食物限制对高山姬鼠能量代谢和内脏器官形态的影响

为探讨栖息于横断山区高山姬鼠对食物匮乏的适应策略,在实验室条件下,以每日能量需求为标准,测定了饲喂食量为130%每日能量需求(DER)和70%DER两组高山姬鼠的体重、体温、基础代谢率(BMR)、非颤抖性产热(NST)等的变化,并在限食28d后,测定了肝脏鲜重和消化道形态的变化。结果显示:限食组高山姬鼠的体温、体重、BMR、NST显著降低,比0d分别下降了4.4%、23.6%、38.6%、20.3%。肝脏鲜重显著下降,小肠长度和小肠含内容物重显著增加。在限食条件下,高山姬鼠主要通过降低体重、体温、减少肝脏重量和能量代谢水平及消化器官适应性变化来减少能量支出,以适应食物资源短缺的外部环境。     

高山姬鼠冷驯化过程中的能量收支

为探讨栖息于横断山地区高山姬鼠的能量代谢特征,采用食物平衡法,在冷驯化条件下,对其能量收支进行了测定。分别测定了冷驯化(5 ± 1℃ ,42 d)过程中,高山姬鼠体重、体温、每日摄入能、消化能、消化率、粪便能及可代谢能、可代谢率的变化。结果表明:随着冷驯化时间的延长,高山姬鼠的体重和体温降低,28 d 时达到最低值后保持稳定,其中体重在冷驯化14 d 时即与对照组有显著差异,28 d 时平均比对照组降低了15.5% ,体温在14 d 后和对照组有显著差异。每日摄入能、消化能、可代谢能升高,三者均在冷驯化14 d 后与对照组有极显著差异,21 d 时达到最高后保持稳定。粪便能、消化率和可代谢率在冷驯化过程中没有显著变化。高山姬鼠在冷暴露过程中,通过降低体重减少绝对能量需求;通过降低体温减少用于维持体温恒定所消耗的能量;通过增加能量摄入维持正常的生理机能。高山姬鼠在冷驯化过程中表现出的变化模式,与其低纬度、高海拔、年平均温度较低的生存环境有关,这在一定程度上反映了横断山区小型哺乳动物在低温胁迫下的生存机制和适应对策。     

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     

冷驯化对大绒鼠和高山姬鼠肝脏线粒体呼吸的影响

大绒鼠Eothenomys miletus和高山姬鼠Apodemus chevrieri为横断山地区小型哺乳动物的代表.分别测定大绒鼠和高山姬鼠冷驯化组(7 d、14 d、21 d、28 d)与对照组(0 d)中肝脏线粒体蛋白含量、呼吸状态Ⅲ和状态Ⅳ、呼吸磷氧比的变化以及较大绒鼠和高山姬鼠的相应项,探讨大绒鼠和高山姬鼠对不同冷环境的适应情况以及肝脏产热的机理.结果 表明:在冷驯化条件下,大绒鼠和高山姬鼠的产热显著增加,无论是大绒鼠还是高山姬鼠实验组比对照组肝脏线粒体蛋白含量、呼吸状态Ⅲ和状态Ⅳ、呼吸磷氧比有着显著的提高,在两者的比较中,在同等冷驯化条件下高山姬鼠增加的程度高于大绒鼠.     

光周期和高脂食物对雌性高山姬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,将成年雌性高山姬鼠分别驯化于长光照低脂、高脂食物和短光照低脂、高脂食物条件下,7周后测定动物的体重、能量摄入、产热、身体组成、血清瘦素浓度以及体脂含量等参数。结果发现:1)短光照抑制体重增长,降低血清瘦素浓度,增加非颤抖性产热;2)高脂食物使摄入能减少,消化率和体脂含量提高,但未显著影响体重、基础代谢率、非颤抖性产热和血清瘦素浓度;3)血清瘦素浓度与摄入能不相关,但与体脂重量正相关。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,高山姬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。     

