Immunohistochemical detection of serotonin in the skin of frogs (Rana ridibunda) kept at different temperatures

Abstract

This study investigates the location of serotonin in the skin of frogs (Rana ridibunda) kept at two different temperatures (24-25 degreesC and 4 degreesC) and discusses its possible function from a different point of view. In the frogs kept at 24-25 degreesC, some cells of several small and large mucus glands and lumen material of some large mucus glands are serotonin immunoreactive. Additionally, depending on the secretion activities, the secretory epithelium, secretion granules and myoepithelial cells of poison glands are also serotonin-immunoreactive. However, in frogs kept at 4 degreesC, all poison glands are filled with secretory material and the above mentioned components are more serotonin-immunoreactive. No difference was found in the immunohistochemical reactions observed in the mucus glands of the two groups. Considering these results, it is concluded that serotonin found in Rana ridibunda skin might be responsible for the regulation of secretion processes in mucus glands and may stimulate the secretion of material from poison glands. Since serotonin is detected in the secretory material of both type of skin glands, it could also regulate the permeabilty of surface epithelial cells.