TFF2 and Parkinson disease: Presently, numerous NPs have been elucidated to exhibit substantial neuronal protection in both in vivo and in vitro models of PD, for instance, substance P (SP) [30], ghrelin [31,32], neuropeptide Y (NPY) [33], neurotensin [34], pituitary adenylate cyclase-activating polypeptide (PACAP) [35], nesfatin-1 [36], and somatostatin (SST) [37] via suppressing apoptosis, cytotoxicity, oxidative stress, autophagy, inflammation, nerve cell toxicity, microglia stimulation, attenuating disease-associated manifestations, and stimulating chondriosomal bioenergetics.