Abstract: Small mammals respond to environmental stress by adjusting their thermogenic capacity. To investigate the effect of exogenous leptin on the induction of adaptive thermogenesis in Eothenomys miletus from Kunming (KM) and Dali (DL), 14 voles were selected from each region and placed at 25℃ ± 1℃ with a photoperiod of 12L:12D, and daily intraperitoneal leptin injection last for 28 days. LT502 electronic balance was used to measure the body mass every two days in E. miletus, the food intake was measured by the food balance method every two days, and the resting metabolic rate (RMR) and nonshivering thermogenesis (NST) were measured by a portable respiratory metabolic measurement system every seven days. After the animals were killed on day 28, mitochondrial protein content (MtP), mitochondrial cytochrome c oxidase (COX) activity and uncoupling protein 1 (UCP1) content, serum levels of triiodothyronine (T₃), thyroxine (T₄), leptin, thyrotropin-releasing hormone (TRH) and adrenal corticotropin-releasing hormone (CRH) were determined by enzyme-linked immunosorbent assay (ELISA). The results showed that leptin injection significantly reduced body mass and food intake, enhanced RMR and NST, increased MtP and COX activity in liver, COX activity and UCP1 content in brown adipose tissue (BAT), and serum T₃, T₄, T₃/T₄ ratio, TRH and CRH concentrations in E. miletus from KM and DL. Leptin levels were negatively correlated with body mass and food intake, and serum T₃ levels were positively correlated with NST and UCP1 levels. Moreover, body mass and food intake were higher in voles from KM region than those from DL region before injection, but RMR and NST were lower in animals from KM region. The changes in body mass in E. miletus from KM after exogenous leptin injection were higher than those from DL, while the changes in food intake, RMR, and NST were lower in KM voles than those in DL. In conclusion, exogenous injection of leptin reduced body mass and food intake and increased thermogenic capacity and energy metabolism in the two regions, suggesting that leptin was involved in their body mass and thermogenic regulation. Furthermore, E. miletus in the DL region was more sensitive to exogenous leptin injection, which may be related to low habitat temperature or poor food quality in DL.

Key words: Eothenomys miletus, Leptin, Thyroid hormones, Adaptive thermogenesis, Geographic distribution

摘要： 小型哺乳动物通过产热能力的调整来应对环境的胁迫。为探究外源瘦素对不同地区大绒鼠(Eothenomys mi-letus)适应性产热的影响，选取云南昆明和大理地区捕获的大绒鼠各14只，置于25℃±1℃，光周期为 12L∶12D的环境中，每日腹腔注射瘦素，持续28d。以LT502电子天平每两天测定大绒鼠的体重，采用食物平衡法每两天测定大绒鼠摄食量，以便携式呼吸代谢测量系统每7天测定静止代谢率(RMR)、非颤抖性产热(NST)。第28天处死动物后，采用酶联免疫吸附法测定线粒体蛋白含量、线粒体细胞色素c氧化酶(COX)活性、解偶联蛋白1(UCP1)含量、血清三碘甲状腺原氨酸(T₃)、甲状腺素(T₄)、瘦素水平以及促甲状腺激素释放激素(TRH)和促肾上腺皮质激素释放激素(CRH)水平。结果表明，注射瘦素后昆明和大理地区大绒鼠的体重和摄食量显著降低，RMR和NST增强，肝脏中线粒体蛋白含量和COX活性，褐色脂肪组织(BAT)中COX活性和UCP1含量，及血清T₃、T₄、T₃/T₄比值、TRH和CRH浓度均增加。瘦素水平与体重、摄食量呈负相关，血清T₃水平与NST和UCP1含量呈正相关。此外，注射前昆明地区大绒鼠的体重和摄食量高于大理地区，但RMR和NST低于大理地区。外源注射瘦素后昆明地区大绒鼠的体重变化高于大理地区大绒鼠，而摄食量、RMR和NST的变化低于大理地区大绒鼠。总之，外源瘦素注射降低了两地区大绒鼠的体重和摄食量，增加了其产热能力和能量代谢，说明瘦素参与了其体重和产热调节。此外，大理地区大绒鼠对外源瘦素注射更为敏感，这可能与该地区大绒鼠栖息环境温度较低，食物质量较差有关。

关键词: 大绒鼠, 瘦素, 甲状腺激素, 适应性产热, 地理分布