Research: KANETO and colleagues,

Listed in Issue 51

Abstract

KANETO and colleagues, Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Suita, Japan write that oxidative stress is produced under diabetic conditions and may cause various forms of tissue damage in patients with diabetes. The authors conducted a study in diabetic mice to examine the involvement of oxidative stress in the progression of pancreatic beta-cell dysfunction in type 2 diabetes, and to evaluate the potential usefulness of antioxidants in its treatment .

Background

Methodology

Antioxidant treatment (N-acetyl-L-cysteine (NAC), vitamins C plus E, or both) was started at 6 weeks. The effects were evaluated at 10 and 16 weeks of age.

Results

Treatment with NAC retained glucose-stimulated insulin secretion and moderately decreased blood glucose levels. Vitamins C and E were not effective when use alone, but were slightly effective when used in combination with NAC. No effect upon secretion of insulin was observed when the same antioxidants were given to control nondiabetic mice. Histological examination revealed that the beta-cell mass was significantly larger in the diabetic mice treated with the antioxidants than in the controls. A possible cause of this was that the antioxidant treatment suppressed apoptosis in beta-cells without changing the rate of beta-cell proliferation. This would support the hypothesis than in chronic hyperglycaemia apoptosis induced by oxidative stress causes reduction of beta-cell mass. The antioxidant treatment also preserved the amounts of insulin content and insulin mRNA, which made the extent of insulin degranulation less evident. Also, expression of pancreatic and duodenal homeobox factor-1 (PDX-1) a beta-cell-specific transcription factor, was more visible in the nuclei of islet cells following antioxidant treatment.

Conclusion

The results from this study indicate that antioxidant treatment may exert beneficial effects in diabetes, with preservation of in vivo beta-cell function. This finding suggests the potential use of antioxidants for the treatment of diabetes and provides further support for the implication of oxidative stress in beta-cell dysfunction in diabetes.

References

Kaneto H. Beneficial effects of antioxidants in diabetes: possible protection of pancreatic beta-cells against glucose toxicity . Diabetes 48(12): 2398-406. Dec 1999.

Comment

This interesting study demonstrates that antioxidants modulate, at the molecular level, the enhanced expression of insulin genes, via insulin mRNA, as well as a beta-cell-specific transcription factor. Good news eventually for diabetics.

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