METHOD OF TREATING AND PREVENTING ARTHRITIS, CUTANEOUS AND CARDIOVASCULAR INFLAMMATORY-RELATED DISEASES USING NICOTINIC RECEPTOR AGONISTS
BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a composition and method of treatment and prevention of arthritis, cutaneous diseases and cardiovascular diseases.
Description of Prior Art Rheumatoid arthritis (RA) is characterized by chronic inflammation and destruction of the joints and affects about 1% of the world population. Mild cases of RA can be treated with non-steroid anti-inflammatory drugs. However, many patients develop more severe diseases that require immunosuppressive therapy. Systemic corticosteroids are the immunosuppressive agents of choice but their long term use induces debilitating side effects including hypertension, osteoporosis, diabetes, cataracts, etc. Targeting the events leading to RA such as cell activation, cell migration into affected areas, production of inflammatory mediators , release of various enzymes involved in matrix degradation, as well as intracellular signalling mechanisms may constitute a promising approach to drug development for the treatment of RA. In particular tumour necrosis factor (TNF) has been shown to play a major role in promoting the inflammation and joint destruction seen in RA. Recently the use of anti-TNF drugs have been approved to treat RA. These drugs are highly effective but very costly and have significant side effects. PCT Application No. CA02/00412, filed March 25, 2002, discloses that an agent that binds to and modulates the function of nicotinic receptors may be used to alleviate or prevent pulmonary inflammatory diseases. Although the Application indicates that these agents may be used to treat any inflammation, there is no showing establishing that they may be applicable for other medical treatments, and it therefore seems that the invention disclosed in the above Application is strictly restricted to the treatment of pulmonary inflammatory diseases.
There are very few drugs that are used to treat multiple diseases in different organs, and therefore under normal circumstances it is logical to assume that nicotinic agonists are not useful for other treatments than the pulmonary diseases mentioned in the above Application. The fact that nicotinic agonists could be useful to treat inflammatory and bronchospastic pulmonary diseases does not suggest to anyone skilled in the art that these compounds could be useful to treat other totally different diseases. Considering the state of the art above mentioned , there is still needs in developing compounds and compositions for treating and alleviating different inflammatory-related diseases, such as inflammation in the context of arthritis, cardiovascular or cutaneous related diseases.
SUMMARY OF THE INVENTION It has surprisingly been found that nicotinic agonists and even analogues thereof can be used to treat the above diseases. The present invention relates to a method for the treatment or prevention of inflammatory-related diseases, such as arthritis, cutaneous diseases and cardiovascular diseases, which comprises administering to a patient suffering from at least one of these inflammatory-related diseases, a compound or a composition comprising at least one nicotinic acetylcholine receptor agonist, alternatively named herein nicotinic receptor agonist or nicotinic receptor ligand, and a physiologically acceptable carrier, in an amount effective to alleviate or cure or prevent arthritis or the above diseases. For example, but not limited to, the physiological carrier is of nutritional, topical, or pharmaceutical class carriers. The invention also relates to the use of nicotinic receptor agonists for the preparation of a composition for the treatment or prevention of arthritis, cutaneous diseases and cardiovascular diseases. For the purpose of the present invention the following terms are defined below.
The term "treating", as used herein, refers to reversing, alleviating, inhibiting the progression of, or preventing the disorder or condition to which such term applies, or one or more symptoms of such disorder or condition. The term "treatment", as used herein, refers to the act of treating, as "treating" is defined immediately above. The expression "inflammatory disorders" as used herein refers to disorders such as rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, psoriatic arthritis, psoriasis, contact dermatitis, cardiovascular diseases, allergic dermatitis, chondrocalcinosis. The expression "cardiovascular diseases" as used herein refers to disorders such as atherosclerosis including atherosclerotic plaque rupture; aortic aneurysm including abdominal aortic aneurysm; congestive heart failure; myocardial and cerebral infarction; stroke; cerebral ischemia; coagulation and acute phase response; left ventricular dilation; post ischemic reperfusion injury; and restenosis. By "effective amount", it is meant that the administration of that amount to an individual, either in a single dose or as part of a series, is effective for treatment or prevention. This amount varies depending upon the health, age and physical condition of the individual to be treated, the taxonomic group of individual to be treated (e.g., non- human primate, primate, etc.), the treating doctor's assessment of the medical situation, and other relevant factors.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates nicotine analogues-inhibiting effect on TNF release; Fig. 2 illustrates the effect of nicotinic agonists from different families on TNF release; Fig. 3 illustrates the inhibiting effect of dexamethasone and DMPP on TNF production; Figs. 4a and 4b illustrate the inhibiting effect of DMPP on NF-κB expression ;
Fig. 5 illustrates the decrease in triglycerides in nicotinic agonist-treated obese animals; Fig. 6 illustrates the decrease in total blood cholesterol in nicotinic agonist- treated obese animals; Fig. 7 illustrates the DMPP inhibiting effect on IgE production in mouse; Fig. 8 illustrates the inhibitory activity of different nicotinic receptor agonists on eosinophil trans-migration; and Fig. 9 illustrates the positive effect of nicotinic receptor agonists on skin inflammation.
