Diabetes & Metabolism Journal

Original Articles

Effects of Aminoguanidine on Nitric Oxide Production, Insulin Release and Hsp 70 Expression in Cultured Rat Islets Exposed to IL-1betabeta.: Kyu Chang Won, Mi Jung Eun, Jae Hong Kim, Jung Hyun Oh, Sang Yub Nam, Ji Sung Yoon, Hyun Dae Yoon, In Ho Cho, Hyoung Woo Lee; Korean Diabetes J. 2001;25(4):273-285. Published online August 1, 2001

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Abstract PDF: BACKGROUND
IL-1beta has been implicated to play an important role in the autoimmune beta cell lesion of type 1 diabetes because of its inhibition of insulin secretion and direct islet cytotoxicity. Thus, this study evaluated the effect of aminoguanidine on No production, insulin release and hsp 70 expression in cultured rat islets exposed to IL-1beta. METHOD: Islets isolated from Sprague-Dawley rats were cultured with IL-1beta , aminoguanidine AG and GSNO, individually and in combination for 24hours. Accumulated nitrite production, insulin release and islet expression of hsp 70 were measured. RESULTS: IL-1beta increased nitrite production, inhibited insulin release, and increased hsp 70 expression. AG alone had no effect on nitrite production, insulin release and hsp 70 expression. In combination, AG completely blocked IL-1beta but increased nitrite production, reversed IL-1beta inhibited insulin release and reversed IL-1beta increased hsp 70 expression. Moreover, nitric oxide NO donor, GSNO stimulated hsp 70 expression. CONCLUSION: Findings from this study suggest that hsp 70 may be one potential protein that is expressed in response to NO and that participates in islet recovery from NO mediated islet damage.

Effect of Aminoguanidine on Lipid Peroxidation in Streptozotocin-induced Diabetic Rats.: Kwon Yeop Lee, Sung Hee Ihm, Hyung Joon Yoo, Sung Woo Park, Ja Hei Ihm; Korean Diabetes J. 1997;21(4):372-380. Published online January 1, 2001

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Abstract PDF: BACKGROUND
Diabetes mellitus is postulated to be associated with increased lipid peroxidation which may contribute to vascular complications. One potential mechanism of the increased lipid peroxidation in diabetes is lipid-linked advanced glycosylation and oxidation. Aminoguanidine(AMGN), the prototype inhibitor of advanced glycosylation end-product formation, has been recently shown to prevent oxidative moditication of LDL in vitro at moderate concentration. It is unknown whether AMGN might act as an anti-oxidant against lipid peroxidation under hyperglycemia in vivo. METHODS: To investigate the in vivo effect of AMGN on lipid peroxidation in diabetes, we administered AMGN(1 g/L in drinking water) or vitamin E (400mg/day, 5 days/week) to streptozotocin(STZ)-induced diabetic rats for 9 weeks and measured plasma lipid hydroperoxides by ferrous oxidation with xylenol orange II method and RBC membrane malon-dialdehyde(MDA) by thiobarbituric acid method. RESULTS: Plasma lipid hydroperoxide level was higher in STZ-induced diabetic rats than in control rats(7.53+/-2.03 vs.5.62+/-0.44*pmol/L). RBC membrane MDA was also higher in STZ-induced diabetic rats than in control rats(2.67+/-0.46 vs. 1.81+/-0.19* nmol/mL). Plasma lipid hydroperoxide level was lower in AMGN-treated(6.23+/-0.59*umol/L) and vitamin E-treated(5.29+/-0.27*umol/L) diabetic rats than in untreated diabetic rats. RBC membrane MDA was also lower in AMGN-treated(1.93+/-0.12""'nmol/ mL) diabetic rats than in untreated diabetic rats. There was no significant difference in plasma glucose, triglyceride levels among diabetic groups(Mean +/-S.D; *, P<0.05 vs. untreated STZ-induced diabetic rats; n=8-14/group). CONCLUSION: Although the mechanisms of action of AMGN on lipid peroxidation in vivo should be studied further, these results suggest that AMGN might have an additional beneficial effect as an antioxidant against lipid peroxidation in prevention trial for diabetic vascular complications.

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