Transcriptome reveals probiotics mitigating MCLR-induced reproductive toxicity in male zebrafish: Regulation of...

Microcystin-LR (MCLR) is widely distributed in aquatic ecosystems, exhibiting strong reproductive toxicity to male fish. Several previous studies have reported probiotics could mitigate reproductive system damage caused by environmental pollutants. Whether MCLR-induced negative effects on reproduction could be mitigated by probiotics and the mechanisms involved are little studied. In this study, adult male zebrafish (Danio rerio) received MCLR exposure for 28 days, supplemented or not with the probiotic Lactobacillus rhamnosus GG (LGG). The results showed MCLR exposure impaired male zebrafish reproductive function, evidenced by reduced sperm motility and density, and testicular damage; LGG supplementation mitigated these effects. To investigate the underlying mechanisms, we performed transcriptomic analysis and evaluated the protective effects of LGG in terms of reproductive endocrinology, oxidative stress and inflammatory responses. The results indicated LGG mitigated those injury in male zebrafish by regulating sex hormone synthesis genes, the Nrf2 (NF-E2-related factor 2)/ARE (antioxidant response element) pathway, and the TLR4 (toll-like receptor 4)/NF-κB (nuclear factor-κB) pathway, respectively. Transcriptomic analysis provides evidence that apoptotic regulation may also contribute to the mitigation of MCLR-induced reproductive toxicity. The present study validates a new approach to effectively control the MCLR-induced reproductive toxicity.