DESCRIPTION OF PREFERRED EMBODIMENTS The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. All patents, patent applications, articles and publications mentioned herein, both supra and infra, are hereby incorporated herein by reference. According to the preferred embodiment of the present invention, there is provided compounds and compositions and method of uses thereof for RA based on the use of nicotinic acetylcholine agonists. The present invention provides nicotinic acetylcholine receptor agonists or analogues or ligands or derivatives thereof or composition containing same for treating or preventing arthritis related inflammation.
Another embodiment of the invention provides nicotinic acetylcholine receptor agonists or analogues or ligands or derivatives thereof or composition containing same for treating or preventing inflammatory-related cardiovascular diseases. Also, the present invention according to another embodiment provides nicotinic acetylcholine receptor agonists or analogues or ligands or derivatives thereof or composition containing same for treating or preventing skin or cutaneous related inflammation. Nicotinic acetylcholine receptors are expressed on neuronal and a wide variety of non-neuronal cells including structural cells such as keratinocytes, fibroblasts, endothelial cells, cells of the immune system such as lymphocytes, monocytes polymorphonuclear cells and macrophages and adipocytes. It is another object of the present invention to use nicotinic agonists as well as ligands and analogues thereof to treat arthritis, skin diseases and cardiovascular diseases. The preferred nicotinic receptor ligands include dimethylphenylpiperazinium (DMPP), nicotine, epibatidine, cytisine, mecamylamine, acetylcholine, pyridylether, tubocurarine, trimethaphan, hexamethonium, N-methylcarbamylcholine, ABT-418, GTS-
21, MLA, DHβE, Arecoline, lobeline, philanthotoxin-433, azabicyclin, SIB-1553, imidacloprit, and analogues thereof.
More specifically, nicotinic receptor agonists that can be used for the treatments and uses according to the invention include the following nicotinic receptor agonists and analogues thereof:
The compounds of the present invention are generally available through chemical companies, either commercially, or by synthetic methodology, also generally well known to those skilled in the art of chemistry. Intermediates for the synthesis of a compound of the invention, or carriers, or pharmaceutically acceptable salts or derivative thereof, may be prepared by one of ordinary skill in the art of organic chemistry by adapting various synthetic procedures incorporated that are well-known in the art of organic chemistry.
