[Subacute toxicity study of combination of adrenocorticotropine 1-13 and met-enkephalin].

PURPOSE Combination FAR4 consists from two peptide components: met-enkephalin and alpha adrenocorticotropine 1-13 (ACTH 1-13) named before as alpha-melanocyte-stimulating hormone-like (alpha-MSH-like). Met-enkephalin and alpha-MSH exhibited cytoprotective effects individually and statistically significant additive effect was registered when both peptides were applied in combination on the model of ethanol induced gastric lesions in rats. We performed subacute toxicity study with subcutaneous application. WORK METHOD Wistar rats were randomized in 3 test groups (treatments) consisted of 10 male and to female rats and one control group consisted of 20 male and 20 female rats. One daily dose was applied 3 days a week. Three dose ranges as multiplication of expected maximal human therapeutic dose (10 mg of met-enkephalin and 2 mg of alpha-ACTH 1-13) were estimated: equivalent dose, dose that was 5 times higher and 10 times higher dose. Animals were treated during 4 weeks with 10-days long observation period without the treatment after. After the planned scarification at the end of study, necropsy with histopathology examination was performed. RESULTS No lethality, toxic signs or histopathological changes were observed during the subacute toxicity testing. Variation of laboratory animals body mass was observed through six terms of body mass deternimation. Increase in body mass was noted in all test and control groups. Statistical analysis with Kruskal Wallis single variance test showed statisticaly significant difference in the number of respirations between the groups of ma-. les for the first measurement (p = 0.040332) and second measurement (p = 0.016852), but multiple comparation with control group showed statisticaly significant difference. Afterthe planned scarification at the end of the study, necropsy did not reveal changes in macroscopic structure of organs and tissues. Histopathology examination was performed on the samples of liver, kidneys, lungs, heart, brain, spleen and thymus and no pathological changes were noted, while microscopic structure of tissues was perserved. The changes regarding postmortem organ mass as percentual ratio towards total group mass were not noted nor for males, nor for females. DISCUSSION Study was conducted following the rules of the Guide for the Care and Use of Laboratory Animals made by the U.S. National Institutes of Health. Methodologicaly our study complys with rutine design of thistipe of studies. Subacute toxicity studies usually last for fourweeks and the way of test substance application to laboratory animals should comply to future way of application in human use. In our study no lethality was registered and low toxicity