Immunohistochemical and in situ hybridization studies of gonadotropin releasing hormone (GnRH) and its receptor in rat digestive tract

GnRH(LH-RH) is first discovered in the hypothalamus and found to have a rol e in regulation of reproduction. With the study on it deepening, GnRH was d emonnstrated that it also exists in a number of organs beyond the hypothala mus and acts on extrapituitary organs. To study whether digestive tract syn thesizes GnRH and its receptor and, if it does, by what cells. In the exper iment, the locallizations of GnRH and its receptors in rat digestive tract were studied using immunohistochemistry and in situ hybridization. The pari etal cells of gastric gland, the villous and glandular epithelium in small and large intestine and parasympathetic ganglion cells of myenteric plexus showed GnRH immunoreactivity; GnRH mRNA hybridization signal was detected. The epithelium of gastric pit and the cells above in digestive tract showed GnRH receptor immunoreactivity; GnRH receptor mRNA hybridization signal wa s detected. The immunoreactive and signal materials distributed in cytoplas m of all positive cells, with nuclei being immunonegative and with no hybri dization signal. These results suggested that the digestive tract can produ ce GnRH and express GnRH receptor; GnRH may also be a gastrointestinal horm one. (C) 2001 Elsevier Science Inc. All rights reserved.