Developmental parameters in placentas of female rats exposed to α-cypermethrin during gestation

The placenta is a temporary multifunctional organ with a key role in the maintenance of pregnancy and necessary for foetal growth and development. Exposure to endocrine disruptive chemicals (EDCs) during vulnerable period of life such as pregnancy can affect placental development and function as well as pregnancy outcome. Due to the high abundance of hormone receptors, the placenta is a highly sensitive organ to EDCs. Pyrethroids are the fourth most used group of insecticides worldwide, with proven endocrine disruptive effects. Alpha-cypermethrin (α-cyp) is a type II synthetic pyrethroid insecticide whose effect as an EDC on placental development has still not been explored. Thus, the aim of this investigation was to evaluate the effects of gestational exposure to α-cyp on developmental parameters in placentas of female rats by determination and quantification of protein expression of proliferating and apoptotic markers using an immunohistochemical method and assessment of histopathological changes by classical histopathological analyses. Pregnant Wistar rats were orally exposed to α-cyp at 1, 10 and 19 mg/kg bw/day, diethylstilbestrol (positive control), corn oil (solvent control) and water (negative control) from the 6th to the 21st day of gestation (DG). The gravid uterus was dissected under general anaesthesia at 21st DG and placentas were sampled. Immunohistochemical analysis of phosphorylated histone H3 expression revealed a statistically significant decrease in cell proliferation in α-cyp treated groups at 10 and 19 mg/kg bw/day. Analysis of the expression of cleaved caspase-3 showed that, at the tested concentrations, α-cyp does not cause apoptosis. Numerous histopathological changes were detected in placentas of rats exposed to α-cyp, but their occurrence was not statistically significant in comparison with controls. Further research is needed to better understand the effects of α- cypermethrin as an endocrine disruptor on developmental parameters in placentas of female rats exposed during gestation.