Increased galanin and neuropeptide-Y immunoreactivity within the hypothalamus of ovariectomised ewes following a prolonged period of reduced body weight is associated with changes in plasma growth hormone but not gonadotropin levels

Abstract

Manipulation of diet is known to affect the secretion of the gonadotropins and growth hormone (GH). The former are under the direct regulation of hypothalamic gonadotropin-releasing hormone (GnRH) and the latter is under the dual control of GH-releasing hormone (GHRH) and somatostatin (SRIH). At the level of the hypothalamus, both galanin (GAL) and neuropeptide Y (NPY) are thought to regulate the secretion of the above releasing and inhibiting factors. Both peptides are also potent orexigenic agents. We have studied ovariectomised ewes that were either well-fed (HIGHs) or underfed (LOWs) and used immunocytochemistry and image analysis to measure the levels of GAL and NPY in hypothalamic nucl..