ANTAGONISTIC ACTION OF ORPHANIN FQ ON ACUPUNCTURE ANALGESIA IN RAT-BRAIN

The influence of orphanin FQ (OFQ) ( a newly discovered 17-amino acid peptide) on acupuncture analgesia (AA) was assessed in rat tail-flick model. Intracerebroventricular (icv) injection of OFQ(1 mu g) elicited a significant decrement of pain threshold which was abolished by the repeated pretreatment with antisense oligonucleotide (ASO) to OFQ rece ptor. Electroacupuncture (EA) induced an obvious analgesic effect; whe n OFQ was used combined with EA, it showed a dose-dependent effect on antagonizing the EA analgesia. When rat was repeatedly icy injected wi th ASO to block the synthesis of OFQ receptor, the EA analgesia was en hanced markedly. In this instance, the OFQ did not show antagonistic e ffect on EA analgesia any more. The results suggest that the OFQ play its antagonistic role on EA analgesia via activating OFQ receptor.