Valeric acid reduction by chitosan oligosaccharide induces autophagy in a Parkinson's disease mouse model.

Parkinson's disease (PD) is a central nervous system disease with the highest disability and mortality rate worldwide, and it is caused by a variety of factors. The most common medications for PD have side effects with limited therapeutic outcomes. Many studies have reported that chitosan oligosaccharide (COS) crossed blood-brain barrier to achieve a neuroprotective effect in PD. However, the role of COS in PD remains unclear. The present study demonstrated that COS increased dopaminergic neurons in the substantia nigra (SN) and ameliorated dyskinesia in a PD mouse model. Moreover, COS reduced gut microbial diversity and faecal short-chain fatty acids. Valeric acid supplementation enhanced the inflammatory response in the colon and SN, and it reversed COS - suppressed dopamine neurons damage. Autophagy was involved in COS modulating inflammation through valeric acid. These results suggest that COS reduces bacterial metabolites - valeric acid, which diminishes inflammation via activating autophagy, ultimately alleviating PD.