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Neuronal Nitric Oxide Synthase in the Rostral Ventrolateral Medulla of Hindlimb Unloaded Rats
Author(s) -
Zidon Terese M,
Fong Angelina Y,
Foley C Michael,
Mueller Patrick J,
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.1169.12
Subject(s) - rostral ventrolateral medulla , medicine , endocrinology , baroreflex , nitric oxide synthase , gabaergic , medulla oblongata , chemistry , rostral ventromedial medulla , brainstem , glutamate decarboxylase , hindlimb , nitric oxide , biology , central nervous system , enzyme , inhibitory postsynaptic potential , heart rate , blood pressure , biochemistry , nociception , receptor , hyperalgesia
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 and exhibit blunted baroreflex sympathoexcitation. Neurons in the rostral ventrolateral medulla (RVLM) are important for baroreflex function. Previous studies have shown that GABAergic inhibition in the RVLM is increased in HU rats. Nitric oxide (NO) is a neuromodulator that increases GABA inhibition and may contribute to enhanced GABAergic inhibition in the RVLM following HU. We hypothesized that 14 days of HU increases the number of neuronal NO synthase (nNOS) and GAD67 positive neurons in the RVLM. The RVLM distribution of nNOS and GAD67 was examined using immunohistochemistry in brainstem sections (30μm) from male Sprague Dawley (300–350g) control (n=5) and HU (n=5) rats. The number of nNOS and GAD67 positive cells was not different between control and HU rats. Interestingly, there was substantial colabeling of RVLM cells with GAD67 and nNOS in both groups. The number of GAD67 positive cells colabeled with nNOS (11 – 13%) and the number of nNOS positively labeled cells colabeled with GAD67 (40–45%) was similar between control and HU rats. Thus, HU does not appear to alter the number or colabeling of nNOS or GAD67 containing neurons in the RVLM. (HL55306)