乌龙茶减肥适宜剂量选择及对β_3-肾上腺素能受体基因表达的影响(英文)

Dose selection and effect of Oolong tea on the expression of β_3-adrenergic receptor gene for weight reducing

背景:目前肥胖是国内外关注的问题,在不影响正常饮食的情况下达到控制体质量和减肥则成为研究的重点。目的:探讨乌龙茶的减肥作用及对β3-肾上腺素能受体基因表达的影响。设计:完全随机分组,对照实验。单位:南京医科大学公共卫生学院营养与食品卫生学系与南京医科大学儿科医学研究所。材料:实验于2003-09/2004-02在南京医科大学实验室完成,选用体质量80g左右的雄性大鼠,经高营养饲料制备肥胖大鼠模型后,从中选用32只雄性肥胖大鼠。制备乌龙茶浸出液,每毫升浸出液相当于0.24g茶叶。干预:将32只雄性肥胖大鼠随机分为4组:肥胖对照组、乌龙茶低剂量组、中剂量组、高剂量组,每组8只。肥胖对照组大鼠每日灌以蒸馏水,乌龙茶叶浸出液低、中、高剂量组大鼠每日则分别灌以0.4g/kg,1.2g/kg,2.4g/kg(相当于茶叶的数量)的乌龙茶,同时喂饲高营养饲料,大鼠单笼饲养,饲养场所室温保持在22℃左右,湿度保持55%。大鼠自由饮水,饲料每日定量喂饲两次,吃完不再添加。30d测量体质量、脂肪细胞最大径,并检测脂肪组织中β3-肾上腺素能受体mRNA水平。主要观察指标:体质量、体质量增加、腹膜后、附睾周及肩胛间脂肪组织重量,脂肪细胞最大径,并用RT-PCR的方法检测上述脂肪组织中β3-ARmRNA水平。结果:按意向处理分析,32只雄性大鼠均进入结果分析。①体质量情况:乌龙茶中、高剂量组体质量增加明显低于肥胖对照组和低剂量组犤(58.4±46.7),(68.1±30.4),(125.7±34.4),(96.3±26.2),P<0.01犦。饲料总摄取量在各组间的差异不显著(P>0.05)。②脂肪系数:乌龙茶中、高剂量组大鼠腹膜后、附睾周脂肪系数明显低于肥胖对照组和低剂量组犤(1.57±0.53,2.14±0.90)比(2.71±0.49,2.50±0.53);(1.14±0.38,1.43±0.53)比(2.00±0.00,1.88±0.35)犦,而肩胛间脂肪组织重量在各组间无显著差异(P>0.05)。③脂肪细胞的最大径:乌龙茶低、中、高剂量组大鼠腹膜后、附睾周、肩胛间脂肪细胞的最大径明显低于肥胖对照组犤(113±24),(86±29),(90±23),(120±30)μm;(94±20),(80±18),(64±17),(111±21)μm;(24±11),(21±11),(22±10),(27±11)μm,P<0.05犦。④脂肪组织中β3-肾上腺素能受体mRNA检测:乌龙茶中、高剂量组大鼠腹膜后、附睾周、肩胛间显著高于肥胖对照组和低剂量组犤腹膜后:(0.72±0.11,0.64±0.112,0.40±0.08,0.34±0.10);附睾周:(1.06±0.21,1.02±0.24,0.42±0.13,0.43±0.11);肩胛间(1.01±0.42,0.70±0.17,0.42±0.10,0.49±0.16),P<0.01犦。结论:乌龙茶具有一定的减肥作用,与其增加脂肪组织中β3-肾上腺素能受体mRNA水平有关,中剂量(1.2g/kg)可能为一适宜剂量。该结果有助于对饮茶减肥理论的支持及有效剂量的选择。

