Effect of selective cyclooxygenase-2 (COX-2) inhibitor treatment on glucose-stimulated insulin secretion in C57BL/6 mice

Previous studies have shown that Prostaglandin E2 (PGE2) inhibits glucose-stimulated insulin secretion. However, the role of cyclooxygenase (COX)-1 vs. COX-2 derived PGE2 production in glucose-stimulated insulin secretion remains poorly understood. Here we investigated the expression of COX-1 and COX-2 in pancreatic islets and the effect of selective inhibition of COX-1 and COX-2 on glucose-stimulated insulin secretion using C57BL/6 (B6) mice. Although immunofluorescence histochemistry showed the constitutive expression of both COX-1 and COX-2 in B6 mouse pancreatic islets, insulin secretion and hyperglycemia after glucose loading were ameliorated in B6 mice treated with selective COX-2 inhibitor (SC58236) for 18 weeks. Interestingly, incubation with selective COX-2 inhibitor for 24 h led to a reduction in PGE2 production in pancreatic islets isolated from B6 mice. In addition, selective COX-2 inhibition enhanced insulin secretion from the isolated islets. These results collectively suggest that selective inhibition of COX-2 enhances glucose-stimulated insulin secretion through a reduction in PGE2 production in pancreatic islets.