Circadian rhythms of lipoprotein lipase and hepatic lipase activities in intermediate metabolism of adult rat
Circadian rhythms of lipoprotein lipase and hepatic lipase activities in intermediate metabolism of adult rat
复制标题
DOI：
10.1152/ajpregu.1998.275.3.r811
复制
发表时间：
1998-09-01
影响因子：
2.8
通讯作者：
Llobera, M
中科院分区：
文献类型：
--
作者：
Benavides, A;Siches, M;Llobera, M
虽然已知中间代谢遵循昼夜节律，但关于24小时内脂蛋白脂肪酶（LPL）和肝脂肪酶（HL）活性变化的信息很少，也缺乏足够的统计分析。在这里，成年雄性大鼠自由进食，并在21℃下保持12:12 h的明暗循环。在24小时内，每3小时分批杀死它们。测定了血浆和新鲜附睾匀浆中的脂肪酶活性。白色脂肪组织（EWAT）、肩胛间棕色脂肪组织（IBAT）、心脏、骨骼肌和肝脏。测定血浆胰岛素、皮质酮、葡萄糖、三酰甘油（TAG）、胆固醇、甘油、对羟基丁酸、肝糖和肌糖原。余弦分析用于评估可能的昼夜节律[顶相（phi），中值和振幅]的存在（余弦曲线对数据的拟合意义和由节律解释的方差）和特征。1)除TAG、胆固醇和肝脏HL活性外，所有代谢产物的昼夜节律均有统计学意义；2)血浆中LPL和HL活性（均为光相phi）；3) LPL在所有组织中的活性（phi：心脏在光期，骨骼肌、IBAT和EWAT在暗期）。肝脏的LPL活性也有昼夜节律，其phi值与血浆的相近。这些发现首次证明，在生理条件下，血浆和各种组织（包括肝脏）中的LPL活性和血浆中的HL活性遵循昼夜节律。讨论了它们的代谢意义。
Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variations in lipoprotein Lipase (LPL) and hepatic lipase (HL) activities during the 24-h period, and there is also a lack of adequate statistical analysis. Here, adult male rats were fed ad libitum and kept at 21 degrees C under 12:12-h light-dark cycles. They were killed in batches every 3 h over a 24-h period. Lipase activities were determined in plasma and fresh homogenates of epididymal. white adipose tissue (EWAT), interscapular brown adipose tissue (IBAT), heart, skeletal muscle, and liver. Plasma insulin, corticosterone, glucose, triacylglycerol (TAG), cholesterol, glycerol, P-hydroxybutyrate, and liver and muscle glycogen were determined. Cosinor analysis was used to evaluate the presence (significance of fit of cosine curve to data and variance explained by rhythm) and characteristics of possible circadian rhythms [acrophase (phi), mesor, and amplitude]. Statistically significant circadian rhythms were detected for 1) all metabolites studied, except TAG, cholesterol, and liver HL activity; 2) LPL and HL activity in plasma (both phi in light phase); and 3) LPL activity in all tissues studied (phi: heart in light phase; skeletal muscle, IBAT, and EWAT in dark phase). Liver also showed a circadian rhythm of LPL activity, with phi near that in plasma. These findings demonstrate for the first time that, in physiological conditions, LPL activities in plasma and various tissues, including liver, and HL activity in plasma follow circadian rhythms. Their metabolic significance is discussed.