Central noradrenergic neurones concentrate 3H-oestradiol

Abstract

Central catecholamines play an important part in the regulation of hormone secretion from the pituitary gland and in the mediation of male and female sexual behavior. Noradrenaline [norepinephrine, NE] stimulates the release of luteinizing hormone (lutropin, LH) probably by influencing the secretion of LH-releasing hormone (luliberin). The medial preoptic and hypothalamic areas, including the median eminence, contain NE-containing terminals which originate from discrete NE-containing cell groups in the lower brain stem. The cell groups were identified in the pons and the medulla oblongata by histochemical methods and pharmacological experiments. Recent studies with antiserum to dopamine-.beta.-hydroxylase (DBH), the enzyme that converts dopamine to NE, provided evidence for the existence of noradrenergic cells. These include the locus ceruleus (group A6), a ventrally located more diffuse but continuous subceruleus group (group A5), a cell group located dorsal to the nucleus (n.) dorsalis motorius nervi vagi (group A2) and a cell group in or near the n. reticularis lateralis (group A1). Using the thaw-mount autoradiographic technique, estradiol-concentrating neurons were localized in many areas of the lower brain stem, including the locus ceruleus, n. tractus solitarii, n. dorsalis motorius nervi vagi and reticular formation where catecholamine-containing neurons exist. The simultaneous localization, in the same histological section, of 3H-estradiol and the enzyme dopamine-.beta.-hydroxylase in neurons of the rat lower brain stem with a combined technique of thaw-mount autoradiography and immunohistochemistry, is reported. NE- or adrenaline[epinephrine]-containing neurons are estradiol target cells.