Among nicotinic acethylcholine agonists that can be considered in different embodiment of the present invention are for example, but not limited to, the folio wings:
1- DMPP and analogues thereof
where:
Compound Ri R2 X n DMPP CH3 CH3 CH 1 CH3 CH2CH2CH3 CH l or 2 CH2CH3 CH2CH3 CH l or 2 CH2CH3 CH3 CH l or 2 CH3 CH3 CH 2 CH3 - N 1 H - N halogen 1
or,
2- Nicotine and analogues
where
Compound X Ri Position R2
3- Analogues of pyridylether
or
4- Epibatidine and analogues
where
or
5- Tubocurarine and analogues
where
Compound Ri R2 R3 R4
Tubocurarin CH3 CH3 CH3 H e CH3 CH3 CH3 CH3 CH2CH3 CH3 CH3 H CH2CH3 CH2CH3 CH2CH3 H or
6- Trimethaphan and analogues
where
Compound R X Trimethaphan
Halogen
N+(CH3)3 N+(CH2CH3)3
or
7-Mecamylamine and analogues
where
Compound R Mecamylamine NHCH3 N+(CH2CH3)2CH3 N+(CH2CH3)3 N+(CH3)3
or
8- Hexamethonium and analogues
Or
9- Cytisine and analogues
where
Compound R W X Y Z Cytisine H O H H H nBu O H H H H O halogen H halogen H s H H . H (CH3)2 OorS halogen H halogen (CH2CH3)CH3 OorS H H H (CH2CH3)2 OorS H H H
or
10- Acetylcholine and analogues
or
11- 7V-methyIcarbamylchoIine and analogues
where
Compound R N- N+(CH3)3 methylcarbamylcoline * N+(CH2CH3)2 CH3 * N+(CH2CH3)3
or
12- ABT-418 and analogues
where
Compound R ABT-418 CH3 (CH3)2 (CH2CH3)CH3 (CH2CH3)2
or
13- GTS-21 and analogues
where
Compound Rq R2 GTS-21 OCH3 OCH3 N+(CH3)3 OCH3 OCH3 N+(CH3)3
or
14- MLA and analogues
where
Compound R MLA CH2CH3 * (CH3)2 * (CH2CH3)CH3 * (CH2CH3)2
or
15- DHβE and analogues
where
Compound Rg R2 DHβE OCH3 CH3 OCH3 CH2CH3 OCH3 CH3 Halogen
or
16- Arecoline and analogues
where
Compound R Arecoline CH3 (CH3)2 (CH2CH3)CH3 (CH2CH3)2
or
17- Lobeline and analogues
where
Compound R Lobeline H (CH3)2 (CH2CH3)CH3 (CH2CH3)2
or
18- Analogues of philanthotoxin-433
where
Compound R n m NH2 3 rΛCH,), 1, 2, 3 or 4 1, 2 or 3 N+(CH2CH3)2 CH3 1, 2, 3 or 4 1, 2 or 3 N+(CH2CH3)3 1, 2, 3 or 4 1, 2 or 3
or
19- Azabicyclic analogues
20- Analogues of SIB-1553
Compound R n CH3 1 (threo) CH3 0 (erythro) CH3 0 (threo) (CH3)2 Oorl (CH2CH3)CH3 Oorl (CH2CH3)2 Oorl or
21- Analogues of imidacloprit
where
Compound R X Y Z NO2 Cl H NH H Cl N3 S NO2 Cl N3 S N+(CH3)3 Cl H NH NO2 N+(CH3)3 H NH NO2 Cl N+(CH3)3 NH
The diseases of interest according to this invention include arthritis (eg rheumatoid arthritis) skin diseases (eg. eczema and psoriasis) and obesity/cardiovascular diseases.
Formulation of the present invention can be found in the form of or integrated to different supports. The nicotinic agonists of the present invention may be, for example but not limited to, presented in various forms, i.e. liquid formula, cream, ointment, pills, caplets, tablets, powders or granules where the component of the formulation is active on a target physiological dysfunction due to arthritis, cutaneous or cardio-vascular inflammatory related disease. Preferably, the compounds and compositions contemplated are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid vehicles prior to injection may also be prepared.
Alternatively, the compounds and compositions can be orally or intra-nasally administered. The preparation also may be emulsified or encapsulated in, for example, liposomes. The compounds and compositions of the present invention can be administered, depending on the needs, through the ways known in the art, such as, but not
limited to, orally, intravenously, intradermally, sublingually, subcutaneously, topically, intra-peritoneally, parenterally, or intramuscularly.
One of ordinary skill in the art will appreciate that the compounds of the invention are useful in treating a diverse array of diseases described herein. One of ordinary skill in the art will also appreciate that when using the compounds of the invention in the treatment of a specific disease that the compounds of the invention may be combined with various existing therapeutic agents used for that disease.
For example, the treatment of rheumatoid arthritis, the compounds of the invention may be combined with agents such as TNF-α inhibitors such as anti-TNF monoclonal antibodies (such as infliximab, D2E7 and CDP-870) and TNF receptor immunoglobulin molecules (such as etanercept), ACE inhibitors, MEKK1 inhibitors, COX-2 inhibitors such as celecoxib, rofecoxib, valdecoxib and etoricoxib; low dose methotrexate, lefunimide, steroids, glucosamines, chondrosamines/sulfates, gabapentin, A- agonists, IL-1 process and release inhibitors, IL-1 receptor antagonists such as Kineret®, CCR-1 antagonists, hydroxychloroquine, d-penicilamine, auranofm or parenteral or oral gold.
