Physiological variations of energy metabolism and body fat accumulation are the main energy budgets in small mammals to cope with natural environmental changes. However, the energy mechanisms underpinning the adaptive regulations in different stages of lifespan remain unclear. The present study was aimed to examine the changes in energy metabolism, fat accumulation and the endocrine mechanisms in striped hamsters (Cricetulus barabensis) during lactation and post-lactation. The food intake, fat depots mass, serum leptin levels and the gene expression of leptin receptor (Ob-Rb) and neuropeptides related to food intake regulation in hypothalamus were measured. The results showed that the fat depots were almost decreased to zero at peak lactation, and then were increased significantly during post-lactation. The masses of subcutaneous fat, perirenal fat and abdominal fat were 1.5, 37.1 and 1.9 fold higher in post-lactating females than that in non-reproductive controls. Food intake and serum leptin level of post-lactating females were significantly higher than that of non-reproductive controls, while the gene expression of Ob-Rb was significantly down-regulated in post-lactating females. The gene expression of orexigenic and anorexigenic neuropeptides did not differ between the two groups. The litter size raised during lactation had no significant effects on food intake, resting metabolic rate and body components in post-lactating females. These findings suggest that body fat accumulation is adaptively regulated in the different stages of reproduction.

Leptin resistance may be one of the most important endocrine mechanisms underpinning the fat accumulation during post-lactation. This is of significance for the mothers to restore fat accumulation and to cope with the periods of high energy demands and food shortage, increasing the fitness.

小型哺乳动物能量代谢和脂肪累积的适应性调节是其应对自然环境变化的主要能量学策略，但在不同的生活史阶段，脂肪组织适应性调节的特征和能量机理尚不清楚。为探讨不同繁殖阶段能量代谢和脂肪累积的变化及其内分泌机理，本文测定了黑线仓鼠哺乳期和断乳后摄食量、脂肪重量，以及血清瘦素水平、下丘脑瘦素受体（Ob-Rb）和相关神经肽的基因表达。结果显示，哺乳高峰期黑线仓鼠的脂肪重量几乎降低至零，断乳后显著增加；与非繁殖对照组相比，皮下脂肪、肾周脂肪与腹腔脂肪重量分别增长了1.5倍、37.1倍和1.9倍。断乳后摄食量、血清瘦素水平显著高于非繁殖对照组，Ob-Rb基因表达显著下调，而促食与抑食神经肽的基因表达均未发生显著变化。哺育不同胎仔数的黑线仓鼠在断乳后能量摄入、静止代谢率、身体组分未出现显著差异。研究表明，在不同的繁殖阶段脂肪累积呈现显

著的适应性调节，瘦素抵抗是断乳后脂肪累积补偿性增长的重要内分泌机制之一。这对迅速恢复脂肪累积，以应对将来的能量需求增加或者食物资源短缺的环境，进而提高自身的适合度具有重要意义。