Catecholaminergic Regulation of the Production of Gonadotropins in Female Rats

The involvement of the central monoaminergic systems in regulation of the gonadotropic function of the hypophysis is not, at present, in question. At the same time, the question of whether catecholamines influence only the release of luliberin by neurons of the median eminence (ME) or these agents affect simultaneously other structures of the preoptico-tubero-infundibular luliberin-producing system remains open. In experiments with recording of an evoked increase (surge) in the level of gonadotropins in ovariectomized rats that received sex steroids, we studied the effects of some agonists and antagonists of catecholamines on the amount of luliberin in the mediopreoptic region (MPR), arcuate nucleus (ANs), and ME of the hypothalamus, as well as on the levels of luteinizing and follicle-stimulating hormones (LH and FSH, respectively) in the blood. Important fundamental differences in modulation of the evoked surge of hypophyseal gonadotropins under the action of a few pharmacological agents (agonists and antagonists of catecholamines) were observed. Noradrenergic influences on the preoptic region play a dominant role in the control of cyclic release of LH, while the release of FSH is regulated by influences coming from the dopaminergic system.