The compounds and compositions of the invention can also be used in combination with existing therapeutic agents for the treatment of osteoarthritis. Suitable agents to be used in combination include standard non-steroidal anti-inflammatory agents (hereinafter NSAID's) such as piroxicam, diclofenac, propionic acids such as naproxen, flubiprofen, fenoprofen, ketoprofen and ibuprofen, fenamates such as mefenamic acid, indomethacin, sulindac, apazone, pyrazolones such as phenylbutazone, salicylates such as aspirin, COX-2 inhibitors such as celecoxib, valdecoxib, paracoxib, etoricoxib and rofecoxib, analgesics, steroids, glucosamines, chondrosamines/sulfates, gabapentin, A- agonists, IL-1 process and release inhibitors, CCR-1 antagonists, LTD-4, LTB-4 and 5-LO inhibitors, p38 kinase inhibitors and intraarticular therapies such as corticosteroids and hyaluronic acids such as hyalgan and synvisc.
The compounds and compositions of the present invention may also be used in combination with cardiovascular agents such as calcium channel blockers (such as amlodipine and nifedipine), lipid lowering agents such as statins (such as lovastatin, atorvastatin, pravastatin and simvastatin), adrenergics such as doxazosin and terazosin; fϊbrates, beta-blockers, Ace inhibitors (such as captopril, lisinopril, fosinopril, enalapril and quinaprill), Angiotensin-2 receptor antagonists such as losartan and irbesartan; nitrates, CCB's, diuretics such as digitalis, and platelet aggregation inhibitors. The compounds of the present invention may also be used in combination with plaque rupture preventitive agents such as statins, NSAIDs including aspirin, heparin, urarfarin, abciximab, TPA and platelet Inhibitors. The compounds of the present invention may also be used in combination with stroke treatment agents such as NIB, NHEI's and CCRTR antagonists.
The compounds and compositions of the present invention may also be used in combination with agents for the treatment of skin disorders such as tretinoin, isotretinoin, steroids such as cortisone and mometasone, antibiotics such as tetracycline, antifungals such as clotrimazole, miconazole and fluconazole and PDE-IV inhibitors. It can further been considered that inflammatory conditions of the skin may be effectively treated in accordance with the present invention by providing the concurrent therapy with separate topical compositions comprising the anti-inflammatory corticosteroid and the non- steroidal, anti-inflammatory prostaglandin synthetase inhibitor. In this embodiment, both compositions can be applied to the skin at substantially the same time, i.e. one right after the other. The order of application of the drugs is not important, although the two vehicles are preferably compatible.
EXAMPLE I Nicotinic agonists inhibit TNF production Materials and Methods
Mononuclear cells were isolated from peripheral blood of human volunteers by ficoll-paque gradient centrifugation, and monocytes were further purified by adherence onto culture plates, cells were incubated with the various nicotinic agonists and stimulated with lipopolysaccharide (LPS) for 18 hours, cell culture supernatant were collected and tested for TNF production by enzyme like immunoenzymatic assay.
Results Several nicotinic receptor agonists from different families were shown having the capacity to inhibit TNF production by lipolysaccharide (LPS)-stimulated blood monocytes in vitro (Figs 1, 2, and 3) by interfering with intracellular signalling pathways.
In Fig. 1, Nic 1= Cio HM N2, Nic 2= Cn H17 N21, Nic 3= Cι2 H20 N212, Nic 4= Cj2 H19 N21, Nic 5= C1 H24 N212> and having the following structures:
In Fig. 2, DBO 83, an epibatidine analogue, Anabasine, a nicotine analogue, and RJR-2403= a nicotinic agonist specific to alpha 4 Beta 2 subunits receptors. Other nicotinic agonists present the same anti-inflammatory effect as nicotine analogues.
In Fig. 3, Dimethylphenylpiperazinium (DMPP), another nicotinic agonist, is as potent as dexamethasone to inhibit TNF release from human blood monocytes.
