The expression level of nuclear factor-kappa B (NF-κB) is hindered in PD mice model administered with MPTP as a result of PYC therapy, which implicates IDO-1 suppression in monocytic cells, especially microglia, as NF-κB being a regulator of upstream metabolic processes, inducing IDO-1 expression [129]. This evidence concerns the gene NFKB1 and Parkinson disease.