Lactobacillus brevis GKJOY Supplementation Ameliorates Oxidative Stress and Reproductive Dysfunction in Male Rats with Polystyrene Microplastics-Induced Reproductive Toxicity

The growing demand for plastic products has led to an increase in human exposure to microplastics (MPs). MPs have been shown to have detrimental effects on reproductive function, while probiotics have demonstrated promise in enhancing fertility. This study aimed to determine the protective effects of Lactobacillus brevis GKJOY against reproductive damage induced by polystyrene microplastics (PS-MPs) in male rats. In the cell study, LC540 cells were treated with L. brevis GKJOY postbiotic (PGK), gamma-aminobutyric acid (GABA), and PS-MPs to evaluate their effects on cell viability and reactive oxygen species (ROS) production. In the animal experiment, rats were treated with a low dose of L. brevis GKJOY (GK1X, 50 mg/kg), a medium dose (GK2X, 100 mg/kg), or a high dose (GK4X, 200 mg/kg). The results showed that PGK and GABA reduced the levels of ROS and protected against oxidative stress. In contrast, PS-MPs increased ROS levels and had harmful effects on cell viability. In the animal study, testicular injuries caused by PS-MPs led to disruption of the hypothalamic-pituitary-gonadal (HPG) axis and a decrease in reproductive hormone levels. However, treatment with L. brevis GKJOY reduced oxidative stress and pro-inflammatory cytokine levels, restored hormonal imbalances, and led to significant improvements. L. brevis GKJOY effectively mitigated reproductive damage in male rats due to its dual function as a probiotic and neurotransmitter modulator. In conclusion, L. brevis GKJOY, which functions as both a probiotic and a GABA producer, may offer superior protection against male reproductive damage.