Mammals with increased requirements for adipose tissue stores, such as marine mammals, have altered nutrient allocation priorities compared to many terrestrial mammals and thus the physiological response to undernutrition (low nutritional status) and realimentation (refeeding) may differ. Key regulators of nutrient allocation and tissue specific growth include metabolic hormones of the somatotropic axis, growth hormone (GH) and insulin-like growth factor (IGF)-I, as well as satiety and adipose promoting ghrelin and the stress hormone cortisol. Longitudinal measurements of metabolic hormones, blood metabolites, and morphometrics were collected over a 10-week period in twelve (male n = 3, female n = 9) harbor seal pups (< 6 weeks of age). Blood metabolites were used to indicate metabolic response during realimentation while morphometrics estimated tissue specific growth priorities. Harbor seal pups undergoing refeeding after nutritional deprivation show a preference for protein sparing despite severe malnutrition. Both BUN and total protein were negatively associated with GH and positively associated with IGF-I and ghrelin highlighting the importance of these metabolic hormones in the regulation of protein metabolism. While the response of the somatotropic axis to realimentation was typical of the mammalian pattern, the surprising increase of ghrelin across the study period suggests the priority of adipose accretion in addition to a possible mechanism regulating compensatory growth of vital adipose stores in a species, which prioritizes adipose accretion for survival.

中文翻译：

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代谢激素和血液代谢物对康复海豹 (Phoca vitulina) 幼崽的反应

与许多陆生哺乳动物相比，对脂肪组织储存需求增加的哺乳动物（如海洋哺乳动物）改变了营养分配优先级，因此对营养不良（低营养状态）和补给（再喂食）的生理反应可能不同。营养分配和组织特异性生长的关键调节因子包括生长激素轴的代谢激素、生长激素 (GH) 和胰岛素样生长因子 (IGF)-I，以及促进饱腹感和脂肪的生长素释放肽和应激激素皮质醇。在 10 周内收集了 12 只（雄性 n = 3，雌性 n = 9）海豹幼崽（<6 周龄）的代谢激素、血液代谢物和形态测量的纵向测量值。血液代谢物用于指示实现过程中的代谢反应，而形态计量学估计组织特异性生长优先级。尽管严重营养不良，但在营养剥夺后接受再喂养的海豹幼崽表现出对蛋白质保留的偏好。BUN 和总蛋白均与 GH 呈负相关，与 IGF-I 和 ghrelin 呈正相关，突出了这些代谢激素在调节蛋白质代谢中的重要性。虽然促生长轴对恢复的反应是哺乳动物模式的典型反应，但整个研究期间生长素释放肽的惊人增加表明除了调节物种中重要脂肪储存的补偿性生长的可能机制之外，脂肪积累的优先性，它优先脂肪堆积以求生存。