Scherbarth Frank, Rozman Jan, Klingenspor Martin, Brabant Georg, Steinlechner Stephan
Institute of Zoology, Univ. of Veterinary Medicine Hannover, Buenteweg 17, D-30559 Hannover, Germany.
Am J Physiol Regul Integr Comp Physiol. 2007 Sep;293(3):R1368-75. doi: 10.1152/ajpregu.00106.2007. Epub 2007 Jun 27.
Wheel running was previously shown to influence body mass and torpor in short-day-acclimatized Djungarian hamsters (Phodopus sungorus). To determine whether the exercise-induced effect on body mass depends on the annual phase, hamsters were exposed to the natural change in photoperiod and given access to a running wheel (RW), either before, in the middle of, or at the end of the descending body mass trajectory during seasonal acclimatization. Due to wheel running, the seasonal weight cycle was prevented or aborted by abruptly rising body mass, resulting in a weight appropriate for summer, despite exposure to short days. Torpor was inhibited, and testicular recrudescence was advanced, compared with controls. In contrast, the change into winter fur remained unaltered. Analysis of body composition and plasma leptin revealed a low body fat mass in RW hamsters, not only in winter but also in summer, suggesting a lack of seasonal adiposity. Chronic leptin infusion in winter only decreased body mass in RW individuals, although their relative body fat mass probably was even lower than in sedentary hamsters. A constantly low body fat mass is conceivably reflecting an exercise-dependent change in metabolism, consistent with increased bone mineral content and density in RW hamsters. Additionally, bone area was increased, again supported by elongated vertebral columns. Together, the results show a striking effect of wheel running on body composition and the seasonal pattern of body mass, and they suggest that the photoperiodic regulation of body mass is regulated differently than the reproductive and pelage responses.
先前的研究表明，转轮运动对适应短日照的黑线仓鼠（Phodopus sungorus）的体重和蛰伏有影响。为了确定运动对体重的影响是否取决于年度阶段，在季节性适应过程中，仓鼠在体重下降轨迹的开始、中间或结束阶段，暴露于自然的光周期变化中，并给予它们使用转轮（RW）的机会。由于转轮运动，季节性体重循环被突然增加的体重阻止或中断，尽管处于短日照环境，但体重仍保持在适合夏季的水平。与对照组相比，蛰伏受到抑制，睾丸重新发育提前。相比之下，换成冬毛的过程没有改变。对身体成分和血浆瘦素的分析表明，RW仓鼠的体脂量较低，不仅在冬季，在夏季也是如此，这表明缺乏季节性肥胖。仅在冬季对RW个体进行慢性瘦素输注，虽然它们的相对体脂量可能甚至低于久坐不动的仓鼠，但仅降低了体重。持续低体脂量可能反映了运动依赖的代谢变化，这与RW仓鼠骨矿物质含量和密度的增加一致。此外，骨面积增加，这再次得到了拉长的脊柱的支持。总之，结果表明转轮运动对身体成分和体重季节性模式有显著影响，并且表明体重的光周期调节与生殖和被毛反应的调节方式不同。
