Neonatal exposure to 2,2',5,5'-tetrachlorobiphenyl causes increased susceptibility in the cholinergic transmitter system at adult age.

Polychlorinated biphenyls (PCBs) constitute a large category of chlorinated hydrocarbons that can have developmental neurotoxic effects. We have recently reported that neonatal exposure to a lightly chlorinated ortho-substituted PCB, 2,2',5,5'-tetrachlorobiphenyl, can induce persistent aberrations in spontaneous behaviour and also affect learning and memory functions in the adult animal. Furthermore, in the adult animal the cholinergic nicotinic receptors in cerebral cortex were affected. The present study presents further evidence that the developing cholinergic system can be sensitive to lightly chlorinated ortho-substituted PCBs. Neonatal exposure of male NMRI mice on postnatal day 10 to 2,2',5,5'-tetrachlorobiphenyl (4.1 mg/kg body weight, per os) was shown to alter the response to a cholinergic agent, nicotine, at an adult age of 4 months, but not to d-amphetamine, an agent known to affect the dopaminergic system.