Oxolinic acid and diazepam: their reciprocal antagonism in rodents.

The stimulant effects of oxolinic acid were investigated in rats and mice. This drug, given orally, consistantly induced, in doses ranging from 16 to 256 mg.kg-1, locomotor stimulation and stereotyped behavior. These effects were antagonized by pimozide (1 mg.kg-1), alpha-methyltyrosine (64 mg.kg-1) or reserpine (4 mg.kg-1, 24 h before testing) pretreatment, suggesting a facilitatory role of oxolinic acid on catecholaminergic processes. Diazepam (4-16 mg.kg-1) reduced the stimulant effects induced by oxolinic acid but not those induced by amphetamine; oxolinic acid (8 mg.kg-1) markedly reduced the antipunishment effect elicited in rats by diazepam (2 mg.kg-1). Since benzodiazepines have been reported to enhance GABA functioning, these data suggest that oxolinic acid may impair GABA transmission. However, neither muscimol (0.5-1 mg.kg-1) or gamma-acetylenic-GABA (16-64 mg.kg-1) selectively reduced the stimulant effects elicited by oxolinic acid. Therefore, the possible facilitation exerted by this drug on catecholaminergic systems may not derive from the release of an inhibitory GABAergic control.