Hormonal Disruptions Induced by Pesticide Mixtures in Postpartum and Non-Postpartum Female Wistar Rats

This study evaluates the endocrine-disrupting effects of a mixture of dichlorvos, dimethoate, and cypermethrin on reproductive hormones in female Wistar rats at various biological stages, including exposure, pregnancy, and postpartum periods. Sixty-four adult virgin female rats, aged 2-3 months and weighing 190-200 g, were divided into eight groups (n=8 per group) and exposed to pesticides in single, double, and triple combinations for 28 days. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, progesterone, prolactin, and testosterone were measured using enzyme-linked immunoassay (ELISA) and other standard methods. Non-postpartum rats showed significant reductions in FSH (up to 45%), estradiol (up to 35%), and progesterone (up to 50%) compared to controls, with the greatest disruptions observed in groups exposed to the triple pesticide combination. Combined exposures exhibited synergistic effects, amplifying hormonal imbalances beyond the impacts of individual pesticides. In contrast, postpartum rats maintained relatively stable levels of estradiol and progesterone, with less than 10% fluctuations, suggesting partial physiological resilience. However, dichlorvos alone reduced progesterone in postpartum rats by approximately 20%. These findings highlight the greater susceptibility of non-postpartum rats to pesticide-induced endocrine disruption and suggest that lactation-associated hormonal regulation provides some protection. Despite this resilience, combined pesticide exposures remain a significant risk to reproductive health, potentially leading to infertility and hormonal dysfunction. This study emphasizes the urgent need for stricter pesticide regulation and further research into protective strategies for at-risk populations, particularly lactating females exposed to environmental toxicants.