EXAMPLE II Molecular mechanisms of TNF inhibition by nicotinic agonists. TNF is produced through the activation of Nuclear factor kappa B (NF-kB), a transcription factor that regulates the expression of a wide range of inflammatory genes. This transcription factor is activated through the degradation of its inhibitory subunit, IKB. In order to translocate to the nucleus and induce the transcription of the TNF gene, NFKB must be released from its cytoplasmic subunit IKB, which is degraded in the proteasome upon LPS stimulation Materials and Methods Alveolar macrophages (AM) isolated from bronchoalveolar lavages were plated onto a 12 well plates, incubated at 37°C and let to adhere for lh. Cells were incubated with or without DMPP at 160 μM for 24 hours and stimulated with LPS 50 ng/ml for 30 min, lh or 2h . Cells were lysed with a Western Blot lysis buffer and expression of IKB protein detected by Western Blot. Densitometry (Scion Image) analysis was used to quantify the bands.
Results It has been demonstrated that DMPP, a potent nicotinic agonist that does not cross the blood-brain barrier, inhibits NF-kB activation by blocking the degradation of IKB, as shown in Figs. 4a and 4b. A time-dependant increase in IkB protein expression is
detected by western blot analysis (Fig. 4a) , densitometry quantification of the bands is shown in fig 4b. The blockade of IKB degradation may result in the blockade of the translocation of NFKB to the nucleus which normally occurs after LPS stimulation. This result goes along with the inhibitory effect of DMPP on TNF production by AM. Nicotinic agonists may therefore inhibit pro-inflammatory mediators by down- regulating NF-kB activation.
EXAMPLE III In vivo inhibition of RA in a mouse model It has been demonstrated in this example that cytisme, a potent nicotinic agonist, inhibits experimental RA induced by collagen-specific monoclonal antibody in mice.
Materials and Methods Arthritis was induced in mice by subjecting them to a single IV injection of an anti-collagen antibody cocktail on day 0, followed by LPS injection on day 3. Cytisine was administered IP on day 0 and thereafter daily for 9 days. Experimental Arthritis was evaluated by measuring hind paw thickness of each animal in mm on Day 0 (pre-experimental baseline control), and day 3, 5, 6, 7, and 10, using a dial caliper (Kroeplin, Munich, Germany). A negative control group included vehicule-treated animals and a positive-control group dexamethasone-treated animals
Arthritic scores were graded from 0 No reaction, normal. 1 Mild, but definite redness and swelling of the ankle or apparent redness and swelling limited to individual digits, regardless of the number of affected digits. 2 Moderate redness and swelling of ankle. 3 Severe redness and swelling of the entire paw including digits.
Maximally inflamed limb with involvement of multiple joints 0 no reaction normal, 1 mild redness and swelling, 2 moderate redness.
Table 1 Arthritic score.
Table 2 Paw thickness.
Results As shown in Tables 1 and 2, a reduction in arthritic scores (60 to 80% inhibition) and a return to baseline level in paw thickness (from 2 mm to 1,7mm) are observed with cytisine-treated animals on days 6 and 7, clearly indicating an anti-arthritic activity. By comparison, dexamethasone, a potent corticosteroid, had comparable effects to those of cystisine. Taken together, these results strongly show that specific nicotinic agonists either naturally occurring or synthesized may provide anti-inflammatory drugs for the treatment of rheumatoid arthritis.
EXAMPLE IV Obesity-related cardiovascular risk factors. The prevalence of obesity in industrialised countries is increasing dramatically.
A strong association between visceral obesity and metabolic disorders which is associated with cardiovascular diseases, hypertension and type 2 diabetes has been reported. The effect of obesity on these diseases is apparently mediated by a chronic low-grade inflammation. It follows therefore, that to attenuate the inflammatory process associated with obesity, nicotinic agonists constitute important therapeutic products to improve the endothelial functions and prevent diabetes and cardiovascular diseases. The reported anti- inflammatory effects of nicotinic agonists provide such a therapeutic tool.
Materials and Methods 3 different nicotinic receptor agonists were tested for their effects on lipid and insulin profiles of obese Zucker rats compared to non-obese rats. Six groups of animals were included in the present study: 1. Control lean rats 2. Control obese non-treated rats 3. DMPP -treated (4mg/kg/day) obese rats 4. ASM-002, a DMPP analogue (4 mg/kg/day) obese rats 5. Nicotine-treated (2mg/kg/day) obese rats 6. Cytisine-treated (lmg/kg/day) obese rats The drugs were administered by oral gavage twice daily for 28 days. Plasma was collected on the day of sacrifice and levels of trigycerides and cholesterol, were measured.
