EFFECT OF OPIOID PEPTIDE ANTISERA ON NITROUS-OXIDE ANTINOCICEPTION INRATS

This study was performed to examine the effects of ICV injection of an tiserum against beta-endorphin (beta-EP) or methionine-enkephalin (ME) on nitrous oxide-induced antinociception in rats using the hot plate test. The injection of beta-EP antiserum reversed the antinociceptive effect of nitrous oxide in a dose-related manner up to 200 mu g/rat. H owever, antagonism of nitrous oxide by 400 mu g beta-EP antiserum was comparable to that produced by 200 mu g. On the other hand, similar am ounts of ME antiserum had little effect against nitrous oxide antinoci ception. These findings suggest that beta-EP may play an important rol e in the antinociceptive effect of nitrous oxide.