Gwóźdź Kinga, Szkudelski Tomasz, Szkudelska Katarzyna
Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland.
Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland.
Biochimie. 2016 Jun;125:195-203. doi: 10.1016/j.biochi.2016.04.003. Epub 2016 Apr 7.
Adipocytes, cells of white fat tissue, store energy in the form of lipids and have also endocrine functions. Disturbances in adipocyte metabolism lead to decreased or excessive fat tissue accumulation and are associated with numerous diseases. Pathologic alterations in adipose tissue are known to develop with age, however, changes in young, growing subjects are poorly elucidated. In the present study, glucose transport and metabolism, hyperpolarization of the inner mitochondrial membrane and the lipolytic activity were compared in the epididymal adipocytes of 8-week-old and 16-week-old rats. It was demonstrated that glucose conversion to lipids, glucose transport and oxidation was decreased in the adipocytes of the older animals. These effects were accompanied by increase in lactate release and by decrease in hyperpolarization of the mitochondrial membrane. Lipolytic response to epinephrine was increased (at lower concentrations of the hormone) or reduced (at higher concentration) in the adipocytes of the older rats. However, induction of lipolysis by the direct activation of protein kinase A induced similar response. It was also demonstrated that inhibition of phosphodiesterase 3B or adenosine A1 receptor blocking caused lower lipolysis in the cells of the older rats. Moreover, antilipolytic action of insulin was impaired in the adipocytes of these rats, probably due to changes in the initial steps of the insulin signaling pathway. However, the use of the pharmacologic inhibitor of protein kinase A instead of insulin resulted in similar antilipolysis in both groups of cells. These results show that, in spite of relatively small age difference, substantial changes in adipose tissue metabolism develop in these animals. Decreased response to insulin action seems to be particularly relevant finding.
脂肪细胞是白色脂肪组织的细胞，以脂质形式储存能量，同时还具有内分泌功能。脂肪细胞代谢紊乱会导致脂肪组织积累减少或过多，并与多种疾病相关。已知脂肪组织的病理改变会随着年龄增长而出现，然而，对于年轻、正在生长的个体的变化却了解甚少。在本研究中，对8周龄和16周龄大鼠附睾脂肪细胞中的葡萄糖转运与代谢、线粒体内膜超极化以及脂解活性进行了比较。结果表明，老年动物脂肪细胞中葡萄糖向脂质的转化、葡萄糖转运和氧化均减少。这些效应伴随着乳酸释放增加以及线粒体膜超极化减少。老年大鼠脂肪细胞对肾上腺素的脂解反应在较低激素浓度时增加，而在较高浓度时降低。然而，通过直接激活蛋白激酶A诱导脂解会产生类似的反应。还表明，抑制磷酸二酯酶3B或阻断腺苷A1受体可导致老年大鼠细胞中的脂解作用降低。此外，这些大鼠脂肪细胞中胰岛素的抗脂解作用受损，这可能是由于胰岛素信号通路初始步骤的变化所致。然而，使用蛋白激酶A的药理抑制剂而非胰岛素在两组细胞中产生了类似的抗脂解作用。这些结果表明，尽管年龄差异相对较小，但这些动物的脂肪组织代谢仍发生了显著变化。胰岛素作用反应降低似乎是一个特别相关的发现。
