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。     

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。     

达乌尔黄鼠产热的季节性变化

达乌尔黄鼠（Ｃｉｔｅｌｌｕｓｄａｕｒｉｃｕｓ）的产热表现出明显的季节性变化。在非冬眠期,静止代谢率（ＲＭＲ）和非颤抖性产热（ＮＳＴ）于春季最高,秋季次之,夏季最低。冬眠期,ＲＭＲ降到极低水平,只为春季的３．０％。肝脏的线粒体蛋白含量、线粒体呼吸和细胞色素Ｃ氧化酶活力在秋季显著高于其它各季。褐色脂肪组织（ＢＡＴ）的重量、线粒体蛋白含量、细胞色素Ｃ氧化酶活力和α－磷酸甘油氧化酶活力,在夏季处于一年中的最低水平,到了冬季这些指标达到一年中的最高水平。在非冬眠季节ＢＡＴ产热能力升高时,ＮＳＴ能力也相应升高,这表明ＢＡＴ产热能力的增强是ＮＳＴ能力提高的部分机制。达乌尔黄鼠血清Ｔ＿４含量在年周期中没有明显改变,冬眠时血清Ｔ＿３含量显著高于其它各季。     

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。     

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.     

小哺乳动物在高寒环境中的生存对策Ⅱ.高原鼠兔和根田鼠非颤抖性产热（NST）的季节性变化

本文对生存在高寒地区的两种非冬眠草食性小哺乳动物--高原鼠兔(Ochotona curzoniae)和根田鼠(Microtus oeconomus)的非颤抖性产热(Nonshlvering thermogenesis,NST)的季节性变化进行了测定,并对NST与褐色脂肪组织(Brown adipose tissue,BAT)的关系进行了分析,同时阐述了高寒环境中非冬眠草食性小哺乳动物的生存对策。     

Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals

Winter-active small mammals residing in seasonal environments employ many different behavioral, anatomical and physiological mechanisms to cope with cold. Herein we review research on survival mechanisms in cold employed by small mammals with emphasis on the families Soricidae, Muridae and Sciuridae. The focus of this review is on research delineating the role of seasonal changes in resting metabolic rate (RMR), nonshivering thermogenesis (NST), body mass, and communal nesting in enhancing winter survivorship of six species of small mammals (masked shrewSorex cinereus, short-tailed shrewBlarina brevicauda, southern red-backed voleClethrionomys gapperi, white-footed mousePeromyscus leucopus, deer mouseP. maniculatus, and southern flying squirrelGlaucomys volans) residing in the Appalachian Mountains of Pennsylvania, USA. Each species shows good over-winter survivorship but exhibits a different suite of mechanisms to maximize survival in cold.B. brevicauda, S. cinereus, andG. volans show slight increases in RMR during winter, whereasPeromyscus andC. gapperi exhibit decreased RMR overwinter. All six species experience elevated NST in winter. The comparatively low RMR and NST ofG. volans during winter was attributable to a decreased energy expenditure due to a larger body mass, coupled with communal nesting in cavities of trees that provided insulation from low ambient temperatures. Squirrels nesting singly experienced a longer period of elevated NST in winter and higher mean NST year-round than did squirrels nesting communally. Energy conservation in the form of growth retardation in winter was exhibited byC. gapperi andS. cinereus but not the other species.     

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。     

云南下关地区大绒鼠（Eothenomys miletus）体温调节和产热特征日节律的初步研究

为探讨横断山区小型哺乳动物体温调节和产热特征的日节律,对横断山区固有种大绒鼠（Eothenomys mile-tus）在24h中4个时间段（05：00—07：00、11：00—13：00、17：00—19：00、23：00—01：00）的体温、基础代谢率、非颤抖性产热进行了测定。结果显示大绒鼠的体温、基础代谢率、非颤抖性产热在24h内具有节律性波动,且变化趋势基本同步;各生理参数的最高值和最低值都分别出现在05：00—07：00和11：00—13：00时间段。结果表明,横断山区大绒鼠的基础代谢率、非颤抖性产热在其体温调节的日节律中起到了重要作用,同时,大绒鼠其夜间体温调节、产热特征显著高于白天,以适应横断山日温差大、食物资源丰富的特征。     

