title: Cocaine- and amphetamine-regulated transcript in catecholamine and noncatecholamine presympathetic vasomotor neurons of rat rostral ventrolateral medulla.
abstract: 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.
authors.affiliation: Cardiovascular Medicine and Centre for Neuroscience, Flinders University, Bedford Park, South Australia 5042, Australia.
authors.forename: Kathleen J
authors.initials: KJ
authors.lastname: Burman
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Sartor
authors.forename: Anthony J M
authors.initials: AJ
authors.lastname: Verberne
authors.forename: Ida J
authors.initials: IJ
authors.lastname: Llewellyn-Smith
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D017704:Baroreflex / Q000502:physiology; D015415:Biomarkers; D002395:Catecholamines / Q000378:metabolism*; D004525:Efferent Pathways / Q000378:metabolism*; D004837:Epinephrine / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D007022:Hypotension / Q000139:chemically induced / Q000378:metabolism; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009431:Neural Conduction / Q000502:physiology; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000166:cytology / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D014666:Vasomotor System / Q000166:cytology / Q000378:metabolism*; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D015415:Biomarkers; D002395:Catecholamines; D009419:Nerve Tissue Proteins; D016760:Proto-Oncogene Proteins c-fos; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D009599:Nitroprusside; D014446:Tyrosine 3-Monooxygenase; D009638:Norepinephrine; D004837:Epinephrine