ALTERATIONS IN THE ONTOGENY OF RAT PUP ULTRASONIC VOCALIZATION PRODUCED BY PRENATAL EXPOSURE TO NITROGEN-DIOXIDE

Wistar female rats were exposed to low concentrations of nitrogen diox ide, NO2 (1.5 and 3 ppm) from day O to day 20 of pregnancy. The result s show that prenatal exposure to this oxidant gas produced significant changes in the duration pattern of ultrasonic vocalizations emitted b y male pups removed from their nest. In particular, a significant decr ease in the length of ultrasonic calls was found in both 10- and 15-da y-old rats exposed to N0(2) (3 ppm) during gestation. These alteration s were found at dose levels which did not significantly affect reprodu ction parameters, body weight gain and motor activity development. The se findings suggest that gestational exposure to NO2, at concentration s below those associated with overt signs of toxicity, induces in rat offspring subtle behavioral changes characterized by altered ontogeny of ultrasonic emission.