Early behavioral effects of lead perinatal exposure in rat pups

Acoustic analysis of infants crying, a sensitive and selective index for measuring the effect of pre and perinatal lead exposure, may provide an early marker for central nervous system damage produced by the toxic. The present study evaluated the effects of exposure to low lead levels during perinatal and early postnatal periods on ultrasonic vocalization (USV), an early behavior of rat pups essential to their development. Non-sexually experienced females were gavaged daily with 8, 16 or 24 mg/kg of lead acetate or the control solution (1 ml/kg) for 30 days prior to breeding and until their pups were weaned. After crossover of dams, pups had been exposed to lead during pregnancy + lactation, pregnancy or lactation. The physiological variables measured on postnatal days 7 or 14 were USV, locomotion, rectal temperature, body weight and blood lead levels. Lead exposition during pregnancy + lactation, pregnancy or lactation induced a significant dose-dependent decrease of USV of 7-day-old pups. On the contrary, lead exposition during the different phases of pregnancy induced a significant dose-dependent increase of USV in 14-day-old rat pups. Blood lead levels varied from 5.7 to 36.5 μg/dl in pups. Body weight and temperature were not influenced by lead exposition. Lead-exposed 14-day-old pups were significantly more active. This study provides evidence of developmental changes in USV emission in rat pups exposed with low lead levels.