The Effect of Different Oral Doses of Hydroalcoholic Extract of Silymarin on the Blood Oxidative Stress Indicators in Streptozotocin Induced Diabetic Rats

Antioxidant and anti-inflammatory effect of olive leaf extract treatment in diabetic rat brain

OBJECTIVES

Olive (Olea europaea L.) plays a promising role in pharmaceutical, nutraceutical, and cosmetic production. On the other hand, olive leaf is widely used in folk medicine due to its antihyperglycemic activity. For this aim, possible effects of olive leaf extract (OLE) in the brain tissue of streptozotocin-induced diabetic rats were investigated.

METHODS

A total of 28 male rats were divided into four equal groups as control, diabetic (single dose of 45 mg/kg streptozotocin, i.p.), OLE (500 mg/kg/day), and diabetic + OLE groups. The study was terminated 21 days after the diabetes model was formed. At the end of the study, all the animals were sacrificed and blood and brain tissues were isolated. Relative brain weights, complete blood count, blood glycated hemoglobin, serum glucose, total protein, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, insulin, gonadal hormone levels, production and messenger ribonucleic acid (mRNA) levels of proinflammatory cytokines and mediators, total thiol, total oxidative stress, and total antioxidant status levels and fatty acid composition in brain tissue were measured in all study groups.

RESULTS

In diabetic rats, relative brain weight and serum insulin level decreased, glycated hemoglobin, oxidative stress, production and mRNA level of proinflammatory cytokines and mediators increased, hyperglycemia, hypercholesterolemia and hypertriglyceridemia, degraded fatty acid composition, anemia, leukopenia, and thrombocytopenia occurred. After OLE treatment, a remarkable improvement in most of these parameters, except gonadal hormones, has been observed in diabetic rats.

CONCLUSIONS

This study suggests that olive leaf can be a precious neuroprotective agent in diabetes.

The susceptibility to autoxidation of erythrocytes in diabetic mice: Effects of melatonin and pentoxifylline

Oxidative stress had a great importance in development of complications in diabetes. We investigated effects of melatonin and pentoxifylline in diabetic mice. Swiss albino mice (n = 40) were divided into four groups: alloxan-induced diabetes mellitus (DM), alloxan-induced diabetes with melatonin supplementation (DM + MLT), alloxan-induced diabetes with pentoxifylline supplementation (DM + PTX), and control. Glutathione-peroxidase (GSH-Px) activity, malondialdehyde (MDA) and reduced glutathione (GSH) levels, and susceptibility to oxidation of erythrocytes were measured. MDA levels were higher than control in the DM and DM + MLT. The DM had more MDA level than the DM + MLT and DM + PTX (P < 0.001). After in vitro oxidation, MDA levels of all groups were found higher than the control. However, they were significantly lower than the DM in DM + PTX and DM + MLT (P < 0.001). Although GSH levels of the DM and DM + PTX were less than the control, GSH-Px activity of the DM was lower than the control and DM + PTX (P < 0.05). We suggest that there is increased oxidative stress and compromised antioxidant status of erythrocytes in diabetes; however, it can be effectively prevented by melatonin or pentoxifylline supplementation.