Interactions of TRH, LH-RH, and Somatostatin in the Anterior Pituitary Gland

Publisher Summary This chapter focuses on the interactions of TRH, LH-RH, and somatostatin in the anterior pituitary gland. The secretory activity of anterior pituitary cells is controlled by specific hypothalamic hormones and the feedback action of gonadal, adrenal, and thyroid hormones. The neurohormones are released from the nerve endings containing these peptides in the median eminence and transported to their site of action by a small vascular portal system, growth hormone (GH) prolactin (PRL), adrenocorticotropin (ACTH), and thyrotropin (TSH) are secreted by different cell types, while there is evidence that luteinizing hormone (LH) and follicle-stimulating hormone (FSH) could originate from the same cell. The influence of the hypothalamus on LH, FSH, and ACTH secretion appears to be only positive, while the best available evidence indicates that both positive and negative effects are exerted on GH, TSH, and PRL secretion. The secretory activity of anterior pituitary cells is controlled by the specific hypothalamic hormones and the feedback action of gonadal, adrenal, and thyroid hormones. The neurohormones are released from the nerve endings containing these peptides in the median eminence and transported to their site of action by a small vascular portal system. The observed effects on the spontaneous proestrus plasma LH surge and ovulation support the possibility of developing a contraceptive method based on inhibitory L H-R H analogs.