Melatonin controlled apoptosis and protected the testes and sperm quality against bisphenol A-induced oxidative toxicity.

Epidemiological reports have indicated a correlation between the increasing bisphenol A (BPA) levels in the environment and the incidence of male infertility. In this study, the protective effects of melatonin on BPA-induced oxidative stress and apoptosis were investigated in the rat testes and epididymal sperm. Melatonin (10 mg/kg body weight (bw)) was injected concurrently with BPA (50 mg/kg bw) for 3 and 6 weeks. The administration of BPA significantly increased oxidative stress in the testes and epididymal sperm. This was associated with a decrease in the serum testosterone level as well as sperm quality, chromatin condensation/de-condensation level, and the percentage of haploid germ cells in the semen. BPA administration caused a significant increase in apoptosis accompanied by a decrease in the expression of the antiapoptotic proteins Bcl-2 in the testes and epididymal sperm. The concurrent administration of melatonin decreased oxidative stress by modulating the levels of glutathione, superoxide dismutase, and catalase as well as the malondialdehyde and hydrogen peroxide concentrations in the testes and sperm. Melatonin sustained Bcl-2 expression and controlled apoptosis. Furthermore, melatonin maintained the testosterone levels, ameliorated histopathological changes, increased the percentages of seminal haploid germ cells, and protected sperm chromatin condensation process, indicating appropriate spermatogenesis with production of functional sperm. In conclusion, melatonin protected against BPA-induced apoptosis by controlling Bcl-2 expression and ameliorating oxidative stress in the testes and sperm. Thus, melatonin is a promising pharmacological agent for preventing the potential reproductive toxicity of BPA following occupational or environmental exposures.

Othman AI ，Edrees GM ，El-Missiry MA ，Ali DA ，Aboel-Nour M ，Dabdoub BR ... -  《-》

Bisphenol a induces autophagy and apoptosis concurrently involving the Akt/mTOR pathway in testes of pubertal SD rats.

Bisphenol A (BPA), a typical endocrine disrupting chemical (EDC), has been proven to cause male reproductive toxicity. However, the precise mechanisms of this effect are still unclear. Puberty is a crucial period of reproductive development, and adolescents are more susceptible to xenobiotics. This research was designed to explore the mechanism of BPA toxicity on pubertal male reproduction. Rats were exposed to 0, 2, 10, 50 mg kg-1 bw BPA, then the levels of sex hormones, oxidative stress, and semen quality were detected. HE staining, TUNEL assay and transmission electron microscopy were used to investigate the morphological changes, apoptosis, and autophagy in testes, respectively. Expressions of relevant genes and proteins were measured by RT-PCR, western blotting, and immunohistochemical staining. The results indicated that BPA exposure led to oxidative stress and endocrine disorders in pubertal male SD rats, caused apoptosis and autophagy in testes, and then damaged spermatogenesis ultimately. The Akt pathway was activated and the mTOR pathway was inhibited in the process. Taken together, BPA induced apoptosis and autophagy concurrently in pubertal testes, and this added a new layer to our understanding on male reproductive toxicity of BPA. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1977-1989, 2017.

Quan C ，Wang C ，Duan P ，Huang W ，Chen W ，Tang S ，Yang K ... -  《-》

Melatonin ameliorates oxidative stress, modulates death receptor pathway proteins, and protects the rat cerebrum against bisphenol-A-induced apoptosis.

Epidemiological reports have indicated a correlation between the increasing of bisphenol-A (BPA) levels in the environment and the incidence of neurodegenerative diseases. In the present study, the protective effect of melatonin on oxidative stress and the death receptor apoptotic proteins in the cerebrum of the bisphenol-A-treated rats were examined. Adult male rats were orally administered melatonin (10mg/kg bw) concurrently with BPA (50mg/kg bw) 3 days a week for 6 weeks. BPA exposure resulted in significant elevations of oxidative stress, as evidenced by the increased malondialdehyde level and the decreased glutathione level and superoxide dismutase activity in the cerebrum. BPA caused an upregulation of p53 and CD95-Fas and activation of capsases-3 and 8, resulting in cerebral cell apoptosis. Melatonin significantly attenuated the BPA-evoked brain oxidative stress, modulated apoptotic-regulating proteins and protected against apoptosis. These data suggest that melatonin modulated important steps in the death receptor apoptotic pathway which likely related to its redox control properties. Melatonin is a promising pharmacological agent for preventing the potential neurotoxicity of BPA following occupational or environmental exposures.

