达乌尔黄鼠入眠准备期的体温、代谢率及能量特征

贮脂类动物在冬眠前大量积累脂肪来准备冬眠,并在入眠时迅速降低体温和代谢率。为探究入眠准备期达乌尔黄鼠体温、代谢率、呼吸商及能量代谢的变化,将其入眠准备期分为育肥期、体重高峰期、育肥后期和冬眠前的试降期,使用植入式半导体温度记录元件iButton、开放式代谢仪和改进的代谢笼,监测其体温、代谢率及呼吸商和能量摄入的变化。结果显示:(1)达乌尔黄鼠体温在冬眠前13 - 34 d 开始下降,远早于冬眠但晚于体重高峰期;体重高峰期体温有降低的趋势,持续时间为1 - 3 d;育肥后期体温显著下降,体温日波动幅度增加。(2)体重高峰期的静止代谢率高于育肥期,育肥后期有降低的趋势,试降期最低。(3)呼吸商在体重高峰期先升高,之后迅速衰减;入眠准备期的能量摄入在体重达高峰期前达到最大值。结果表明,达乌尔黄鼠在入眠准备期,其体温和代谢率已开始降低,能源物质已开始转变;体重高峰期可能是达乌尔黄鼠入眠的一个转折点或启动入眠的开关。

Body temperature,metabolic rate and energetic characteristics of daurian ground squirrels (Spermophilus dauricus)during preparation of hibernation

Fat-storing hibernators accumulate body fat before hibernation,and quickly reduce body temperature and metabolic rate during hibernation. Recent studies show that body temperature,metabolism and other physiological parameters of hibernators have changed before hibernation. We recorded body temperature (Tb ),metabolic rate (MR),respiratory quotient (RQ)and energy intake in individual daurian ground squirrels (Spermophilus dauricus)to understand the switch of Tb ,MR,RQ and energy intake before hibernation. Preparation before hibernation was divided into the fattening phase,the maximum body mass phase,post-fattening phase and drop test phase. Tb ,MR,RQ and energy intake were estimated by implanted iButtons,Sable FOXBOX O2 and CO2 analyzer and the improved-metabolic cages method. Results show that,(1)Daurian ground squirrels start to drop body temperature 13 -34 days before hibernation,which is later than the period of maximum body mass (BMmax ). There was a reduction tendency daily fluctuations of Tb for three days during the period of BMmax,but a significant reduction of Tb was observed during the phase of body mass reduction,during which the magnitude of daily fluctuations of Tb became larger. (2)Resting metabolic rate (RMR)was at maximum during BMmax ,then declined during the phase of body mass reduction. RMR was at minimum during test drop. (3)During BMmax RQ increased first and then reduced drastically. Energy intake reached maximum before BMmax . The results indicated that the switches of Tb ,MR,RQ and energy source in daurian ground squirrels had been completed before hibernation. BMmax phase may be a key point for entering hibernation or may be served as an important switch to initiate hibernation in daurian ground squirrels.