UI - 000215

AU - Cohen SR

AU - Melzack R

TI - Morphine injected into the habenula and dorsal posteromedial thalamus produces analgesia in the

formalin test

AB - AB - Microinjection of morphine into the area of the habenula and dorsal posteromedial thalamus (H-

PMT) produces analgesia for tonic pain as measured by the formalin test in the rat. Control injections of

morphine into sites near the H-PMT result in less or no reduction in pain, indicating that the analgesia

observed is probably due to a site of action within the H-PMT rather than at surrounding neural structures.

The analgesia is fully developed by the first time of testing, 10-16 min following the microinjection, and is

completely reversible by naloxone, an opiate antagonist. The analgesia recorded is most likely due to

morphine's action on the habenula, parafascicular or paraventricular nucleus of the thalamus, or a

combination of these structures UI - 86078584

SO - Brain Res 1985;359:131-139