ASM-002 (DMPP analogue)
Results As shown in Figs. 5 and 6, a 30 % decrease in triglycerides and 15 to 20 % decrease in total blood cholesterol are observed in nicotinic agonist-treated obese animals
Conclusion It can be observed from the present example that nicotinic receptor agonists are effective to inhibit some risk factors associated with cardio-vascular diseases.
EXAMPLE V Inflammatory skin diseases. Atopic dermatitis (eczema), an exaggerated cutaneous immune response to environmental allergens, is closely related with the atopy profile of allergic rhinitis and asthma. This disorder is characterized by an IgE-mediated humoral immune response associated with T cells that produce type 2 cytokines and eosinophil infiltration. Allergic contact dermatitis or contact hypersensitivity, is a T-cell-dependent skin disease caused by contact-sensitizing antigens. Upon contact with the antigens, resident cell populations of the skin contribute to the inflammatory response by producing chemokines that attract leukocytes from the circulation. TNF-alpha is a major pro- inflammatory mediator produced by keratinocytes. Subsequent contact with the antigen, even months later, will lead to the recruitment of antigen-specific memory T cells generated from previous encounters with the contact-sensitizing antigen.
Psoriasis is also a T-cell-mediated auto-immune disease, characterized by scaly, red cutaneous plaques that contain inflammatory infiltrates and epidermal hyperproliferation. Anti-histaminic drugs have been used to treat atopic dermatitis together with topical corticosteroids or immunosuppressive drugs like cyclosporin. However , in the long term these treatments present important side effects or may cause the rebound phenomenon after discontinuation of the treatment. Since all these skin disorders have a common inflammatory component nicotinic receptor agonists have been found efficient as anti-inflammatory agents to treat these diseases.
Results Down-regulation of NFkB can be observed in Fig. 4 following administering of DMPP. This supports that activation of nicotinic receptors on other cells including keratinocytes by a variety of nicotinic agonists can down-regulate TNF production and limit the initial inflammation. DMPP was administered intra-nasally to ovalbumin-sensitized mice, either during allergen sensitization, allergen challenge or throughout the whole protocol. Serum was collected and ovalbumin-specific IgE measured by ELISA assay. DMPP given either during sensitization, challenge or both, inhibits IgE production in a mouse model of asthma (Fig. 7). Also, nicotinic agonists inhibit eosinophil migration in vitro through an artificial basement membrane thus potentially preventing eosinophil infiltration on sites of inflammation in vivo (Fig. 8). Blood eosinophils from asthmatic patients were isolated, plated in cell culture inserts coated with a reconstituted basement membrane (Matrigel™) and eotaxin, a chemotactic factor was added in the lower chamber. Various nicotinic agonists were tested for their inhibitory effect on eosinophil migration.
An inhibition of eosinophil migration was observed after 24h incubation with DMPP (up to 40.7 + 6.4 % inhibition with 160 μM DMPP,). A similar inhibitory effect on eosinophil migration was observed with 100 μM nicotine (38.5 ± 12.5 %), 10 nM epibatidine (31 ± 7 %) and 100 μM cytisine (31.2%) (fig 8)
EXAMPLE VI In vivo dermatitis model.
Materials and Methods Each test animal was sensitized with 0.1ml of 1.5% oxazolone in acetone solution on the shaved abdomen. A subsequent application 7 days later to the surface of right ear elicits an inflammatory reaction. This can be monitored by measuring the change in ear thickness and compared it to the unchallenged left ear. Test compounds DMPP, nicotine, cytisine (lmg/ear) and vehicle (ethanol,20μl/ear) were each administered topically to test animals to the anterior and posterior surfaces of the ear 30 minutes before and 15 minutes after challenge by a second application of oxazolone (1% in acetone , 25μl/ear). The positive control Indomethacin (0.3mg/ear ) was given using the same test regime.
Ear thickness was measured 24 hours following oxazolone challenge with a Dyer model micrometer gauge.
This can be monitored by measuring the change in ear thickness from the baseline. Treatments were administered either topically or orally.
Results An inhibition of ear thickness is observed following topical application of DMPP (33%>), nicotine (19%) and cytisine (62%) respectively (Fig. 9), indicating that skin inflammation is reduced by the treatment with nicotinic receptor agonists. The effect of nicotinic agonists from 3 different families were tested in a murine contact dermatitis model of skin inflammation induced by oxazolone, a sensitizing chemical.
Dermatitis can therefore be treated or reduced by the treatment with nicotinic receptor agonists.