Effect of benzo(a)pyrene treatment of neonatal and growing rats on steroid receptor binding capacity in adulthood.

A single treatment to rats of a low dose of benzo(a)pyrene within 24 hr after birth or at 3 weeks of age accounted for a considerable depression of the binding capacity of glucocorticoid receptors for dexamethasone at 4 months of age. The influence of pretreatment with benzo(a)pyrene was greater in the growing than in the neonatal age. Since the applied treatment did not alter receptor affinity, the decrease in binding capacity was in all probability due to a benzo(a)pyrene-induced decrease in the number of receptors.