Evaluation of long-term consequences in behavioral and/or neural function following neonatal chlordecone exposure

The effects of neonatal exposure of rats to chlordecone, during the major postnatal period of neuroendocrine differentiation were assessed after the animals matured to 90 days of age. On day 4 postpartum, pups received a s.c. injection of either DMSO vehicle or chlordecone (1 mg/pup) dissolved in DMSO. The neonatal exposure produced a significant sex-dependent alteration in adult body weight; chlordecone-exposed males were lighter than vehicle-exposed controls and chlordecone-exposed females were heavier than vehicle-exposed controls. Behavioral tests sensitive to neonatal chlordecone exposure during preweaning development--i.e., spectral analysis of movement, activity, and auditory startle responsiveness--gave no statistically significant evidence for residual effects of the early organochlorine treatment. When challenged with harmine, a known tremorogen with putative effects on olivocerebellar pathways, chlordecone-exposed males were less responsive than vehicle-exposed littermates in a spectral analysis of movement. The movement spectrum of chlordecone-exposed females was not differentially sensitive to the harmine challenge. However, subsequent evaluation of the auditory startle reflex indicated that harmine interacted with the neonatal treatment and sex of the animal; chlordecone-exposed males were less responsive and chlordecone-exposed females more responsive than same sex vehicle-exposed littermates. The responsiveness to a d-amphetamine challenge, expressed as a ratio of baseline activity in a pre- and post-test design, suggested the chlordecone-exposed males gave an exaggerated response to the drug challenge. Collectively, these findings suggest that the neonatal chlordecone exposure had a significant organizational effect on the development of behavioral and/or neural function. These findings also suggest the predictive utility of early behavioral tests; that is, long-term alterations were noted in each component of the toxicological syndrome previously identified during preweaning development.