BDNF and Parkinson disease: IDO-1 inhibition with 1-MT has been examined in mouse models of PD and has shown a generally neuroprotective effect with the restoration of function [74]; mechanistically, multiple routes have been demonstrated for this improvement, including reduced neuroinflammatory bio-markers (TNF-α, IFN-γ and IL-6), mitochondrial dysfunction and neuronal apoptosis (caspase-3) combined with the restoration of neurotransmitter levels (dopamine and homovanillic acid) in the striatum and increased striatal brain-derived neurotrophic factor (BDNF) levels [75].