No abstract

Exogenous insulin decreased atherosclerosis by lowering inflammatory cytokines, macrophages, and plasma lipids in HFD-induced hyperlipidemia, insulin resistant and mildly diabetic ApoE mice.

In diabetes, increased flux through the polyol pathway has been implicated in the development of diabetic complications such as cataract, retinopathy, neuropathy, and nephropathy. Aldose reductase (AR) appears to be the key factor in the reduction of glucose to sorbitol. Aldose reductase inhibitors have been found to prevent sorbitol accumulation in tissues. A series of thiazolyl-2,4-thiazolidinediones was prepared by Knoevenagel reaction of substituted benzyl-2,4-thiazolidinediones with chlorothiazolecarbaldehydes and were evaluated for their ability to inhibit rat kidney AR by an in vitro spectrophotometric assay. Results showed that compounds containing piperidine at the C-2 position of thiazole ring showed better inhibitory activity than thiazole compounds having 4-chlorobenzylsulfanyl at the same position.

Protein kinase C (PKC) and aldose reductase (AR) enzyme activities are increased in diabetes and complications are include retinopathy, nephropathy, and neuropathy. However, the relationship between PKC and AR and the underlying molecular mechanisms is still unclear. We aimed to evaluate the relationship between these two enzymes and clarify the underlying molecular mechanisms by the related signaling molecules. The effects of hyperglycemia and oxidative stress on AR and PKC enzymes and the signaling molecules such as nuclear factor-kappa B (NF-κB), inhibitor kappa B-alpha (IkB-α), total c-Jun, phospho c-Jun, and stress-activated protein kinases (SAPK)/Jun amino-terminal kinases (JNK) were evaluated in human retinal pigment epithelial cells (ARPE-19). AR, PKC protein levels, and related signaling molecules increased with hyperglycemia and oxidative stress. The AR inhibitor sorbinil decreased PKC expression and activity and all signaling molecule protein levels. Increased AR expression during hyperglycemia and oxidative stress was found to be correlated with the increase in PKC expression and activity in both conditions. Decreased expression and activity of PKC and the protein levels of related signaling molecules with the AR inhibitor sorbinil showed that AR enzyme may play a key role in the expression of PKC enzyme and oxidative stress during diabetes.