| Research Abstract |
To elucidate the mechanism of diabetic complications and establish a logical approach to their therapy, we have generated the transgenic mice expressing human aldose reductase (hAR) driven by mouse MHC class I molecule promoter (hAE-Tg). Northern and Western blot analyzes and immunoassay of hAR revealed that both hAR mRNA and hAR protein were expressed in all tissues tested. In the kidney of hAR-Tg, the level of hAR mRNA was 1.6 times as much as mouse AR (mAR) mRNA.Streptozotocin (STZ)-induced diabetes increased not only mAR mRNA by a factor of 3.9, but also hAR mRNA and hAR protein by a factor of 3.2 and 3.1, respectively. In STZ-induced diabetes, renal sorbitol content in hAR-Tg increased more than that in the littermates. In both hAR-Tg and the littermates, renal glutathione content was reduced by STZ-induced diabetes, but not by the galactose diet, whereas the ratio of lactate to pyruvate was increased by both STZ-induced diabetes and the galactose diet. Although the administration of AR inhibitor, epalrestat, improved the changes of renal sorbitol content, glutathione content, the lactate-to-pyruvate ratio, and polyuria in diabetic hAR-Tg, it had little effect on albuminuria. Retinal microaneurysms were observed in hAR-Tg with the galactose diet. The incidence and severity of the lesion were higher in hAR-Tg than those in the littermates, and suppressed by ARI.
Furthermore, to comprehensively investigate the association of the acceleration of polyol pathway with diabetic complications, we have obtained sorbitol dehydrogenase (SDH)-deficient mouse, cloned hSDH cDNA from HeLa cells by RT-PCR method, and generated hSDH-Tg. We are going to examine whether the diabetic complications observed in hAR-Tg improve or progress by crossbreeding hAR-Tg with SDH-deficient mice or hSDH-Tg.
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