冷驯化条件下大绒鼠的产热和能量代谢特征

本文主要研究了冷驯化(5℃±1℃)条件下,大绒鼠(Eothenomys miletus)的能量收支、基础代谢率(BMR)、非颤抖性产热(NST)和肝脏线粒体呼吸.结果表明:随着冷驯化的进行,大绒鼠的体重、体温降低;摄入能、消化能、可代谢能增加;BMR和NST增加;肝脏线粒体呼吸状态Ⅲ呼吸先增加,28天后趋于平稳;线粒体状态Ⅳ呼吸先增加,28天后下降.说明在冷驯化条件下,大绒鼠采取适当降低体重和体温、增加能量摄入、增加BMR和NST产热的对策来维持能量平衡     

大绒鼠在不同驯化温度下产热和能量代谢的变化

为研究不同温度驯化条件下大绒鼠体重、体温和能量代谢水平的可塑性变化,本实验测定了热驯化(30℃ ;12L∶ 12D)转脱热驯化(5℃ ;12L∶ 12D)和冷驯化(5℃ ;12L∶ 2D) 转脱冷驯化(30℃ ;12L∶ 12D)条件下,大绒鼠体重、体温、能量收支、静止代谢率和非颤抖性产热的变化。结果表明:大绒鼠在热驯化转脱热驯化过程中,随着热驯化时间的延长,大绒鼠体重和体温增加,摄入能、静止代谢率和非颤抖性产热逐渐降低,在28 d 时降到最低;转到脱热驯化条件下,表现出相反的趋势。冷驯化转入脱冷驯化过程中,随着冷驯化时间的延长,大绒鼠的体重和体温降低,摄入能、静止代谢率和非颤抖性产热逐渐升高,28 d 时达到最高;转移到脱冷驯化条件时,表现出相反的趋势。以上结果说明大绒鼠在不同温度驯化条件下,其体重、能量代谢和产热具有可塑性变化,即通过调节体重、体温和能量代谢来适应不同温度变化。     

外源瘦素注射对昆明和大理地区大绒鼠适应性产热的影响

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 miletus)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28 d。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...     

限食程度对大绒鼠体重和产热特征的影响

为阐明动物应对食物短缺的能量学对策,将成年大绒鼠按自由取食量的90%、80%和70%限食4周。测定了不同限食程度下大绒鼠的存活率、体重、体脂含量、血清瘦素浓度、基础代谢率和非颤抖性产热。结果发现,90%限食驯化4周后,动物没有死亡,80%限食驯化4周后,存活率为90%,而70%限食驯化4周后,存活率仅为60%。限食使大绒鼠体重、体脂含量、血清瘦素浓度、基础代谢率和非颤抖性产热降低。血清瘦素浓度与体重、基础代谢率和非颤抖性产热呈显著正相关。结果表明,在限食条件下,大绒鼠主要通过降低体重、基础代谢率和产热的能量支出以及动用体内脂肪以应对食物资源短缺的环境条件,符合"代谢率转换"假说。瘦素作为饥饿信号可能参与了限食条件下大绒鼠能量代谢和体重的适应性调节。     

冷驯化对中缅树qu产热能力的影响

在(5±1)℃条件下对中缅树qu(Tupaia belangeri)进行低温胁迫处理(0-28 d)，测定其冷驯化过程中的静止代谢率(RMR)、非颤抖性产热(NST[max])、冷诱导最大产热(CIRMR)、体重、体温等生理指标，探讨低温对中缅树qu产热能力的影响。结果表明：①冷驯化期间中缅树qu体重增加，体温降低，产热能力显著增强；②在冷驯化过程中，增加RMR和CIRMR是中缅树qu抵抗低温胁迫的主要产热模式。     

冷驯化条件下长爪沙鼠血清瘦素浓度的变化及其与能量收支和产热的关系

为研究低温胁迫条件下长爪沙鼠的适应对策及瘦素对体重和能量平衡的调节作用 ,我们将 7只成年雌性长爪沙鼠在 5℃条件下驯化 2 1d ,另选 7只作为对照 ,对体重、血清瘦素含量、体脂含量、摄入能、基础代谢率、非颤抖性产热等进行了测定。结果发现 :1 ) 5℃条件下长爪沙鼠的体重没有明显变化 ;2 ) 5℃条件下长爪沙鼠的血清瘦素浓度和体脂含量均明显低于对照组 ,且瘦素浓度与体脂含量呈显著正相关 ;3) 5℃条件下长爪沙鼠的摄入能、基础代谢率和非颤抖性产热等显著高于对照。这些结果表明 :长爪沙鼠在低温条件下产热能力和自身维持能量消耗都增加 ,能量摄入因此而增加 ;瘦素参与了能量平衡和体重的调节 ,但没有直接参与产热调节     

