TNF and Parkinson disease: The expression levels of TNF-α and TNF-α receptor R1 were also enhanced in the nigrostriatal dopamine regions and ventricular cerebrospinal fluid of patients with PD, which may be responsible for degeneration of dopaminergic neurons in the substantia nigra pars compacta and loss of nerve terminals with dopamine deficiency in the striatum, leading to development of PD [53].