雷公藤甲素对雄性布氏田鼠繁殖力的抑制效果

为评价植物源鼠类不育剂雷公藤甲素对雄性布氏田鼠的不育效果,本研究采用每千克体重0 mg、0.1 mg、0.2 mg,0.4 mg的雷公藤甲素溶液对雄鼠进行连续7 d灌胃处理,并在停药2周和4周后检测其体重、性腺重、精子密度及配对雌鼠怀孕率与胎仔数.结果表明,雷公藤甲素处理未显著降低雄性布氏田鼠的体重、性腺相对重量、附睾...     

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]。     

Isolation and characterization of polymorphic microsatellite loci from Brandt's voles (Lasiopodomys brandtii)

Ten polymorphic microsatellite loci from Lasiopodomys brandtii have been isolated and characterized. Two to 11 alleles per locus were detected from 52 Brandt's voles samples collected from a single population. Expected heterozygosities ranged from 0.406 to 0.840. For the majority of loci observed heterozygosities were similar to or greater than the expected heterozygosity. One locus pair appeared to be in linkage disequilibrium. The microsatellite markers will enable the studies of genetic diversity, population structure and relatedness in this species, and perhaps in closely related species of vole.     

炔雌醚对布氏田鼠繁殖的抑制效果

明确炔雌醚对鼠类繁殖抑制最适剂量及持续有效作用时间,对其后续相关理论研究和实践应用具有基础性作用。本研究以0.5 mg/kg、1.0mg/kg、2.0mg/kg、3.0mg/kg、6.0mg/kg浓度炔雌醚分别连续灌胃雄性和雌性布氏田鼠7d 后,与正常异性配对观察90ｄ。按繁殖启动期、繁殖率和繁殖力等最直观的指标综合评价了5个浓度炔雌醚对雌雄布氏田鼠的不育效果。室内条件下,炔雌醚能够延迟雌雄布氏田鼠的生殖启动,但可能由于样本量小,未达统计显著性。90ｄ 内,一定浓度的炔雌醚能够降低雌雄个体的繁殖率和平均每窝产仔数,同样未达统计显著性。一些浓度的药物能够显著降低布氏田鼠的繁殖力,其抑制效果无剂量相关性。推断炔雌醚对雄性布氏田鼠的最适不育作用浓度为2.0mg/kg左右,对雌性的最适不育作用浓度为1.0mg/kg左右。实际综合应用剂量2.0mg/kg左右,能有效降低布氏田鼠产仔总数,其持续时间可达90d。     

Litter size variation in hypothalamic gene expression determines adult metabolic phenotype in Brandt's voles (Lasiopodomys brandtii)

Background

Early postnatal environments may have long-term and potentially irreversible consequences on hypothalamic neurons involved in energy homeostasis. Litter size is an important life history trait and negatively correlated with milk intake in small mammals, and thus has been regarded as a naturally varying feature of the early developmental environment. Here we investigated the long-term effects of litter size on metabolic phenotype and hypothalamic neuropeptide mRNA expression involved in the regulation of energy homeostasis, using the offspring reared from large (10–12) and small (3–4) litter sizes, of Brandt''s voles (Lasiopodomys brandtii), a rodent species from Inner Mongolia grassland in China.

Methodology/Principal Findings

Hypothalamic leptin signaling and neuropeptides were measured by Real-Time PCR. We showed that offspring reared from small litters were heavier at weaning and also in adulthood than offspring from large litters, accompanied by increased food intake during development. There were no significant differences in serum leptin levels or leptin receptor (OB-Rb) mRNA in the hypothalamus at weaning or in adulthood, however, hypothalamic suppressor of cytokine signaling 3 (SOCS3) mRNA in adulthood increased in small litters compared to that in large litters. As a result, the agouti-related peptide (AgRP) mRNA increased in the offspring from small litters.

Conclusions/Significance

These findings support our hypothesis that natural litter size has a permanent effect on offspring metabolic phenotype and hypothalamic neuropeptide expression, and suggest central leptin resistance and the resultant increase in AgRP expression may be a fundamental mechanism underlying hyperphagia and the increased risk of overweight in pups of small litters. Thus, we conclude that litter size may be an important and central determinant of metabolic fitness in adulthood.     

Behavioral and neuroendocrine response of Brandt's voles,Lasiopodomys brandtii,to odors of different species

Predator odors are nonintrusive natural stressors of high ethological relevance. Behavioral and hormonal responses and changes in the expression of medial hypothalamic c-fos mRNA were examined in Brandt's voles (Lasiopodomys brandtii) after exposure to feces of a domestic cat (Felis catus), weasel (Mustela sibirica), snake (Xenopeltis hainanensis), goat (Capra aegagrus), and distilled water (control). One hundred voles were tested in the defensive withdrawal apparatus. Voles showed an aversion to the predator odors by showing significant high levels of flight-related behaviors, more freezing behavior, and less and higher grooming behavior when they exposed to weasel and cat feces and more vigilant rearing compared to goat and control groups. Adrenocorticotropic hormone and corticosterone serum levels significantly increased when voles were exposed to the predator odors compared to voles exposed to goat and control odors. A significant high c-fos mRNA level indicates a strong predator odor-induced activation of the medial hypothalamus of the tested voles. Our results display significant fear responses of Brandt's voles exposed to predator odors and that they can skillfully differentiate between odors from different species with odors from sympatric predators triggering the highest responses.     

