McDevitt R M, Speakman J R
Department of Zoology, University of Aberdeen, Scotland, UK.
J Comp Physiol B. 1996;166(4):286-93. doi: 10.1007/BF00262873.
We investigated the changes that occurred in basal and noradrenaline-induced metabolic rate, body temperature and body mass in short-tailed field voles, Microtus agrestis, during exposure to naturally increasing photoperiod and ambient temperature. These parameters were first measured in winter-acclimatized voles (n = 8) and then in the same voles which had been allowed to seasonally acclimatize to photoperiod and ambient temperature (6 months later). Noradrenaline induced metabolic rate, basal metabolic rate and non-shivering thermogenesis were significantly higher in winter-acclimatized compared to summer-acclimatized voles. There was a significant positive relationship between basal metabolic rate and noradrenaline-induced metabolic rate. Body mass was significantly higher in summer-acclimatized compared to winter-acclimatized voles. There was a significant positive relationship between body mass and noradrenaline-induced metabolic rate in both winter-acclimatized and summer-acclimatized voles; however, there was no relationship between basal metabolic rate and body mass in either seasonal group of voles. Body temperature after measurements of basal metabolic rate was not significantly different in the seasonal cohorts of voles. However, body temperature was significantly higher in winter-acclimatized compared to summer-acclimatized voles after injection of noradrenaline. Previously we have found that a long photoperiod was not a sufficient stimulus to reduce thermogenic capacity in winter-acclimatized voles during cold exposure, since basal metabolic rate increased to compensate for a reduction in regulatory non-shivering thermogenesis. Here we found that a combination of increased ambient temperature and photoperiod did significantly reduce thermogenic capacity in winter-acclimatized voles. This provided evidence that the two aspects of non-shivering thermogenesis, obligatory and regulatory, are stimulated by different exogenous cues. Summer acclimatization in the short-tailed field vole is manifest as a significant decrease in both basal and noradrenaline-induced metabolic rate, combined with a significant increase in body mass.
我们研究了在暴露于自然增加的光周期和环境温度期间，短尾田鼠（Microtus agrestis）基础代谢率、去甲肾上腺素诱导的代谢率、体温和体重的变化。这些参数首先在冬季适应环境的田鼠（n = 8）中进行测量，然后在同一批田鼠中进行测量，这些田鼠随后经过了季节性的光周期和环境温度适应（6个月后）。与夏季适应环境的田鼠相比，冬季适应环境的田鼠中，去甲肾上腺素诱导的代谢率、基础代谢率和非颤抖性产热显著更高。基础代谢率与去甲肾上腺素诱导的代谢率之间存在显著的正相关关系。与冬季适应环境的田鼠相比，夏季适应环境的田鼠体重显著更高。在冬季适应环境和夏季适应环境的田鼠中，体重与去甲肾上腺素诱导的代谢率之间均存在显著的正相关关系；然而，在任何一个季节组的田鼠中，基础代谢率与体重之间均无关联。在基础代谢率测量后，不同季节组的田鼠体温没有显著差异。然而，注射去甲肾上腺素后，冬季适应环境的田鼠体温显著高于夏季适应环境的田鼠。此前我们发现，长光周期不足以刺激冬季适应环境的田鼠在冷暴露期间降低产热能力，因为基础代谢率会增加以补偿调节性非颤抖性产热的减少。在此我们发现，环境温度升高和光周期增加的组合确实显著降低了冬季适应环境的田鼠的产热能力。这提供了证据，表明非颤抖性产热的两个方面，即强制性和调节性，受到不同的外源性线索刺激。短尾田鼠的夏季适应表现为基础代谢率和去甲肾上腺素诱导的代谢率均显著降低，同时体重显著增加。
