Exercise Training and Grape Seed Extract Co-administration Improve Endothelial Dysfunction of Mesenteric Vascular Bed in STZ-induced Diabetic Rats

Health Effects of Grape Seed and Skin Extracts and Their Influence on Biochemical Markers

This review is focused on the study of the effects of grape seed and skin extract (GSSE) on human health. GSSE contains high concentrations of important polyphenolic substances with high biological activity. This review is a summary of studies that investigate the effects of GSSE on diabetes mellitus, cardiovascular disease and cancer, its neuroprotective effect, and its effects on the gastrointestinal tract and other health complications related to these diseases. The results of the studies confirm that the anti-inflammatory, antiapoptotic, and pro-proliferative effects of “Vitis vinifera L.” seed extract reduce the level of oxidative stress and improve the overall lipid metabolism.

Gallic acid improves endothelium-dependent vasodilatory response to histamine in the mesenteric vascular bed of diabetic rats

BACKGROUND

Endothelial dysfunction is one of the many complications caused by diabetes mellitus. The aim of the present study was to evaluate the effects of gallic acid (GA) on the mesenteric vascular bed (MVB) response to histamine in diabetic rats.

METHODS

Forty male Wistar rats were randomly assigned to a control group, an untreated alloxan-induced diabetic group and three diabetic groups treated with different doses of GA. Six weeks after induction of diabetes and GA treatment, total antioxidant capacity (TAC), malondialdehyde (MDA) concentrations, and the vasodilatory response to histamine of the MVB (measured as changes in perfusion pressure) were determined.

RESULTS

The vasodilatory response to histamine and TAC decreased, whereas MDA increased in the plasma from diabetic rats (P < 0.01). However, in the presence of 3 × 10^-5  mol/L N ^G -nitro-l-arginine methyl ester (a nitric oxide synthase inhibitor) and 1 × 10^-5  mol/L indomethacin (an inhibitor of prostaglandin production), the vasodilatory response of the MVB to histamine was reduced in all groups (P < 0.001). Treatment of diabetic rats with 20 and 40 mg/kg per day GA, but not 10 mg/kg per day GA, increased TAC and decreased MDA concentrations (P < 0.01 and P < 0.001 vs untreated diabetic rats, respectively) and significantly improved the vasodilatory response to histamine (P < 0.05 and P < 0.001, respectively).

CONCLUSION

The results show that, in diabetic rats, the endothelium-dependent vasodilatory response of the MVB to histamine is significantly decreased and depends on both nitric oxide- and prostaglandin-producing pathways and may be mediated by oxidative stress. Treatment with the antioxidant GA restored the vasodilatory response of the MVB to histamine.

Co-administration of Grape Seed Extract and Exercise Training Improves Endothelial Dysfunction of Coronary Vascular Bed of STZ-Induced Diabetic Rats

Background

One of the known complications of diabetes mellitus is vascular dysfunction. Inability of the coronary vascular response to cardiac hyperactivity might cause a higher incidence of ischemic heart disease in diabetic subjects. It has been indicated that regular exercise training and antioxidants could prevent diabetic cardiovascular problems enhanced by vascular damage.

Objectives

The aim of this study was to determine the effects of grape seed extract (as antioxidant), with and without exercise training on coronary vascular function in streptozotocin induced diabetic rats.

Materials and Methods

Fifty male Wistar rats weighing 200 – 232 grams were randomly divided into five groups of 10 rats each: sedentary control, sedentary diabetic, trained diabetic, grape seed extract (200 mg/kg) treated sedentary diabetic and, grape seed extract treated trained diabetic. Diabetes was induced by one intraperitoneal injection of streptozotocin. After eight weeks, coronary vascular responses to vasoactive agents were determined.

Results

The endothelium dependent vasorelaxation to acetylcholine was reduced significantly in diabetic animals; exercise training or grape seed extract administration partially improves this response. However, exercise training in combination with grape seed extract restores endothelial function completely. The endothelium independent vasorelaxation to sodium nitroprusside was improved by combination of exercise training and grape seed extract. On the other hand, the basal perfusion pressure and vasoconstrictive response to phenylephrine did not change significantly.

Conclusions

The data indicated that co-administration of grape seed extract and exercise training had more significant effects than exercise training or grape seed extract alone; this may constitute a convenient and inexpensive therapeutic approach to diabetic vascular complications.