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Cocaine‐ and amphetamine‐regulated transcript in catecholamine and noncatecholamine presympathetic vasomotor neurons of rat rostral ventrolateral medulla
Author(s) -
Burman Kathleen J.,
Sartor Daniela M.,
Verberne Anthony J.M.,
LlewellynSmith Ida J.
Publication year - 2004
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.20198
Subject(s) - rostral ventrolateral medulla , cocaine and amphetamine regulated transcript , cart , tyrosine hydroxylase , vasomotor , endocrinology , medicine , catecholamine , biology , dopamine , medulla oblongata , central nervous system , receptor , neuropeptide , mechanical engineering , engineering
Presympathetic vasomotor adrenergic (C1) and nonadrenergic (non‐C1) neurons in the rostral ventrolateral medulla (RVLM) provide the main excitatory drive to cardiovascular sympathetic preganglionic neurons in the spinal cord. C1 and non‐C1 neurons contain cocaine‐ and amphetamine‐regulated transcript (CART), suggesting that CART may be a common marker for RVLM presympathetic neurons. To test this hypothesis, we first used double‐immunofluorescence staining for CART and tyrosine hydroxylase (TH) to quantify CART‐immunoreactive (‐IR) catecholamine and noncatecholamine neurons in the C1 region. Next, we quantified the proportion of CART‐IR RVLM neurons that expressed Fos in response to a hypotensive stimulus, using peroxidase immunohistochemistry for Fos and dual immunofluorescence for CART and TH. Finally, we fluorescently detected CART immunoreactivity in electrophysiologically identified, juxtacellularly labeled RVLM presympathetic neurons. In the RVLM, 97% of TH‐IR neurons were CART‐IR, and 74% of CART‐IR neurons were TH‐IR. Nitroprusside infusion significantly increased the number of Fos‐IR RVLM neurons compared with saline controls. In nitroprusside‐treated rats, virtually all Fos/TH neurons in the RVLM were immunoreactive for CART (98% ± 1.3%, SD; n = 7), whereas 29% ± 8.3% of CART‐positive, TH‐negative neurons showed Fos immunoreactivity. Six fast (2.8–5.8 m/second, noncatecholamine)‐, two intermediate (2.1 and 2.2 m/second)‐, and five slow (<1 m/second, catecholamine)‐conducting RVLM presympathetic vasomotor neurons were juxtacellularly labeled. After fluorescent detection of CART and biotinamide, all 13 neurons were found to be CART‐IR. These results suggest that, in rat RVLM, all catecholamine and noncatecholamine presympathetic vasomotor neurons contain CART. J. Comp. Neurol. 476:19–31, 2004. © 2004 Wiley‐Liss, Inc.