Tomaz Luciane M, Barbosa Marina R, Farahnak Zahra, Lagoeiro Cristiani G, Magosso Natalia S S, Lavoie Jean-Marc, Perez Sérgio E A
Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP Brazil.
Department of Education and Health, Federal University of Sergipe, Lagarto, SE Brazil.
J Exerc Nutrition Biochem. 2016 Jun;20(2):51-7. doi: 10.20463/jenb.2016.06.20.2.7. Epub 2016 Jun 30.
This study investigated the effects of ovariectomy (Ovx) and 12 weeks of resistance training (RT) on gene expression of GLUT2, the main glucose transporter in the liver, and on PPARγ, a transcription factor known to target GLUT2 expression.
Forty Holtzman rats were divided into 5 groups: Sham-sedentary (Sed), Sham- RT, Ovx-Sed, Ovx-RT, and Ovx-Sed with hormone replacement (E2). The RT protocol consisted of sessions held every 72 h for 12 weeks, during which the animals performed 4 to 9 vertical climbs (1.1 m) at 2 min intervals with progressively heavier weights (30 g after the fourth climb) tied to the tail. The E2 silastic capsule was inserted into the rats' backs 48 hours before the first RT session.
In addition to liver fat, GLUT2 protein levels and PPARγ transcripts were increased (P < 0.05) in Ovx compared to Sham-Sed animals, suggesting increased hepatic glucose uptake under estrogen deficient conditions. RT and E2 in Ovx rats decreased liver fat accumulation as well as GLUT2 and PPARγ gene expression to the level of Sham- Sed animals.
The results of this study suggest that liver GLUT2 as well as PPARγ expression in Ovx rats are accompanied by increased fat accumulation and glucose uptake, thus providing a substrate for increased de novo lipogenesis. RT appears to be an appropriate exercise model to circumvent these effects.
本研究调查了卵巢切除术（Ovx）及12周抗阻训练（RT）对肝脏主要葡萄糖转运蛋白GLUT2的基因表达以及对已知靶向GLUT2表达的转录因子PPARγ的影响。
40只霍尔茨曼大鼠被分为5组：假手术-久坐组（Sed）、假手术-RT组、卵巢切除-久坐组、卵巢切除-RT组以及接受激素替代（E2）的卵巢切除-久坐组。RT方案包括每72小时进行一次，共持续12周，在此期间动物每隔2分钟进行4至9次垂直攀爬（1.1米），尾巴上系着逐渐增加重量的重物（第四次攀爬后为30克）。在第一次RT训练前48小时将E2硅橡胶胶囊植入大鼠背部。
与假手术-久坐组动物相比，卵巢切除组除肝脂肪外，GLUT2蛋白水平和PPARγ转录本增加（P<0.05），表明在雌激素缺乏条件下肝脏葡萄糖摄取增加。卵巢切除大鼠进行RT和给予E2可减少肝脏脂肪堆积以及GLUT2和PPARγ基因表达，使其达到假手术-久坐组动物的水平。
本研究结果表明，卵巢切除大鼠肝脏中的GLUT2以及PPARγ表达伴随着脂肪堆积和葡萄糖摄取增加，从而为增加从头脂肪生成提供了底物。RT似乎是规避这些影响适宜的运动模型。
