Stimulation of uterine deoxyribonucleic acid synthesis by 1,1,1-trichloro-2-( p-chlorophenyl)-2-( o-chlorophenyl)ethane ( o, p′-DDT)

The administration of 1,1,1-trichloro-2-( p-chlorophenyl)-2-( o-chlorophenyl) ethane ( o, p′-DDT) to immature female rats produced a maximum increase in uterine wet weight and DNA synthesis measured by tritiated thymidine incorporation into uterine DNA 24 hr after treatment. These responses were maximal at a dose of 250–1000 mg/kg of ( o, p′-DDT); half-maximal responses occurred in the range of 10–40 mg/kg. These responses were specific for o, p′-DDT, since ( o, p′-DDT)T was much less potent. 17β-Estradiol and ( o, p′-DDT) also produced increases in total uterine DNA content and in total uterine protein content. The uterine responses to maximum doses of 17β-estradiol and ( o, p′-DDT) were not additive, suggesting that both compounds interact with the same receptor. In a series of experiments, the administration of 250 mg/kg of ( o, p′-DDT) produced increases in uterine weight that were the same as those seem after 17β-estradiol treatment, increases in DNA synthesis that were 60–80 per cent of those produced by 17β-estradiol and an increase in total uterine DNA that was 66 per cent of that observed after 17β-estradiol treatment. 17β-Estradiol and ( o, p′-DDT) also produced significant increases in uterine wet weight and DNA synthesis in ovariectomized/adrenalectomized rats, indicating that the effects of the pesticide are not mediated via adrenal steroids.