Membrane-bound guanylyl cyclase-G deficiency impairs nitric oxide–mediated epithelial repair in intestinal ischemia-reperfusion injury in male mice

Membrane-bound guanylyl cyclase (GC-G), a noncanonical receptor, has been implicated in intestinal epithelial homeostasis. This study investigated the role of GC-G in intestinal ischemia-reperfusion (IIR) injury and its involvement in nitric oxide (NO)–related responses using male wild-type (WT) and GC-G knockout (KO) mice. Mice underwent superior mesenteric artery occlusion followed by 3- or 24-hour reperfusion and were intraperitoneally administered arginine (NO donor), aminoguanidine (selective iNOS inhibitor), or L-NAME (non-selective NOS inhibitor). In WT mice, IIR reduced jejunal mass, increased IL-6 and TUNEL-staining at 3 h, and suppressed nitrate/nitrite (NOx) and Ki-67 at 24 h. Arginine reduced caspase-3 activity at 3 h and enhanced Ki-67 and DNA content at 24 h. Aminoguanidine suppressed early apoptosis and improved later proliferation. L-NAME reduced early injury but enhanced later proliferation without restoring DNA content. GC-G deficiency was associated with attenuated early apoptotic responses but impaired mucosal regeneration following IIR. In KO mice, arginine failed to enhance proliferation and was associated with elevated apoptosis and cytokines, while NOS inhibitors reduced systemic NOx and IL-6 without improving epithelial proliferation or altering caspase-3 activity or bulk cGMP levels. Notably, intestinal NOx levels remained elevated in KO mice. Together, these findings suggest that GC-G contributes to the coordination of NO-related epithelial responses and influences intestinal sensitivity to NO-associated interventions during IIR, without detectable changes in total tissue cGMP levels.