14 - In Vivo and in Vitro Models for Evaluating Effects of Interleukin 1 on Hypothalamic–Pituitary–Gonadal Axis

Abstract

Publisher Summary The cytokines interleukin 1 (IL-1) and interleukin 6 (IL-6), secreted by activated macrophages in response to an immune challenge, are the chemical messengers that constitute a regulatory link in the opposite direction to alter hypothalamic-pituitary secretions. Pituitary gonadotrophs are the source of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These two gonadotropins control gonadal function, which includes secretion of steroids and inhibin by gonads and follicle growth, ultimately leading to ovulation in female and spermatogenesis in male. The secretion of pituitary gonadotropins is, in turn, regulated by hypothalamic luteinizing hormone-releasing hormone (LHRH), a decapeptide released in an episodic fashion into the fenestrated capillaries of the hypophysial portal system in the median eminence , for transportation to the pituitary gonadotrophs to stimulate the release of LH and FSH . Cytokines can, therefore, act at several levels in the hypothalamo-pituitary axis to affect the secretion of pituitary gonadotrophs. This chapter describes a variety of experimental protocols employed in male and female rats to systematically evaluate the effects of the cytokine, IL-1 on pituitary LH and hypothalamic LHRH release.