Regional distribution of gonadotropin-releasing hormone-like, beta-endorphin-like, and methionine-enkephalin-like immunoreactivities in the central nervous system of the goat

Regional distribution of gonadotropin-releasing hormone (GnRH)-like-, beta- endorphin (beta-end)-like-, and methionine-enkephalin (met-enk)-like-immuno reactivity, was quantified across various regions of the central nervous sy stem (CNS) of male and female goats by using highly specific radioimmunoass ays, All the animals were sacrificed during the months of March through Jun e (non-breeding season). Although the distribution of these three neuropept ides was similar to other mammalian species, species-specific gender differ ences in the levels of neuropeptides were noticed in the goat CNS. Highest levels of GnRH-like immunoreactivities were found in the hypothalamus, The hypothalamus of male goats exhibited significantly higher levels of GnRH-li ke immunoreactivities compared to female goats. Other regions exhibiting Gn RH-like immunoreactivities included olfactory bulbs, preoptic and supraopti c regions, and mamillary bodies, Both beta-end- and met-enk immunoreactivit ies were detected in all selected regions of goat CNS, but highest levels o f these opioid peptide-like immunoreactivities were limited to the forebrai n regions of the goat, The supraoptic area of the female goats contained si gnificantly higher levels of beta-end-like immunoreactivities than that of the male goats. Met-enk-peptide-like immunoreactivity also exhibited gender -specific differences in its content in some regions of the CNS, The male g oats exhibited significantly higher levels of met-enk-like immunoreactivity in both the striatal and hypothalamic regions of the brain. (C) 2000 Elsev ier Science Inc.