. The method of any of claims 1-29, wherein the composition does not cross the blood-brain barrier.

31. A method of increasing food intake in a monogastric animal, said method comprising: administering to the monogastric animal an effective amount of a composition that increases hepatic GABA production or release, wherein increasing hepatic GABA production or release causes the monogastric animal to increase its food intake as compared to its food intake prior to being administered the composition.

32. The method of claim 31, wherein the method is for weight gain.

33. The method of claim 31, wherein the composition is a drug, a compound, or a molecule.

34. The method of claim 33, wherein the molecule is an anti-sense oligonucleotide.

35. The method of claim 31, wherein the composition activates GABA signaling on the hepatic vagal afferent nerve.

36. The method of claim 31, wherein the composition increases expression of or activity of GABA transaminase (GABA T) or increases GABA production.

37. The method of claim 31, wherein the composition increases or activates GABA release.

38. The method of claim 37, wherein the composition increases expression or activity of GABA transporters that export hepatic GABA.

39. The method of claim 37, wherein the composition that increases GABA release increases mRNA expression of the Solute Carrier Family 6 Member 6 ( SLC6A6 ) gene or the Solute Carrier Family 6 Member 8 ( SLC6A8 ) gene.

40. The method of claim 37, wherein the composition increases expression of or activity of TauT, a GABA transporter protein encoded by the SLC6A6 gene.

41. The method of claim 37, wherein the composition increases expression of or activity of creatine transporter (CRT), a GABA transporter protein encoded by SLC6A8 gene.

42. The method of claim 31, wherein the composition decreases GABA re-uptake.

43. The method of claim 42, wherein the composition decreases expression of the Solute Carrier Family 6 Member 12 (SLC6A12) gene or the Solute Carrier Family 6 Member 13 ( SLC6A13 ) gene.

44. The method of claim 42, wherein the composition decreases expression of SLC6A12 mRNA or activity of BGT 1 , a GABA transporter protein encoded by the SLC6A12 gene.

45. The method of claim 42, wherein the composition decreases expression of SLC6A13 mRNA or activity of GAT2, a GABA transporter protein encoded by the SLC6A13 gene.

46. The method of claim 31, wherein the composition increases expression or activity of succinate semialdehyde dehydrogenase.

47. The method of claim 31, wherein the composition comprises an activator of sodium potassium ATPase.

48. The method of claim 31, wherein the composition increases hepatic mitochondrial uncoupling.