Regulation of the Autonomic Nervous System on Intestine

Abstract

Intestine is composed of various types of cells including absorptive epithelial cells, goblet cells, endocrine cells, Paneth cells, immunological cells, and so on, which play digestion, absorption, neuroendocrine, immunological function. Intestine is innervated with extrinsic autonomic nerves and intrinsic enteric nerves. The neurotransmitters and counterpart receptors are widely distributed in the different intestinal cells. Intestinal autonomic nerve system includes sympathetic and parasympathetic nervous systems, which regulate cellular proliferation and function in intestine under physiological and pathophysiological conditions. Presently, distribution and functional characteristics of autonomic nervous system in intestine were reviewed. How autonomic nervous system regulates intestinal cell proliferation was discussed. Function of autonomic nervous system on intestinal diseases was extensively reviewed. It might be helpful to properly manipulate autonomic nervous system during treating different intestinal diseases.

Keywords: autonomic nerve system; cellular proliferation; enteric nervous system; intestinal disease; intestine.

FIGURE 1

Distribution of intestinal neural network. Extrinsic sympathetic and parasympathetic nerve fibers enter the whole layer of the intestinal wall to form complex neural networks with intrinsic enteric nervous and EGCs that innervate gastrointestinal epithelial and immune cells. Epitheliums are differentiated from intestinal stem cells, demonstrating enterocytes, endocrine cells, goblet cells, and Paneth cells. Intestinal stromal cells and various immune cells reside in the intestinal wall, the later including macrophages (Mϕs), lymphocytes, mast cells (MCs), dendritic cells (DCs), and innate lymphoid cells (ILCs). Intestinal neural networks regulate intestinal cells, via neurotransmitters (ACh, NE, ATP etc.), neurotrophic factors (GDNF etc.) and receptors (AChR, AR, P2Y4, RET etc.).

FIGURE 2

Mechanisms of cholinergic anti-inflammatory pathway. The CAIP depends on norepinephrine produced by splenic sympathetic fibers, which can lead ChAT⁺T cell to release ACh through β2 receptor. ACh from ChAT⁺T cell binds to the α7-nAChR on the bone marrow-derived non-T cells like macrophages along with inhibiting LPS-mediated cytokine production.