[D-Ala2]-methionine enkephalinamide reflexively induces antinociception by activating vagal afferents.

Abstract

Experiment 1 showed that intravenous administration of [D-Ala2]-methionine enkephalinamide resulted in dose-dependent inhibition of the tail-flick reflex, mild hypotension, and bradycardia. The enkephalinamide-induced inhibition of the tail-flick reflex and cardiovascular effects were eliminated in the bilateral cervical vagotomized anesthetized rat preparation, but were unaffected by either a unilateral right vagotomy or bilateral sinoaortic deafferentation in the conscious rat preparation. Experiment 2 demonstrated that the antinociceptive and cardiovascular actions of enkephalinamide were eliminated by pretreatment with intravenous administration of the opioid-receptor antagonist naloxone. These experiments strongly suggest that peripherally circulating enkephalins could reflexively induce analgesia by activating cardiopulmonary receptors whose afferents travel in the vagi.

• Authors: A Randich, W Maixner
• Journal: Pharmacology, biochemistry, and behavior (Pharmacol Biochem Behav) Vol. 21 Issue 3 Pg. 441-8 (Sep 1984) ISSN: 0091-3057 [Print] United States
• PMID: 6494213 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Enkephalin, Methionine
• enkephalinamide-Met, Ala(2)-

Topics

• Afferent Pathways (drug effects)
• Analgesia
• Analysis of Variance
• Animals
• Blood Pressure (drug effects)
• Enkephalin, Methionine (analogs & derivatives, pharmacology)
• Heart Rate (drug effects)
• Male
• Rats
• Rats, Inbred Strains
• Reflex (drug effects)
• Vagus Nerve (drug effects, physiology)