Neurobehavioral development in rats following transplacental exposure to ethylnitrosourea

The ontogeny of spontaneous motor and sensorimotor behaviors of preweaning rats, and ambulation and emotionality at 21, 45, and 60 days, were studied in offspring transplacentally exposed to N-ethyl-N-nitrosourea (ENU), a potent neurotropic carcinogen. Female Sprague-Dawley albino rats received IP injections (15, 60, 100 or 150 mg/kg) of ENU on the 18th day of gestation. The initial appearance of various behaviors was delayed by several days in the offspring of ENU-injected mothers in comparison to that observed in controls, and the time interval between initial appearance of the behavior for any group member and the age that all group members exhibited the response was protracted. A dose-response effect was noted for tests involving spontaneous motor activity, but impaired performance in reflexive tests was found to be independent of dosage. Ambulatory activity tended to be increased for all ages of rat offspring of mothers treated with 60, 100, and 150 mg/kg ENU, with the most marked elevations occurring for rats in the 100 mg/kg group. Emotionality appeared to be relatively unaffected by prenatal exposure to ENU.