布氏田鼠体温调节能力的胎后发育

为探讨布氏田鼠幼体体温调节能力的发育特点,我们对其胎后发育过程中代谢产热和体温的变化进行了观察。测定记录了1—40日龄的布氏田鼠幼体在巢中的体温,在23℃和30℃条件下的静止代谢率,以及在23℃和30℃时暴露1．52h后体温的变化,计算了幼体的总热传导率和恒温指数,并测定了聚群对幼体代谢产热的影响。布氏田鼠是典型的晚成型发育类型,幼体出生时身体裸露,体温调节能力很差。17日龄前,幼体在23℃冷暴露1．5—2h不能维持恒定的体温,9—17日龄幼体的恒温能力发育迅速,1713龄后幼体在23℃时开始表现出有效的恒温能力。幼体发育过程中逐渐升高的恒温指数和逐渐下降的总热传导率,也反映了幼体不断增强的恒温能力。虽然幼体在发育早期恒温能力差,表现出变温性的特点,但代谢率的测定表明,即使刚出生的幼体也具有受到冷刺激而增加产热的反应。聚群实验结果表明,幼体的聚群行为在降低代谢率、节约能量方面有明显的作用。巢中幼体体温的测定表明,1—40日龄幼体体温逐渐升高的趋势明显,且始终保持在33℃以上。这些结果说明,布氏田鼠的幼体在生长发育过程中,主要靠细致的母体关怀、聚群行为、巢的保温作用以及自身较弱的产热能力来使体温维持在较高的水平,从而不会因体温过低而使幼体的生长速度降低[动物学报51（5）：780—789,2005]。     

高蛋白食物和繁殖对布氏田鼠能量摄入和产热的影响

为探讨高蛋白食物和繁殖对布氏田鼠食物摄入和产热等特征的效应,将成年雌性布氏田鼠分为非繁殖对照食物组、非繁殖高蛋白组、繁殖对照食物组和繁殖高蛋白组。对照食物蛋白含量为17.7%,高蛋白食物的蛋白含量为36.6%。实验过程中测定动物的体重、食物摄入量、静止代谢率(RMR)、身体成分、内脏器官重量、褐色脂肪组织(BAT)解偶联蛋白1(UCP1)含量、血清瘦素和催乳素水平等。结果发现:高蛋白食物明显抑制布氏田鼠的体重,但动物在妊娠期和哺乳期,这种抑制作用消失。高蛋白食物明显抑制非繁殖组动物的干物质摄入、摄入能和消化能,但对哺乳期动物没有影响。高蛋白食物提高了非繁殖期和繁殖期动物的消化率,降低了血清瘦素浓度,但仅提高了繁殖期动物肾脏的重量,而降低了盲肠的重量。RMR、UCP1含量和血清催乳素浓度等则不受高蛋白食物的影响。繁殖期动物的体重、能量摄入、RMR和血清催乳素浓度等均高于非繁殖动物。这些结果表明,食物蛋白含量可影响布氏田鼠的能量代谢和产热特征等,且在繁殖期和非繁殖期有不同的反应方式。     

布氏田鼠冷暴露中褐色脂肪组织的增补及解偶联蛋白基因表达

布氏田鼠 (Microtusbrandti)随机分组暴露在冷环境 [12L∶12D ,(4± 2 )℃ ]中 12h ,1d ,3d ,7d ,14d ,2 1d和 2 8d ;对照组生活在温暖环境下 [12L∶12D ,(2 5± 2 )℃ ]。与对照组相比 ,布氏田鼠的褐色脂肪组织 (BAT)重量在冷暴露 12h～ 3d时降低 ,7～ 2 1d时则增加。 7～ 2 8d冷暴露组动物的BAT总蛋白和总DNA含量均比对照组明显提高。冷环境中的布氏田鼠解偶联蛋白 (UCP)的mRNA随时间的延长而表达上调 ,在冷暴露 2 1d时达到高峰。结果表明 ,冷暴露能够诱导布氏田鼠BAT细胞增补和UCP基因表达 ,从而使适应性产热增加。     

