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Oxidative stress disrupts purinergic neuromuscular transmission in the inflamed colon
Author(s) -
Roberts Jane A.,
Durnin Leonie,
Sharkey Keith A.,
MutafovaYambolieva Violeta N.,
Mawe Gary M.
Publication year - 2013
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2013.254136
Subject(s) - purinergic receptor , oxidative stress , neuromuscular transmission , oxidative phosphorylation , purinergic signalling , medicine , chemistry , neuroscience , biology , biochemistry , adenosine , receptor , adenosine receptor , agonist
Key points• Colitis is associated with an attenuation of purinergic inhibitory neuromuscular transmission. • In this study we tested the hypothesis that purine release is disrupted due to an effect of oxidative stress on mitochondrial purine synthesis. • Stimulus‐induced release of purines was decreased in inflamed colons. • Disruption of mitochondrial purine synthesis, or induction of oxidative stress, mimicked the effects of inflammation on purinergic neuromuscular transmission. • Treatment of animals with a free radical scavenger resulted in a protection of the purinergic neuromuscular transmission. • Treatment with a free radical scavenger also resulted in an improvement of propulsive motility in inflamed colons.Abstract Colitis, induced by trinitrobenzene sulfonic acid (TNBS) in guinea pig, leads to decreased purinergic neuromuscular transmission resulting in a reduction in inhibitory junction potentials (IJPs) in colonic circular muscle. We explored possible mechanisms responsible for this inflammation‐induced neurotransmitter plasticity. Previous studies have suggested that the deficit in inflamed tissue involves decreased ATP release. We therefore hypothesized that decreased purinergic transmission results from inflammation‐induced free radical damage to mitochondria, leading to decreased purine synthesis and release. Stimulus‐induced release of purines was measured using high‐performance liquid chromatography, and quantities of all purines measured were significantly reduced in the inflamed colons as compared to controls. To test whether decreased mitochondrial function affects the IJP, colonic muscularis preparations were treated with the mitochondrial ATP synthase inhibitors oligomycin or dicyclohexylcarbodiimide, which resulted in a significant reduction of IJP amplitude. Induction of oxidative stress in vitro , by addition of H 2 O 2 to the preparation, also significantly reduced IJP amplitude. Purinergic neuromuscular transmission was significantly restored in TNBS‐inflamed guinea pigs, and in dextran sodium sulfate‐inflamed mice, treated with a free radical scavenger. Furthermore, propulsive motility in the distal colons of guinea pigs with TNBS colitis was improved by in vivo treatment with the free radical scavenger. We conclude that oxidative stress contributes to the reduction in purinergic neuromuscular transmission measured in animal models of colitis, and that these changes can be prevented by treatment with a free radical scavenger, resulting in improved motility.