Postnatal behavioral development in methylazoxymethanol-induced microcephalic rats--a behavioral teratology study.

Behavioral testings in methylazoxymethanol (MAM)-induced microcephalic rats were conducted. Pregnant Sprague-Dawley rats were treated intraperitoneally with 0, 20 or 40 mg/kg of MAM once a day on day 14 of gestation and were allowed to delivery. Male pups from each litter were examined for open field test at 6 weeks of age and shuttle-box avoidance test at 7 weeks or more of age. In the open field activity of pups, the counts of ambulation and locomoting distance in 40 mg/kg group have increased significantly as compared with those in control group. In the shuttle-box avoidance test, the avoidance response rate was dose-dependently high in the session of the 1st day. As to the interaction between the avoidance response rate and sequence of sessions, however, the avoidance response rate in 40 mg/kg group was significantly low. Rate of the rats with errors and number of response during the intertrial interval was significantly high in 40 mg/kg group. Thus, we could demonstrate functional disturbance in the memory retaining ability in utero MAM-exposed rats.