高原鼠兔冷驯化和脱冷驯化中的产热变化

本文探讨了冷驯化和脱冷驯化对高原鼠兔代谢产热的影响。在冷驯化中，鼠兔的静止代谢率逐渐增加，血清Ｔ３‘／Ｔ４比率上升，肝线粒体状态３呼吸明显增加，线粒体细胞色素Ｃ氧化酶激活，而肝脏线粒体蛋白含量没有明显变化。     

光周期和高脂食物对布氏田鼠能量代谢和产热的影响

为了研究光周期和高脂食物对小型哺乳动物能量代谢和产热的影响,将成年雌性布氏田鼠(Lasiopodomys brandtii)分别驯化于长光照低脂、高脂食物和短光照低脂、高脂食物,7周后测定动物的体重、能量摄入、产热、血清瘦素浓度以及褐色脂肪组织解偶联蛋白1(BAT-UCP1)含量等参数.结果发现:1)短光照抑制体重增长、降低体脂重量和血清瘦素水平,增加非颤抖性产热(NST)和UCP1含量;2)高脂食物使摄入能减少和消化率提高,但未显著影响体重、基础代谢率、NST、UCP1含量和血清瘦素;3)血清瘦素与摄入能不相关,但与体脂含量正相关.结果暗示:短光照下瘦素作用敏感性增加和产热能力增强,可能介导了抵抗高脂食物诱导的肥胖.在野外条件下草食性的布氏田鼠能通过能量代谢和产热的适应性调节避免体重的过度增长,有利于降低捕食风险,增强生存能力.同时布氏田鼠是研究食物诱导肥胖机理的一个好模型     

冷驯化对中缅树鼩产热能力的影响

在 ( 5± 1)℃条件下对中缅树 (Tupaiabelangeri)进行低温胁迫处理 ( 0～ 2 8d) ,测定其冷驯化过程中的静止代谢率 (RMR)、非颤抖性产热 (NSTmax)、冷诱导最大产热 (CIRMR)、体重、体温等生理指标 ,探讨低温对中缅树产热能力的影响。结果表明 :①冷驯化期间中缅树体重增加 ,体温降低 ,产热能力显著增强 ;②在冷驯化过程中 ,增加RMR和CIRMR是中缅树抵抗低温胁迫的主要产热模式。     

冷驯化条件下高山姬鼠能量对策的初步研究

为进一步了解横断山区小型哺乳动物的能量代谢对策,本文主要研究了横断山的外来物种——高山姬鼠(Apodemus chevrieri)持续冷暴露28d的能量变化。结果表明,随着冷驯化时间延长,体重和体温降低;摄入能、消化能和可代谢能增加,至21d后这3项指标又下降;BMR和NST增加,并且28d后它们分别是对照组的187.19%和155.97%;(NST-BMR)/BMR比值7d时增加到1.02,21d后下降至0.53,并保持稳定。因此,在持续冷暴露下,高山姬鼠采取适当降低体重和体温、增加能量摄入、增加BMR和NST产热等途径来维持能量代谢平衡,但是NST在产热中的作用逐渐降低。这种能量模式很可能代表了一种外来小型啮齿动物对于在横断山生存独特的能量适应策略。     

Energy metabolism, thermogenesis and body mass regulation in tree shrew (Tupaia belangeri) during subsequent cold and warm acclimation

Environmental cues play important roles in the regulation of an animal's physiology and behavior. The purpose of the present study was to test the hypothesis that ambient temperature is a cue to induce adjustments in body mass, energy intake and thermogenic capacity, associated with changes in serum leptin levels in tree shrews (Tupaia belangeri). We found that tree shrews increased basal metabolic rate (BMR), energy intake and subsequently showed a significant decrease in body mass after being returned to warm ambient temperature. Uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT) increased during cold acclimation and reversed after rewarming. The trend of energy intake increased during cold acclimation and decreased after rewarming; the trend of energy intake during cold acclimation was contrary to the trend of energy intake during rewarming. Further, serum leptin levels were negatively correlated with body mass. Together, these data supported our hypothesis that ambient temperature was a cue to induce changes in body mass and metabolic capacity. Serum leptin, as a starvation signal in the cold and satiety signal in rewarming, was involved in the processes of thermogenesis and body mass regulation in tree shrews.     

