The probiotic strain Lactococcus lactis MG1363-pMG36e-GLP-1 exerts significant neurotrophic effects on MPTP-induced PD mouse models, and its mechanism is mainly achieved through inhibiting ferroptosis, alleviating oxidative stress, improving intestinal microbiota imbalance, and enhancing intestinal barrier integrity (263). Here, GCG is linked to Parkinson disease.