Effects of gestational undernutrition, stress and diazepam treatment on spatial discrimination learning and retention in young rats.

Effects of prenatal undernutrition, stress and diazepam treatment on learning acquisition, and subsequent retention of a spatial discrimination task was assessed in the offsprings. Undernutrition of the dams was induced by restricting food intake to half, throughout the period of gestation, whereas footshock stress and diazepam (0.5 mg/kg, ip) treatment was given from day 13 to 20 of gestation, this being the critical period for neural development in this species. The pups born were subjected to spatial discrimination learning, and retention of the learning acquisition after an interval of one week, in a single unit black/white T-maze, at 8-9 weeks of age. The results indicate that prenatal undernutrition induces significant learning and retention deficits in the offspring, whereas the effect of prenatal stress was limited to only deficit in learning acquisition. Prenatally administered diazepam induced significant deficits in learning acquisition and subsequent retention of the discrimination task in pups culled from normally nourished dams. However, offsprings from diazepam administered undernourished dams exhibited less marked cognitive deficits, which may be attributable to the altered emotional reactivity of pups born to undernourished mothers. Prenatally administered diazepam also induced differential effects in stressed and non-stressed dam offsprings, though the effects were statistically insignificant. The results suggest that prenatal insults, in the form of undernourishment, stress and anxiolytic drugs, leave a lasting imprint on cognitive behaviour of the offspring. The final effect on this behaviour may be determined by the co-existence of these prenatal factors, particularly at a time when the foetus is vulnerable because of neural development and differentiation.