Objective To investigate the effect of acute exposure to cadmium combined with bacitracin on the endoplasmic reticulum stress (ERS) in testes and ovaries of rats and its regulation by nuclear factor erythroid-2-related factor 2 (Nrf2). Methods According to the 4×2 factorial design model, 48 specific pathogen free adult SD rats were divided into four groups: the control group and the low-, medium- and high- dose cadmium chloride exposure groups. Each group was further divided into with- or without bacitracin combined subgroup. There were six rats in each subgroup with 3 males and 3 females. The low-, medium- and high- dose groups were intraperitoneally injected with 5, 10, 20 mg/kg body weight of cadmium chloride solution, respectively. The control group was intraperitoneally injected with the same amount of 0.9% sodium chloride solution. Among them, rats in the bacitracin combined subgroup were given a one-time intraperitoneal injection of bacitracin at a dose of 20 mg/kg body weight two hours before cadmium chloride exposure. After 48 hours, the rats were sacrificed. The mRNA expression of glucose regulated protein78 kD (Grp78), protein kinase R-like endoplasmic reticulum kinase (Perk), Nrf2 in testes and ovaries of rats was determined using quantitative real-time polymerase chain reaction. The protein expression of GRP78, PERK, NRF2 was determined using Western blotting. Results The mRNA expression of Grp78, Perk, Nrf2 and the protein expression of GRP78, PERK, NRF2 in testes and ovaries of rats in the no bacitracin combined subgroups of the three dose groups showed different degrees of up-regulated changes compared with the no bacitracin combined subgroup of the control group (all P<0.05). Among them, the expression of the three kinds of mRNAs and proteins in the testes and ovaries of rats in the no bacitracin combined subgroups of the high-dose group was up-regulated (all P<0.05), and most of them were higher than those in the no bacitracin combined subgroups of the low- and medium-dose groups (all P<0.05). The expression of most of the three kinds of mRNAs and proteins in testes of rats showed different degrees of down-regulated changes (all P<0.05), but the expression of the three kinds of mRNAs and proteins showed different degrees of up-regulated changes in ovaries (all P<0.05) in the bacitracin combined subgroups of the three doses groups than that in the bacitracin combined subgroups of the control group, and especially in the bacitracin combined subgroups of the high-dose subgroup. The expression of the three kinds of mRNAs and proteins in testes and ovaries of rats in the bacitracin combined subgroups of the three doses groups showed different degrees of changes (all P<0.05) compared with the no bacitracin combined subgroup in the same group, and the expression in the bacitracin combined subgroups of the medium- and high-dose groups showed mainly down-regulated changes (all P<0.05). Conclusion Acute exposure to cadmium can induce different degrees of ERS, activate PERK/NRF2 signaling pathway, and improve the toxicity to testis and ovary. Bacitracin can inhibit cadmium-induced ERS, thereby inhibiting the activation of PERK/NRF2 signaling pathway, and enhancing the synergistic effect of cadmium on testis and ovary toxicity. The higher the exposure dose of cadmium, the more obvious the inhibitory effect.

OBJECTIVE: To investigate the effect of n-hexane on the level of sex hormones and expression of estrogen receptor(ER) in rats and the protective effect of Lyciumbarbarum polysaccharide(LBP) on n-hexane-induced reproductive toxicity. METHODS: Based on factorial design model of 4×2, specific pathogen free adult female SD rats were divided into control group and low-, medium-and high-n-hexane exposure groups, and each group was divided into non-LBP intervention and LBP intervention sub-group. There were 8 subgroups with 6 rats in each group. On the first day, the rats in the 4 groups were given intraperitoneal injection of n-hexane at 0, 675, 1 350 and 2 700 mg/kg body weight, respectively. On day 2-4, the rats in the non-LBP intervention subgroup were given intragastric administration of 0.9% sodium chloride solution, and the rats in the LBP intervention subgroup were given intragastric administration of LBP at 50 mg/kg body weight once a day. On the fifth day, all animals were sacrificed, and the levels of follicle stimulating hormone(FSH), luteinizing hormone(LH), estradiol, progesterone were detected by enzyme linked immunosorbent assay. The mRNA expression of Erα, Erβ and G protein coupled estrogen receptor 1(Gper1) was detected by real time fluorescence polymerase chain reaction, and the expression of ERα, ERβ and GPER1 protein was detected by Western blotting. RESULTS: i) In the absence of LBP intervention(i.e. simple n-hexane exposure), there was no significant difference in the level of serum FSH, LH, estradiol and progesterone in the 4 groups(P>0.05). The relative expression of Erβ mRNA in ovary of low dose group decreased, while the relative expression of proteins of ERα and GPER1 increased(P<0.05) when compared with the control group. The relative expression of Erα mRNA and GPER1 protein in the ovary of medium-and high-dose groups increased(P<0.05), while the relative expression of Erβ, Gper1 mRNA and ERβ protein decreased(P<0.05). The relative expression of ERα protein in ovary of high-dose group increased(P<0.05). ii) At the same dose of n-hexane exposure, the relative expression of Erα mRNA in ovary of rats in low dose group increased(P<0.05), while the relative expression of ERβ and GPER1 protein decreased in LBP intervention group compared with the no LBP intervention group(P<0.05). The relative expression of ERα and GPER1 protein in ovary of medium dose group increased(P<0.05), while the relative expression of Gper1 mRNA and GPER1 protein in ovary of high dose group decreased in LBP intervention group compared with the no LBP intervention group(P<0.05). CONCLUSION: n-Hexane can up-regulate the expression of ERα and GPER1 in rat ovary, but has no significant effect on female endocrine system. LBP may play a protective role in female reproductive system by up-regulating the expression of ERα and GPER1.