Neurodevelopmental Disorders and Environmental Risk Factors: Neurobehavioural Analysis In A Mouse Model Of Developmental Exposure To Lead

Lead (Pb) is one of the most neuro-toxic metals and its detrimental effects on early development of children have been repeatedly shown even at low doses (< 5 µg/dL, children threshold for blood lead level [BLL]). In this study, we mimicked the real-life scenario of human lead exposure by exposing mice to Pb (0, 25, 100 ppm) in drinking water for 8 weeks (from periconceptional stage to end of lactation). Effects of Pb exposure were observed in both dams and offspring. Maternal behaviour assessment in the first week after parturition revealed increased active nursing in 100-ppm treated dams. Behavioural effects of Pb in the offspring were assessed in several tasks including spontaneous movement test on postnatal day (PND) 8, homing test on PND 11, 3-chamber social interaction test at young adulthood. On PND 8, 100-ppm pups showed increased nose probing (a spontaneous response associated with nipple searching). On PND 11, during homing test (an olfactory-based spatial task) 100-ppm pups showed a reduced sniffing response to the nest odor, although time to reach the nest area was not different in the three treatment groups. At young adulthood, 100-ppm male mice (BLL: 2,546 µg/dL) showed a decreased preference for the social stimulus; alterations of social responsiveness in 25-ppm group (BLL: 1,021 µg/dL) were not evident. Consequently, we found both early and late behavioural effects of Pb which suggest Pb interference with maturation of social competencies by low doses of Pb exposure.