Carbon tetrachloride exposure induces ovarian damage through oxidative stress and inflammatory mediated ovarian fibrosis

Abstract

Carbon tetrachloride (CCL₄) is widely used as a chemical intermediate and as a feedstock in the production of chlorofluorocarbons. CCL₄ is highly toxic in the liver, kidney, testicle, brain and other tissues. However, the effect of CCL₄ on ovarian function has not been reported. In this study, we found that the mice treated with CCL₄ showed decreased ovarian function with disturbed estrus cycle, decreased serum level of 17β-estradiol and the reduced number of healthy follicles. Ovarian damage was accompanied by oxidative stress and the production of proinflammatory cytokines, especially interleukins. The indicators of oxidative stress, 4-Hydroxynonenal (4-HNE), 8-hydroxy-2´-deoxyguanosine (8-OHdG), 3-Nitrotyrosine (3-NT) and malondialdehyde (MDA), and the levels of proinflammatory cytokines IL-1α, IL-1β, IL-6 and IL-11 were increased, while the antioxidants, including superoxide dismutase (SOD), nuclear factor erythroid2-related factor 2 (NRF2) and heme oxygenase-1 (HO-1), were decreased in the CCL₄ group. In the CCL₄ treated group, the results of Sirius Red staining, immunohistochemistry and qPCR indicated that proinflammatory cytokines caused further ovarian fibrosis. And CCL₄ could also promote ovarian thecal cells to secrete inflammatory cytokines, resulting in fibrosis in vitro. In addition, CCL₄ inhibited oocyte development and triggered oocyte apoptosis. In conclusion, CCL₄ exposure causes ovarian damage by strong oxidative stress and the high expression of the proinflammatory cytokine mediated ovarian fibrosis.

Keywords: Carbon tetrachloride (CCL(4)); Ovarian fibrosis; Oxidative stress; Proinflammatory cytokines.