Effects of flurochloridone on apoptosis and Nrf2/HO-1 and NFκB signaling pathways in mouse testis and TM4 cells

BackgroundFlurochloridone (FLC) is toxic to male reproduction and can induce apoptosis of testicular tissue and supporting cells under oxidative stress. Of particular concern is whether nuclear factor-erythrocyte 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway and nuclear factor kappa B (NFκB) signaling pathway participate this process. ObjectiveTo observe apoptosis of testicular tissue and sertoli TM4 cells and alterations of Nrf2/HO-1 and NFκB signaling pathways in mice treated with FLC in vivo/in vitro. Methods(1) Animal experiment. Testis samples were harvested from male C57BL/6 mice after 28-day FLC (0, 3, 15, 75, and 375 mg·kg−1 per day) exposure via oral route. Malondialdehyde (MDA) and superoxide dismutase (SOD) in homogenate of testicular tissue were measured by colorimetry. Apoptosis of testicular tissue was evaluated by TUNEL staining. Expression and distribution of Nrf2 and NFκB were detected by immunohistochemistry. Protein expression levels of Nrf2, HO-1, NAD(P)H: quinone oxidoreductase 1 (NQO1), NFκB, inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ), and phosphorylated recombinant inhibitory subunit of nuclear factor kappa-B alpha (P-IκBα) in testicular tissue homogenate were determined by Western blotting. (2) Cell experiment. TM4 cell lines were treated with 40, 80, 120, 160, and 200 μmol·L−1 FLC for 6 h, and cell viability was detected by CCK-8. After 6 h exposure to 40, 80, and 160 μmol·L−1 FLC, the apoptosis rate was detected by flow cytometry, and the protein expression levels of Nrf2, HO-1, NQO1, NFκB, IKKβ, and IκBα were detected by Western blotting. Results(1) Animal experiment. Apoptosis occurred in the interstitial and basal parts of spermatogenic tubules in male C57BL/6 mice after 28 days of oral FLC exposure. Compared with the control group, the MDA level in testicular tissue of the 375 mg·kg−1 FLC-treated group was significantly increased (P