| AD | Alzheimer’s disease | 
| BDNF | Brain-derived neurotrophic factor | 
| CNS | Central nervous system | 
| CD14 | Cluster of differentiation 14 | 
| DA | Dopaminergic | 
| ENS | Enteric nervous system | 
| EAE | Experimental autoimmune encephalomyelitis | 
| FTD | Frontotemporal dementia | 
| GSH | Glutathione | 
| GABA | γ-aminobutyric acid | 
| H2 | Hydrogen | 
| HD | Huntington’s disease | 
| HPA | Hypothalamic–pituitary–adrenal | 
| H2S | Hydrogen sulfide | 
| IBD | Inflammatory bowel disease | 
| IBS | Irritable bowel syndrome | 
| KYN | Kynurenine | 
| MS | Multiple sclerosis | 
| MPTP | 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine | 
| NDs | Neurodegenerative diseases | 
| NO | Nitric oxide | 
| NFTs | Neurofibrillary tangles | 
| PA | Proanthocyanidins | 
| PD | Parkinson’s disease | 
| p-JNK | phosphorylation-c-Jun N-terminal kinase | 
| ROS | Reactive oxygen species | 
| RNS | Reactive nitrogen species | 
| SOD1 | Superoxide dismutase 1 | 
| SCFAs | Short-chain fatty acids | 
| SIRT1 | Sirtuin-1 | 
| TLRs | Toll-like receptors | 
| TH17 | T helper 17 | 
| TUDCA | Taurine deoxycholic acid |