Protective Antioxidant and Antiapoptotic Effects of ZnCl2 in Rat Pancreatic Islets Cultured in Low and High Glucose ConcentrationsReport as inadecuate




Protective Antioxidant and Antiapoptotic Effects of ZnCl2 in Rat Pancreatic Islets Cultured in Low and High Glucose Concentrations - Download this document for free, or read online. Document in PDF available to download.

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 TUNEL-positive β-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, β-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 µM ZnCl2 to the culture medium strongly increased Mt1a-2a mRNA and protein levels, reduced early mt-roGFP oxidation and significantly decreased late β-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 β-cell survival during culture in the presence of low and high vs. intermediate glucose concentrations without improving their acute GSIS.



Author: Jessica Duprez, Leticia P. Roma, Anne-Françoise Close, Jean-Christophe Jonas

Source: http://plos.srce.hr/



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