Effects of Exogenous Melatonin on Colon Glial Cells in Experimental Desynchronosis

Abstract

The effect of exogenous and endogenous melatonin on GFAP and S-100 positive cells of the colon mucosa of rats kept under different lighting conditions was studied. The aim was to estimate the effect of melatonin on the structural and functional characteristics of colon glial cells in normal conditions and in experimental desynchronosis. Material and methods . The study was conducted on laboratory male Wistar rats (n=72), 2-months old, weighing 180–200 g, divided into 6 groups 12 rats in each. Group I consisted of animals treated in natural light conditions; Group II – rats treated in natural light conditions, receiving synthetic melatonin (Melaxen, Unipharm, Inc., USA) ad libitum at a concentration of 4 mg/l with drinking water; Group III – animals treated in constant darkness; Group IV – animals treated in constant darkness and received melatonin; Group V consisted of animals treated under constant lighting conditions; Group VI included rats treated in constant lighting conditions and received melatonin. Astrocytes were identified using an indirect immunohistochemical method using polyclonal antibodies to glial fibrillary acidic protein (Dako, Germany 750 µg/ml) and protein S-100 (Spring Bio Science USA 1:300). Cells were counted using a Carl Zeiss Axio Scope A1 microscope at 400 magnification and SigmaScan Pro 5 software. Statistical processing was carried out using the MS Excel and Statistica 17 programs. Results. The number of GFAP positive cells decreased in groups III and V. Conditions II and VI resulted in a decrease in the number of gliocytes. In group IV, the administration of melatonin led to an increase in the number of studied cells. A significant increase in the optical density of GFAP in colon gliocytes was observed only when rats were treated under constant lighting conditions. The number of S-100 positive cells decreased in groups III and II. Conditions V and IV led to an increase in the number of S-100 positive cells. The optical density of S-100 does not depend on photoperiod. Conclusion. S-100B and GFAP positive glial cells of the colon respond both to changes in photoperiod and to the administration of exogenous melatonin. In particular, under constant dark conditions, the number of GFAP and S-100B positive cells decreases. The obtained data can be used in the elaboration of new therapeutic approaches to the treatment of intestinal diseases.