A STUDY ON THE INVOLVEMENT OF GABA(B) RECEPTOR LIGANDS IN STRESS-INDUCED ANTINOCICEPTION IN MALE-MICE

Swimming at 21 degrees C for 3 min induced antinociceptive effects in male mice with all animals showing a significant increase in response time to the hot plate test measured 10 min after swimming. This antino ciceptive activity was still evident at 20 min after swimming. Prior a dministration of the GABA(B) receptor agonist, baclofen, potentiated t he swimming-induced antinociception. For the group receiving the highe r dose of baclofen (2.0 mg/kg s.c.) the potentiation was still evident 40 min postswimming. However, prior administration of CGP-35348, a GA BA(B) receptor antagonist, had no effect on the antinociceptive activi ty observed after swimming. Restraint for 1 h also induced significant antinociceptive activity in male mice. This restraint-induced antinoc iceptive activity was enhanced by prior administration of baclofen and was completely abolished by the administration of CGP-35348 before re straint. The present feelings suggest that GABA(B) reclay a role in st ress-induced antinociception and different GABA(B) recpes may be invol ved depending on the nature of the stress.