Caimari A, Oliver P, Palou A
Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears and CIBER de Fisiopatología de la Obesidad y Nutrición, CIBEROBN, Palma de Mallorca, Spain.
Int J Obes (Lond). 2008 Aug;32(8):1193-200. doi: 10.1038/ijo.2008.69. Epub 2008 May 20.
Fasting-induced lipolysis becomes less effective with age. We have studied whether nutritional regulation of adipose triglyceride lipase (ATGL)--with an important role in lipolysis in low energy states--is affected by age.
Wistar rats of different ages (from 1 to 13 months) were distributed in control and fasted groups (14 h-food deprivation). ATGL mRNA expression was measured in different adipose depots at different ages and in only one depot at 13 months by reverse transcription (RT)-PCR. ATGL protein levels were determined at 3 and 7 months (not at 13 months) by western blot. Nonesterified fatty acid (NEFA), insulin and leptin levels were assessed in serum by enzymatic assays.
ATGL expression was dependent on regional fat distribution, with higher levels in brown than in white adipose tissue depots; and was affected by age: ATGL mRNA was increased with age in the brown adipose tissue and was decreased in two of the studied white depots, the inguinal and retroperitoneal, not being affected in the epididymal and mesenteric. Age also affected ATGL nutritional regulation: fasting increased ATGL gene expression and protein levels in the different white adipose depots of the youngest rats (up to the age of 5 months), whereas there was no change in the oldest rats studied (7 and 13-months old). This was in agreement with the pattern of NEFA levels, which did not increase in serum of fasted rats in the oldest animals, whereas other homeostatic parameters, such as insulin and leptin, responded to fasting independently of age. ATGL expressed by brown adipose tissue was not affected by feeding conditions at any age.
Nutritional regulation of ATGL expression in white adipose tissue is impaired with age, which could contribute to the increased difficulty for mobilizing lipids when animals are exposed to nutritional stress such as fasting.
禁食诱导的脂肪分解随着年龄增长而效果降低。我们研究了脂肪甘油三酯脂肪酶（ATGL）（在低能量状态下的脂肪分解中起重要作用）的营养调节是否受年龄影响。
将不同年龄（1至13个月）的Wistar大鼠分为对照组和禁食组（禁食14小时）。通过逆转录（RT）-PCR在不同年龄的不同脂肪库以及13个月时仅在一个脂肪库中测量ATGL mRNA表达。通过蛋白质印迹法在3个月和7个月时（而非13个月时）测定ATGL蛋白水平。通过酶促测定法评估血清中的非酯化脂肪酸（NEFA）、胰岛素和瘦素水平。
ATGL表达取决于局部脂肪分布，棕色脂肪组织中的水平高于白色脂肪组织库；并且受年龄影响：棕色脂肪组织中ATGL mRNA随年龄增加，而在所研究的两个白色脂肪库（腹股沟和腹膜后）中降低，附睾和肠系膜脂肪库未受影响。年龄也影响ATGL的营养调节：禁食增加了最年幼大鼠（5个月龄以下）不同白色脂肪库中的ATGL基因表达和蛋白水平，而在所研究的最年长大鼠（7个月和13个月龄）中没有变化。这与NEFA水平的模式一致，在最年长动物的禁食大鼠血清中NEFA水平没有增加，而其他稳态参数，如胰岛素和瘦素，对禁食的反应与年龄无关。棕色脂肪组织表达的ATGL在任何年龄均不受喂养条件影响。
白色脂肪组织中ATGL表达的营养调节随着年龄增长而受损，这可能导致动物在面临禁食等营养应激时动员脂质的难度增加。
