Parkinson's disease (PD), one of the most common
neurodegenerative diseases, is characterized by the loss of dopaminergic neurons in the substantia nigra. Increasing epidemiological evidence has indicated that
type 2 diabetes (T2D) may be implicated in the pathogenesis of PD. However, the exact association and the underlying mechanism remain unclear. In the present study, ob/ob and db/db mice, the well accepted T2D models, were acutely treated with
MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) to mimic PD-like neural injury. We found that
insulin signaling impairment occurred not only in pancreas and livers, but also in the midbrain of ob/ob and db/db mice. Notably, the expressions of monomeric and oligomeric α-
synuclein as well as endoplasmic reticulum stress markers (CHOP and
GRP78) were significantly upregulated in both pancreas and midbrain of T2D mice, accompanied by the increased activation of NLRP3
inflammasomes to produce excess IL-1β. Furthermore, we found that acute
MPTP administration aggravated the loss of dopaminergic neurons and increased the activation of glial cells in the substantia nigra of db/db mice. Collectively, these findings demonstrate that α-
synuclein accumulation and
neuroinflammation are aggravated in the midbrain of T2D mice and T2D mice are more susceptible to the neurotoxicity induced by
MPTP. Our study indicates that metabolic
inflammation exacerbates DA neuronal degeneration in the progress of PD, which will provide a novel insight into the etiology of PD.