Crocin Protects Mice Pancreatic Islets from Oxidative Stress Induced by Methylglyoxal and Increases Insulin Secretion

Abstract

Aim: Islets of Langerhans are more sensitive to oxidative damage because of their low antioxidant capacity. In diabetes, methylglyoxal (MG) accumulates in the pancreas. The present study examined the effect of crocin on oxidative stress induced by MG in isolated Langerhans islets from male mice.
 Material and Methods: Twenty-four male mice weighing 20 to 25 g were prepared. The isolated Langerhans islets were transferred to the culture medium. Oxidative stress was induced through MG administration for 30 min, and then 10, 20, 30, and 40 μM of crocin was used for 2 h. Samples were divided into seven groups with 2.8, 5.6, and 16.7 mM glucose concentrations: control, MG 300 μM, MG+glibenclamide 10 μM, and MG+crocin in four doses of 10, 20, 30, and 40 μM. At the end, the islet’s insulin, antioxidant levels, and lipid peroxidation were assessed by ELISA and calorimetry methods.
 Results: Increased levels of malondialdehyde (MDA) in MG groups significantly decreased in 2.8 (p=0.008), 5.6 (p=0.004), and 16.7 (p˂0.001) mM glucose concentrations, with administration of 30 and 40 μM crocin. Total antioxidant capacity (TAC) was reduced in MG groups (p˂0.001) and significantly restored in all crocin-treated groups in 2.8, 5.6, and 16.7 mM glucose concentrations. Also, a significant decrease in insulin secretion and content was observed in MG groups of all three glucose concentrations (p˂0.001). Crocin at high doses improved these alterations.
 Conclusion: MG caused oxidative damage and reduced insulin secretion in isolated islets. Crocin improved the antioxidant defense system, diminished MDA, and increased insulin secretion.