El-Missiry MA ，Othman AI ，Al-Abdan MA ，El-Sayed AA ... -  《-》

Melatonin ameliorates bisphenol A-induced DNA damage in the germ cells of adult male rats.

Bisphenol A (BPA) is a well-known endocrine-disrupting chemical (EDC) that has received particular attention because of its widespread distribution in humans. Due to its chemical similarity to diethylstilbestrol, which is carcinogenic to mammals, the possible genotoxicity of BPA has already largely been evaluated. However, the results are still inconclusive and controversial. To investigate the genotoxic effects of BPA in rat germ cells and the potential protective action of melatonin against these effects, adult male Sprague-Dawley rats were orally administered BPA at a dose of 200mg/kg body weight per day for ten consecutive days with or without melatonin pretreatment. The thiobarbituric acid reactive substances (TBARS) level and superoxide dismutase (SOD) activity in the testes were evaluated. Subsequently, their spermatocytes were isolated, and DNA damage was assessed using an alkaline comet assay and the meiotic spread method. BPA administration did not significantly affect the weights of rats and their reproductive organs, and no alteration in sperm count was found. However, we demonstrated that BPA administration induced a significant increase in TBARS levels and a decrease in SOD activity that were concomitant with an increase in DNA migration within male germ cells and γH2AX foci formation on the autosomes of pachytene spermatocytes. Furthermore, a decrease in the proportion of 4C-cells was observed. These BPA effects were significantly alleviated by melatonin pretreatment. Nevertheless, the genotoxic effects of BPA were not accompanied by apoptosis in germ cells and morphological changes in the testes. These results indicate that BPA exposure may induce DNA damage accumulation in germ cells via oxidative stress. Moreover, melatonin may be a promising pharmacological candidate for preventing the potential genotoxicity of BPA following occupational or environmental exposure.

Wu HJ ，Liu C ，Duan WX ，Xu SC ，He MD ，Chen CH ，Wang Y ，Zhou Z ，Yu ZP ，Zhang L ，Chen Y ... -  《-》

Mutual promotion of apoptosis and autophagy in prepubertal rat testes induced by joint exposure of bisphenol A and nonylphenol.

BPA and NP are both typical endocrine disruptors, the exposed populations are widespread, and the health risks mustn't be ignored. However, the interactions between them on spermatogenesis are rarely mentioned. And the underlying mechanism is unclear yet. In the present study, prepubertal SD rats were exposed to different low doses of BPA and NP separately or jointly for 4 weeks. The results indicate that the joint exposure induced excessive apoptosis and autophagy in the testes, as proved by a series of characteristics such as chromatin condensation and autophagosomes formation. Besides, endocrine disorders and oxidative stress were also caused by the exposure. Apoptosis was mediated by the mitochondrial apoptosis pathway, since the Bax and Caspase-3 gene expressions significantly increased with a prominent decrease of Bcl-2. While autophagy was caused by the inhibition of the Akt/mTOR pathway, as the expressions of the downstream genes Beclin-1, Atg5, Atg12 and the split of LC3 protein increased altogether. Worse yet, autophagy and apoptosis might reinforce each other and make the situation more severe in the joint group. What's more, remarkable histopathological changes such as spermatogenic epithelium atrophy, germ cell loss, and various ultrastructural modifications were strongly related to the apoptosis and autophagy. In aggregate, this study shows the enormous risk on male reproductive system brought by the interactions between BPA and NP. The findings provide a broader vision to understand the roles of apoptosis and autophagy induced by the joint exposure in the aggravation of spermatogenesis impairment, which could be a reference for the situation of complex EDCs exposure-induced male reproductive toxicity, and possibly inspire us to find new ideas for preventive and therapeutic treatments.

Su Y ，Quan C ，Li X ，Shi Y ，Duan P ，Yang K ... -  《-》