Evaluation of the protective effects of tocotrienol-rich fraction from palm oil on the dentate gyrus following chronic restraint stress in rats

Abstract

Exposure to chronic restraint stress has been shown to cause a number of morphological changes in the hippocampal formation of rats. Tocotrienol, an isoform of vitamin E, exhibits numerous health benefits, different from those of tocopherol. Recent studies have demonstrated that tocotrienol prevents stressinduced changes in the gastric mucosa, thus indicating that it may also protect other organs such as the brain from the damaging effects of stress. Therefore, the aim of the present study was to investigate the protective effect of tocotrienol-rich fraction (TRF) extracted from palm oil on the dentate gyrus of rats following exposure to chronic restraint stress. Thirty-six male Sprague Dawley rats were divided into four groups: control, stress, tocotrienol and combination of stress and tocotrienol. Animals were stressed by restraining them for 5 hours every day for 21 consecutive days. TRF was administered via oral gavage at a dose of 200 mg/kg body weight. Our results showed that the plasma corticosterone level was significantly increased in response to stress, compared to the control. The results confirmed previous findings that chronic restraint stress suppresses cellular proliferation and reduces granule cell number in the dentate gyrus. However, TRF supplementation failed to prevent or minimize these stressinduced changes. Therefore, we conclude that TRF at the current dosage is not effective in preventing the morphological changes in the dentate gyrus induced by chronic restraint stress.Uniterms: Tocotrienol. Tocotrienol rich fraction. Restraint stress. Dentate gyrus. Hippocampus.A exposição crônica ao estresse por restrição causa série de alterações morfológicas na formação do hipocampo de ratos. Tocotrienol, uma isoforma da vitamina E, apresenta inúmeros benefícios para a saúde, diferente do tocoferol. Estudos recentes demonstraram que o tocotrienol impediu alterações induzidas por estresse na mucosa gástrica, indicando, assim, a possibilidade de que ele pode, também, proteger outros órgãos, como o cérebro, dos efeitos nocivos do estresse. Dessa forma, o objetivo do presente estudo foi investigar o efeito protetor da fração rica em tocotrienol (TRF), extraída do óleo de palma, no giro denteado após exposição crônica ao estresse por restrição. Trinta e seis ratos machos Sprague Dawley foram divididos em quatro grupos: controle, estresse, tocotrienol e combinação de estresse e tocotrienol. Os animais foram estressados por restrição, 5 horas por dia, durante 21 dias consecutivos. TRF foi administrado por gavagem oral na dose de 200 mg/kg de peso corporal. Nossos resultados mostraram que o nível de corticosterona plasmática foi significativamente aumentado em resposta ao estresse em comparação ao controle. Os resultados confirmam os achados anteriores de que o estresse por restrição suprime a proliferação celular e reduz o número de células granulares do giro denteado. No entanto, a suplementação de TRF foi ineficaz para evitar ou minimizar as alterações induzidas por estresse. Assim, concluímos que TRF na ...

Safety and Neuroprotective Efficacy of Palm Oil and Tocotrienol-Rich Fraction from Palm Oil: A Systematic Review

“…However, the ad libitum 100 mg/kg of diet-admixed TRF significantly enhanced the cognitive function of young rats [34]. However, the oral daily dose of 200 mg/kg of TRF in healthy stressed and unstressed rats for 5 weeks did not alter the proliferation and survival of granular cells in the dentate gyrus of the hippocampus [37], which could support the hypothesis of the poor penetration of tocotrienols through the blood-brain barriers, depending on the maturity of blood-brain barriers between adults and natal animals and the situation of the health status of the blood-brain barriers [50].…”

“…A five-week single oral daily dose (200 mg/kg) of TRF was also shown to improve morphological features in parts of the brain of rats. Accordingly, it induced significant proliferation of granular cells in the dentate gyrus in the hippocampus of chronic stressed or unstressed healthy male Sprague-Dawley rats [37], ( Table 7).…”

Effect of Tocotrienol Rich Fraction (TRF) on synaptogenic molecules in aging Caenorhabdis elegans

“…Tocotrienols have unsaturated isoprenoid side-chains with double bonds in the 3', 7' and 11' positions that occur naturally in esterified forms [18]. It has been found to have strong neuroprotective properties, independent of their antioxidant activities [19].…”