Visceral
hypersensitivity and impaired gut barrier are crucial contributors to the pathophysiology of
irritable bowel syndrome (IBS), and those are mediated via
corticotropin-releasing factor (CRF)-
Toll like receptor 4-pro-inflammatory
cytokine signaling.
Phlorizin is an inhibitor of
sodium-linked
glucose transporters (SGLTs), and known to have anti-
cytokine properties. Thus, we hypothesized that
phlorizin may improve these gastrointestinal changes in IBS, and tested this hypothesis in rat IBS models, i.e.,
lipopolysaccharide (LPS) or CRF-induced visceral
hypersensitivity and colonic hyperpermeability. The
visceral pain threshold in response to colonic balloon distention was estimated by abdominal muscle contractions by electromyogram, and colonic permeability was measured by quantifying the absorbed
Evans blue in colonic tissue. Subcutaneous (s.c.) injection of
phlorizin inhibited visceral
hypersensitivity and colonic hyperpermeability induced by LPS in a dose-dependent manner.
Phlorizin also blocked CRF-induced these gastrointestinal changes.
Phlorizin is known to inhibit both SGLT1 and SGLT2, but intragastric administration of
phlorizin may only inhibit SGLT1 because gut mainly expresses SGLT1. We found that intragastric
phlorizin did not display any effects, but
ipragliflozin, an orally active and selective
SGLT2 inhibitor improved the gastrointestinal changes in the LPS model. Compound C, an
adenosine monophosphate-activated
protein kinase (AMPK) inhibitor,
NG-nitro-L-arginine methyl ester, a
nitric oxide (NO) synthesis inhibitor and
naloxone, an
opioid receptor antagonist reversed the effects of
phlorizin. In conclusions,
phlorizin improved visceral
hypersensitivity and colonic hyperpermeability in IBS models. These effects may result from inhibition of SGLT2, and were mediated via AMPK, NO and
opioid pathways.
Phlorizin may be effective for the treatment of IBS.