BDNF and Parkinson disease: The results presented above confirm observations that physical activity counteracts damage to midbrain dopaminergic neurons in an animal model of PD [17,18,27] and that this effect is accompanied by an increase in GDNF and BDNF levels in the substantia nigra pars compacta and striatum [28,29,30] and a reduction in the development of inflammation in dopaminergic structures [31,32,33,34,35].