中缅树鼩能量代谢的季节变化

小型哺乳动物的体重和产热特征的季节调节对其生存至关重要。为探讨中缅树鼩的能量代谢适应特征随季节的变化,采用耗氧量测定、食物平衡法、形态测量等方法,分别对其冬季和夏季的基础代谢率(BMR)、非颤抖性产热(NST)、体温、体重、蒸发失水、能量收支和消化道的长度和重量进行了测定。中缅树鼩冬季体温、体重、基础代谢率、NST、蒸发失水散热分别为37. 9℃ ± 0.14℃ ,126.1 ± 2.1 g,42. 94 ± 2.65 J/g· h,54. 97 ±2.14 J/ g·h,5. 69 ±0.33 J/ g·h;夏季体温、体重、基础代谢率、NST、蒸发失水散热分别为38.5℃ ± 0. 27℃ ,106.9 ±5.1 g,28. 69 ±3.06 J/ g·h,47.43 ± 2.45 J / g·h,7.12 ±0. 57 J/ g·h;中缅树鼩的每日摄入能、消化能、可代谢能冬季均比夏季显著增加,消化道特征冬季和夏季存在变化,随着温度降低、食物质量下降,小肠长度和重量增加。这些结果表明:中缅树鼩在冬季,通过增加体重、基础代谢率和NST、能量摄入、消化能和可代谢能,降低蒸发失水等方式应对季节性环境变化。代谢产热和消化生理调节在季节性适应过程中具有重要地位。     

大绒鼠和高山姬鼠的体温调节和产热特征

大绒鼠和高山姬鼠为横断山地区小型哺乳动物的代表。为探讨它们在该地区的生理生态适应特征,对其体温调节和产热特征进行了测定。代谢率采用封闭式流体压力呼吸计进行测定。结果表明:大绒鼠和高山姬鼠热中性区分别为25～32.5℃ 和25～30℃;平均体温分别为35.92 ±0.37℃和36.01±0.83℃,前者体温在20～27.5℃ 范围内维持恒定,后者体温在15～27.5℃范围内维持恒定;大绒鼠和高山姬鼠基础代谢率(BMR)分别为3.76±0.07 ml O₂/g.h和4.58±0.09 ml O₂/g.h;大绒鼠和高山姬鼠平均最小热传导(Cm) 分别为0.28±0.005 ml O₂/g.h ℃ 和0.32±0.009 ml O₂/g.h℃;热中性区内,大绒鼠和高山姬鼠的F值(RMR/ Kleiber 期望RMR)/(C/Bradley 期望C) 分别为0.88±0.05 和1.10±0.05。它们的产热特征和体温调节模式很可能反映了横断山地区小型啮齿动物的特征,即体温较低、维持体温稳定的环境温度范围较窄、BMR水平较高、热传导率高。高山姬鼠的体温、C值和BMR 都比大绒鼠的高,并且高山姬鼠维持体温稳定的环境温度范围比大绒鼠的宽,它们产热特征和体温调节模式的这些差异与其分类地位、生活习性和栖息生境等因素密切相关。     

大绒鼠冷驯化和脱冷驯化能量代谢特征的变化

通过测定冷驯化(5℃)到脱冷驯化(30℃)条件下,大绒鼠(Eothenomys miletus)的体重、摄入能、静止代谢率(RMR)、非颤抖性产热(NST)和血清瘦素含量等参数,探讨了血清瘦素浓度与能量收支的关系。结果表明,冷驯化可致大绒鼠体重下降,RMR、NST、摄入能升高,血清瘦素浓度降低;脱冷驯化后大绒鼠体重增加,RMR、NST、摄入能降低,血清瘦素浓度增加。血清瘦素含量与体重呈正相关,与RMR、NST、摄入能呈负相关。表明大绒鼠的体重、摄入能和产热能力具有较强的可塑性,且瘦素可能参与了大绒鼠适应冷驯化及恢复过程中的能量平衡和体重的调节。     

被毛在黑线仓鼠能量代谢、产热和体温调节中的作用

为阐明小型哺乳动物被毛的季节性变化及其在能量代谢和体温调节中的作用,测定了季节性驯化,以及不同光周期和温度驯化的黑线仓鼠的被毛重量、体温和能量收支。结果显示: (1)冬季黑线仓鼠的被毛重量和产热显著高于夏季;(2)短光照(8L∶16D)和低温(5℃ ) 对被毛生长的影响不显著; (3)与室温组(21℃ )相比,低温组(5℃ )摄入能、基础代谢率(BMR)、非颤抖性产热(NST) 、褐色脂肪组织细胞色素c 氧化酶活性和热传导率显著增加,而暖温组(30℃ )显著降低; (4)室温和低温下,剃毛导致摄入能、BMR、NST 和热传导率显著增加;结果表明:被毛的作用与环境温度有关,低温下被毛降低了能量需求,增强了动物应对低温环境的适应能力;被毛的适应性变化是独居的野生小型哺乳动物应对环境温度季节性波动的主要适应策略之一,在其能量代谢和体温调节中具有重要作用和意义。     

