FFAR2 and Parkinson disease: In addition, SCFAs enable signaling through G-protein-coupled free fatty acid receptors FFAR2 and FFAR3 on the intestinal epitheliums, initiate gluconeogenesis, act on the vagus nerves and DMV, affect CNS transmission processes as well as facilitate the cognitive recovery of patients with PD (Delaere et al., 2012) (Lacassagne and Kessler, 2000; Lal et al., 2001).