BACKGROUND：Obesity is an important problem concerned domestically and internationally. How to control the body mass and to reduce the weight without any effect on normal food intake is the focus for study.OBJECTIVE：To probe into the weight-reducing effect of Oolong tea and its effect on the mRNA level of β3-adrenergic receptor（β3-AR）.DESIGN： Completely randomized grouping, controlled trial SETTING：Department of Nutrition and Food Hygiene, College of Public Health, Nanjing Medical University; Institute of Pediatric Medicine, Nanjing Medical University.MATERIALS： This experiment was conducted in the laboratory of Nanjing Medical University from September 2003 to February 2004. The obese rat models were made with the diet of high energy and high fat in male rats weighing about 80 g. Thirty-two male obese rats were selected.And Oolong tea extract was prepared, whose concentration was equivalent to 0.24 g of tea.INTERVENTIONS：Thirty-two male obese rats were divided randomly in-to 4 groups： obese control group, low, middle and high dose of oolong tea groups. There were 8 rats in each group. The rats in the control group were fed by gavage with distilled water every day. The other rats in low, middle or high dose of Oolong tea groups were fed by gavage with 0.4 g/kg, 1.2 g/kg, and 2.4 g/kg of Oolong tea respectively. They were all fed with diet of high energy and high fat. Each rat was raised in separate cage. The room temperature for the rats remained about 22 ℃ with the humidity of 55%. The rats were free access to water, but the diet was fed twice a day at a fixed amount. If it was finished, no more diet would be added. Thirty days later, body mass, maximal diameter of adipocytes were measured, and β3-ARmRNA levels in adipose tissues were measured.MAIN OUTCOME MEASURES： Body mass, increased body mass,the weight of adipose tissues in retroperitoneal, peri-epididymal and interscapular regions and the maximal diameter of adipocytes were measured,β3- AR mRNA levels in the adipose tissues above were measured with the method of RT-PCR.RESULTS：According to intention-to-treat analysis, thirty-two male rats entered result analysis. [1]Body mass： Increased weight of rats in 1.2 g/kg and 2.4 g/kg Oolong tea groups were significantly lower than that in the rats of control group and rats in 0.4 g/kg Oolong tea group （58.4±46.7,68.1±30.4,125.7±34.4,96.3±26.2,P ＜ 0.01）, but the amount of total diet consumption was similar in each group （P ＞ 0.05）. [2]Lipid coefficient in retroperitoneal and peri-epididymal regions of rats in 1.2 g/kg and 2.4 g/kg Oolong tea groups was lower than that in the rats of control group and rats in 0.4 g/kg Oolong tea group,（1.57±0.53,2.14±0.90 to 2.71±0.49,2.50±0.53, 1.14±0.38,1.43±0.53 to2.00±0.00,1.88±0.35）, but there was no significant difference among groups of the ratio in inter-scapular regions （P ＞0.05）. [3]The maximal diameter of adipocytes： The maximal diameter in retroperitoneal, periepididymal and inter-scapular regions of the rats in 0.4 g/kg, 1.2 g/kg and 2.4 g/kg Oolong tea groups was significantly lower than that in the rats of control group[（113±24）, （86±29）, （90±23）, （120±30）μm;（94±20）, （80±18）, （64±17）, （111±21）μm; （24±11）, （21 ±11）, （22±10）,（27±11）μm,P ＜ 0.05]. [4]β3-AR mRNA levels in adipose tissues：The β3-AR mRNA levels in retroperitoneal, peri-epididymal and interscapular regions of the rats in 1.2 g/kg and 2.4 g/kg Oolong tea groups were significantly higher than those in rats of control group and rats with0.4 g/kg of Oolong tea （0.72±0.11,0.64±0.112,0.40±0.08,0.34±0.10 for retroperitoneal region, 1.06±0.21,1.02±0.24,0.42±0.15,0.43±0.11 for epididymal region, 1.01±0.42,0.70±0.17,0.42±0.10,0.49±0.16 for interscapular region, P ＜ 0.01）.CONCLUSION：Oolong tea was of weight～reducing effect,which may be related to its effect to increase β3-AR mRNA level The middle dose （1.2 g/kg） may be optimal.These results may be helpful to the theory of weight reducing with tea and the selection ofoptimal dose.