Neuroendocrine regulation of gonadotropins in the male and the female

For the past decade, neuroendocrinology, in general, and neuroendocrine reg ulation of reproduction, in particular, were strongly dominated by molecula r genetics and molecular endocrinology. In very recent years, however, neur oendocrinology is taking back its place. Beyond doubt GnRH is the neuroendo crine signal for ovulation. But there are still many unexplored pathways wi thin the 'black box' triggering and regulating this signal. Neuroendocrine control of reproduction starts very early in life, well before birth. Hypop hyseal gonadotropin secretion is under hypothalamic control at around mid-g estation in the fetal sheep and the fetal pig. These two species could be c onsidered as best-studied farm animals considering neuroendocrinology. This minireview thus will give in the first part a short survey of developmenta l processes of some of the neuroendocrine systems in the pig and sheep. In the second part, the opioidergic and catecholaminergic control of gonadotro pins in adults will be briefly discussed. The last part will focus on the n ew less known pathways mediating effects on hormones which regulate the rep roductive functions. (C) 2000 Elsevier Science B.V. All rights reserved.