Nitrate induced changes in sensoro-motor development and learning behaviour in rats

Development of sensoro-motor functions and adult learning behaviour was studied in rats subjected to nitrate exposure. Pregnant and lactating dams and their offspring were supplied with drinking water containing nitrate, 1.12 or 2.24 mM KNO3, and compared with nitrate-free controls. Postnatal maturation of reflexes, that of sensory and somatic parameters and motor activity, furthermore, the acquisition of one-way avoidance and rewarded discriminative learning behaviour in adulthood were examined. Reflexes (righting, cliff-avoidance) and hearing startle reaction maturated earlier in nitrate treated groups. No difference was found in olfactory homing behaviour, in the time of eye opening and in body weight growth. Open-field motor activity was higher at days 5, 7, 10 after birth, but hypoactivity ensued after day 20. A marked learning deficit was observed both in punished and in rewarded learning paradigms. The results indicate a nitrate induced deviation in behavioural development, and an impairment in learning behaviour, particularly of discriminative type.