Purinergic signalling is remarkably
plastic during gastrointestinal
inflammation. Thus, selective drugs targeting the "purinome" may be helpful for inflammatory
gastrointestinal diseases. The myenteric neuromuscular transmission of healthy individuals is fine-tuned and controlled by
adenosine acting on A(2A) excitatory receptors. Here, we investigated the neuromodulatory role of
adenosine in TNBS-inflamed longitudinal muscle-myenteric plexus of the rat ileum. Seven-day postinflammation
ileitis lacks
adenosine neuromodulation, which may contribute to acceleration of gastrointestinal transit. The loss of
adenosine neuromodulation results from deficient accumulation of the
nucleoside at the myenteric synapse despite the fact that the increases in
ATP release were observed. Disparity between
ATP outflow and
adenosine deficit in postinflammatory
ileitis is ascribed to feed-forward inhibition of
ecto-5'-nucleotidase/CD73 by high extracellular
ATP and/or
ADP. Redistribution of
NTPDase2, but not of NTPDase3, from
ganglion cell bodies to myenteric nerve terminals leads to preferential
ADP accumulation from released
ATP, thus contributing to the prolonged inhibition of muscle-bound
ecto-5'-nucleotidase/CD73 and to the delay of
adenosine formation at the inflamed neuromuscular synapse. On the other hand, depression of endogenous
adenosine accumulation may also occur due to enhancement of
adenosine deaminase activity. Both membrane-bound and soluble forms of
ecto-5'-nucleotidase/CD73 and
adenosine deaminase were detected in the inflamed myenteric plexus. These findings provide novel therapeutic targets for inflammatory gut motility disorders.