中缅树鼩体温、代谢率和蒸发失水日节律

为研究中缅树鼩(Tupaia belangeri)体温、代谢率和蒸发失水的日节律变化,采用植入式体温计测定了中缅树鼩24 h的体温,以及24 h中4个时间段(05:00～07:00时、11:00～13:00时、17:00～19:00时和23:00～01:00时)热中性区(30℃)的静止代谢率(RMR)、非颤抖性产热(NST)和蒸发失水(EWL)。结果显示,中缅树鼩的体温具有日节律变化,最高值和最低值分别出现在11:00时和03:00时,各为(39.45±0.26)℃和(36.34±0.24)℃;静止代谢率、非颤抖性产热和蒸发失水在4个时间段都有显著差异,表现出显著的日节律变化,代谢率在23:00～01:00时最大,O2含量为(2.58±0.04)ml/(g.h),在11:00～13:00时最小,O2含量为(2.28±0.09)ml/(g.h);非颤抖性产热在05:00～07:00时最大,O2含量为(3.08±0.14)ml/(g.h),在11:00～13:00最小,O2含量为(2.69±0.63)ml/(g.h);蒸发失水在17:00～19:00时最大,失水量为(3.60±0.31)mg/(g.h)。结果表明,体温的日节律变化主要与环境温度的日节律变化和下午出窝取食活动性增强有关;当夜晚环境温度相对较低的时候,通过增强静止代谢率和非颤抖性产热来增加产热,而白天环境温度相对较高的时候,通过增强蒸发失水散热来调节体温。     

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。     

Seasonal changes in thermogenesis and body mass in wild Mongolian gerbils (Meriones unguiculatus)

Seasonal adjustments in body mass (BM), nonshivering thermogenesis (NST) and several physiological, hormonal, and biochemical markers were measured in wild-trapped Mongolian gerbils (Meriones unguiculatus) from Inner Mongolia, China. Sexual differences were detected in BM, NST, brown adipose tissue (BAT) mass, and mitochondrial protein content. BM and NST in males were higher in winter (January) and spring (May) than in summer (August), and BM of females was also the highest in winter, but NST remained relatively constant throughout the year. Cytochrome c oxidase activity and mitochondrial uncoupling protein 1 (UCP1) content in BAT were enhanced in winter in males or females, respectively. Serum leptin concentration was the lowest in winter and positively correlated with BM and body fat mass but was negatively correlated with BAT UCP1 content. These data suggest that wild Mongolian gerbils do not depend on a decrease in BM, but instead increase their thermogenic capacity to cope with cold stress. Leptin may be involved in the seasonal regulation in energy balance and thermogenesis in field Mongolian gerbils.     

Changes in plasma cortisol during acute cold exposure in euthermic European hedgehogs: thermoregulatory role of the hypothalamo-pituitary-adrenal axis

Summary During acute cold exposure regulatory heat production of European hedgehogs was significantly increased with a simultaneous rise in the plasma cortisol level. Soon after cold exposure, at the time when standard metabolic rate was measured, the plasma cortisol level was reduced again. This finding indicates a highly reactive hypothalamo-pituitary-adrenal axis in euthermic hedgehogs exposed to a cold environment.Two effects of the adrenocorticostatic agent metopirone ditartrate were observed: (1) A metopirone-induced increase in nonshivering thermogenesis (NST) starting 18 min after application, reaching a maximum after 43 min and disappearing after 90 min (Fig. 1, Table 1). Simultaneously a profound long lasting hyperglycemia was observed (Fig. 2). (2) In contrast to untreated hedgehogs, animals which were given metopirone did not show an increase in the plasma cortisol level, when exposed to cold within 2 to 3 h (Fig. 6).When animals were pretreated with dexamethasone the metopirone-induced NST was suppressed, indicating that the effect of metopirone is mediated by the hypothalamo-pituitary-adrenal system (Fig. 4).The effect of metopirone at doses used in this study was reversible.It is suggested that a combined action of corticosteroids and catecholamines is involved in the control of regulatory heat production.Abbreviations SMR standard metabolic rate - NST nonshivering thermogenesis Supported by the Deutsche Forschungsgemeinschaft Wu 63/5     

Thermosensitivity of the preoptic region and the spinal cord in the golden hamster

1. 1.|The effects of thermal stimulation of the preoptic region (POAH) and the spinal cord on non-shivering thermogenesis (NST) and shivering were studied in euthermic golden hamsters.

2. 2.|Shivering intensity is suppressed by heating the POAH but is independent of spinal cord temperature. Therefore, NST in the interscapular brown adipose tissue does not suppress shivering.

3. 3.|NST is inhibited by heating of the POAH as well as of spinal cord. It is discussed that the control of NST by two different central thermosensitive areas is significant for thermoregulation during exercise.

