ABSTRACT
This chapter focuses on neuromuscular and neuroepithelial transmission in the intestine. There seems to be an ever increasing number of putative neurotransmitters in the enteric nervous system, but relatively few have a defined role in either neuromuscular or neuroepithelial transmission even though their chemical coding may have been established. In addition to covering the “old” classic transmitters, acetylcholine and noradrenaline, some more novel candidate transmitters such as endothelin and pituitary adenylate cyclase-activating polypeptide are discussed, as well as the “modern” classical transmitters ATP and vasoactive intestinal polypeptide (VIP), and the notso-classical nitric oxide. Co-transmission is a widespread phenomenon in the enteric nervous system and particularly with regard to inhibitory transmission, it is difficult to discuss one transmitter, such as ATP, in isolation from others such as nitric oxide and VIP. An area of current research is the plasticity of the enteric nervous system, and how expression of neurotransmitters changes in response to ageing, trauma, surgery or chronic drug treatment, and what the mechanisms underlying these changes are. Some pathological conditions are considered, namely diabetes mellitus, idiopathic chronic constipation, Hirschsprung’s disease and ulcerative colitis, in all of which intestinal neuromuscular transmission may be affected.
