Premium
Neuronal Nitric Oxide Synthase and Vasopressin in the Paraventricular Nucleus of Hindlimb Unloaded Rats
Author(s) -
Zidon Terese M,
Austgen James R,
Heesch Cheryl M,
Hasser Eileen M
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.739.15
Subject(s) - endocrinology , medicine , vasopressin , nitric oxide synthase , hindlimb , chemistry , spinal cord , hypothalamus , nucleus , nitric oxide , biology , neuroscience
Prolonged periods of bed rest or spaceflight result in cardiovascular deconditioning and a predisposition for orthostatic intolerance. Hindlimb unloaded (HU) rats are an animal model of deconditioning. Following HU, rats exhibit altered arterial and cardiopulmonary baroreflex control of sympathetic nerve activity (SNA) and altered vasopressin (AVP) release. The paraventricular nucleus (PVN) is important in control of both SNA and AVP. NADPH Diaphorase, a marker for nitric oxide (NO) synthase activity is increased in the PVN of HU rats and NO influences SNA and AVP. We hypothesized that 14 days of HU increases the number of neuronal NO synthase (nNOS) and AVP positive neurons in the PVN, possibly in presympathetic PVN neurons. Rats were injected unilaterally with the retrograde tracer FluoroGold (FG) in the spinal cord. The ipsilateral PVN distribution of nNOS and AVP relative to spinally projecting neurons was examined using immunohistochemistry in hypothalamic sections (30 μm) from male Sprague Dawley control (n=3) and HU (n=3) rats. The percent of the spinally projecting (FG) neurons (58–67%) was greatest in the more caudal region of the PVN. The percent of AVP (62%) and nNOS (43–49%) neurons was greatest in the intermediate region. Thus, it appears that HU does not alter the overall number of AVP or nNOS containing neurons in the PVN. (HL55306)