暖温经历对雌性黑线仓鼠能量代谢、产热和体脂含量的影响

能量代谢的生理调节是小型哺乳动物应对不同环境温度的重要策略之一,为探讨暖温下代谢产热在体重和体脂适应性调节中的作用和机理,本研究将雌性黑线仓鼠(Cricetulus barabensis)暴露于暖温(30°C)1个月、3个月和4个月,测定体重、摄入能、代谢产热、体脂含量、褐色脂肪组织(BAT)细胞色素c氧化酶(COX)活性和解偶联蛋1 (UCP1) mRNA表达等。结果显示,暖温对黑线仓鼠体重无显著影响,但使脂肪含量显著增加。与室温组相比(21°C),暖温组消化率显著升高,但摄入能和消化能显著降低;暖温下非颤抖性产热(NST)显著降低,脑、肝脏和心脏COX活性、BAT COX活性和UCP1 mRNA的表达显著下调。结果表明,暖温下降低代谢产热补偿了能量摄入的减少,机体处于正能量平衡状态,是脂肪含量显著增加的主要原因之一。脑、肝脏、心脏和BAT代谢活性降低是代谢产热降低的主要机制,与脂肪累积有关。     

光照和温度对根田鼠褐色脂肪组织产热能力的影响

测定了根田鼠在室内驯化2周后褐色脂肪组织（BAT）的蛋白含量、线粒体蛋白含量和细胞色素C氧化酶活性的变化。动物进行如下4种处理:23℃,16L:8D;23℃,8L：16D;5℃,16L：8D和5℃,8L:16D.。结果表明,短光照可刺激根田鼠的BAT线粒体细胞色素C氧化酶的活性增加;低温驯化可导致根田鼠的BAT线粒体蛋白含量增加;短光照加低温可进一步促进酶的活性增加。结合个体水平的产热特点,说明根田鼠在产热能力的季节驯化过程中,光周期是一主要的季节调节信号,环境温度进一步增强光照的作用,环境温度和光周期共同作用以诱导其产热能力等方面的生理调节。研究结果支持了环境温度和光周期共同作用以调节动物产热变化的学说。     

小哺乳动物在高寒环境中的生存对策 Ⅰ.高原鼠兔和根田鼠褐色脂肪组织(BAT)重量和显微结构的季节性变化

本文研究了高寒草甸生态系统中两种非冬眠草食性哺乳动物——高原鼠兔和根田鼠的褐色脂肪组织(BAT)的重量和显微结构的季节性变化,结果表明严寒季节BAT增多、BAT细胞中的脂肪滴小而多、线粒体增大及嵴数目增多,温暖季节较低,这些变化与产热需要有关。     

高温暴露对黑线仓鼠能量代谢和组织氧化应激的影响

动物能量代谢的适应性调节影响动物生长、发育、繁殖、衰老等生活史特征。代谢率和组织线粒体呼吸率与自由基水平有关，是影响机体衰老的重要因素。为了探讨高温环境下能量代谢、主要代谢活性器官组织呼吸率、自由基水平和抗氧化能力的内在联系，我们将室温(21℃)和暖温(32.5℃)驯化4周的黑线仓鼠(Cricetulus barabensis)分别进行急性高温暴露(37℃) 48 h，分别测定摄入能、代谢率，以及褐色脂肪组织(brown adipose tissue, BAT)、肝脏和肌肉的线粒体呼吸率，解偶联蛋白(uncoupling protein, UCP)基因(ucp)表达，蛋白羰基和丙二醛(malondialdehyde, MDA)水平，以及超氧化物歧化酶(superoxide dismutase, SOD)和谷胱甘肽过氧化物酶(glutathione peroxidase, GSH-Px)活性。结果显示，暖温驯化和急性高温暴露使摄入能、消化能、基础代谢率和非颤抖性产热显著降低。暖温驯化后BAT、肝脏和肌肉的细胞色素c氧化酶(cytochrome c oxidase, COX)活性分别降低了...     

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     

布氏田鼠冷习服过程中的适应性产热特征

布氏田鼠冷习服过程中的适应性产热特征侯建军李庆芬黄晨西（北京师范大学生物学系北京１００８７５）关键词布氏田鼠适应性产热环磷酸腺苷钠、钾ＡＴＰ酶Ｔ４－５′脱碘酶将内蒙草原上捕捉的布氏田鼠（Ｍｉｃｒｏｔｕｓｂｒａｎｄｔｉ）随机分组（体重在３５－４０ｇ...     

