Cocaine- and amphetamine-regulated transcript peptide attenuates phenylephrine-induced bradycardia in anesthetized rats

Am J Physiol Regul Integr Comp Physiol. 2003 Dec;285(6):R1496-503. doi: 10.1152/ajpregu.00183.2003. Epub 2003 Aug 21.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anesthesia
  • Animals
  • Antibodies / pharmacology
  • Baroreflex / physiology*
  • Blood Proteins / pharmacology
  • Bradycardia / chemically induced
  • Bradycardia / physiopathology*
  • Cardiotonic Agents
  • Heart Rate / drug effects
  • Immunohistochemistry
  • Male
  • Nerve Fibers / physiology
  • Nerve Tissue Proteins / immunology
  • Nerve Tissue Proteins / pharmacology
  • Nerve Tissue Proteins / physiology*
  • Neural Pathways
  • Nodose Ganglion / cytology
  • Nodose Ganglion / physiology
  • Phenylephrine
  • Rats
  • Rats, Sprague-Dawley
  • Sodium Chloride / pharmacology
  • Solitary Nucleus / cytology
  • Solitary Nucleus / physiology


  • Antibodies
  • Blood Proteins
  • Cardiotonic Agents
  • Nerve Tissue Proteins
  • cocaine- and amphetamine-regulated transcript protein
  • Phenylephrine
  • Sodium Chloride