Immunohistochemical analysis of magnocellular elements in rat hypothalamus: Distribution and numbers of cells containing neurophysin, oxytocin, and vasopressin

Abstract

A cell-by-cell analysis of the magnocellular elements in hypothalami of fifty Long-Evans (normal) and Brattleboro (diabetes insipidus) rats was done using the unlabeled antibody enzyme technique (PAP) with primary antisera directed against oxytocin (OXY), vasopressin (ADH), and the neurophysins. The magnocellular neurons of the hypothalamus were found in the supraoptic (SON), paraventricular (PVN), and anterior commissural (ACN) nuclei, a number of accessory nuclei, and as individual cells in the anterior hypothalamic area. SON was divided by the optic tract into the principal part and retrochiasmatic SON. In retrochiasmatic SON a majority of the cells contained vasopressin. Within the principal part of SON oxytocin-producing cells tended to be found rostrally and dorsally, while the vasopressin cells were more common caudally and ventrally. PVN was divided into three subnuclei, the medial, lateral, and posterior subnuclei, on the basis of cellular morphology and peptide content. The magnocellular cells of the medial and lateral PVN were closely packed together and nearly round, while those of posterior PVN were more separated and fusiform in shape with their long axis running in a medio-lateral direction. Medial PVN consisted primarily of oxytocin-producing cells, while lateral PVN was formed by a core of vasopressin-producing cells with a rim of oxytocin cells. Posterior PVN contained largely oxytocin-producing cells. Both ADH and OXY cells were found in the accessory nuclei. In the Long-Evans rat the SON had, on the average, 1443 OXY and 3236 ADH cells; the PVN had 1174 OXY and 976 ADH cells; and the accessory magnocellular groups in the hypothalamus (including the ACN) had 1286 OXY and 552 ADH cells. The Brattleboro strain animal had similar numbers of cells in these nuclei. (The cells which contain ADH in normal animals were identified in the Brattleboro rat as large, neurophysin-negative cells.) Thus, a large fraction of the magnocellular oxytocin- and vasopressin-producing cells in the rat were located outside of the PVN and SON. One accessory cell group in particular, ACN, had 616 OXY cells, or about 50% as many as PVN. In each nucleus the sum of the numbers of OXY and ADH cells was approximately the number of neurophysin cells.

Alcohol Tolerance in Large-Conductance, Calcium-Activated Potassium Channels of CNS Terminals Is Intrinsic and Includes Two Components: Decreased Ethanol Potentiation and Decreased Channel Density

“…In freshly isolated tissue (Fig. 1 D, graph) the SON contained 3080 Ϯ 42 AVP neurons and a slightly smaller number of OXT neurons (2170 Ϯ 38), in accordance with previous reports (Swaab et al, 1975;Rhodes et al, 1981;Marciano et al, 1989;Harding et al, 1995;House et al, 1998;Burbach et al, 2001) presence or absence of ethanol. Thus, we did not observe increased cell death during culture or after ethanol exposure.…”

Persistent Increase in Hypothalamic Arginine Vasopressin Gene Expression During Protracted Withdrawal from Chronic Escalating-Dose Cocaine in Rodents

“…AVP neurons are localized in the MPOA (Rhodes et al, 1981), a region that is directly responsive to cocaine: sitespecific infusion of cocaine into the MPOA has been shown to impair maternal behavior in rats (Vernotica et al, 1999). Since intra-MPOA injection of AVP induces grooming behavior in mice (Lumley et al, 2001), our present finding suggests that the AVP-EGFP-expressing neurons in the MPOA are involved in cocaine withdrawal-related behaviors.…”

Plasticity in GABAAReceptor Subunit mRNA Expression by Hypothalamic Magnocellular Neurons in the Adult Rat

“…Because the GABA A receptor subunits expressed by oxytocin and vasopressin neurons do not differ in any qualitative sense, we have taken advantage of the topographical distribution of oxytocin and vasopressin neurons within the SON and pPVN (Rhodes et al, 1981;Sawchenko and Swanson, 1982) to try to differentiate receptor subunit mRNA expression in these two cell types. The partially overlapping topography of these cells within the SON means that we can claim only to be examining oxytocin neuron-and vasopressin neuron-enriched cell populations in this nucleus; indeed, the significant increase in ␣ 1 subunit mRNA detected in the ventral SON between day 10 and 19 of pregnancy may reflect this incomplete differentiation between oxytocin and vasopressin neurons.…”

“…Despite their potential for oxytocin/vasopressin coexpression, the great majority of magnocellular neurons synthesizes only oxytocin or vasopressin (Jirikowski, 1992) and resides, in general, within different subregions of the PVN and SON (Rhodes et al, 1981;Sawchenko and Swanson, 1982). In this reanalysis, care was taken to identify and analyze, in two to three sections from each animal, a minimum of 40 magnocellular neurons equally from the oxytocin neuron-enriched dorsal half of the SON ( (Fig.…”