The potential role of combined antioxidant treatment on pancreas of STZ-diabetic mice

Hydroxysafflor yellow A attenuates high glucose-induced pancreatic β-cells oxidative damage via inhibiting JNK/c-jun signaling pathway

Pancreatic β-cells apoptosis and dysfunction induced by glucose toxicity were attributed to the formation of excess oxidative damage. Some studies have found that hydroxysafflor yellow A has strong effects to scavenge oxidative stress and inhibit apoptosis. In order to explore the influence of HSYA on oxidative stress induced by high glucose and the potential mechanisms, we set up a high glucose damage model and induced oxidative stress in INS-1 rat insulinoma cells. N-acetylcysteine was added as a group of oxidative stress scavenger. After 72 h of cultivation, the related indexes of oxidative stress (reactive oxygen species, catalase, glutathione peroxidase, lipid peroxidation, and superoxide dismutase), apoptosis (caspase3, parp) and the function of glucose stimulated insulin secretion were determined. In addition, the signaling pathway proteins of C-Jun NH2 -terminal kinases (JNK), phosphorylated JNK, C-jun, phosphorylated C-jun were evaluated. Fluorescence microscopy, qRT-PCR, western blotting were the main methods used in the experiment. Our results showed that hydroxysafflor yellow A reduced pancreatic β-cells apoptosis by attenuating oxidative damage, and JNK/c-Jun signaling pathway was involved. It indicated a significant mechanism for the positive impacts of HSYA on oxidative stress induced by high glucose, and provide important basis for using HSYA in diabetic prevention and therapy.

Maternal antioxidants prevent β-cell apoptosis and promote formation of dual hormone-expressing endocrine cells in male offspring following fetal and neonatal nicotine exposure

BACKGROUND

Fetal and neonatal nicotine exposure causes β-cell oxidative stress and apoptosis in neonates, leading to adult-onset dysglycemia. The aim of the present study was to determine whether an antioxidant intervention could prevent nicotine-induced β-cell loss.

METHODS

Nulliparous female Wistar rats received daily subcutaneous injections of either saline or nicotine bitartrate (1.0 mg/kg per day) for 2 weeks prior to mating until weaning. Nicotine-exposed dams received either normal chow or diet containing antioxidants (1000 IU/kg vitamin E, 0.25% w/w coenzyme Q10, and 0.1% w/w α-lipoic acid) during mating, pregnancy, and lactation; saline-exposed dams received normal chow. Pancreatic tissue was collected from male offspring at 3 weeks of age to measure β-cell fraction, apoptosis, proliferation, and the presence of cells coexpressing insulin and glucagon.

RESULTS

The birth weight of offspring born to nicotine-exposed dams was significantly reduced in those receiving dietary antioxidants compared with those fed normal chow. Most interestingly, the antioxidant intervention to nicotine-exposed dams prevented the β-cell loss and apoptosis observed in nicotine-exposed male offspring whose mothers did not receive antioxidants. Male pups born to nicotine-treated mothers receiving antioxidants also had a tendency for increased β-cell proliferation and a significant increase in islets containing insulin/glucagon bihormonal cells compared with the other two treatment groups.

CONCLUSION

The present study demonstrates that exposure to maternal antioxidants protects developing β-cells from the damaging effects of nicotine, thus preserving β-cell mass.