Leptin cDNA cloning and its mRNA expression in plateau pikas (Ochotona curzoniae) from different altitudes on Qinghai-Tibet Plateau

Leptin, an adipocyte-derived hormone, plays an important role in body energy homeostasis. Plateau pika (Ochotona curzoniae), an endemic and keystone species living only at 3000-5000 m above sea level on Qinghai-Tibet Plateau, is a typically high hypoxia and low temperature tolerant mammal with high resting metabolic rate (RMR), non-shivering thermogenesis (NST), and high ratio of oxygen utilization to cope with harsh plateau environment. To explore the molecular mechanism of ecological acclimation in plateau pika, we first cloned pika leptin cDNA and compared its mRNA expression in different altitudes (3200 and 3900 m) using real-time RT-PCR (Taqman probe) technology. The full-length pika leptin cDNA was 3015 with 504 bp open-reading frame encoding the precursor peptide of 167 amino acids including 21 residues of signal peptide. Pika leptin was 70-72% homologous to that of other species and was of similarly structural characteristics with other species. The pika-specific genetic diversity in leptin sequence occurred at twenty sites. With the increase in altitude, there were larger fat store and high level of ob gene expression in plateau pika. Our results indicated that leptin is sensitive to cold and hypoxia plateau environment and may play one of important roles in pika's ecological adaptation to harsh plateau environment.     

锡林郭勒草原布氏田鼠数量的周期性和啮齿动物群落的演替

根据内蒙古阿巴嗄旗那仁宝力格苏木１９７９－１９９７年啮齿动物监测资料,利用变动指数（Ｓ）,得知布氏田鼠密度的年际动态具有一定的周期性,１９８９－１９９７年共捕啮齿动物１０种,其中田鼠占８８．４５％,达乌尔鼠兔占５．３７％。总密度（单位面积上啮齿动物的密度之和）、田鼠密度、鼠兔密度间均呈正相关,回归模型为：总密度＝０．８８０６＋１．００４８（田鼠密度）＋０．８７７９（鼠兔密度（Ｐ＝０．０００１）。田     

大绒鼠幼仔的生长发育和产热特征

为阐明大绒鼠幼仔的生长发育和代谢产热特征,本实验测定了1-49 日龄大绒鼠幼仔的体重、体温、静止代谢率(RMR)和非颤抖性产热(NST)。依据逻辑斯蒂曲线的拐点(24 d),大绒鼠的体重生长可划分为加速生长相和减速生长相,幼仔的体温在19 日龄前逐渐升高,22 日龄时接近成体水平;RMR 和NST分别在28日龄、19日龄前随日龄逐渐增加,RMR 在28日龄时接近成体水平,BAT 产热活性在7 日龄内被激活。结果表明,大绒鼠胎后发育及产热能力符合晚成性动物的一般特征,即具有短的妊娠期,较少的胎仔数,较长的哺乳期,这些特征对适应横断山特殊多变的环境条件具有重要意义。     

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。     

Adaptive thermogenesis in Brandt's vole (Lasiopodomys brandti) during cold and warm acclimation

Brandt's voles (Lasiopodomys brandti) exposed to cold (5±1 °C) or warm (23±1 °C) showed some physiological and biochemical variations which might be important in adaptation to their environments. Cold acclimation induced increases in resting metabolic rate (RMR) and the serum triiodothyronine (T₃) level, the state-4 respiration of liver and muscle mitochondria were activated after 7 days when animals exposed to cold, and the activity of cytochrome c oxidase (COX) of liver and muscle mitochondria tended to rise with cold exposure. RMR and T₃ level decreased during warm acclimation. The state-4 respiration of liver mitochondria declined after 3 days and muscle after 7 days when animals exposed to warm, and the activities of COX of liver and muscle mitochondria tended to decrease with warm acclimation. The cold activation of liver and muscle mitochondrial respiration (regulated by T₃) was one of the cytological mechanisms of elevating RMR. Both state-4 respiration and COX activity of brown adipose tissue (BAT) mitochondria increased significantly during cold acclimation and decreased markedly after acclimated to warm. The uncoupling protein 1 (UCP1) contents in BAT increased after exposure to cold and decreased after warm acclimation. Nonshivering thermogenesis (NST) plays an important role in the process of thermoregulation under cold acclimation for Brandt's voles. Changes in thermogenesis is a important way to cold adaptation for Brandt's voles in natural environments.     

繁殖经历对黑线仓鼠哺乳期能量收支的影响

为探讨繁殖经历与哺乳期最大持续能量收支的关系,对连续4 次繁殖的黑线仓鼠哺乳期的能量收支情况进行了测定。结果显示:1)不同繁殖组哺乳高峰期的摄食量、泌乳能量支出(MEO)、胎仔数和胎仔重差异不显著,静止代谢率(RMR)、非颤抖性产热(NST)、褐色脂肪组织(BAT)线粒体细胞色素c 氧化酶(COX)活性、血清甲状腺激素(T3 、T4 )和催乳素水平也无明显变化;2)摄食量与MEO、胎仔重和RMR 呈显著正相关。结果表明,不同繁殖经历的黑线仓鼠主要通过降低产热和增加能量摄入来满足哺乳高峰期的能量需求;哺乳期最大持续代谢率(SusMR)可能受乳腺组织泌乳能力的限制,与“外周限制假说” 的预测一致,不支持“中心限制假说”;SusMR 限制因素和哺乳期能量收支策略可能与繁殖经历无关。