Effect of gamma-tocotrienol on blood pressure, lipid peroxidation and total antioxidant status in spontaneously hypertensive rats (SHR)

The aim of this study was to determine the effects of gamma tocotrienol on lipid peroxidation and total antioxidant status of spontaneously hypertensi ve rats (SHR), comparing them with normal Wistar Kyoto (WKY) rats. SHR were divided into three groups and treated with different doses of gamm a tocotrienol (gamma 1, 15 mg/kg diet; gamma 2, 30mg/kg diet and gamma 3, 1 50mg/kg diet). Normal WKY and untreated SHR were used as normal (N) and hyp ertensive control (HC). Blood pressure were recorded every fortnightly for three months. At the end of the trial, animals were killed and measurement of plasma total antioxidant status, plasma superoxide dismutase (SOD) activ ity and lipid peroxide levels in plasma and blood vessels were carried out following well established methods. Study shows that lipid peroxides were significantly higher in hypertensive plasma and blood vessels compared to that of normal rats (Plasma- N: 0.06+/ -0.01, HC: 0.13+/-0.008; p<0.001, B1. Vessels - N: 0.47+/-10.17, HC: 0.96+/ -0.37; p<0.001). SOD activity was significantly lower in hypertensive than normal rats (N=148.58+/-29.56 U/ml, HC=110.08+/-14.36 U/ml; p=0.014). After three months of antioxidant trial with gamma-tocotrienol, it was found tha t all the treated groups have reduced plasma lipid peroxides concentration but was only significant for group gamma 1 (gamma 1: 0.109+/-0.026, HC: 0.1 32+/-0.008; p=0.034). On the other hand, lipid peroxides in blood vessels r educed significantly in all treated groups (gamma 1; p<0.05, gamma 2; p<0.0 01, gamma 3; p<0.005). All the three treated groups showed improve total an tioxidant status (p<0.001) significantly. SOD activity also showed signific ant improvement in all groups (gamma 1: p<0.001, gamma 2: p<0.05, gamma 3: p<0.001). Correlation studies showed that, total antioxidant status (TAS) and SOD wer e significantly negatively correlated with blood pressure in normal rats (p =0.007; p=0.008) but not in SHR control. This correlation regained in all t hree groups SHR's after treatment with tocotrienol. Lipid peroxides in bloo d vessel and plasma showed a positive correlation with blood pressure in no rmal and SHR control. This correlation also remains in treated groups signi ficantly except that in gamma 3 where positive correlation with plasma lipi d peroxide was not significant. In conclusion it was found that antioxidant supplement of gamma-tocotrienol may prevent development of increased blood pressure, reduce lipid peroxide s in plasma and blood vessels and enhanced total antioxidant status includi ng SOD activity.