| Research Abstract |
This study was aimed to examine the influences of analgesics on endogenous opioid peptide system of the rat.
1) in adjuvant-induced arthritis of the rat, met-enkephalin-like peptide levels in adrenal medulla and plasma, but not in dental pulp, were increased and decreased to correlate lowering of the pain threshold, respectively. Y-20003, a non-steroidal basic anti-inflammatory agent, which did not inhibit prostaglandin synthesis, had a remarkable effect of recovery from lowering of the pain threshold, while the effect was antagonized by opiate antagonists. On the other hand, Y-20003 decreased the content of met-enkephalin-like peptide in adrenal medulla, while Y-20003 increased the content of the peptides in the plasma.
2) Amfenac, a non-steroidal acidic anti-inflammatroy agent, which had an inhibitory effect on prostaglandin synthesis, remarkably decreased the content and the release of met-enkephalin-like peptides in and from the pulp of the rat.
3) Amfenac also inhibited degradation of BANA, a synthetic substrate for trypsin, by the tissue enzymes in dental pulp and adrenal medulla.
4) Amfenac remarkably inhibited the production of bradykinin-like peptides from plasma of the rat by trypsin. On the other hand, indomethacin did not influence it. From these results, it was suggested that analgesic effect of Y-20003 was mediated through endogenous opioid peptide system, while that of Amfenac was mediated by inhibition of bradykinin formation.
|
