Tocopherol in brain metabolism and disease: a review

Nano-antioxidants: An emerging strategy for intervention against neurodegenerative conditions

Oxidative stress has for long been linked to the neuronal cell death in many neurodegenerative conditions. Conventional antioxidant therapies have been less effective in preventing neuronal damage caused by oxidative stress due to their inability to cross the blood brain barrier. Nanoparticle antioxidants constitute a new wave of antioxidant therapies for prevention and treatment of diseases involving oxidative stress. It is believed that nanoparticle antioxidants have strong and persistent interactions with biomolecules and would be more effective against free radical induced damage. Nanoantioxidants include inorganic nanoparticles possessing intrinsic antioxidant properties, nanoparticles functionalized with antioxidants or antioxidant enzymes to function as an antioxidant delivery system. Nanoparticles containing antioxidants have shown promise as high-performance therapeutic nanomedicine in attenuating oxidative stress with potential applications in treating and preventing neurodegenerative conditions. However, to realize the full potential of nanoantioxidants, negative aspects associated with the use of nanoparticles need to be overcome to validate their long term applications.

Protective effect of 21-aminosteroid pretreatment in peripheral nerve low-load crush injury in mature and immature rats

The effects of U-74006F (tirilazad mesylate), a 21-aminosteroid antioxidant, on injured peripheral nerve were studied. Twenty-two immature and 44 mature rats were divided equally into two groups. The experimental group received two injections of 3 mg/kg of U-74006F at a 2 hour interval. The control group received the same volumes of a citrate buffer. A 5 mm segment of the sciatic nerve was subjected to a crush load of 100 g for 2 hours. Motor function (sciatic functional index) was assessed to day 48 postoperatively. There was total paralysis of the crushed limb in all rats the first week after crushing. The experimental group had a statistically significant improvement in motor function compared with the controls on days 14, 21, 25, and 28 for the mature rats and on days 11 and 14 for the immature rats. The mature controls attained complete recovery on day 42 and had a significantly slower recovery rate than the immature controls, which had recovered fully by day 25. The recovery rates were almost similar among mature and immature groups pretreated with U-74006F, both of which had fully recovered motor function by day 28. The results indicate that pretreatment with U-74006F can significantly promote peripheral nerve function after low-load crush injury and that the age of the animal influences the rate of peripheral nerve recovery.

Serum levels of ascorbic acid (vitamin C) in patients with Parkinson's disease

To elucidate the possible role of vitamin C in the risk for developing Parkinson's disease (PD), we compared serum levels of ascorbic acid (vitamin C), measured by a fluorometric method, of 63 PD patients using their spouses as the control group. The serum levels of vitamin C did not differ significantly between the groups (47.13 +/- 0.89 micrograms/ml for PD and 47.60 +/- 0.60 micrograms/ml for controls). There was no influence of antiparkinsonian therapy on vitamin C. Serum levels of vitamin C did not correlate with age, age at onset and duration of the disease, scores of the Unified PD Rating Scale or the Hoehn and Yahr staging in the PD group. These results suggest that serum vitamin C concentrations are apparently unrelated to the risk of developing PD.

Lipid peroxidation does not appear to be a factor in late radiation injury of the cervical spinal cord of rats

PURPOSE

We tested the role of lipid peroxidation in the demyelination and white matter necrosis associated with radiation injury of the central nervous system.

METHODS AND MATERIALS

We irradiated the cervical spinal cords of female F344 rats (23 Gy) and assayed for the accumulation of the peroxidation byproducts malondialdehyde and hydroxyeicosatetraenoic acids, and for the consumption of the endogenous free radical scavengers vitamins E and C. We further tested the role of lipid peroxidation in radiation injury of the central nervous system by determining the sensitivity of the cervical spinal cord to radiation in rats on diets containing deficient, normal, and supplemental levels of the antioxidant vitamin E. Rats were placed on these diets at 4 weeks of age and irradiated (18.5-21.5 Gy) 16 weeks later.

RESULTS

During the 5 months between irradiation and the onset of paralysis, no accumulation of peroxidation byproducts or consumption of endogenous scavengers was seen in the cervical spinal cords of the irradiated rats. The cervical spinal cords of some of the rats placed on the diets with deficient, normal, and supplemental levels of vitamin E were analyzed at the time of irradiation and contained 197 +/- 57, 501 +/- 19, and 717 +/- 35 pmol vitamin E/mg protein, respectively. Despite the statistical differences in these levels, the radiation sensitivity of the cervical spinal cord (ED50 for white matter necrosis) in rats receiving the three diets was not different (20.4, 20.7, and 20.6 Gy).

CONCLUSION

These data do not support a role for free radical-induced lipid peroxidation in the white matter damage seen in radiation injury of the central nervous system.

Intracerebral administration of alpha-tocopherol-containing liposomes facilitates behavioral recovery in rats with bilateral lesions of the frontal cortex

Adult rats with bilateral frontal cortex lesions received intracerebral infusion of phosphatidylcholine liposomes, or D-alpha-tocopherol-enriched liposomes, delivered continuously for 7 days to the damaged cortex by subcutaneous osmotic pumps. All subjects were first tested on a delayed spatial alternation task and then, 90 days later, on a spatial navigation task in the Morris water maze. Both tests showed that brain-injured rats with alpha-tocopherol treatment were less impaired than counterparts treated with plain liposomes. Alpha-tocopherol also reduced some of the injury-induced, secondary reactive changes that typically follow damage to the frontal cortex.

Necrotizing myopathy with paracrystalline inclusion bodies in hypervitaminosis E

A necrotizing, nonprogressive myopathy with unusual paracrystalline inclusion bodies is described in a patient who underwent long-term treatment with megadoses of vitamin E. The clinical course and morphological findings suggest a close relationship to the administration of the vitamin. The theoretical pathogenesis of muscle damage and the possible origin of paracrystalline inclusion bodies are discussed.