The effects of chronic L-arginine treatment on vascular responsiveness of streptozotocin-diabetic rats

Abstract

In this study, the protective effects of L-arginine treatment in vivo on vascular reactivity of streptozotocin (STZ)-induced 12-week-old diabetic rats were examined. Loss of weight, polydipsia, polyphagia, hyperglycemia, hypoinsulinemia, and elevated levels of plasma cholesterol and triglyceride were observed in diabetic rats. L-arginine treatment (1 mg/mL in drinking water) did not significantly affect these metabolic and biochemical abnormalities. Plasma malondialdehyde (MDA) levels in untreated diabetic rats were also significantly higher than untreated controls. However, L-arginine treatment prevented the increase in MDA level of plasma of diabetic rats. Contractile responses, but not sensitivity to noradrenaline (NA), were significantly increased in diabetic rats compared to controls. Treatment of diabetic rats with L-arginine completely prevented the increase in NA responses. Relaxation response to acetylcholine (ACh), but not to sodium nitroprusside (SNP), in diabetic aorta has been found to be significantly decreased as compared with controls. However, there were no significant differences in pD 2 values of acetylcholine in either of the groups. L-arginine treatment increased the ACh responses to the control level. All effects of L-arginine on vascular reactivity were found to be specific for diabetic rats and not controls. These results suggest that functional abnormalities occurred in aorta from diabetic rat might at least in part result from L-arginine deficiency, and the lipid peroxidation-lowering effect of L-arginine may account for its protective effect on vascular reactivity of diabetic rats.

Protective Effect of Ethanolic Extract of Gongronema Latifolium Leaves in Alloxan-Induced Diabetic Rats

“…This finding appears to be consistent with the previous report of World Health Organization, that diabetes mellitus is often characterized by rapid and significant weight loss leading to fatigue [17,18]. Other researchers have also reported that diabetes mellitus is characterized by a progressive weight loss and some plant extracts are known to reverse the weight loss to near normal [19,20,21]. The weight loss observed may be attributed to the loss in muscle and adipose tissue resulting from excessive breakdown of tissue protein and fatty acids [21,22].…”

Alpha Lipoic Acid Treatment Improved Endothelium-dependent Relaxation in Diabetic Rat Aorta

“…23) The results of this study revealed that the endothelium-dependent relaxant response was reduced in aortas from STZ-induced diabetic rats. Although some researchers asserted that the sensitivity to ACh decreased in diabetes, 24,25) the results of this research, in accordance with those of many previous ones, 21,25,26) revealed that diabetes decreased the responses to ACh in maximum relaxation but not the sensitivity.…”

Δ9-tetrahydrocannabinol treatment improved endothelium-dependent relaxation on streptozotocin/nicotinamide-induced diabetic rat aorta

“…Although, some researchers demonstrated that the maximum relaxation response of Ach decreased but not the sensitivity in diabetes (28,34). The results of the present study, in accordance with others (12,15) revealed that diabetes decreased the maximum relaxation and the sensitivity of Ach.…”