Endoplasmic reticulum stress promotes blood-testis barrier impairment in mice with busulfan-induced oligospermia through PERK-eIF2α signaling pathway.

Busulfan, a chemotherapeutic agent for cancer, has detrimental effects on germ cells and fertility, yet the specific mechanisms remain largely uncertain. The blood-testis barrier (BTB) maintains a suitable microenvironment for germ cells self-renewal and spermatogenesis by blocking the interference and damage of deleterious substances. Therefore, we hypothesized that BTB abnormalities might be involved in busulfan-induced oligospermia. To verify the hypothesis, thirty male Balb/c mice were randomly administered with busulfan (at a total dose of 40 mg/kg body weight) by intraperitoneal injection for 4 weeks to establish the model of oligospermia. The results displayed that busulfan caused testicular histopathological lesions and spermatogenesis disorder. Meanwhile, busulfan disrupted BTB integrity and lessened the expressions of BTB junction proteins, including Occludin, Claudin-11 and Connexin-43. Furthermore, busulfan activated the endoplasmic reticulum (ER) stress and PERK-eIF2α signaling pathway, reflected by the increased protein expressions of GRP78, p-PERK, p-eIF2α, ATF4 and CHOP. Finally, to evaluate whether the ER stress is involved in busulfan-induced BTB destruction, the ER stress inhibitor 4-Phenylbutyric acid (4-PBA, 1 mM) was used to intervene in busulfan-exposed TM4 cells. The results displayed that inhibition of ER stress alleviated the reduction of BTB junction protein expressions induced by busulfan in TM4 cells. These data collectively indicated that busulfan-induced BTB impairment was mediated by triggering ER stress and activation of the PERK-eIF2α signaling pathway, thereby damaging the spermatogenesis, providing a new therapeutic target for male infertility induced by busulfan.

Aflatoxin B1 induces microglia cells apoptosis mediated by oxidative stress through NF-κB signaling pathway in mice spinal cords.

Many studies have shown that aflatoxin B1 (AFB1) can cause cytotoxicity in numerous cells and organs induced by oxidative stress. However, the toxic effects and related mechanism of AFB1 on the microglia cells in the spinal cords have not been studied yet. Our results showed that AFB1 significantly reduced the number of microglia cells, increased the oxidants (malonaldehyde and hydrogen peroxide) but decreased the anti-oxidants (superoxide dismutase and total antioxidant capacity) in a dose dependent manner in mice spinal cords. In addition, AFB1 significantly increased the oxidative stress, promoted apoptosis and cell cycle arrest in G2-M phase, and activated NF-κB phosphorylation in BV2 microglia cells. However, the addition of active oxygen scavenger N-acetylcysteine can significantly reduce the ROS production, improve cell cycle arrest, reduce apoptosis, and the expression of phosphorylated NF-κB in BV2 microglia cells. These results indicate that AFB1 induces microglia cells apoptosis through oxidative stress by activating NF-κB signaling pathway.