The Muscarinic Acetylcholine Receptor in Dermal Papilla Cells Regulates Hair Growth

This study explores the role of the cholinergic system in hair growth, specifically focusing on muscarinic acetylcholine receptors (mAChRs) in dermal papilla cells. In M4 mAChR knockout mice, hair follicles exhibited a prolonged telogen phase and failed to produce hair shafts, indicating the importance of mAChRs in hair growth regulation. The study found that inhibiting acetylcholinesterase (AChE) or stimulating mAChRs in dermal papilla cells, cultured vibrissae, and skin epidermis promoted hair growth. Treatment with bethanechol, an mAChR agonist, activated Wnt/β-catenin signaling through PI3K/AKT and ERK pathways, as evidenced by various biomarkers. This activation led to increased hair shaft elongation in mouse vibrissae, highlighting the cholinergic system's role in promoting hair growth.