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。     

Seasonal adjustments in body mass and thermogenesis in Mongolian gerbils (<Emphasis Type="Italic">Meriones unguiculatus</Emphasis>): the roles of short photoperiod and cold

Seasonal adjustments in body mass and thermogenesis are important for the survival of small mammals during acclimatization in the temperate zone. To determine the contributions of short photoperiod and cold temperatures to seasonal changes in thermogenesis and body mass in Mongolian gerbils (Meriones unguiculatus), body mass, basal metabolic rate (BMR), nonshivering thermogenesis (NST), energy intake and energy digestibility were determined in seasonally acclimatized and laboratory acclimated animals. Body mass showed significant seasonal changes and decreased to a minimum in winter. Both BMR and NST increased in winter, and these changes were mimicked by exposing animals to short photoperiod or cold temperatures in the animal house. Digestible energy intake also increased significantly in winter, and also during exposure of housed animals to both short photoperiod and cold. These results suggest that Mongolian gerbils overcome winter thermoregulatory challenges by increasing energy intake and thermogenesis, and decreasing body mass to reduce total energy requirements. Short photoperiod and cold can serve as effective environmental cues during seasonal acclimatization.     

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.     

食物限制对黑线仓鼠能量代谢和产热的影响

为阐明动物应对食物短缺的能量学对策与其自身的代谢水平的关系,测定了不同限食程度下黑线仓鼠的体重、基础代谢率和非颤抖性产热。结果发现,限食使基础代谢率、非颤抖性产热、褐色脂肪组织细胞色素c氧化酶活性降低。90% 限食驯化4 周后,存活率为80% ,60% 限食驯化4 周后,存活率为30% 。低温驯化使黑线仓鼠基础代谢率和非颤抖性产热显著增加,使80% 限食动物的体重和存活率显著降低。高基础代谢率组的摄食量比低基础代谢率组多23.8% ,80% 限食后两组体重降低的幅度和存活率差异不显著。结果表明:高水平的代谢率使黑线仓鼠对食物资源短缺的敏感性增加;支持“代谢率转换假说”,符合“具有储食习性的动物对食物短缺的生理耐受性较低” 的预测。     

Contribution of shivering and nonshivering thermogenesis to thermogenic capacity for the deer mouse (Peromyscus maniculatus)

Small mammals that are active all year must develop ways to survive the cold winters. Endotherms that experience prolonged cold exposure often increase their thermogenic capacity. Thermogenic capacity incorporates basal metabolic rate (BMR), nonshivering thermogenesis (NST), and shivering thermogenesis (ST). Increasing the capacity of any of these components will result in increased thermogenic capacity. It is often thought that NST should be the most plastic component of thermogenic capacity and as such is the most likely to increase with cold acclimation. We used deer mice to test this hypothesis by acclimating 27 animals to one of two temperatures (5 degrees or 22 degrees C) for 8 wk. We then measured and compared values for thermogenic capacity--BMR, ST, and NST--between the two groups. Thermogenic capacity and NST increased by 21% and 42%, respectively, after cold acclimation. Neither BMR nor ST showed any change after acclimation. Therefore, it appears that deer mice raise their thermogenic capacity in response to prolonged cold by altering NST only.     

