The male reproductive system is highly susceptible to noxious influences, such as oxidative stress, inflammation, drugs, and even diseases that can induce germ cell damage and alterations in spermatogenesis. All of these factors, which are caused by actions at the testicular level and/or at the excurrent ducts and accessory glands, significantly affect sperm parameters and male fertility. For this reason, it is of major importance to investigate possible ways to protect the male reproductive system since males are exposed to these toxic factors constantly. For centuries, natural products have been used by humans in folk medicine as therapeutic agents, and because of their beneficial properties for human health, plenty of them have been introduced to the pharmaceutical market as supplementary therapies. The present review aims to compile available information regarding different natural exogenous factors that demonstrate potential useful activity in the male reproductive system. The studies presented here reopen the perspective of using natural products as protective agents and eventually as new supplementary therapeutic options for the recovery of hampered spermatogenesis and/or male infertility.

Endocrine disrupting chemicals (EDCs) have become an issue of scientific and public discussion. Vinclozolin (VNZ) is a fungicide that competitively antagonizes the binding of natural androgens to their receptor, disturbing the function of tissues that are sensitive to these hormones, as is the case of the male reproductive organs. A systematic review with meta-analyses of rodent studies was conducted to answer the following question: does exposure to VNZ affect sperm parameters and testicular/epididymal weight? The methodology was prespecified according to the Cochrane Handbook for Systematic Reviews and PRISMA recommendations. Sixteen articles met the inclusion criteria, comprising a total of 1189 animals. The risk of publication bias was assessed using the Trim and Fill adjustment, funnel plot and Egger’s regression test. Heterogeneity and inconsistency across the findings were tested using the Q-statistic and I2 of Higgins, respectively. Sensitivity was also analysed. Statistical analysis was performed on Comprehensive Meta-Analysis software (Version 2.0), using random models and weighted mean differences along with a 95% confidence interval. Sperm motility, counts, daily sperm production (DSP, evidence of publication bias) and epididymis weight were decreased in VNZ-treated animals. Exposure length and dose, as well as the time point of exposure, influenced the obtained results. Despite the moderate/high heterogeneity observed, the sensitivity analysis overall demonstrated the robustness of the findings. The quality scores of the included studies were superior to 4 in a total of 9, then classified as good. The obtained data corroborate the capability of VNZ exposure to disrupt spermatogenic output and compromise male fertility.

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