Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
Comp Biochem Physiol A Mol Integr Physiol. 2010 May;156(1):84-91. doi: 10.1016/j.cbpa.2009.12.020. Epub 2010 Jan 6.
We tested three hypotheses regarding the cues that elicit facultative hypothermia in Japanese quail (Coturnix japonica): H(1)) Ambient temperature (T(a)), alone, influences the onset and depth of hypothermia; H(2)) Fasting, alone, influences the onset and depth of hypothermia; H(3)) T(a) acts synergistically with fasting to shape the use of hypothermia. Eight quail were maintained within their thermoneutral zone (TNZ) at 32.6+/-0.2 degrees C, and eight below their lower critical temperature (T(lc)) at 12.7+/-3.0 degrees C. All quail entered hypothermia upon food deprivation, even quail kept within their TNZ. Body temperature (T(b)) decreased more (38.36+/-0.53 degrees C vs. 39.57+/-0.57 degrees C), body mass (m(b)) loss was greater (21.0+/-7.20 g vs.12.8+/-2.62g), and the energy saved by using hypothermia was greater (25.18-45.01% vs. 7.98-28.06%) in low the T(a) treatment than in TNZ treatment. Interestingly, the depth of hypothermia was positively correlated with m(b) loss in the low T(a) treatment, but not in TNZ treatment. Our data support H(3), that both thermoregulatory costs and body energy reserves are proximate cues for entry into hypothermia in quail. This outcome is not surprising below the T(lc). However, the quail kept at their TNZ also responded to food deprivation by entering hypothermia with no apparent dependence on m(b) loss. Therefore inputs, other than thermoregulatory costs and body condition, must serve as cues to enter hypothermia. Consequently, we address the role that tissue sparing may play in the physiological 'decision' to employ hypothermia.
我们检验了三个关于诱发日本鹌鹑（Coturnix japonica）适应性低体温的线索的假设：H(1)) 环境温度（T(a)）单独影响低体温的发生和深度；H(2)) 禁食，单独影响低体温的发生和深度；H(3)) T(a) 与禁食协同作用，影响低体温的使用。八只鹌鹑在 32.6+/-0.2 摄氏度的热中性区（TNZ）内维持，八只鹌鹑在 12.7+/-3.0 摄氏度的下临界温度（T(lc)）以下。所有鹌鹑在禁食后都进入低体温状态，即使在 TNZ 内的鹌鹑也是如此。体温（T(b)）下降更多（38.36+/-0.53 摄氏度比 39.57+/-0.57 摄氏度），体重（m(b)）损失更大（21.0+/-7.20 克比 12.8+/-2.62 克），使用低体温节省的能量更多（25.18-45.01%比 7.98-28.06%）在低 T(a)处理中比在 TNZ 处理中。有趣的是，低 T(a)处理中低体温的深度与 m(b)损失呈正相关，但在 TNZ 处理中则没有。我们的数据支持 H(3)，即体温调节成本和身体能量储备都是鹌鹑进入低体温的近因线索。在 T(lc)以下，这一结果并不奇怪。然而，在 TNZ 内饲养的鹌鹑在没有明显依赖 m(b)损失的情况下，也会因禁食而进入低体温状态。因此，除了体温调节成本和身体状况外，其他输入必须作为进入低体温的线索。因此，我们探讨了组织节约可能在利用低体温的生理“决策”中所起的作用。
