Effects of fetal treatment with methylazoxymethanol acetate on radial maze performance in rats.

Pregnant rats (Wistar-Imamichi strain) were treated with 15 mg/kg/d of methylazoxymethanol acetate (MAM) on days 13-15 of gestation. Nine male rats, which were randomly selected from the MAM-treated offspring (MAM rats), were examined for their spatial recognition ability by the radial maze technique and compared with control offspring. Although the performances of MAM rats were inferior to the control, they could reach the predetermined criterion within 15 trials. Subsequent retention tests revealed the drastic impairment of performance in MAM rats when the retention interval was over 15 min. The total activity of choline acetyltransferase showed a significant decrease in the hippocampus and cerebral cortex of MAM rats. These results suggest that working memory disorders of MAM rats on radial maze tasks may be due to the lowering of cholinergic functions in their hippocampus and cerebral cortex.