随机饥饿和重喂食对小鼠能量代谢和行为的影响

为阐明能量代谢和行为的可塑性对动物适应食物资源变化的意义,将成年雄性KM 小鼠随机饥饿驯化4
周,再重喂食驯化4 周。采用食物平衡法测定摄食量、封闭式流体压力呼吸计测定基础代谢率(BMR) 和非颤
抖性产热(NST)、观察法测定行为。随机饥饿使摄食量、消化道重量显著增加,BMR 和NST 显著降低。与对照
组相比,饥饿组休息行为显著增加,活动显著降低。重喂食后,上述指标均恢复到对照组水平,表现出显著的
可塑性。研究结果表明,动物适应难以预测的食物资源短缺的主要策略包括:增加自由取食期间的摄食量;降
低BMR、NST 和活动行为,从而保存身体贮存的能量。能量代谢和活动行为在较短的时间尺度内表现出显著的
可塑性对小鼠适应不可预测的食物资源短缺的应激环境具有重要意义。     

When nonshivering thermogenesis equals maximum metabolic rate: thermal acclimation and phenotypic plasticity of fossorial Spalacopus cyanus (Rodentia)

Many small mammals inhabiting fluctuating and cold environments display enhanced capacity for seasonal changes in nonshivering thermogenesis (NST) and thermoregulatory maximum metabolic rate (MMR). However, it is not known how this plasticity remains in a mammal that rarely experiences extreme thermal fluctuations. In order to answer this question, we determined body mass (m(b)), basal metabolic rate (BMR), NST, MMR, and minimum thermal conductance (C) on a Chilean fossorial caviomorph (Spalacopus cyanus) from a coastal population, acclimated to cold (15 degrees C) and warm (30 degrees C) conditions. NST was measured as the maximum response of metabolic rate (NST(max)) after injection of norepinephrine (NE) in thermoneutrality minus BMR. Maximum metabolic rate was assessed in animals exposed to enhanced heat-loss atmosphere (He-O2) connected with an open-flow respirometer. Body mass and metabolic variables increased significantly after cold acclimation with respect to warm acclimation but to a low extent (BMR, 26%; NST, 10%; and MMR, 12%). However, aerobic scope (MMR/BMR), calculated shivering thermogenesis (ST), and C did not change with acclimation regime. Our data suggest that physiological plasticity of S. cyanus is relatively low, which is in accordance with a fossorial mode of life. Although little is known about MMR and NST in fossorial mammals, S. cyanus has remarkably high NST; low MMR; and surprisingly, a nil capacity of ST when compared with other rodents.     

Seasonal changes in body mass and thermogenesis in tree shrews (Tupaia belangeri): The roles of photoperiod and cold

Environmental factors play an important role in the seasonal adaptation of body mass and thermogenesis in small, wild mammals. To determine the contributions of photoperiod and cold on seasonal changes in energy metabolism and body mass, the resting metabolic rates (RMR), nonshivering thermogenesis (NST), energy intake and gut morphology of the tree shrews were determined in winter and summer and in laboratory acclimated animals. Body mass, RMR and NST increased in winter, and these changes were mimicked by exposing animals to short-day photoperiod or cold in the animal house. Energy intake and digested energy also increased significantly in winter, and also during exposure of housed animals to both short-day photoperiod and cold. The lengths and weights of small intestine increased in winter. These results indicated that Tupaia belangeri overcomes winter thermoregulatory challenges by increasing energy intake and thermogenesis, and adjusted gut morphology to balance the total energy requirements. Short-day photoperiod and cold can serve as environmental cues during seasonal acclimatization.     

Modulation of mitochondrial nitric oxide synthase and energy expenditure in rats during cold acclimation

To preserve thermoneutrality, cold exposure is followed by changes in energy expenditure and basal metabolic rate (BMR). Because nitric oxide (NO) modulates mitochondrial O(2) uptake and energy levels, we analyzed cold effects (30 days at 4 degrees C) on rat liver and skeletal muscle mitochondrial NO synthases (mtNOS) and their putative impact on BMR. Cold exposure delimited two periods: A (days 1-10), with high systemic O(2) uptake and weight loss, and B (days 10-30), with lower O(2) uptake and fat deposition. mtNOS activity and expression decreased in period A and then increased in period B by 60-100% in liver and skeletal muscle (P < 0.05). Conversely, mitochondrial O(2) uptake remained initially high in the presence of l-arginine and later fell by 30-50% (P < 0.05). On this basis, the estimated fractional contribution of liver plus muscle to total BMR varied from 40% in period A to 25% in period B. The transitional modulation of mtNOS in rat cold acclimation could participate in adaptive responses that favor calorigenesis or conservative energy-saving mechanisms.