Polystyrene Microplastics-Induced Reproductive Toxicity and Blood-Testis Barrier Disruption in Male Rodents

學生姓名: 許瑜真

指導教授: 龔瑞林

學　　期: 112上

摘　　要: Microplastics (MP) are plastic particles with a size of less than 5 mm and are derived from any kind of plastic. Humans may be exposed to MP by ingesting contaminated food and water, and MP may infiltrate and accumulate in human tissues, posing a health risk. Studies on the reproductive system have shown that microplastics can increase oxidative stress and inflammation in male rodents testis. Therefore, the reproductive toxic effects and potential toxicity mechanisms of polystyrene microplastics (PS-MP) in mice and rats were investigated. After exposure to 0.5 µm, 4 µm and 10 µm of PS-MP, it was observed that 4 µm and 10 µm of PS-MP accumulated in the testis and entered testicular cells. Additionally, the exposure to PS-MP decreased sperm count and motility and caused damage to blood–testis barrier (BTB) in both mice and rats. Histological analysis revealed disordered spermatogenic cells, the occurrence of multinucleated gonocytes, and testicular inflammation. In the rat study, exposure to PS-MP for 90 days at doses of 0 mg/day (control group), 0.015 mg/day, 0.15 mg/ day, and 1.5 mg/day, respectively, The results have shown that PS-MP exposure led to the damage of seminiferous tubules, spermatogenic cell apoptosis, reduced sperm motility and concentration, and increased sperm abnormalities. Mechanistically, PS-MP induced oxidative stress, activated the p38 MAPK pathway, and decreased nuclear factor erythroid-2 related factor 2 (Nrf2) protein expression. Importantly, PS-MP were shown to decrease the expression of BTB-related proteins, suggesting that they impair BTB integrity and cause apoptosis of spermatogenic cells via the p38 MAPK-Nrf2 pathway triggered by oxidative stress. These findings provide new insights into the toxic effects of PS-MP on male reproductive systems and suggest potential mechanisms involving the p38 MAPK-Nrf2 pathway. In conclusion, these studies demonstrate that PS-MP can induce male reproductive dysfunctions and disrupt the BTB integrity, highlighting concerns about the reproductive toxicity of microplastics in mammals.