Effects of cold acclimation on body mass,serum leptin level,energy metabolism and thermognesis in Eothenomys miletus in Hengduan Mountains region

Eothenomys miletus is an important species inhabiting Hengduan mountains region. In order to study adaptive strategy and the role of serum leptin level in response to a 49 d cold exposure, body mass, energy intake, basal metabolic rate (BMR), nonshivering thermogenesis (NST) in E. miletus were measured. During cold exposure (5±1 ^oC), body mass decreased; serum leptin levels decreased significantly and were positively correlated with body mass and fat mass; energy intake, BMR and NST were higher at 5 °C than that of controls. These results suggest that E. miletus enhanced thermogenic capacity and increased maintenance cost during cold acclimation, resulting in increased energy intake. Serum leptin participated in the regulation of energy balance and body mass in E. miletus.     

食物限制对雄性大绒鼠能量代谢特征的影响

为探讨横断山区大绒鼠适应食物匮乏的适应对策,将成年雄性大绒鼠随机分为自由取食组和饲喂正常摄食量的80% 限食组。测定了自由取食组和限食组雄性大绒鼠的体重、静止代谢率、非颤抖性产热以及体脂含量、血清瘦素含量、肝脏鲜重、褐色脂肪组织重量和消化道形态。结果显示:限食使雄性大绒鼠的体重、体脂含量、静止代谢率、非颤抖性产热、褐色脂肪组织重量和大肠、小肠长度显著降低,使盲肠内容物重量显著增加。血清瘦素含量与体重、体脂含量呈极显著正相关。在限食条件下,大绒鼠主要通过降低体重、基础代谢和产热的能量支出以及动用体内脂肪以应对食物资源短缺的环境条件,瘦素可能参与了能量代谢和体重的适应性调节。     

Energy metabolism, thermogenesis and body mass regulation in Brandt's voles (Lasiopodomys brandtii) during cold acclimation and rewarming

Environmental cues play important roles in the regulation of an animal's physiology and behavior. The purpose of the present study was to test the hypothesis that ambient temperature was a cue to induce adjustments in body mass, energy intake and thermogenic capacity, associated with changes in serum leptin levels in Brandt's voles (Lasiopodomys brandtii). We found that Brandt's voles increased resting metabolic rate (RMR) and energy intake and kept body mass stable when exposed to the cold while showed a significant increase in body mass after rewarming. The increase in body mass after rewarming was associated with the higher energy intake compared with control. Uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT) increased in the cold and reversed after rewarming. Serum leptin levels decreased in the cold while increased after rewarming, associated with the opposite changes in energy intake. Further, serum leptin levels were positively correlated with body mass and body fat mass. Together, these data supported our hypothesis that ambient temperature was a cue to induce changes in body mass and metabolism. Serum leptin, as a starvation signal in the cold and satiety signal in rewarming, was involved in the processes of thermogenesis and body mass regulation in Brandt's voles.     

Thermogenesis, energy intake and serum leptin in Apodemus chevrieri in Hengduan Mountains region during cold acclimation

Environmental factors play an important role in the seasonal adaptation of body mass and thermogenesis in small, wild mammals. The purpose of the present study was to test the hypothesis that ambient temperature was a cue to trigger the adjustments in body mass, energy intake, and serum leptin level in Apodemus chevrieri during 42 days of cold exposure. Our data demonstrated that cold acclimation induced a decrease in body mass and a significant increase in energy intake in A. chevrieri. Serum leptin levels were positively correlated with body mass and fat mass. These data suggest that A. chevrieri reduced the body mass and increased energy intake and thermogenic capacity under cold acclimation. Further, serum leptin appears to be involved in the energy intake regulation and thermoregulation.     

