Kauffman A S, Cabrera A, Zucker I
Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
Physiol Biochem Zool. 2001 Nov-Dec;74(6):876-84. doi: 10.1086/324098.
After approximately 10 wk of exposure to decreasing day lengths, Siberian hamsters (Phodopus sungorus) begin to display spontaneous torpor bouts several times each week. Torpor is associated with reduced daily energy expenditure and lower food consumption and ameliorates the thermoregulatory challenges of winter. We tested the extent to which the energy savings conferred by daily torpor depend on the presence of an insulative pelage. Female hamsters were housed in a winter day length (8L:16D) at 5 degrees C; daily food intake and torpor characteristics were recorded for 5 wk in shaved (furless) or normal hamsters. Torpor-bout incidence decreased by 62% in furless hamsters, but the duration of individual bouts and the minimum body temperature attained during torpor were unaffected by loss of pelage. Body temperature declined more rapidly during entry into torpor and increased more slowly during arousal from torpor in furless than in control hamsters. Energy savings per torpor bout, assessed by the amount of food consumed on days that included a torpor bout, was substantially greater in normal than in furless hamsters (16.0% vs. 3.3%); this difference likely reflects the increased cost of thermoregulation during torpor, as well as the increased caloric expenditure incurred by furless hamsters during arousal from torpor. An insulative pelage may be a prerequisite for the energetic benefits derived from heterothermy in this species.
在经历大约10周日照时长逐渐缩短的环境后，西伯利亚仓鼠（Phodopus sungorus）开始每周出现几次自发性的蛰伏发作。蛰伏与每日能量消耗减少和食物摄入量降低有关，并且缓解了冬季的体温调节挑战。我们测试了每日蛰伏所带来的能量节省在多大程度上依赖于具有隔热作用的皮毛。将雌性仓鼠饲养在5摄氏度、模拟冬季日照时长（8小时光照：16小时黑暗）的环境中；记录剃毛（无毛）或正常仓鼠5周内的每日食物摄入量和蛰伏特征。无毛仓鼠的蛰伏发作发生率降低了62%，但单次发作的持续时间以及蛰伏期间达到的最低体温不受皮毛缺失的影响。与对照仓鼠相比，无毛仓鼠在进入蛰伏时体温下降更快，从蛰伏中苏醒时体温上升更慢。通过包含一次蛰伏发作的日子里所消耗的食物量来评估，每次蛰伏发作节省的能量在正常仓鼠中比在无毛仓鼠中要高得多（分别为16.0%和3.3%）；这种差异可能反映了蛰伏期间体温调节成本的增加，以及无毛仓鼠从蛰伏中苏醒时产生的热量消耗增加。隔热的皮毛可能是该物种从异温性中获得能量益处的一个先决条件。
