Kim T S, Freake H C
Department of Nutritional Sciences, University of Connecticut, Storrs, 06269-4017, USA.
J Nutr. 1996 Mar;126(3):611-7. doi: 10.1093/jn/126.3.611.
We have previously shown that the effects of a high carbohydrate, fat-free diet and 24-h starvation on fatty acid synthesis in rats are tissue specific. In the present study we examine the tissue-specific pretranslational effects of high carbohydrate feeding, starvation and refeeding a high carbohydrate diet after starvation on the lipogenic pathway by measuring the levels of mRNA encoding acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) using Northern analysis. Additionally, we measured mRNA S14, a sequence tightly associated with lipogenesis. In rats fed the high carbohydrate diet, hepatic levels of the three mRNA were 3-5 fold higher than in controls. The level of S14 mRNA was doubled in epididymal fat, but other effects of this diet in adipose tissues were not significant. Expression in kidney, heart, lung and brain was not altered. Starvation significantly reduced the level of these mRNA in all tissues examined except brain. In liver, refeeding the high carbohydrate diet induced the expression of ACC, FAS and S14 mRNA 20-30 fold compared with the values found in 48-h starved animals. Hyperinduction of ACC and FAS, but not S14 mRNA expression was also observed in adipose tissues. The tissue-specific nature of these effects is consistent with previous measurements of fatty acid synthesis and confirm that this regulation occurs at the pretranslational level.
我们之前已经表明，高碳水化合物、无脂肪饮食以及24小时饥饿对大鼠脂肪酸合成的影响具有组织特异性。在本研究中，我们通过Northern分析测量编码乙酰辅酶A羧化酶（ACC）和脂肪酸合酶（FAS）的mRNA水平，来研究高碳水化合物喂养、饥饿以及饥饿后重新喂养高碳水化合物饮食对生脂途径的组织特异性翻译前效应。此外，我们还测量了与脂肪生成紧密相关的mRNA S14。在喂食高碳水化合物饮食的大鼠中，这三种mRNA的肝脏水平比对照组高3至5倍。附睾脂肪中S14 mRNA的水平增加了一倍，但这种饮食对脂肪组织的其他影响并不显著。在肾脏、心脏、肺和大脑中的表达没有改变。饥饿显著降低了除大脑外所有检测组织中这些mRNA的水平。在肝脏中，与48小时饥饿动物相比，重新喂养高碳水化合物饮食诱导ACC、FAS和S14 mRNA的表达增加了20至30倍。在脂肪组织中也观察到ACC和FAS的超诱导，但S14 mRNA表达没有增加。这些效应的组织特异性性质与之前对脂肪酸合成的测量结果一致，并证实这种调节发生在翻译前水平。
