Nocturnal hyperactivity induced by prenatal methylazoxymethanol administration as measured in a computerized residential maze.

Treatment of female Sprague-Dawley rats with 15 or 25 mg/kg (IP) of methylazoxymethanol acetate (MAM) at gestational day 15 (15 DG) resulted in a dose-dependent reduction of total brain weight of the adult offspring. When tested for spontaneous activity in a residential maze over a 23 hour period, those animals treated with the highest dose of MAM showed an increase in both locomotion and local activity during night hours without changes in the structure of behavior. Animals treated with 15 mg/kg of MAM showed no difference in activity compared to controls despite a significant reduction in brain weight.