Kim Yong-Woon, Scarpace Philip J
Department of Veterans Affairs Medical Center, Gainesville, FL 32608-1197, USA.
Physiol Behav. 2003 Mar;78(3):459-64. doi: 10.1016/s0031-9384(03)00016-7.
It is known that repeated fasting and refeeding increase capacity of fat storage in adipose tissue as an adaptive response to fasting. However, the amount of weight gain in fasted/refed animals falls behind the control level in most rodent studies. Leptin, an adipocyte-derived hormone that impacts on energy homeostasis, may be up-regulated by repeated cycles of fasting and refeeding. In this study, we investigated the adaptive response of leptin to repeated cycles of 1-day fasting and 1-day refeeding for 42 days in rats. The repeated fasting and refeeding (RFR) rats gained less body weight than the controls. Daily food intake of the RFR rats was decreased after Day 16 and remained suppressed. Circulating leptin levels of the RFR rats were significantly elevated at Day 35 compared with the controls and at Day 44 compared with the controls and pair-fed (PF) rats. Leptin mRNA levels of these rats were also significantly increased in retroperitoneal white adipose tissue (RT-WAT) compared with the controls and PF rats. Moreover, hypothalamic proopiomelanocortic (POMC) gene expression was augmented in the RFR rats compared with the controls and PF rats. However, there was no statistical difference in percent visceral fat mass among the experimental groups. Lipoprotein lipase (LPL) mRNA levels of RFR rats were significantly increased in RT-WAT compared with the controls and PF rats. These data indicated that leptin was up-regulated in response to chronic repeated fasting and refeeding cycles without a concomitant increase in adiposity, and the augmented leptin levels were associated with an increase in POMC gene expression, reduced food intake, and diminished body weight gain.
众所周知，反复禁食和再进食可增加脂肪组织中脂肪储存的能力，这是对禁食的一种适应性反应。然而，在大多数啮齿动物研究中，禁食/再进食动物的体重增加量低于对照水平。瘦素是一种由脂肪细胞分泌的影响能量稳态的激素，可能会因反复的禁食和再进食周期而上调。在本研究中，我们调查了大鼠在42天内每天禁食1天和再进食1天的反复周期下瘦素的适应性反应。反复禁食和再进食（RFR）大鼠的体重增加量低于对照组。RFR大鼠在第16天后每日食物摄入量减少，并一直受到抑制。与对照组相比，RFR大鼠在第35天时循环瘦素水平显著升高，与对照组和配对喂养（PF）大鼠相比，在第44天时也显著升高。与对照组和PF大鼠相比，这些大鼠的瘦素mRNA水平在腹膜后白色脂肪组织（RT-WAT）中也显著增加。此外，与对照组和PF大鼠相比，RFR大鼠下丘脑促阿片黑素皮质激素（POMC）基因表达增强。然而，各实验组之间内脏脂肪质量百分比没有统计学差异。与对照组和PF大鼠相比，RFR大鼠的脂蛋白脂肪酶（LPL）mRNA水平在RT-WAT中显著增加。这些数据表明，瘦素在慢性反复禁食和再进食周期中上调，而脂肪量没有相应增加，瘦素水平升高与POMC基因表达增加、食物摄入量减少和体重增加减少有关。
