Diabetic gastroparesis is a serious and debilitating complication of diabetes. In the parent grant to this application, we have tested the central hypothesis that interstitial cells of Cajal (ICC) and neuronal nitric oxide synthase (nNOS) are lost in diabetic gastroparesis due to loss of upregulation of heme oxygenase 1 (H01). This results in a marked increase in reactive oxygen species and subsequent oxidative stress. We
recently showed that administration of hemin to diabetic, non-obese diabetic (NOD) mice with delayed gastric emptying results in upregulation of HO1, reduced oxidative stress, restoration of.nNOS levels and of Kit, a marker of ICC and complete reversal of the delay in gastric emptying. Use of hemin as a therapeutic. agent is limited by side effects, including thrombophlebitis, the need for it to be given intravenously, and its expense. In this administrative supplement application under Recovery Act NOT-OD-09-056, we propose the novel hypothesis that IL-10, given subcutaneously, can be used to upregulate H01 and reverse delayed gastric emptying in diabetic NOD mice. IL-10 has been shown to upregulate H01 in BALB/c mice. It has been extensively investigated in humans as a treatment for Crohn's disease. It can be given subcutaneously, and has a good safety profile. We will use a 13 carbon octanoic acid based breath test to determine gastric emptying in diabetic NOD mice. Once delay is determined, we will use IL-10 with and without an inhibitor of H01 in the mice with delayed gastric emptying and use Western blots to measure H01, Kit, riNOS, and Ano-1; immunohistochemistry to immunolabel for Kit, Ano-1, H01 and CD206 (a macrophage marker). We will also measure HO activity and carry out electrophysiology experiments to record slow wave activity. This work, a direct extension of the work proposed in the parent grant, will provide employment to 2 persons and will accelerate the pace of research by identifying a drug that, if it is proven to work in our animal model, could then be rapidly tested inhuman clinical trials, providing a new treatment option for a disease that currently lacks effective treatments.