Cold adaptive thermogenesis in small mammals from different geographical zones of China

The mechanisms of thermogenesis and thermoregulation were studied in the tree shrew (Tupaia belangeri) and greater vole (Eothenomys miletus) of the subtropical region, and Brandt's vole (Microtus brandti), Mongolian gerbil (Meriones unguiculatus), Daurian ground squirrel (Spermophilus dauricus) and plateau pika (Ochotona curzoniae) of the northern temperate zone. Resting metabolic rate (RMR) and non-shivering thermogenesis (NST) increased significantly in T. belangeri, E. miletus, M. brandti and M. unguiculatus after cold acclimation (4 degrees C) for 4 weeks. In T. belangeri, the increase in RMR and thermogenesis at liver cellular level were responsible for enhancing the capacity of enduring cold stress, and homeothermia was simultaneously extended. Stable body temperature in M. brandti, E. miletus, M. unguiculatus and O. curzoniae was maintained mainly through increase in NST, brown adipose tissue (BAT) mass and its mitochondrial protein content, and the upregulation of uncoupling protein (UCP1) mRNA, as well as enhancement of the activity of cytochrome C oxidase, alpha-glycerophosphate oxidase and T(4) 5'-deiodinase in BAT mitochondria. The RMR in O. curzoniae and euthermic S. dauricus was not changed, while NST significantly increased during cold exposure; the former maintained their stable body temperature and mass, while body temperature in the latter declined by 4.8 degrees C. The serum T(3) concentration or ratio of T(3)/T(4) in all the species was enhanced after cold acclimation. Results indicated that: (1) the adaptive mechanisms of T. belangeri residing in the subtropical region to cold are primarily by increasing RMR and secondly by increasing NST, and the mechanisms of thermogenesis are similar to those in tropical mammals; (2) in small mammals residing in northern regions, the adaptation to cold is chiefly to increase NST; (3) the mechanism of cold-induced thermogenesis in E. miletus residing in subtropical and high mountain regions is similar to that in the north; (4) a low RMR in warm environments and peak RMR and NST in cold environments enabled M. unguiculatus to tolerate a semi-desert climate; (5) O. curzoniae has unusually high RMR and high NST, acting mainly via increasing NST to adapt to extreme cold of the Qinghai-Tibet Plateau; (6) the adaptation of euthermic S. dauricus to cold is due to an increase in NST and a relaxed homeothermia; and lastly (7) the thyroid hormone is involved in the regulation of cold adaptive thermogenesis in all the species studied.     

Seasonal changes in body mass, energy intake and thermogenesis in Maximowiczi’s voles (Microtus maximowiczii) from the Inner Mongolian grassland

Small mammals inhabiting temperate and arctic regions exhibit annual adaptive adjustments in physiology, anatomy, and behavior. No data on the physiology of Maximowicz’s voles (Microtus maximowiczii) are available at present. Here we examined the seasonal changes in body mass, food intake, thermogenic capacity, serum leptin and thyroid hormone levels in wild-captured individuals from Inner Mongolian grassland, China. We further examined the effects of photoperiod on these parameters. Energy intake, resting metabolic rate, nonshivering thermogenesis (NST), and serum tri-iodothyronine (T3) levels increased while serum leptin and body mass decreased in the cold seasons. Serum T3 levels were positively correlated with NST and uncoupling protein 1 (UCP1) contents in brown adipose tissue, and leptin levels were negatively correlated with energy intake and resting metabolic rate. Furthermore, laboratory data showed these changes could be induced by short photoperiod alone. Taken together, our results indicate that Maximowicz’s voles can increase thermogenic capacity and energy intake to cope with cold stress. Serum leptin seems to be involved in the regulation of energy intake and changes in T3 level may be important for the variations in NST and/or UCP1. Short photoperiod can serve as a seasonal cue for the winter acclimatization of energy balance in free-living Maximowicz’s voles.     

自愿转轮运动对雄性长爪沙鼠体重和能量代谢的影响

运动是影响动物能量平衡和体重变化的重要因素之一。为研究自愿转轮运动对体重和能量代谢的影响,我们监测了8 周自愿转轮运动过程中,雄性长爪沙鼠的体重、能量摄入、消化率、静止代谢率(RMR) 和非颤抖性产热(NST)的变化,以及8 周后的体脂含量、血清甲状腺激素(T3、T4 )和瘦素(leptin)水平的变化等。结果发现,8 周自愿转轮运动增加了长爪沙鼠的体重和能量摄入以及血清瘦素水平(血清瘦素浓度比对照组高27% ),但对消化率、RMR 和褐色脂肪组织的线粒体蛋白浓度等没有明显影响。尽管体脂含量和血清T₃ 和T₄ 没有显著差异,但运动组体脂含量比对照组高33%,血清T₃ 和T₄ 水平分别比对照组低10% 和38%。血清瘦素浓度与体脂重量呈正相关。因此,自动转轮运动并没有降低动物的体重和体脂含量,但瘦素和甲状腺素在雄性长爪沙鼠能量代谢和能量平衡中的作用尚需进一步确定。