Faculty Collaboration Database

The role of mu and kappa opioid receptors within the periaqueductal gray in the expression of conditional hypoalgesia. Brain Res 1998 Apr 27;791(1-2):83-9

Date

06/19/1998

Pubmed ID

9593835

DOI

10.1016/s0006-8993(98)00057-2

Scopus ID

2-s2.0-0032571778 (requires institutional sign-in at Scopus site)   49 Citations

Abstract

The periaqueductal gray (PAG) is a midbrain structure involved in the modulation of pain and expression of classically conditioned fear responses. Non-selective opioid antagonists applied to the PAG block the expression of hypoalgesia in rats exposed to a Pavlovian signal for shock. This study was conducted to determine the anatomical and pharmacological specificity of the PAG's role in conditional hypoalgesia. Rat subjects received injections of either the mu opioid antagonist CTAP (6.6 nMol), the kappa opioid antagonist Nor-binaltorphimine (Nor-BNI, 6.6 nMol) or saline. Injections were made into either the dorsolateral (dlPAG) or ventrolateral (vlPAG) PAG prior to the presentation of an auditory stimulus that had previously been paired with foot shock while measuring nociception with the radiant heat tail flick (TF) test. Elevation in TF latency in response to the auditory stimulus was blocked only by administration of CTAP into the vlPAG. These results suggest that conditional hypoalgesia (CHA) is subserved by mu but not kappa opioid receptors located in the vlPAG but not the dlPAG.

Author List

Bellgowan PS, Helmstetter FJ

Author

Fred Helmstetter PhD Professor in the Psychology / Neuroscience department at University of Wisconsin - Milwaukee

MESH terms used to index this publication - Major topics in bold

Acoustic Stimulation
Analysis of Variance
Animals
Conditioning, Classical
Electroshock
Fear
Male
Microinjections
Naltrexone
Narcotic Antagonists
Pain Threshold
Periaqueductal Gray
Rats
Reaction Time
Receptors, Opioid, kappa
Receptors, Opioid, mu