Pii: S0306-4522(00)00005-1

The present study was performed in rats with experimentally induced mononeuropathy after left common sciatic nerve ligation. The hindpaw withdrawal latencies to thermal and mechanical stimulation increased significantly after intra-periaqueductal grey injection of 2 or 3 nmol, but not 1 nmol of galanin in rats with mononeuropathy. Intraperitoneal administration of 4.5 mg/kg morphine induced significant increases in hindpaw withdrawal latencies to both noxious stimulation, which were attenuated by following intra-periaqueductal grey injection of 2 nmol of the galanin antagonist galantide. Furthermore, the antinociceptive effect induced by intra-periaqueductal grey injection of 26.6 nmol of morphine was attenuated significantly by following intraperiaqueductal gray administration of 2 nmol of galantide. The results demonstrated that in periaqueductal grey galanin plays an antinociceptive role in rats with mononeuropathy and galanin is involved in the mechanisms of opioid-induced antinociception. q 2000 IBRO. Published by Elsevier Science Ltd.