Deltamethrin exposure induces oxidative stress and affects meiotic maturation in mouse oocyte

Pyrethroid insecticides are commonly used as insecticides and considered to be less toxic to mammals, but may still impair the reproduction of animals and humans. The aim of this research was to evaluate the tendency of deltamethrin induced oxidative stress and its effects on meiosis, apoptosis and autophagy of mouse oocytes in vitro maturation after deltamethrin exposure. Especially, the maturation rate of oocytes decreased significantly after 14 h exposure of deltamethrin in concentration-dependent manners, which was manifested as abnormal spindle morphology and DNA double strand breaks. Oxidative stress was found in mouse oocytes exposed to deltamethrin, as shown by changes in the expression of CAT and SOD2. Our results also show that deltamethrin affects the quality of oocytes by causing abnormal mitochondrial distribution and by decreasing mitochondrial membrane potential. The apoptosis of oocyte regulated by the expression of Bax and Bcl-2 protein was obviously affected by deltamethrin. Compared with the control group, the expression of key regulatory factors in the autophagy pathway, LC3, Atg12, Atg14, and Beclin, increased in the experimental group. In summary, these results revealed that deltamethrin might inhibit the maturation of mouse oocytes and adversely affect the survival of oocytes.