SNCA and Parkinson disease: Animal studies have shown that obese rats [29] or mice [30] or transgenic mice [31] with a diabetic profile are more susceptible to the neurotoxins used in PD animal models, such as by the development of brain insulin resistance [29, 31], accumulation of intracytoplasmic α-synuclein protein in the SNpc [31], activation of microglia cells (neuroinflammation) [31], endoplasmic reticulum stress in the midbrain [31], dopamine depletion in the SNpc and striatum [29], oxidative stress in dopaminergic neurons [29, 30] and/or dopaminergic neuronal loss [31].