Protective antioxidant and antiapoptotic effects of ZnCl2 in rat pancreatic islets cultured in low and high glucose concentrations.
OBJECTIVE
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 ZnCl(2), 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 ZnCl(2) 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.


CONCLUSIONS
ZnCl(2) 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.
Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium.
Jessica
J
Duprez
Leticia P
LP
Roma
Anne-Françoise
AF
Close
Jean-Christophe
JC
Jonas
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques; D002614:Chelating Agents / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013997:Time Factors; D017967:Zinc Compounds / Q000494:pharmacology*; D000075703:Zinc Transporter 8
D000975:Antioxidants; D027682:Cation Transport Proteins; D002614:Chelating Agents; D002712:Chlorides; D007328:Insulin; D012333:RNA, Messenger; C542071:Slc30a8 protein, rat; D013438:Sulfhydryl Compounds; D017967:Zinc Compounds; D000075703:Zinc Transporter 8; C092392:Slc30a1 protein, rat; C016837:zinc chloride; D008668:Metallothionein; D005947:Glucose