Impact of neonatal benzpyrene imprinting on thymocytic dexamethasone binding in ascitic tumor bearing rats.

1. Rats treated with a single dose of benzpyrene when newborn and inoculated with Walker's ascitic tumor cells when 6 weeks old showed 6 and 9 days later an unequivocal increase, whereas 15 and 20 days later an unequivocal decrease, in dexamethasone binding capacity (receptor number) relative to the control, i.e. a reversion of receptor activity in the course of tumor genesis. 2. The reversion of receptor activity showed a parallelism with the increase of tumor mortality over the control. 3. The experimental observations support the conclusion that neonatal exposure to benzpyrene has a depressive effect on general resistance that is reflected (or probably caused?) among others by a decrease in the binding capacity of glucocorticoid receptors.