LE JOURNAL CANADIEN DES SCIENCES NEUROLOG1QUES The Dorsomedial Hypothalamic Nucleus In Autonomic And Neuroendocrine Homeostasis LEE L. BERNARDIS SUMMARY: Median eminence and ven­ dorsal and a ventral one. Monoamine- INTRODUCTION tromedial hypothalamus have in the past containing systems approach the DMN The localization of diencephalic been the principal foci of research in from the lateral hypothalamus and the "centers" controlling both extra- neuroendocrine and neurovisceral con­ bulk of these fibers are carried in the pituitary homeostatic functions (i.e. trol mechanisms. The present report medium forebrain bundle from their cells provides an overview of work involving of origin in the brain stem. Studies of the food and water intake) and neuroen­ the dorsomedial hypothalamic nucleus vascular supply indicate that both VMN docrine (i.e. hypothalamo-pituitary) (DMN). This structure is located dorsal and DMN receive their blood supply relationships has revealed consider­ to the ventromedial hypothalamic nuc­ from the internal carotid artery. It has able functional specificity of fairly leus (VMN) and extends antero- been recently demonstrated that the well-defined areas and fiber tracts. posteriorly from the plane of the largest DMN is involved in the control of food Thus, the medial hypothalamus has cross section of the VMN to the plane of intake and possibly water intake as well. been implicated in satiety ("satiety the dorsal premammillary nucleus. Fib­ Discrete lesions in the DMN have center") and the lateral ers from the DMN pass with the periven­ caused hypophagia and hypodipsia, and hypothalamus in feeding ("feeding tricular system and the dorsal longitudi­ implantation of epinephrine and center") (Anand and Brobeck, nal fasciculus of Schiitz and have been norepinephrine in this area has initiated traced to the midbrain tegmentum and eating. Many years ago, electrical stimu­ 1951). The supraoptic and paraven­ reticular formation. Intrahypothalamic lation of this area was reported to cause tricular nuclei of the hypothalamus connections involve intensive networks eating. Although DMN lesions cause have been recognized as the forma­ between DMN, lateral hypothalamic hypodipsia, they do not result in the tion sites of anti-diuretic hormone nucleus (LHN) and VMN. Regarding reduced water/food intake ratios that are (Hild and Zetler, 1953) and of oxyto­ neurotransmitters, recent studies indi­ so characteristic of the VMN syndrome. cin (Olivecrona, 1957), and finally, cate that the DMN receives noradrener­ DMN lesions are also followed by re- the ventromedial hypothalamus has gic innervation along two pathways, a (Please turn to page 57) been demonstrated to be involved in the control of growth hormone (GH) secretion (Bernardis and Frohman, RESUME: Dans le passe, I'eminence catecholaminerigique), vasculaire et 1967; Frohman and Bernardis, mediane et V hypothalamus physiologique (demonstration recente du 1968). ventromedian ont le plus regu I'attention role du NDM dans le controle de des chercheurs. Le present travail a pour I'apport calorique et liquidien; role dans The median eminence (ME) has but de faire une revue de nos connais- le "resetting" du controle autunome been the principal focus of most in­ sances au sujet du noyau hypothalami- central; dans le controle de la LTH et vestigators attention (for reviews see que dorsomedian (NDM), tant du point possiblement du facteur inhibiteur de Knigge, Scott and Weindl, 1972; de vue anatomique (voies et fibres de I'hormone de croissance et enfin role Martini, Motta and Fraschini, 1970; connections) qu'histochimique (impor­ important dans le controle de certains Nalbandov, 1963) since interference tance de I 'innervation mecanismes neurovisceraux). with its structural integrity invari­ ably results in functional disruption of all adenohypophyseal hormone secretion. However, the concept that the hypophysiotrophic princi­ ples — releasing and inhibiting fac­ tors — are formed in the ME has Departments of Surgery and Pathology, State University of New York at Buffalo, Buffalo, New been questioned (Mess, Fraschini, York 14215, U.S.A. Motta and Martini, 1967) and the concept has been advanced that the This review was written and some of the reported studies were conducted while the author was sup­ ME is merely a stopover point from ported by General Medical Sciences Grant GM which the hypophysiotrophic princi­ 15768, National Institutes of Health. ples formed in more distant areas of Reprint requests to Dr. L. L. Bernardis, State the hypothalamus are released into University of New York at Buffalo, 462 Grider St. Buffalo N.Y. 14215 U.S.A. the primary portal plexus. Areas FEBRUARY 1975 - 45 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.58, on 28 Sep 2021 at 14:09:17, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0317167100019971 THE CANADIAN JOURNAL OF NEUROLOGICAL SCIENCES beyond the limits of the ME which Medi'oMediol Strio CorticohypothalamiCorticohypotriolamic exert hypophysiotrophic activity Medullar!