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. This evidence concerns the gene CHAT and xerostomia.