Endocrine Abstracts

Diabetes is associated with an oxidative stress (OS). Free radicals are responsible of β-cell destruction in type 1 diabetes and their dysfunction in type 2. The purpose of this work is to evaluate preventive effect of antioxidative natural compounds on several models of OS induced on β-cells.

The models of oxidative stress were performed with 40 μmol/l H₂O₂ for 30 min, with a mixture of 0.25 mmol/l hypoxanthine and 10 mU/ml xanthine oxidase (HX/XO) for 1 h and with 25 mmol/l streptozotocine (STZ) for 2 h. Antioxidative molecules used were polyphenolic extracts from red wine (RWPs) at 150 μg/ml and green tee extract, epigallocatechine gallate (EGCG) at 500 μg/ml. Cell viability was measured using cell proliferation assay (Cell Titer, Promega), H₂O₂ intracellular production by flow cytometry (DCFH-DA) and expression of antioxidative enzymes catalase (CAT) and superoxide dismutase (SOD) by western blotting.

OS induced by H₂O₂, leads to a significant loss of cell viability of about 80% (P<0.001) associated to an increase of intracellular H₂O₂ (P<0.05) and a decrease of CAT expression. RWPs and EGCG have permit to maintain cell viability but only EGCG decreases intracellular H₂O₂ and only RWPs decreases SOD expression. STZ induces a decrease of cell viability, of intracellular H₂O₂ (P<0.05), of SOD expression but an increase of CAT expression. Both antioxidants maintain cell viability, but only EGCG decreases the expression of both enzymes. HX/XO leads to a significant loss of cell viability of about 80% (P<0.001), induces intracellular H₂O₂ production and an overexpression of CAT. Both antioxidants improve cell viability and only RWPs allows an overexpression of SOD.

These results showed that natural antioxidant molecules could prevent oxidative stress induced on RINm5F cells by different way. Antioxidant regimen could improve β-cells viability and could be a new strategy to protect β-cells during diabetes.