title: Brainstem origins of glutamatergic innervation of the rat hypothalamic paraventricular nucleus.
abstract: Multiple lines of evidence document a role for glutamatergic input to the hypothalamic paraventricular nucleus (PVH) in stress-induced activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. However, the neuroanatomical origins of the glutamatergic input have yet to be definitively determined. We have previously shown that vesicular glutamate transporter 2 (VGLUT2) is the predominant VGLUT isoform expressed in the basal forebrain and brainstem, including PVH-projecting regions, and that the PVH is preferentially innervated by VGLUT2-immunoreactive terminals/boutons. The present study employed a dual-labeling approach, combining immunolabeling for a retrograde tract tracer, Fluoro-Gold (FG), with in situ hybridization for VGLUT2 mRNA, to map the brainstem and caudal forebrain distribution of glutamatergic PVH-projecting neurons. The present report presents evidence for substantial dual labeling in the periaqueductal gray, caudal portions of the zona incerta and subparafascicular nucleus, and the lateral parabrachial nucleus. The current data also suggest that relatively few PVH-projecting neurons in ascending raphe nuclei, nucleus of the solitary tract, or ventrolateral medulla are VGLUT2 positive. The data reveal multiple brainstem origins of glutamatergic input to PVH that are positioned to play a role in transducing a diverse range of stressful stimuli.
authors.affiliation: Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, USA. dana.ziegler@marquette.edu
authors.forename: Dana R
authors.initials: DR
authors.lastname: Ziegler
authors.forename: Monica R
authors.initials: MR
authors.lastname: Edwards
authors.forename: Yvonne M
authors.initials: YM
authors.lastname: Ulrich-Lai
authors.forename: James P
authors.initials: JP
authors.lastname: Herman
authors.forename: William E
authors.initials: WE
authors.lastname: Cullinan
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology* / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D009434:Neural Pathways / Q000166:cytology* / Q000378:metabolism; D056347:Neuroanatomical Tract-Tracing Techniques; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology* / Q000378:metabolism; D016548:Prosencephalon / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D050599:Vesicular Glutamate Transport Protein 2 / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; C493475:Slc17a6 protein, rat; D050599:Vesicular Glutamate Transport Protein 2; D018698:Glutamic Acid