Exploring the influence of stress on aggressive behavior and sexual function: Role of neuromodulator pathways and epigenetics

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.

Genetic Contributions to Aggressive Behaviour in Pigs: A Comprehensive Review

Aggressive behaviour in pigs poses significant challenges to animal welfare, production efficiency, and economic performance in the pork industry. This review explores the multifaceted causes of pig aggression, focusing on genetic, environmental, and physiological factors. Aggression in pigs is categorized into social, maternal, fear-induced, play, and redirected aggression, with early-life hierarchies and environmental stressors playing critical roles. Physiological markers, such as elevated cortisol and reduced serotonin levels, are closely linked to aggressive behaviour, while dietary interventions, including tryptophan supplementation, have shown promise in mitigating aggression. Environmental factors, such as overcrowding, noise, and heat stress, exacerbate aggressive tendencies, whereas enrichment strategies, like music and improved housing conditions, can reduce stress and aggression. Genome-wide analyses have pinpointed specific polymorphisms in neurotransmitter genes (DRD2, SLC6A4, MAOA) and stress-response loci (RYR1) as significant predictors of porcine aggression. Advances in genomic technologies, including genome-wide association studies (GWASs) and transcriptomic analyses, have further elucidated the genetic and epigenetic underpinnings of aggressive behaviour. Practical application in breeding programmes remains challenging due to aggression polygenic nature and industry hesitancy toward genomic approaches. Future research should focus on integrating genetic markers into breeding programmes, developing multitrait selection indices, and exploring epigenetic modifications to improve animal welfare and production efficiency. By addressing these challenges, the pork industry can enhance both the well-being of pigs and the sustainability of production systems.