Nishida Kentaro, Yasuda Eri, Nagasawa Kazuki, Fujimoto Sadaki
Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
Biol Pharm Bull. 2008 May;31(5):857-60. doi: 10.1248/bpb.31.857.
Previously, we revealed that theanine, a green tea component, induced phospholipase C (PLC)-beta1 and -gamma1, stress-responsible molecules, in primary cultured rat cerebral cortical neurons, suggesting its protective effect on oxidative stress in neurons. In this study, we investigated whether the same favorable effect occurs in vivo. On the oral administration of theanine (10 mmol (1.74 g)/kg, once a day) to rats via gastric intubation for 2 weeks, there was no change in the weight of the body or the cerebral cortex (Cx), cerebellum (Cb), or hippocampus (Hip) in the brain. On assessment of oxidation levels in the brain with thiobarbiturate reactive substances as a marker, the levels were found to be 20% lower in the Cx of theanine-treated rats than in that of control ones. The protein expression levels of PLC-beta1 and -gamma1 were significantly increased in the Cx on theanine administration and the same tendency was observed in the Cb, but not the Hip. In addition, the protein expression level of PLC-delta1, which plays an opposite role to the other two isozymes, was not affected in any brain regions on theanine administration. Overall, it was demonstrated that theanine is a safe compound and its repeated oral administration reduces oxidation levels in the brain, especially the Cx, by increasing PLC-beta1 and -gamma1 protein expression, suggesting its favorable effect on the brain in vivo.
此前，我们发现绿茶成分茶氨酸可在原代培养的大鼠大脑皮质神经元中诱导产生磷脂酶C（PLC）-β1和-γ1，这两种分子与应激反应相关，提示其对神经元氧化应激具有保护作用。在本研究中，我们调查了在体内是否也会出现同样的有益效果。通过胃管向大鼠每日口服一次茶氨酸（10 mmol（1.74 g）/kg），持续2周，大鼠的体重以及大脑中的大脑皮质（Cx）、小脑（Cb）或海马体（Hip）均未发生变化。以硫代巴比妥酸反应性物质为标志物评估大脑中的氧化水平，发现茶氨酸处理组大鼠大脑皮质中的氧化水平比对照组低20%。给予茶氨酸后，大脑皮质中PLC-β1和-γ1的蛋白表达水平显著升高，小脑也观察到相同趋势，但海马体未出现此趋势。此外，与其他两种同工酶作用相反的PLC-δ1的蛋白表达水平在给予茶氨酸后，在任何脑区均未受到影响。总体而言，结果表明茶氨酸是一种安全的化合物，其反复口服给药可通过增加PLC-β1和-γ1的蛋白表达来降低大脑尤其是大脑皮质中的氧化水平，提示其在体内对大脑具有有益作用。
