Loss of regulation of lipogenesis in the Zucker diabetic rat. II. Changes in stearate and oleate synthesis
Loss of regulation of lipogenesis in the Zucker diabetic rat. II. Changes in stearate and oleate synthesis
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DOI：
10.1152/ajpendo.00211.2001
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发表时间：
2002-03-01
影响因子：
5.1
通讯作者：
Lee, WNP
中科院分区：
文献类型：
--
作者：
Bassilian, S;Ahmed, S;Lee, WNP
新生脂肪生成和膳食脂肪摄取是肥胖动物脂肪中脂肪酸沉积的两个主要来源。为了确定这两种来源的脂肪酸在肥胖中的相对贡献，我们确定了在两种等热量膳食脂肪条件下，Zucker糖尿病脂肪（ZDF）大鼠及其瘦同窝仔（ZL）血浆、肝脏和附睾脂肪垫中甘油三酯的c16和c18脂肪酸的分布。还使用氘代水方法测定脂肪生成。棕榈酸酯转化为硬脂酸酯和硬脂酸酯转化为油酸酯的转化率通过使用示踪剂稀释原理从氘掺入计算。在ZL大鼠中，脂肪生成被抑制从70%至24%，棕榈酸酯转化为硬脂酸酯从86%至78%，硬脂酸酯转化为油酸酯从56%至7%，以响应饮食中脂肪与碳水化合物比例的增加。结果表明，抑制脂肪酸合成酶和硬脂酰辅酶A去饱和酶的活动是一个正常的适应机制，高脂肪饮食。与此相反，从头脂肪生成，链延长，和去饱和没有抑制ZDF大鼠的膳食脂肪。缺乏适应高脂饮食的能力导致ZDF大鼠血浆甘油三酯浓度升高，饮食和从头合成导致脂肪过度蓄积。
De novo lipogenesis and dietary fat uptake are two major sources of fatty acid deposits in fat of obese animals. To determine the relative contribution of fatty acids from these two sources in obesity, we have determined the distribution of c16 and c18 fatty acids of triglycerides in plasma, liver, and epididymal fat pad of Zucker diabetic fatty (ZDF) rats and their lean littermates (ZL) under two isocaloric dietary fat conditions. Lipogenesis was also determined using the deuterated water method. Conversion of palmitate to stearate and stearate to oleate was calculated from the deuterium incorporation by use of the tracer dilution principle. In the ZL rat, lipogenesis was suppressed from 70 to 24%, conversion of palmitate to stearate from 86 to 78%, and conversion of stearate to oleate from 56 to 7% in response to an increase in the dietary fat-to-carbohydrate ratio. The results suggest that suppression of fatty acid synthase and stearoyl-CoA desaturase activities is a normal adaptive mechanism to a high-fat diet. In contrast, de novo lipogenesis, chain elongation, and desaturation were not suppressed by dietary fat in the ZDF rat. The lack of ability to adapt to a high-fat diet resulted in a higher plasma triglyceride concentration and excessive fat accumulation from both diet and de novo synthesis in the ZDF rat.