Faculty Collaboration Database

Hypoalgesia elicited by a conditioned stimulus is blocked by a mu, but not a delta or a kappa, opioid antagonist injected into the rostral ventromedial medulla. Pain 1999 Dec;83(3):427-431

Date

11/24/1999

Pubmed ID

10568850

DOI

10.1016/S0304-3959(99)00125-6

Scopus ID

2-s2.0-0032751455 (requires institutional sign-in at Scopus site)   26 Citations

Abstract

The present study investigated the role of micro, delta, and kappa receptors within the RVM in mediating expression of conditional hypoalgesia (CHA). Five groups of rats with RVM cannulae were given daily sessions of paired or unpaired presentations of an auditory CS (white noise) and foot shock across three consecutive days. On the test day, rats in the Paired condition were injected with the micro antagonist CTAP, the delta antagonist naltrindole, the kappa antagonist nor-BNI, or saline. Rats in the Unpaired condition were injected with saline. TFLs were measured before and after injections, as well as during and after presentations of the CS. The results showed that none of the drugs affected baseline TFLs. During CS presentation, rats in the Paired condition injected with saline showed longer TFLs than those in the Unpaired condition given saline, confirming the presence of CHA. Expression of this response was blocked by CTAP, but was unaffected by naltrindole or nor-BNI. These results suggest that mu, but not delta or kappa, opioid receptors in the RVM mediate expression of CHA.

Author List

Foo H, 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

Animals
Male
Medulla Oblongata
Naltrexone
Narcotic Antagonists
Pain Measurement
Peptide Fragments
Peptides
Rats
Rats, Long-Evans
Receptors, Opioid, delta
Receptors, Opioid, kappa
Receptors, Opioid, mu
Somatostatin