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Effects of natural free radical scavengers on peripheral nerve and neurovascular function in diabetic rats
1Department of Biomedical Sciences, University of Aberdeen, Scotland.
Abstract:
Increased generation of reactive oxygen species, coupled with impaired endogenous scavenging mechanisms, plays a prominent role in the aetiology of neurovascular abnormalities in experimental diabetes mellitus. We examined the efficacy of the natural anti-oxidants vitamins C, E and beta-carotene in preventing nerve conduction and nutritive blood flow deficits in streptozotocin-diabetic rats. One month of diabetes caused a 19.1% reduction in sciatic motor conduction velocity (p < 0.001). This was approximately prevented 80-90% by high-dose (1000 mg.kg-1.day-1) vitamin E and beta-carotene treatments (p < 0.001). Vitamin C had lesser effects; the maximum protection found for motor conduction velocity was 36% using a dose of 150 mg.kg-1.day-1 (p < 0.001). High dose (500 mg.kg-1.day-1 (p < 0.001). High dose (500 mg.kg-1.day-1) vitamin C had a lesser effect on conduction than intermediate doses. Joint vitamin C and lower dose (500 mg.kg-1.day-1) vitamin E treatment had a predominantly additive preventive effect against nerve dysfunction. Resistance to hypoxic conduction failure for sciatic nerve in vitro was markedly increased by diabetes and this remained relatively unaffected by treatment. Sciatic nutritive endoneurial blood flow, measured using microelectrode polarography and hydrogen clearance, was reduced 46.1% by 1 month of diabetes (p < 0.001). This was prevented to the extent of 87%, 36% and 98% by vitamins E, C and beta-carotene, respectively (p < 0.01). These data emphasize the role of oxidative stress in the development of early neurovascular changes in experimental diabetes and show that naturally available scavengers have a neuroprotective action.
Insights
Antioxidants like vitamins E and beta-carotene significantly prevent nerve damage and blood flow reduction in diabetic rats. These natural compounds show neuroprotective effects against oxidative stress in experimental diabetes.
Area of Science:
- Neuroscience
- Endocrinology
- Biochemistry
Background:
- Oxidative stress from increased reactive oxygen species and reduced antioxidant defenses contributes to neurovascular issues in diabetes.
- Experimental diabetes mellitus is associated with neurovascular abnormalities.
Purpose of the Study:
- To evaluate the effectiveness of natural antioxidants (vitamins C, E, and beta-carotene) in preventing nerve conduction and nutritive blood flow deficits in streptozotocin-induced diabetic rats.
Main Methods:
- Streptozotocin-induced diabetic rat model.
- Assessment of sciatic motor conduction velocity.
- Measurement of sciatic nutritive endoneurial blood flow using microelectrode polarography and hydrogen clearance.
- Administration of varying doses of vitamins C, E, and beta-carotene.
Main Results:
- Diabetes caused significant reductions in sciatic motor conduction velocity (19.1%) and nutritive blood flow (46.1%).
- High-dose vitamin E and beta-carotene treatments largely prevented these deficits (80-90% for conduction, 87-98% for blood flow).
- Vitamin C showed a dose-dependent protective effect, with combined vitamin C and E demonstrating additive benefits.
Conclusions:
- Oxidative stress plays a key role in early neurovascular changes observed in experimental diabetes.
- Naturally occurring antioxidants, particularly vitamins E and beta-carotene, exhibit significant neuroprotective properties against diabetes-induced nerve dysfunction and reduced blood flow.