CRF-evoked bradycardia in urethane-anesthetized rats is blocked by naloxone.
CRF, injected IV at a dose of 6 nmol/kg, produced a fall in blood pressure and in heart rate in urethane-anesthetized rats. The CRF-bradycardia was not obtained in hypophysectomized animals, in animals pretreated with dexamethasone, or in animals pretreated with the narcotic antagonist, naloxone (1 mg/kg, IV). By contrast, the hypotensive effects of CRF were not affected by these procedures. Vagotomy or pretreatment with a low dose of N-methylnaloxone did not affect the CRF-bradycardia, indicating that the slowing of the heart was not due to parasympathetic stimulation or due to a peripherally mediated opioid chemoreflex. The results suggested that the CRF-bradycardia was mediated by the release of opioid peptides from the pituitary.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001812:Blood-Brain Barrier; D003346:Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects*; D007016:Hypophysectomy; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010111:Oxymorphone / Q000494:pharmacology; D051381:Rats; D014520:Urethane / Q000494:pharmacology
D009270:Naloxone; D014520:Urethane; D003907:Dexamethasone; D003346:Corticotropin-Releasing Hormone; D010111:Oxymorphone