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Forebrain origins of glutamatergic innervation to the rat paraventricular nucleus of the hypothalamus: Differential inputs to the anterior versus posterior subregions
Author(s) -
UlrichLai Yvonne M.,
Jones Kenneth R.,
Ziegler Dana R.,
Cullinan William E.,
Herman James P.
Publication year - 2011
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22571
Subject(s) - glutamatergic , forebrain , neuroscience , retrograde tracing , biology , colocalization , hypothalamus , glutamate receptor , nucleus , preoptic area , anterograde tracing , anatomy , central nervous system , receptor , biochemistry
Abstract The hypothalamic paraventricular nucleus (PVN) regulates numerous homeostatic systems and functions largely under the influence of forebrain inputs. Glutamate is a major neurotransmitter in forebrain, and glutamate neurosignaling in the PVN is known to mediate many of its functions. Previous work showed that vesicular glutamate transporters (VGluTs; specific markers for glutamatergic neurons) are expressed in forebrain sites that project to the PVN; however, the extent of this presumed glutamatergic innervation to the PVN is not clear. In the present study retrograde FluoroGold (FG) labeling of PVN‐projecting neurons was combined with in situ hybridization for VGluT1 and VGluT2 mRNAs to identify forebrain regions that provide glutamatergic innervation to the PVN and its immediate surround in rats, with special consideration for the sources to the anterior versus posterior PVN. VGluT1 mRNA colocalization with retrogradely labeled FG neurons was sparse. VGluT2 mRNA colocalization with FG neurons was most abundant in the ventromedial hypothalamus after anterior PVN FG injections, and in the lateral, posterior, dorsomedial, and ventromedial hypothalamic nuclei after posterior PVN injections. Anterograde tract tracing combined with VGluT2 immunolabeling showed that 1) ventromedial nucleus‐derived glutamatergic inputs occur in both the anterior and posterior PVN; 2) posterior nucleus‐derived glutamatergic inputs occur predominantly in the posterior PVN; and 3) medial preoptic nucleus‐derived inputs to the PVN are not glutamatergic, thereby corroborating the innervation pattern seen with retrograde tracing. The results suggest that PVN subregions are influenced by varying amounts and sources of forebrain glutamatergic regulation, consistent with functional differentiation of glutamate projections. J. Comp. Neurol. 519:1301–1319, 2011. © 2010 Wiley‐Liss, Inc.