Vasoactive intestinal peptide fibers innervate neuroendocrine dopaminergicneurons

Citation
Lm. Gerhold et al., Vasoactive intestinal peptide fibers innervate neuroendocrine dopaminergicneurons, BRAIN RES, 919(1), 2001, pp. 48-56
Citations number
28
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences & Behavoir
Journal title
BRAIN RESEARCH
ISSN journal
0006-8993 → ACNP
Volume
919
Issue
1
Year of publication
2001
Pages
48 - 56
Database
ISI
SICI code
0006-8993(20011116)919:1<48:VIPFIN>2.0.ZU;2-2
Abstract
Hypothalamic neuroendocrine, dopaminergic neurons exhibit a diurnal rhythm. Higher level input to these neurons has not been. described. In the presen t study, we identified fibers known to originate in the suprachiasmatic nuc leus (SCN), which were associated with neuroendocrine dopaminergic neurons. Hypothalamic sections were obtained from either ovariectomized (OVX) femal e rats or OVX female rats implanted with estrogen and progesterone (E+P). C onfocal microscopic images were acquired from the periventricular nucleus, as well as the rostral, dorsomedial, ventrolateral, and caudal regions of t he arcuate nucleus. Using antibodies directed against vasoactive intestinal peptide (VIP) and tyrosine hydroxylase (TH) the rate-limiting enzyme in do pamine synthesis, fine VIP fibers in close apposition to TH-immunoreactive (IR) soma and proximal dendrites were revealed. Of the antibodies for the t wo VIP receptor subtypes (VIP1R and VIP2R), only VIP2R was found on TH-IR n eurons. E+P significantly increased the incidence and density of neuroendoc rine dopaminergic neurons expressing VIM, when compared to OVX animals. E+P did not affect the percent of neuroendocrine dopaminergic neurons associat ed with VIP fibers. No VIP fibers or VIP2R were found on dopaminergic neuro ns in the zona. incerta. Brain sections triple labeled for Synapsin (a prot ein localized in synaptic vesicles) VIP, and TH demonstrated that Synapsin was colocalized with VIP fibers that were associated with TH-IR neurons in the arcuate nucleus. Double-label immuno-electron microscopy of hypothalami c sections labeled with antibodies for VIP and TH revealed VIP boutons asso ciated with TH-IR soma and proximal dendrites. These results suggest VIPerg ic neurons may directly regulate neuroendocrine dopaminergic neuron activit y, and ovarian steroids may play a modulatory role. (C) 2001 Published by E lsevier Science B.V.