* TrocTrodl have been well demonstrated by the definition of the hypophysiotrophic area (HTA) by Halasz and his co­ workers (Halasz, Pupp and Uhlarik, 1962). For the aforementioned reasons l it the majority of neuroendocrine Stria Termina Preoptic studies have been concentrated on Component r Periventricula the basal hypothalamus and the Nucleui, ant. HTA, and little attention has been part. directed toward the dorsal neurons of the hypothalamus. In an attempt to correct this the present review addresses itself to the dorsomedial hypothalamus, in particular the dor­ somedial hypothalamic nucleus (DMN), and represents an attempt to integrate many as yet uncoordi­ nated findings in many subdiscip- Oorsol Supraoptic Commissure, lines into a structural-functional Ventral Part Gestalt view of this diencephalic Hypoth. N. area. Figure 1: View of the rat hypothalamus showing relationship of nuclei and fiber tracts (Modified after Krieg, 1932). ANATOMY, HISTOLOGY The DMN are located dorsal to to the VMN, DMN and LHN in her the influence of fibers from the re­ the ventromedial hypothalamic nuc­ studies in monkeys with thalamic ticular zone of the thalamus. Fibers lei (VMN) and Krieg (1932) disting­ dorsomedial lesions. radiating from — and converging on uishes two subdivisions, the nucleus — the area between the medial lem­ dorsomedialis pars ventralis and The pars dorsalis ... "a poorly niscus and the cerebral peduncle pars dorsalis. The former borders on defined and inconspicuous cell group" . extends from the turn dorsally as what Krieg (1932) the VMN, separated by a cell-free has termed submamillothalamic fib­ zone, and is anteriorly and dorsally paraventricular nucleus to the me­ dial margin of the zona incerta and ers. Other fibers turn ventrally as continued with the pars dorsalis of commissura supraoptica dorsalis the nucleus. In its posterior aspect it nucleus reticularis thalami, along a line joining the mamillothalamic pars dorsalis (commissure of is in contact with the nucleus post­ Ganser) and as the fasciculus erior hypothalami. (Figure 1) tract and the fornix (Krieg, 1932). Dorsally the pars dorsalis borders on hypothalamicus. By this term Krieg The fornix column and the com- the nucleus reuniens thalami and the designated certain fibers which turn missura supraoptica dorsalis, pars nucleus centralis thalami while post­ ventrally either ventral or dorsal to dorsalis form the lateral borders. eriorly it fuses with the pars ven­ the fornix and do not decussate. He Axons have been described as pas­ tralis of the DMN. The cells of this noted that they passed medially be­ sing dorsally with the periventricular part of the DMN are indefinite in tween the medial lemniscus and the axons into the periventricular fibers, their connections and the axons pass medial forebrain bundle and became the main bundle of which passes probably with the periventricular lost in the region of the VMN. He through the nucleus (Krieg, 1932). fibers. The constituent cells of both thought that they were intermingled This original work has been con­ pars ventralis and pars dorsalis are with, but in general were caudal to, firmed by recent evidence which is small but the cell nuclei of the pars Ganser's commissure and noted that summarized in Sutin's (1966) re­ ventralis are somewhat larger than they probably synapsed in the view. Periventricular fibers indeed those of the pars dorsalis (Krieg, VMN. Other fibers cross the midline pass from the ventral premamillary 1932). Medially, the DMN borders as commissura interventralis nucleus, posterior periventricular on the ependyma of the third ventri­ thalami. nucleus and the DMN and it is clear cle but its cells do not have the Krieg's (1932) description indi­ that powerful relations exist bet­ intimate contact as found in the ar­ cates that the fiber connections to ween the DMN and the periventricu­ cuate nucleus. and from the DMN were poorly un­ lar system, which is probably its derstood at that time but he sus­ major outflow. It should also be FIBER CONNECTIONS pected that the axons of the DMN noted that Showers (1958) has re­ The nucleus dorsomedialis gener­ probably passed with periventricular ported periventricular degeneration ally is considered as coming under fibers, together with fibers from the Downloaded46 - FEBRUAR from https://www.cambridge.org/coreY 1975 . IP address: 170.106.202.58, on 28 Sep 2021 at 14:09:17, subject to the CambridgeThe Core