Wong Carmen P, Iwaniec Urszula T, Turner Russell T
Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA.
Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA.
Bone Rep. 2023 Aug 8;19:101706. doi: 10.1016/j.bonr.2023.101706. eCollection 2023 Dec.
Mice are typically housed at room temperature (∼22 °C), which is well below their thermoneutral zone and results in cold stress. Chronic cold stress leads to increased adaptive thermogenesis and reductions in cancellous bone volume and bone marrow adipose tissue mass in long bones of growing mice. There is strong evidence that increased neuronal activity initiates the metabolic response of intrascapular brown adipose tissue (BAT) to cold stress, but it is less clear whether bone is regulated through a similar mechanism. Therefore, we compared the short-term response of BAT and whole tibia to a reduction in environmental temperature. To accomplish this, we transferred a group of 6-week-old male mice from 32 °C to 22 °C housing and sacrificed the mice 24 h later. Age-matched controls were maintained at 32 °C. We then evaluated expression levels of a panel of genes related to adipocyte differentiation and fat metabolism in BAT and tibia, and a panel of genes related to bone metabolism in tibia. The decrease in housing temperature resulted in changes in expression levels for 47/86 genes related to adipocyte differentiation and fat metabolism in BAT, including 9-fold and 17-fold increases in and , respectively. In contrast, only 1/86 genes related to adipocyte differentiation and fat metabolism and 4/84 genes related to bone metabolism were differentially expressed in tibia. These findings suggest that bone, although innervated with sensory and sympathetic neurons, does not respond as rapidly as BAT to changes in environmental temperature.
小鼠通常饲养在室温（约22°C）下，这远低于它们的热中性区，会导致冷应激。慢性冷应激会导致适应性产热增加，并且生长中小鼠长骨的松质骨体积和骨髓脂肪组织质量减少。有强有力的证据表明，神经元活动增加会引发肩胛间棕色脂肪组织（BAT）对冷应激的代谢反应，但尚不清楚骨骼是否通过类似机制受到调节。因此，我们比较了BAT和整个胫骨对环境温度降低的短期反应。为了实现这一点，我们将一组6周龄雄性小鼠从32°C转移到22°C的饲养环境中，并在24小时后处死小鼠。年龄匹配的对照组维持在32°C。然后，我们评估了BAT和胫骨中一组与脂肪细胞分化和脂肪代谢相关的基因的表达水平，以及胫骨中一组与骨代谢相关的基因的表达水平。饲养温度的降低导致BAT中47/86个与脂肪细胞分化和脂肪代谢相关的基因的表达水平发生变化，其中 和 分别增加了9倍和17倍。相比之下，胫骨中只有1/86个与脂肪细胞分化和脂肪代谢相关的基因以及4/84个与骨代谢相关的基因差异表达。这些发现表明，尽管骨骼由感觉神经元和交感神经元支配，但它对环境温度变化的反应不如BAT迅速。
