The effect of chronic treatment with phenazone on [3H]-serotonin binding sites in pons and cortex membranes of the rat

We studied 36 male rats, 18 o them were trated orally for 30 days with 60 mg/kg/day of phenazone and 18 used as controls. Our data show that a chronic treatment with phenazone increases the number of serotonin receptors in two brain areas while the affinity is not modified; in the same model we demonstrated that phenzone modifies noradrenergic pontine receptors. The role of these changes in receptors characterstics after a long-term treatment with phenazone may contribute to the antinociceptive effect of phenazone.