Cold-induced mRNA expression of angiogenic factors in rat brown adipose tissue
Cold-induced mRNA expression of angiogenic factors in rat brown adipose tissue
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DOI：
10.1292/jvms.61.403
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发表时间：
1999-04-01
影响因子：
1.2
通讯作者：
Saito, M
中科院分区：
文献类型：
--
作者：
Asano, A;Kimura, K;Saito, M
棕色脂肪组织(BAT)是啮齿动物非颤抖产热的主要部位。当动物暴露在寒冷中时，快速的血管生成与该组织的适应性增殖有关。我们先前证实了肾上腺素能激活大鼠BAT中血管内皮生长因子(VEGF)的mRNA表达，并可能参与了冷诱导的该组织的血管生成。在目前的研究中，我们研究了寒冷暴露对另外两种血管生成因子mRNA表达的影响。血管内皮生长因子-B和碱性成纤维细胞生长因子。常规Northern印迹分析显示，BAT组织中有大量的VEGF-B和VEGF的表达，但不表达bFGFmRNA。4℃冷暴露后，大鼠血管内皮生长因子基因表达水平在1~4小时内增加2.7倍，24小时内恢复到基础水平。相反，在冷暴露过程中，血管内皮生长因子-B的mRNA水平并没有发生变化。逆转录-聚合酶链式反应(RT-PCR)检测到BAT中bFGFm RNA的显著表达。为了定量评价组织中bFGFm RNA的水平，建立了一种以较短的RNA片段为竞争对手的竞争性RT-PCR方法。冷暴露后4h，BAT中bFGFm RNA表达水平增加2.3倍，24 h内降至基础水平。这些结果表明，冷暴露导致BAT迅速而短暂地诱导血管内皮生长因子和碱性成纤维细胞生长因子，进而刺激该组织血管内皮细胞的增殖。
Brown adipose tissue (BAT) is the major site of non-shivering thermogenesis in rodents. Rapid angiogenesis is induced in association with adaptive hyperplasia of this tissue when the animal is exposed to cold. We demonstrated previously adrenergic activation of mRNA expression of vascular endothelial growth factor (VEGF) in rat BAT and its possible contribution to the cold-induced angiogenesis in this tissue. In the present study, we examined the effect of cold exposure on mRNA expression of other two angiogenic factors. VEGF-B and basic fibroblast growth factor (bFGF), in rats. Conventional Northern blot analysis revealed abundant mRNA expression of VEGF-B as well as VEGF, but not bFGF, in BAT. When rats were exposed to cold at 4 degrees C, the VEGF mRNA level was increased by 2.7-fold in 1-4 hr and returned to the basal level within 24 hr. In contrast, the VEGF-B mRNA level did not change throughout the course of cold exposure. A significant expression of bFGF mRNA was detected in BAT by reverse transcription polymerase chain reaction (RT-PCR). To evaluate the tissue bFGF mRNA level quantitatively, a competitive RT-PCR method was developed using a shorter RNA fragment as a competitor. The bFGF mRNA level in BAT was found to increase by 2.3-fold in 4 hr and decreased to the basal level within 24 hr after cold exposure. These results suggest that cold exposure leads to induce VEGF and bFGF rapidly and transiently in BAT, which in turn stimulate the proliferation of vascular endothelial cells in this tissue.