Cocaine- and amphetamine-regulated transcript peptide attenuates phenylephrine-induced bradycardia in anesthetized rats.
The present study was undertaken to investigate the origin of cocaine- and amphetamine-regulated transcript (CART) peptide immunoreactive (irCART) fibers observed in the nucleus of the solitary tract (NTS) and assess the role of CART peptide on phenylephrine (PE)-induced baroreflex. Immunohistochemical and retrograde tract-tracing studies showed that some of the irCART fibers observed in the NTS may have their cell bodies in the nodose ganglia. In urethane-anesthetized rats, intracisternal or bilateral intra-NTS microinjection of the CART peptide fragment 55-102 (0.1-3 nmol), referred to herein as CARTp, consistently and dose dependently attenuated PE-induced bradycardia. CARTp, in the doses used here, caused no significant changes of resting blood pressure or heart rate. Bilateral intra-NTS injections of CART antibody (1:500) potentiated PE-induced bradycardia. Injections of saline, normal rabbit serum, or concomitant injection of CARTp and CART antiserum into the NTS caused no significant changes of PE-induced baroreflex. The result suggests that endogenously released CARTp from primary afferents or exogenously administered CARTp modulates PE-induced baroreflex.
Scruggs
Phouangmala
P
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, PO Box 70577, Johnson City, TN 37614, USA.
Dun
Siok L
SL
Dun
Nae J
NJ
D000758:Anesthesia; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017704:Baroreflex / Q000502:physiology*; D001798:Blood Proteins / Q000494:pharmacology; D001919:Bradycardia / Q000139:chemically induced / Q000503:physiopathology*; D002316:Cardiotonic Agents; D006339:Heart Rate / Q000187:drug effects; D007150:Immunohistochemistry; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000276:immunology / Q000494:pharmacology / Q000502:physiology*; D009434:Neural Pathways; D009620:Nodose Ganglion / Q000166:cytology / Q000502:physiology; D010656:Phenylephrine; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride / Q000494:pharmacology; D017552:Solitary Nucleus / Q000166:cytology / Q000502:physiology; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D000906:Antibodies; D001798:Blood Proteins; D002316:Cardiotonic Agents; D009419:Nerve Tissue Proteins; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D010656:Phenylephrine; D012965:Sodium Chloride