CHRNA7 and major depressive disorder: α7-nAChR-dependent pathways are critically involved in several CNS disorders, including schizophrenia, depression, anxiety, stroke, Alzheimer's disease, and Parkinson disease (43, 44), and increasingly studies highlight the importance of a cholinergic reflex in resolving the inflammatory pathogenesis of several diseases including rheumatoid arthritis (20) and colitis (45).