短光照诱导达乌尔黄鼠产热

本文通过测定静止代谢率(RMR)、非颤抖性产热(NST)、线粒体呼吸酶、脂肪代谢酶活力、褐色脂肪 组织(BAT)线粒体GTP 结合能力、下丘脑促甲状腺激素释放激素(TRH)和促肾上腺激素释放激素(CRH)等指标,探讨短光照对达乌尔黄鼠产热的诱导和调节。结果表明,温暖(22℃ ) 短光照(8D∶ 6L)组,达乌尔黄鼠的RMR、NST、肝脏和BAT 线粒体细胞色素C 氧化酶活力以及BAT 线粒体GTP 结合能力均明显高于温暖长光照(16D∶ 8L)组中的动物,而体重、BAT 重量、肝细胞呼吸、BAT α - 磷酸甘油氧化酶活力则没有明显变化。短光照组黄鼠下丘脑TRH 水平显著高于长光照组,而血清中三碘甲腺原氨酸(T₃ )及甲状腺素(T₄ )浓度、T₃ / T₄ 以及BAT 中T₄ - 5’脱碘酶的活性没有明显变化。短光照组黄鼠下丘脑CRH 水平显著高于对照组,而肾上腺皮质酮含量无明显变化。结果表明短光照能够诱导达乌尔黄鼠产热增加,主要是通过激活细胞色素C 氧化酶活性和增加BAT 中解偶联蛋白浓度;短光照可能激活下丘脑TRH 和CRH,但它们没有直接诱导产热增加,推测其增加了黄鼠潜在的产热能力。     

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...     

长爪沙鼠褐色脂肪组织和肝脏产热特征的季节性变化

长爪沙鼠（Meriones unguiculatus）是一种栖息于典型草原和荒漠草原非冬眠群居性的小型哺乳动物。为研究其产热功能的季节变化,我们分别在2003年秋季（9月下旬）、冬季（11月下旬）、2004年春季（3月底-4月下旬）和夏季（7月下旬）,分别测定了其体重、褐色脂肪组织和肝脏的重量、线粒体总蛋白含量和细胞色素c氧化酶活力,以及褐色脂肪组织中解偶联蛋白1（Uncoupling protein1,UCPl）的含量等。结果显示：除雄鼠的体重显著高于雌鼠外,其它各项指标均无性别差异。体重和褐色脂肪组织的重量都在冬季较高,显著高于夏季,而肝脏的重量在夏季显著高于其它季节。褐色脂肪组织和肝脏的线粒体蛋白含量和细胞色素c氧化酶活力以及UCP1含量,都在冬季较高,夏季较低。这些结果表明：在野外条件下,褐色脂肪组织和肝脏在细胞水平上产热能力的提高和UCP1含量的增加,是长爪沙鼠抵御寒冷的重要方式。     

Suppression of thermogenic capacity during reproduction in primiparous brandt's voles (Microtus brandtii)

• (1)To investigate the changes of brown adipose tissue (BAT) thermogenic capacity in primiparous Brandt's voles during different phases of reproduction, BAT weight, mitochondrial protein concentration, cytochrome c oxidase (COX) activity, and uncoupling protein (UCP1) contents were measured.
• (2)Both cytochrome c oxidase activity and UCP1 contents decreased significantly during lactation, suggesting that thermogenic capacity was suppressed.
• (3)The decrease of thermogenic capacity during reproduction, especially during lactation, is compensation to the large demand of energy for reproduction. This is advantageous for energy conservation and lactation in Brandt's voles. UCP1 is the base of molecular thermogenesis of BAT in Brandt's voles.

     

Effects of fasting and refeeding on body mass,thermogenesis and serum leptin in Brandt's voles (Lasiopodomys brandtii)

(1)

To investigate the effect of fasting and refeeding on the body mass, thermogenesis and serum leptin in Brandt's voles, the changes in body and body fat mass, resting metabolic rate (RMR), mitochondrial cytochrome c oxidase (COX) activity in liver and brown adipose tissue (BAT), uncoupling protein 1 (UCP1) content of BAT, serum leptin level and post-fasting food intake were monitored and measured.     

Photoperiodic regulation in energy intake, thermogenesis and body mass in root voles (Microtus oeconomus)

The present study was designed to examine whether photoperiod alone was effective to induce seasonal regulations in physiology in root voles (Microtus oeconomus) from the Qinghai-Tibetan plateau noted for its extreme cold environment. Root voles were randomly assigned into either long photoperiod (LD; 16L:8D) or short photoperiod (SD; 8L:16D) for 4 weeks at constant temperature (20 degrees C). At the end of acclimation, SD voles showed lower body mass and body fat coupled with higher energy intake than LD voles. SD greatly enhanced thermogenic capacities in root voles, as indicated by elevated basal metabolic rate (BMR), nonshivering thermogenesis (NST), mitochondrial protein content and uncoupling protein-1 (UCP1) content in brown adipose tissue (BAT). Although no variations in serum leptin levels were found between SD and LD voles, serum leptin levels were positively correlated with body mass and body fat mass, and negatively correlated with energy intake and UCP1 content in BAT, respectively. To summarize, SD alone is effective in inducing higher thermogenic capacities and energy intake coupled with lower body mass and body fat mass in root voles. Leptin is potentially involved in the photoperiod induced body mass regulation and thermogenesis in root voles.     

