Pressor effects of orexins injected intracisternally and to rostral ventrolateral medulla of anesthetized rats

Chiung Tong Chen, Ling Ling Hwang, Jaw Kang Chang, Nae J. Dun

Research output: Contribution to journalArticle

176 Citations (Scopus)

Abstract

Orexin A and B, two recently isolated hypothalamic peptides, have been reported to increase food consumption upon intracerebroventricular injections in rats. In addition to the hypothalamus, orexin A-immunoreactive fibers have been observed in several areas of the medulla that are associated with cardiovascular functions. The present study was undertaken to evaluate the hypothesis that orexins may influence cardiovascular response by interacting with neurons in the medulla. Intracisternal injections of orexins A (0.0056- 7.0 nmol) or B (0.028-0.28 nmol) dose dependently increased mean arterial pressure (MAP) by 4-27 mmHg and heart rate (HR) by 26-80 beats/min in urethan-anesthetized rats, with orexin A being more effective in this regard. MAP and HR were not changed by intravenous injection of orexins at higher concentrations. Microinjection of orexin A (14 pmol/50.6 nl) to the rostral ventrolateral medulla, which was confirmed by histological examination, increased MAP and HR. Our results indicate that, in addition to a role in positive feeding behavior, orexins may enhance cardiovascular response via an action on medullary neurons.

Original languageEnglish
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume278
Issue number3 47-3
Publication statusPublished - Mar 2000
Externally publishedYes

Keywords

  • Blood pressure
  • Heart rate
  • Hypocretins
  • Obesity

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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