ACETYLCHOLINE AND ITS SYNTHESIZING ENZYME CHOLINE ACETYLTRANSPHERASE IN THE ENTERIC NERVOUS SYSTEM

Abstract

The enteric nervous system is the largest and most complex division of the peripheral nervous system. Located in the wall of the gastrointestinal tract, it is a regulatory and coordination unit of the nervous system. Neurochemical, pharmacological, and functional studies describe three main classes of neurons in the enteric nervous system– primary afferent, interneurons and motor neurons. These are grouped in ganglia, which are connected and form plexuses. Acetylcholine is a major neurotransmitter that plays a pivotal role in the enteric nervous system and several non-neuronal structures. Internal cholinergic neurons and vagus terminals in the enteric nervous system use acetylcholine as the main excitatory neurotransmitter, regulating motility and mucosal function in the digestive system. The enzyme choline acetyltransferase (ChAT) that catalyzes the synthesis of acetylcholine represents the most specific cholinergic marker. Recent markers used to visualize cholinergic structures are the splicing variants of ChAT mRNA that are transcribed from the ChAT gene. Different alternatively spliced ChAT mRNA variants are transcribed in many animal species, including humans. In the mouse, seven variants in the 5’-noncoding region and two variants that differ in their coding region are described. Morphological, genetic and molecular analysis of ChAT and its splicing variants, as the most reliable and frequently used marker for cholinergic structures, would contribute to a better understanding of the physiological and pathological states of cholinergic neurons in the enteric nervous system.

Keywords

• enteric nervous system
• acetylcholine
• choline acetyltransferase
• mrnasplicing variant
• mouse