Intestinal Secretion and Barrier Function; Implication with Muscarinic Cholinoceptor

Abstract

Two most important physiological functions of intestinal epithelial cells (IECs) are intestinal secretion and barrier function in order to protect the host from invasive microorganisms. Acetylcholine (ACh) is regarded as a central molecule for the regulation of these gut functions. Although, ACh is considered as a classical neurotransmitter, numerous studies report the synthesis and release of ACh from non-neuronal epithelial cells and are believed to regulate gut functions via cholinergic activation. Recently, it is established that IECs express M1 and M3 muscarinic acetylcholine receptors (mAChRs). Although, the role of M3 mAChR-mediated intestinal secretion in Ussing Chamber has been highly established, little is known about M1 mAChR-mediated intestinal secretion and barrier function. Here, we review the current knowledge about the functions of M1 and M3 mAChRs and their downstream signaling in the regulation of intestinal secretion and barrier function. We also discuss the role of mAChRs in IECs under inflammatory conditions.