Steffen J M, Musacchia X J
Cryobiology. 1985 Aug;22(4):385-91. doi: 10.1016/0011-2240(85)90186-5.
Glucocorticoids (GC) are important for thermoregulatory responses to low environmental temperatures. Pretreatment of hamsters, which are capable of natural hibernation, with cortisone acetate has been demonstrated to improve carbohydrate homeostasis during hypothermia. The objectives of the current studies were to evaluate the effects of GC pretreatment of a nonhibernator, the rat, on (i) cooling time, (ii) carbohydrate homeostasis (in terms of liver and cardiac glycogen concentrations and plasma glucose concentration), and (iii) duration of survival in hypothermia. In addition, the effects of liver glycogen depletion on cooling times and survival were examined. Hypothermia was induced in rats by exposure to a helium:oxygen (80:20, Helox) atmosphere at 0 degree C. Pretreatment of rats with triamcinolone acetonide (1.5 mg/kg/day, sc, 48, 24, and 1 hr prior to induction) significantly (P less than 0.05) lengthened induction time, while fasting was associated with a significant decrement (25%). While liver and cardiac glycogen levels in control and GC-treated rats fell approximately 45% during cooling, this reduction occurred over a significantly greater period of time in treated rats and suggests a sparing of glycogen or increased capacity for its production in response to GC. Glycogen utilization was accompanied by a hyperglycemia in control, GC-treated, and fasted groups. Survival in hypothermia at a rectal temperature of 14-15 degrees C in GC-treated (9.5 +/- 1.2 hr) and fasted (10.9 +/- 0.9 hr) rats was not significantly different from control (10.5 +/- 1.1 hr) values. These findings suggest that treatment with GC can increase the thermogenic capacity of the rat (as evidenced by an increased induction time) and promote carbohydrate homeostasis, but does not contribute to an enhancement of survival in the hypothermic nonhibernator.
糖皮质激素（GC）对于机体对低温环境的体温调节反应至关重要。已证实，对能够自然冬眠的仓鼠进行醋酸可的松预处理，可改善体温过低期间的碳水化合物稳态。当前研究的目的是评估对非冬眠动物大鼠进行GC预处理对以下方面的影响：（i）降温时间；（ii）碳水化合物稳态（以肝脏和心脏糖原浓度以及血浆葡萄糖浓度衡量）；（iii）低温状态下的存活时长。此外，还研究了肝脏糖原耗竭对降温时间和存活的影响。通过将大鼠置于0摄氏度的氦气：氧气（80:20，氦氧混合气）环境中诱导其体温过低。用曲安奈德（1.5毫克/千克/天，皮下注射，在诱导前48小时、24小时和1小时）对大鼠进行预处理，显著（P<0.05）延长了诱导时间，而禁食则导致显著缩短（25%）。在降温过程中，对照组和GC处理组大鼠的肝脏和心脏糖原水平均下降了约45%，但在处理组大鼠中，这种下降发生的时间明显更长，这表明糖原得到了节约或其产生能力因GC而增加。在对照组、GC处理组和禁食组中，糖原利用均伴随着血糖升高。在直肠温度为14 - 15摄氏度的低温环境下，GC处理组（9.5±1.2小时）和禁食组（10.9±0.9小时）大鼠的存活时间与对照组（10.5±1.1小时）相比，差异不显著。这些发现表明，GC治疗可提高大鼠的产热能力（诱导时间延长证明了这一点）并促进碳水化合物稳态，但对低温非冬眠动物的存活增强并无贡献。