长爪沙鼠和布氏田鼠汗腺的分布与密度

哺乳动物受到高温胁迫时可通过分泌汗液调节体温。一般认为啮齿类在高温时不出汗,但有关野生啮齿类汗腺的资料不多。我们以长爪沙鼠和布氏田鼠为研究对象,采用苏木精—伊红染色方法,观察了身体各部位皮肤的形态学特征、汗腺的分布和密度。结果显示:(1)两种鼠的头部、口角、胸部、腋窝、腹部、背部和后腿部的皮肤都无汗腺分布,只在不被毛的前足与被毛的后足有外泌汗腺分布;(2)长爪沙鼠前、后足皮肤汗腺的密度分别为(2.40±0.49)个/mm2和(0.15±0.03)个/mm2,前足显著多于后足;布氏田鼠前、后足皮肤汗腺的密度分别为(0.37±0.05)个/mm2和(0.21±0.08)个/mm2,前、后足无显著差异。两种鼠前后足皮肤的汗腺密度可能与被毛状态相关,有被毛则汗腺密度低。推测长爪沙鼠和布氏田鼠前后足的汗腺可能具有辅助散热和运动时增加摩擦力等功能。     

渐变的光周期和温度对布氏田鼠能量代谢和身体成分的影响

为探讨在同时逐渐缩短光照时间和降低温度的过程中,动物能量代谢水平和身体成分的适应性变化, 我们以成年雄性布氏田鼠为对象, 测定了温度为20℃ 和光周期为12L:12D (对照组),以及从温度为20℃ 和长光照条件(16L:8D)逐渐转换到温度为4℃ 和短光照条件(8L:16D)的过程中(实验组), 其体重、静止代谢率和能量摄入的变化, 以及经过8 周驯化后身体器官和组织重量的变化。结果发现:实验组动物的体重增长率低于对照组。在驯化期间, 静止代谢率无组内和组间差异。实验组动物的干物质摄入、能量摄入和消化能等组内差异不明显, 但对照组动物在驯化的第8 周显著降低。实验组动物的能量摄入水平在驯化后显著升高;小肠和胃的干重, 以及小肠和心脏等器官的湿重也都显著高于对照组。结果表明,布氏田鼠能够采取降低体重、增加能量摄入和调整体内某些器官和组织重量的方式来适应变化的环境条件。     

Pre- and post-weaning cold exposure does not lead to an obese phenotype in adult Brandt's voles (Lasiopodomys brandtii)

Evidence has shown that postnatal undernutrition, overnutrition and cold stress are associated with imbalanced metabolic regulation as rodents achieve adulthood. In this study, we used a breeding colony of Brandt's voles (Lasiopodomys brandtii), a wild rodent species from the Inner Mongolia grasslands in China, to examine the effects of pre- and post-weaning cold exposure on the adult body (fat) mass, serum hormones and hypothalamic neuropeptides. Unlike laboratory rodents, vole offspring exposed to pre-weaning cold did not exhibit overweight or obese phenotypes in adulthood compared with unexposed controls. Moreover, adult male voles that remained in colder conditions had less body mass and lower serum leptin levels despite having higher food intake compared to other groups. To understand the mechanism of this unexpected regulation, hypothalamic gene expression was assessed for pre- and post-weaning cold exposure. Voles exposed to cold before weaning increased hypothalamic, orexigenic agouti-related protein (AgRP) and decreased anorexigenic proopiomelanocortin (POMC) mRNA expression at weaning. These expression changes were associated with hyperphagia and catch-up growth after weaning. Interestingly, these changes in hypothalamic neuropeptides were short lasting because in adult voles these differences were no longer apparent, which might explain why the pre-weaning, cold-exposed voles did not become obese in adulthood. These data suggest that some species do not develop an obese phenotype in response to early life cold stress.     

布氏田鼠胎后发育过程中褐色脂肪组织和肝脏的产热特征

为探讨布氏田鼠胎后恒温能力的发育过程,本文测定了1、5、9、17、21、33 和41 日龄幼体的褐色脂肪组织(BAT)和肝脏的重量、线粒体蛋白含量和细胞色素c氧化酶(COX) 的活性。布氏田鼠胎后发育期间BAT 增补明显,主要表现为重量的增加和单位组织重量COX 活性的升高等,属典型的晚成型发育特征。布氏田鼠胎后发育过程中BAT 和肝脏产热特征的变化与幼体的产热特点和恒温能力的发育是相一致的。     

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.     

