Protective Antioxidant and Antiapoptotic Effects of ZnCl2 in Rat Pancreatic Islets Cultured in Low and High Glucose Concentrations
(2012) PLoS One — Vol. 7, n° 10, p. e46831 (2012)
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- Aim/Hypothesis: Rat pancreatic islet cell apoptosis is minimal after prolonged culture in 10 mmol/l glucose (G10), largely increased in 5 mmol/l glucose (G5) and moderately increased in 30 mmol/l glucose (G30). This glucose-dependent asymmetric V-shaped profile is preceded by parallel changes in the mRNA levels of oxidative stress-response genes like Metallothionein 1a (Mt1a). In this study, we tested the effect of ZnCl2, a potent inducer of Mt1a, on apoptosis, mitochondrial oxidative stress and alterations of glucose-induced insulin secretion (GSIS) induced by prolonged exposure to low and high vs. intermediate glucose concentrations. Methods: Male Wistar rat islets were cultured in RPMI medium. Islet gene mRNA levels were measured by RTq-PCR. Apoptosis was quantified by measuring islet cytosolic histone-associated DNA fragments and the percentage of TUNELpositive b-cells. Mitochondrial thiol oxidation was measured in rat islet cell clusters expressing ‘‘redox sensitive GFP’’ targeted to the mitochondria (mt-roGFP1). Insulin secretion was measured by RIA. Results: As observed for Mt1a mRNA levels, b-cell apoptosis and loss of GSIS, culture in either G5 or G30 vs. G10 significantly increased mt-roGFP1 oxidation. While TPEN decreased Mt1a/2a mRNA induction by G5, addition of 50–100 mM ZnCl2 to the culture medium strongly increased Mt1a/2a mRNA and protein levels, reduced early mt-roGFP oxidation and significantly decreased late b-cell apoptosis after prolonged culture in G5 or G30 vs. G10. It did not, however, prevent the loss of GSIS under these culture conditions. Conclusion: ZnCl2 reduces mitochondrial oxidative stress and improves rat b-cell survival during culture in the presence of low and high vs. intermediate glucose concentrations without improving their acute GSIS.
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Duprez, J., Roma, L. P., Close, A.-F., & Jonas, J.-C. (2012). Protective Antioxidant and Antiapoptotic Effects of ZnCl2 in Rat Pancreatic Islets Cultured in Low and High Glucose Concentrations. PLoS One, 7(10), e46831. https://doi.org/10.1371/journal.pone.0046831 (Original work published 2012)