Recently, Park et al. successfully improved the cognitive function of aging mice by transplanting stem cells overexpressing ChAT to restore the depleted Ach level [28] Furthermore, activating Ach receptors with pharmaceutical agonists before irradiation reduces damage to salivary glands [29] Additionally, AAV-mediated Aquaporin 1 improved xerostomia [30] In our study, we observed that AAV-ChAT induced Ach levels in the salivary glands and serum, which in turn induced cholinergic receptor (M1AchR and M3 AchR) expression and improved saliva secretion. The gene discussed is AQP1; the disease is xerostomia.