Effects of photoperiod on energy intake, thermogenesis and body mass in Eothenomys miletus in Hengduan Mountain region

The present study was designed to examine whether photoperiod alone was effective to induce seasonal changes in physiology in voles (Eothenomys.) from the Hengduan Mountain region. Eothenomys miletus were randomly assigned into either long photoperiod (LD; 16L: 8D) or short photoperiod (SD; 8L: 16D) for 4 weeks at constant temperature (25 °C). At the end of acclimation, SD voles showed lower body mass and body fat coupled with higher energy intake than LD voles. SD greatly enhanced the thermogenic capacity of E. miletus, as indicated by an elevated nonshivering thermogenesis (NST), mitochondrial protein in brown adipose tissue (BAT); basal metabolic rate (BMR) was also raised. Although no variations in serum leptin levels were found between SD and LD voles, serum leptin levels were positively correlated with body mass and body fat mass, and negatively correlated with energy intake and UCP1 content in BAT, respectively. To summarize, SD alone is effective in inducing higher thermogenic capacities and energy intake coupled with lower body mass and body fat mass in root voles. Leptin is potentially involved in the photoperiod induced body mass regulation and thermogenesis in E. miletus. Our study shows that SD alone is effective.     

Photoperiod regulates leptin sensitivity in field voles, Microtus agrestis

We have previously shown that cold-acclimated (8°C) male field voles (Microtus agrestis) transferred from short (SD, 8:16 h L:D) to long photoperiod (LD, 16:8 h L:D) exhibit increases in body mass, adiposity and food intake. To assess whether these increases were associated with decreased leptin sensitivity, we infused LD and SD voles with physiological doses of murine leptin (or saline) delivered peripherally for 7 days via mini-osmotic pumps. Measurements were made of body mass (weight-reducing effect of leptin), food intake (anorectic effect of leptin) and gene expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) (thermogenic effect of leptin). The SD animals were sensitive to the weight-reducing effects of leptin (mean body mass decrease of 1.2 g over 7 days) and appetite-reducing effect of leptin (mean food intake decrease of 2.5 g over 7 days), whereas LD voles were resistant to the hormone treatment. The switch from a leptin-sensitive to leptin-resistant state appears to act as a desensitisation mechanism that allows voles transferred from SD to LD to ignore elevated leptin levels generated by increased body fat and accumulate adipose tissue without stimulating compensatory changes opposing the weight gain. Neither SD nor LD voles responded to infusion of leptin by changes in BAT UCP1 gene expression, suggesting dissociation of anorectic and thermogenic effects of leptin, possibly related to chronic cold exposure. Our results indicate that cold-acclimated voles show photoperiod-regulated changes in leptin sensitivity and may provide an attractive model for elucidating molecular mechanisms of leptin resistance.     

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.     

Differentiation of brown adipose tissue and biogenesis of thermogenic mitochondria in situ and in cell culture

Differentiation and biogenesis of mitochondria in brown adipose tissue (BAT) was studied in situ and in cell culture by Western blotting, enzyme activity measurements, [35S]methionine incorporation and immunofluorescence microscopy. In different rodent species the perinatal development of BAT thermogenic function resulted from the formation of thermogenic mitochondria which replaced the preexisting nonthermogenic mitochondria. Their biogenesis was characterized by the sudden appearance and rapid increase of the uncoupling protein (UCP), increase of cytochrome oxidase (COX) and decrease of H(+)-ATPase. In primary cell culture, differentiation of precursor cells from mouse BAT to typical multilocular adipocytes was accompanied by increasing content of COX and H(+)-ATPase. A selective synthesis of UCP was induced by activation of beta-adrenergic receptors or by elevated levels of cellular cAMP. UCP was quantitatively incorporated into mitochondria and within 24 h after stimulation reached near physiological concentration. Both in situ and in cell culture, the conditions enabling the expression of UCP gene were accompanied by activation of intracellular thyroxine 5'-deiodinase.