RESUMO
It has been reported that sodium valproate induces a morphine-like withdrawal syndrome in rats. The effects of acute or chronic treatment with sodium valproate on rat behavior was studied in the open-field test. Acute sodium valproate (320 mg/kg, intraperitoneally) decreases the freuqncy of, and the time spent in grooming even when not modifying locomotion, rearing or defecation (N=15), either 15 or 60 min after an acute treatment. This effect was not modified (n+10) by concomitant administration of morphine (2 mg/kg) or naloxone (1 mg/kg). Interruption of prolonged (30 days) valproate treatment with increasing doses of 40 to 320 mg/kg, by gavage, twice daily (N=10) did not modify raty behavior in the open-field, from the first to the fourtheenth day of th test. We conclude that the decreased novely-induced grooming does not depend on the opioid system and may be related to anti-anxiety effect of valproate