The Localization of R-Spondin1 and R-Spondin 3 Peptides in Rat Hypothalamus: An Immunohistochemical Study

Abstract

The R-spondin protein family is a group of proteins that enhance Wnt/b-catenin signaling and have pleiotropic functions in stem cell growth and development. In the literature reviews, there is no histomorphological study showing the localization and distribution of R-spondins in different hypothalamic nuclei. For this reason, the purpose of this study was to determine the localization, distribution characteristics, and densities in the hypothalamic nuclei of neurons expressing Rspo1 and Rspo3 proteins. The free-floating brain sections of the male rats who were not exposed to any treatment were stained with the indirect immunoperoxidase method using the relevant antibodies. As a result of the immunohistochemical studies, it was determined that neurons expressing the Rspo1 protein were found in large numbers in the supraoptic nucleus (SON), the suprachiasmatic nucleus (SCh), anterior paraventricular nucleus, periventricular hypothalamic nucleus (PeV), anterior hypothalamic area, magnocellular preoptic nucleus (MCPO) and the lateral hypothalamic area (LH) from the hypothalamic nuclei, while they were localized in fewer numbers in the arcuate nucleus (ARC). Rspo3 protein expression was found in neurons localized in the hypothalamic nuclei SON, paraventricular nucleus (PVN), PeV, ARC, ventromedial nucleus (VMH), LH, anterior parvicellular nucleus, and zona inserta (ZI). In addition, neurons synthesizing both peptides were found in the cortex and hippocampus regions (H). Rspo1 and 3 proteins are expressed in hypothalamic energy homeostatic areas, thus these proteins may be involved in the regulation of food intake.