Effects of green tea supplementation on oxidative damage induced by exhaustive exercise in rat liver

Introduction

Tea is the most popular beverage consumed in china. The green tea constituent (-)-epigallocatechin-3-gallate (EGCG) is a potent antioxidant. Exhaustive exercise may promote the formation of reactive oxygen species and subsequently contribute to tissue damage. The purpose of this study was to investigate the exhaustive exercise-induced oxidative stress and the protective effect of supplementation of green tea on malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GPx) in rat liver.

Methods

Thirty two male Sprague-Dawley rats were randomly divided into the following four groups : 1.control (C, n=8), 2.exhaustive exercise(E, n=8),3.green tea(G, n=8), 4.green tea-exhaustive exercise (GE,=n=8).The amount of green tea supplementation was .494g/day for four weeks. The exhaustive exercise started at 10% grade, 15 m/min for 10 min followed by gradual increases of treadmill speed and times as 25 m/min for 40 min, 28 m/min for 20 min, 31 m/min for 20 min, 34 m/min for 20 min, 37 m/min for 20 min, until exhaustive. Exercised duration in E and GE groups were 69.39 17.1 and 61.21 10.11minutes, respectively.Two way ANOVA was performed to examine the effects of exhaustive exercise and green tea supplementation on MDA, SOD, GSH, and GPx activities.

Results

The results showed that MDA in the control rat liver (2.36 .39 mg/ml) significant higher (p<.05) than E group (1.55 .19 mg/ml),G group (1.73 .43 mg/ml) and GE group (1.58 .46 mg/ml). GSH activity of rat liver in exhaustive exercise group (.65±.16 mg/ml) was significant lower (p< .05) than non-exhaustive exercise group (.75±.12 mg/ml), while GSH activity in non-green tea supplemental group (.76±.10 mg/ml) was significant higher (p< .05) than green tea supplemental group (.64±.16 mg/ml). Moreover, GPx activity of rat liver in exhaustive exercise group (7863.66±675.44 mU/ml) was significant higher (p< .05) than GE group (5801.50±1961.52 mU/ml), while there were no significant different in GPx activity among C, E, and G groups.

Discussion/Conclusions

It is concluded that exhaustive exercise could not result in oxidative stress in rat liver. And, green tea supplementation is not beneficial to increase antioxidant status.
Supported by National Science Council, Grant # 91-2413-H-134-010.

References

[1]. Han DW, et al. (2003). Artif Organs. 27(12):1137-42.
[2]. Yanagimoto K, et al. (2003). J Agric Food Chem. 51(25):7396-401.
[3]. Jiao HL, et al. (2003). Free Radic Biol Med. 35(9):1121-8.