EFFECTS OF CHRONIC TREATMENT WITH PHENAZONE ON THE HOT-PLATE TEST AND[H-3] SEROTONIN BINDING-SITES IN PONS AND CORTEX MEMBRANES OF THE RAT

Many reports indicate that nonsteroidal anti-inflammatory drugs exert their antinociceptive effect through adrenergic and serotoninergic sys tems. We investigated the acute and chronic effects of phenazone on th e pain threshold and on brain serotonin binding sites. A relationship between phenazone serum levels and the antinociceptive effect was foun d; acute treatment with phenazone provokes a significant decrease in s erotonin binding sites both in the pons and cerebral cortex after 2, 4 and 8 h, but not after 24 h. After 15 and 30 days of treatment, the n umber of binding sites increases both in the pons and cortex.