The authors say that their findings confirm earlier studies suggesting that the vitamin E could protect against stroke in vivo.
In a previous study, Professor Chandan Sen from the OSU Medical Center showed that the tocotrienol crosses the blood-brain barrier and in neuronal cells, nanomolar levels of alpha-tocotrienol but not alpha-tocopherol (the better-known form of vitamin E) blocked glutamate-induced cell death.
Glutamate-induced toxicity is a major contributor to pathological cell death within the nervous system.
For the new trial, conducted at the Ohio State University Medical Center and funded by the National Institutes of Health, Professor Sen's team supplemented hypertensive rats with the Tocomin brand tocotrienol complex. The tocotrienols are derived from palm oil by Malaysian firm Carotech.
This animal model is commonly used in stroke research as hypertension is one of the major risk factors for stroke.
The brain infarct volume was measured 24 hours subsequent to stroke.
Oral supplementation with Tocomin in the rats led to increased brain levels of tocotrienols and this group showed more protection against stroke-induced injury compared to unsupplemented controls, they write in this month's issue of Stroke (36, e144-152).
The neuroprotective effect was associated with suppression of stroke-associated c-Src activation, which is a key mechanism that contributes to neurodegeneration, said the researchers.
Professor Sen also showed that 12-lipoygenase proved to be critical in executing neuron deaths. Tocotrienol lowers the tyrosine phosphorylation of 12-lipoxygenase and hence protects the neurons from apoptosis.
"Attention to the naturally occurring tocotrienols, especially to their neuroprotective properties, could well provide us with a powerful tool to combat neurodegeneration, especially stroke, by safe dietary means," said Professor Sen.