Short-term effects of a perinatal exposure to the HBCDD α-isomer in rats: Assessment of early motor and sensory development, spontaneous locomotor activity and anxiety in pups.

The present study investigated the developmental neurotoxicity of an early exposure to α-HBCDD through the ingestion of contaminated hen's egg in pregnant and lactating Wistar female rats. Hens were given α-HBCDD-contaminated feed (40 ng/g fresh matter) for 5 and 10 days, which produced eggs with HBCDD content of 33 and 102 ng/glipid weight, respectively. Female rats were administered daily p.o. with an appropriate volume of the whole egg from the day of fertilization (GD0) to the weaning day for pups (PND21). Fetuses and pups were thus exposed continuously to α-HBCDD via the dam over a whole 42-day period that included both gestation and lactation. The administered egg volume was calculated on the basis of daily egg consumption in humans (0.7 egg/person/day) and duration of gestation and lactation in both species, which led animals to be exposed to α-HBCDD at levels of 22 and 66 ng/kg/day, respectively. Neurobehavioral development of pups was investigated from PND3 to PND25 using various tasks including the righting reflex (PND4), the grasping reflex (PND5), the negative geotaxis (PND9), the forelimb grip strength test (PND10) and the locomotor coordination test (PND20). Pup ultrasonic vocalizations were also recorded daily from PND4 to PND14. After weaning, behaviors related to spontaneous locomotor activity and anxiety were examined in the open-field (PND25) and in an elevated-plus maze (PND26), respectively. The results showed a significant decrease in body weight of pups exposed to the lower HBCDD level from PND3 to PND28, whereas the weight of rat pups given 66 ng/kg/day of HBCDD was not different from controls. During the first 3 weeks of life, impairments in motor maturation of pups were observed in a dose-dependent manner depending on the test, whereas no significant differences were reported between male and female pups. At PND26, the anxiety level of female rats exposed to the lowest dose of HBCDD (22 ng/kg/day) was significantly reduced whereas it remained unchanged in males. No significant variations were measured in rats exposed to the higher level of HBCDD (66 ng/kg/day). These results suggest the potent developmental neurotoxicity of an early chronic exposure to the HBCDD α-isomer through the ingestion of hen's eggs contaminated with this pollutant and question the long-lasting consequences of this exposure on behavior abilities and brain functioning in adulthood.