Effects on the reproductive parameters of two generations of Rattus norvegicus offspring from dams exposed to heptachlor during gestation and lactation.

Heptachlor has been targeted for global elimination because of its toxicity and environmental persistence, in accordance with the Stockholm Convention on Persistent Organic Pollutants (POPs). However, there is no regulation of heptachlor use in Mexico, where relatively high levels have been found in maternal breast milk. The aim of this study was to determine the effects of heptachlor on the reproductive system of offspring of two consecutive generations of rats (F1 and F2) from dams orally administered heptachlor during midgestation and lactation. Female offspring were analyzed for different phenotypic, reproductive, and molecular parameters. In the F1 generation, heptachlor treatment induced decreased body weight at weaning, increased female anogenital distance, and delayed vaginal opening. In both generations, serum progesterone levels decreased and estradiol levels remained unchanged, while overexpression of the progesterone receptor was observed in uterine epithelial cells on estrus day. In the F2 generation, expression of the estrogen receptor α increased in the glandular epithelium. Finally, heptachlor treatment did not affect apoptosis in the uterine epithelial cells. Overall, the results indicate that heptachlor induced female reproductive alterations when administered to dams during the perinatal period. Accordingly, exposure to heptachlor may represent a risk for the reproductive health of humans. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 856-868, 2017.