Robertson Cayleih E, McClelland Grant B
Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada.
J Comp Physiol B. 2021 May;191(3):589-601. doi: 10.1007/s00360-021-01355-z. Epub 2021 Mar 1.
Small, non-hibernating endotherms increase their thermogenic capacity to survive seasonal cold, through adult phenotypic flexibility. In mammals, this response is primarily driven by remodeling of brown adipose tissue (BAT), which matures postnatally in altricial species. In many regions, ambient temperatures can vary dramatically throughout the breeding season. We used second-generation lab-born Peromyscus leucopus, cold exposed during two critical developmental windows, to test the hypothesis that adult phenotypic flexibility to cold is influenced by rearing temperature. We found that cold exposure during the postnatal period (14 °C, birth to 30 days) accelerated BAT maturation and permanently remodeled this tissue. As adults, these mice had increased BAT activity and thermogenic capacity relative to controls. However, they also had a blunted acclimation response when subsequently cold exposed as adults (5 °C for 6 weeks). Mice born to cold-exposed mothers (14 °C, entire pregnancy) also showed limited capacity for flexibility as adults, demonstrating that maternal cold stress programs the offspring thermal acclimation response. In contrast, for P. maniculatus adapted to the cold high alpine, BAT maturation rate was unaffected by rearing temperature. However, both postnatal and prenatal cold exposure limited the thermal acclimation response in these cold specialists. Our results suggest a complex interaction between developmental and adult environment, influenced strongly by ancestry, drives thermogenic capacity in the wild.
小型非冬眠恒温动物通过成年期的表型可塑性来提高其产热能力，以度过季节性寒冷。在哺乳动物中，这种反应主要由棕色脂肪组织（BAT）的重塑驱动，棕色脂肪组织在晚成雏物种中出生后成熟。在许多地区，整个繁殖季节的环境温度可能会有很大变化。我们使用第二代实验室出生的白足鼠，在两个关键发育窗口进行冷暴露，以检验成年期对寒冷的表型可塑性受饲养温度影响这一假设。我们发现，出生后时期（14°C，出生至30天）的冷暴露加速了棕色脂肪组织的成熟，并永久性地重塑了该组织。成年后，这些小鼠相对于对照组具有更高的棕色脂肪组织活性和产热能力。然而，当它们成年后随后再次进行冷暴露（5°C，持续6周）时，它们的适应性反应减弱。出生于冷暴露母亲（14°C，整个孕期）的小鼠成年后也表现出有限的可塑性能力，这表明母体冷应激会影响后代的热适应反应。相比之下，对于适应寒冷高山环境的北美鹿鼠，棕色脂肪组织的成熟速率不受饲养温度的影响。然而，出生后和产前的冷暴露都限制了这些耐寒专家的热适应反应。我们的结果表明，发育环境和成年环境之间存在复杂的相互作用，这种相互作用受到祖先的强烈影响，驱动着野外的产热能力。
