Published online Aug 15, 2015. doi: 10.4291/wjgp.v6.i3.51
Peer-review started: February 1, 2015
First decision: March 6, 2015
Revised: March 27, 2015
Accepted: June 1, 2015
Article in press: June 2, 2015
Published online: August 15, 2015
Chronic alcohol abuse damages nearly every organ in the body. The harmful effects of ethanol on the brain, the liver and the pancreas are well documented. Although chronic alcohol consumption causes serious impairments also in the gastrointestinal tract like altered motility, mucosal damage, impaired absorption of nutrients and inflammation, the effects of chronically consumed ethanol on the enteric nervous system are less detailed. While the nitrergic myenteric neurons play an essential role in the regulation of gastrointestinal peristalsis, it was hypothesised, that these neurons are the first targets of consumed ethanol or its metabolites generated in the different gastrointestinal segments. To reinforce this hypothesis the effects of ethanol on the gastrointestinal tract was investigated in different rodent models with quantitative immunohistochemistry, in vivo and in vitro motility measurements, western blot analysis, evaluation of nitric oxide synthase enzyme activity and bio-imaging of nitric oxide synthesis. These results suggest that chronic alcohol consumption did not result significant neural loss, but primarily impaired the nitrergic pathways in gut region-dependent way leading to disturbed gastrointestinal motility. The gut segment-specific differences in the effects of chronic alcohol consumption highlight the significance the ethanol-induced neuronal microenvironment involving oxidative stress and intestinal microbiota.
Core tip: Chronic ethanol administration causes neurodegeneration in the central nervous system. In the enteric nervous system neurodegeneration was not demonstrated, however alcohol-induced quantitative, functional and neurochemical changes of nitrergic myenteric neurons were observed in gut region-dependent way. These suggest that disturbed gastrointestinal transit characteristic to alcoholic patients due to an impairment of a nitric oxide-mediated descending inhibition during peristalsis. The better understanding of the effects of chronic ethanol administration on enteric neurons may reveal new targets for therapy.