RESEARCH OF MELATONIN LEVEL IN RATS OF DIFFERENT SEXES AND AGE WITH ULCERATIVE LESION OF THE STOMACH
He aim of the study was to determine of melatonin level in the blood serum in rats of different sexes and age in ulcerative le- sions of the stomach. Materials and methods. Using the method of alcohol-prednisolone injury, we have simulated ulcerative lesions of the stomach. The level of melatonin in the blood serum in rats of different age and sexes with ulcerative lesions of the stomach was determined by enzyme-linked immunosorbent assay. Experimental animals were divided into groups by the age, namely 3, 9, 15 and 20 months, corresponding to the human age of 14, 29-30, 43-44, 55-56 years, respectively. Results. In the course of the research, it was found that rats with the ulcerative lesions of the stomach had significant (r  0.05) reduction of serum melatonin in animals of all experimental groups. In males, the lowest levels of melatonin in ul- cerative lesion were in groups of 9 and 20 months - (174.0 ± 12.9) pmol/L and (141.5 ± 21.4) pmol/L, respectively. The level of mela- tonin in males aged 9 months was significantly lower (p  0.05), by 26 %, than in rats aged 3 months, and by 16 % - compared with rats aged 15 months (p  0.05). In rats aged 20 months, melatonin levels were reduced by 40 and 32 % with respect to experimental groups of animals aged 3 and 15 months (p  0.05). Relatively to the con- trol group, among male rats the greatest reduction also observed in animals ages 20 months - 43 % and 9 months - 39 % (p  0.05). In male rats aged 3 months, melatonin level was lower by 22 %, and in the age group of 15 months - by 29 % relative to control ani- mals (p  0.05). In females, reduction of melatonin levels occurred gradually with age: from the highest in females aged 3 months tosignificantly lowest compared to other age groups - females aged 20 months in the control and experimental groups. The females rats with ulcerative gastric lesions had a decrease in melatonin levels by 21-23 % relative to controls in all age groups (p  0.05). Discussion. The results indicate that ulcerative lesions of the stomach is likely to result in injury of enterochromaffin cells of the gastric mucosa, ac- companied by a significant reduction in levels of melatonin in rats of both sexes and all age groups. Thus, it was found that despite no sig- nificant difference between levels of melatonin in males and females on the background of ulcerative lesions of the stomach, the overall level of melatonin reduction in males is 22-43 % higher relative to controls than in females - 21-23 %. The biggest gender differences in melatonin levels decrease were found at the age of 9 months (cor- responds to the human age of 29-30 years) - by 39 % in males and by 23 % in females relative to controls and 20 months (corresponds to the human age of 55-56 years) - 43 and 22 %, respectively. The results suggest that in men aged 29-30 and 55-56 years, ulcerative lesions result in significant damage to extrapineal sources of mela- tonin synthesis and more severe course of the stomach ulcer with the development of complications. Conclusions. 1. Ulcerative lesions of the stomach lead to reduce levels of melatonin in the blood serum in rats of different sexes and age. 2. The greatest reduction in lev- els of melatonin in experimental gastric ulcer occurs in rat males aged 9 and 20 months corresponding to the human age of 29-30 and 55-56 years.