L-茶氨酸对大鼠内脏组织抗氧化能力及相关基因表达的影响

目的:通过对大鼠灌胃L-茶氨酸溶液,观察大鼠心脏、肝脏、脾脏和肾脏中抗氧化指标的变化,探究L-茶氨酸对大鼠心、肝、脾和肾抗氧化能力及其相关酶mRNA表达量的影响。方法:64只SD大鼠随机分为对照组、低剂量组、中剂量组和高剂量组4组(每组16只,雌雄各半),分别灌胃0、50、200、400 mg/(kg·d)L-茶氨酸。连续灌胃14 d后采集内脏组织,采用试剂盒检测样品中丙二醛(malondialdehyde,MDA)与一氧化氮(nitric oxide,NO)的含量,以及超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GPX)、过氧化氢酶(catalase,CAT)和一氧化氮合成酶(nitric oxide synthase,NOS)的活性,并采用实时荧光定量聚合酶链反应(real-time fluorescence quantitative polymerase chain reaction,RT-q PCR)法测定相应抗氧化酶的mRNA表达量。结果:L-茶氨酸灌胃影响大鼠心脏组织的NO含量,以及SOD、CAT与NOS活力,其中高剂量组大鼠心脏组织中NO含量最低,SOD与CAT活力最大;同时影响大鼠肾脏中NO的含量,高剂量组最低;但对除上述指标外的肝、脾、肾、心的MDA与NO含量,以及SOD、CAT、GPX与NOS活力无显著影响。低剂量L-茶氨酸灌胃显著抑制肝脏中SOD1 mRNA的表达和脾脏中SOD1、SOD3、GPX1 mRNA的表达;高剂量L-茶氨酸则上调脾脏SOD2 mRNA的表达;同时各剂量组心脏组织中的SOD1、SOD2、SOD3、GPX1 mRNA的表达量都显著增加。结论:L-茶氨酸灌胃增强了心脏的抗氧化能力,其机制可能是通过上调了大鼠心脏中SOD2基因的mRNA的表达,从而增加心脏中SOD的活性,起到抗氧化的保护作用。同时,L-茶氨酸灌胃对大鼠内脏抗氧化功能的影响存在性别差异。

Effect of L-Theanine on Antioxidant Capacity and Related Gene mRNA Expression in Rat Visceral Tissues

Objective: This study aimed to explore the regulatory effect and mechanism of intragastric administration of L-theanine on antioxidant capacity and the mRNA expression of antioxidant enzymes in the heart, liver, spleen and kidney tissues of rats. Methods: Sixty-four Sprague Dawley rats were randomly divided into control group (CON), low-dose group (LT), middle-dose group (MT) and high-dose group (HT) (with 16 animals in each group, half male and half female), which were lavaged daily with L-theanine solution at doses of 0, 50, 200 and 400 mg/kg, respectively for 14 consecutive days. After the last administration, the contents of malondialdehyde (MDA) and nitric oxide (NO), the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and nitric oxide synthase (NOS), and the mRNA expression of SOD1, SOD2, SOD3 and GPX genes were determined in rat visceral tissues. Results: L-Theanine administration influenced the content of NO and the activities of SOD, CAT and NOS in the rat heart. The HT group presented the lowest NO content in the heart tissue among the four groups tested, and increased the activities of SOD and CAT to the highest levels. The NO content in the rat kidney was also impacted by L-theanine administration, and it was the lowest in the HT group. However, no significant effects were observed on the contents of MDA and NO, or the activities of SOD, CAT, GPX and NOS in rat liver, spleen, kidney and heart tissues except the above parameters. The mRNA expression of SOD1 in the liver, and SOD1, SOD3 and GPX1 in the spleen were significantly inhibited in the LT group, the mRNA expression of SOD2 in the spleen was up-regulated in the HT group, and the mRNA expression of SOD1, SOD2, SOD3 and GPX1 in the heart were increased significantly at all doses of L-theanine. Conclusion: L-Theanine administration could enhance antioxidant capacity in the heart, via a mechanism associated with increased SOD activity due to up-regulated mRNA expression of SOD2. At the same time, the effect of L-theanine administration on antioxidant capacity in rat visceral tissues was gender-dependent.