Aim: To study how polychlorinated biphenyls (PCBs) affect fetal growth and the expression of the insulin-like growth factor (IGF II) gene in the mink (Mustela vision).
Methods: Ten female mink were each exposed to 0.65 or 1.3 mg Clophen A50/day, respectively, during the reproductive season. The numbers and sizes of viable fetuses were recorded. The expression of the IGF II gene was studied by northern blotting using a mink specific IGF II cDNA probe.
Results: The number of viable fetuses decreased after PCB exposure in a dose dependent fashion. Expression of the IGF II gene in adult livers from PCB exposed animals was decreased, compared with control animals, in a dose dependent fashion. In contrast, IGF II expression in placentas and fetuses was unaltered. Furthermore, the maternal excretion of urinary cortisol increased in both exposed groups during the implantation period.
Conclusions: Expression of the IGF II gene is downregulated by PCB exposure in the adult liver. There is also an indication that the regulation of the expression of this gene differs between adult and fetal life.