不同去甲肾上腺素剂量下布氏田鼠非颤抖性产热比较

非颤抖性产热是小型哺乳动物的一种重要产热方式。关于其定量测定,一般采用注射去甲肾上腺素（norepinephrine,NE）诱导的最大耗氧量的方式获得。因此,去甲肾上腺素剂量的选择就显得很重要。我们利用常用的3 种经验公式计算剂量,即：（1）NE（mg / kg） = 2.53W^{- 0.4};（2）NE（mg / kg）= 3.3W^-0.458;和（3）NE（mg / kg）= 6.6W^{- 0.458},W 是体重（g）,以布氏田鼠为实验对象,测定了3 种剂量诱导的非颤抖性产热情况。结果表明,3 种剂量都能诱导出最大非颤抖性产热能力,在非颤抖性产热大小上没有显著性差异,分别为6.190±1.342（公式1）、6.166 ±0.852（公式2）和7.005 ±1.501（公式3）,但公式（3）剂量下体温增加程度显著高于前两个剂量,分别增加了1.9 ±0.9 ℃（公式3）、0.9 ±0.2 ℃（公式1）和0.7 ±0.2 ℃（公式2）。为了防止动物体温过高引起死亡,我们推荐公式（1）和（或）（2）。     

猫气味重复暴露对青春期布氏田鼠反捕食和焦虑样行为的影响

捕食者气味对猎物的行为和生理有重要的影响.本研究主要确定猫气味重复暴露对青春期布氏田鼠(Lasiopodomys brandtii)的反捕食行为、焦虑样行为和内分泌水平的影响,以探讨青春期布氏田鼠对猫气味的反应对策.研究结果表明,猫气味暴露1 d,青春期布氏田鼠隐藏行为显著增加,而移动行为、跳跃行为、修饰行为和接触行为...     

Characterization of nine novel microsatellite markers from Brandt's vole (Lasiopodomys brandtii)

Highly polymorphic microsatellite markers are the most powerful tools to infer kinship relations. In this study, a library enriched for (AC)(n) (AG)(n) and (AGAT)(n) was constructed for screening microsatellite markers in Brandt's vole (Lasiopodomys brandtii), and nine novel polymorphic microsatellite markers were developed and characterized. The number of alleles ranged from 4 to 11 per locus and the mean polymorphism information content was 0.7535. The observed and the expected heterozygosity values averaged 0.760 (0.554-0.908) and 0.7914 (0.718-0.845), respectively. Average nonexclusion probability for one candidate parent varied from 0.485 to 0.716. These nine novel markers are highly polymorphic and powerful enough for our future kinship analysis.     

单宁酸对布氏田鼠抗氧化水平和肝脏自噬相关基因表达的影响

单宁为植物中广泛存在的酚类植物次生代谢物,具有抗氧化功能,但是否影响动物细胞的自噬功能,仍不清楚.本研究对4周龄雌雄性布氏田鼠饲喂高、低浓度单宁酸溶液9周后,分别用酶联免疫吸附法和荧光定量PCR法测定血浆抗氧化水平和肝脏细胞自噬相关基因表达的变化.结果 显示,单宁酸对布氏田鼠的体重增长率和肝脏指数均无显著影响.高剂量组...     

单宁酸对布氏田鼠能量代谢的影响

为了解单宁酸对成年布氏田鼠(Lasiopodomys bandtii**)能量代谢和产热的影响,本文采用含0、3.3%和6.6%单宁酸浓度的食物饲喂布氏田鼠21 d,对其体重、基础代谢率、非颤抖性产热和能量收支等进行了测定。代谢率采用封闭式流体压力呼吸计测定;非颤抖性产热用皮下注射去甲肾上腺素诱导;能量摄人采用食物平衡法测定。结果发现:(1) 单宁酸食物对布氏田鼠的体重没有明显影响;(2)取食含6.6%单宁酸食物的动物的基础代谢率于第10 d高于对照组。20 d时,3组动物的基础代谢率没有显著差异;(3) 单宁酸食物对非颤抖性产热没有显著影响;(4) 食用含单宁酸食物的动物的摄人能和消化能于第10 d显著低于对照组,但第20 d时则差异不显著。这些结果表明:布氏田鼠的基础代谢率和能量摄入对单宁酸的反应具有时段性,短期内能量消耗增加,随着动物对食物的适应,生理功能恢复到正常水平。     

Cold exposure does not decrease serum leptin concentration,but increases energy intake and thermogenic capacity in pregnant Brandt's voles (Lasiopodomys brandtii)

In most mammals, maternal body mass and fat mass increase during pregnancy due to hyperphagia. These physiological changes provide the fetus with energy and nutrients and prepare the mother for the high energetic demands of lactation. In the present study, metabolic changes in response to cold and pregnancy were examined in female Brandt's voles (Lasiopodomys brandtii). At 23±1 °C, the voles increased body mass and deposited body fat during pregnancy. However, at 5±1 °C pregnant voles did not deposit body fat even though energy intake increased above the level in the warm. Serum leptin concentration increased during pregnancy and was not influenced by cold exposure. Thermogenic capacity, as indicated by uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT), increased in cold-exposed pregnant voles. The number and mass of fetuses were not affected by cold exposure. Our data may indicate the importance of an increased serum leptin concentration for a successful outcome of the pregnancy and also the independence of leptin secretion from body fat in pregnant voles. It also implies the need to develop central leptin resistance with respect to control of energy balance for pregnant voles.     

繁殖季节和非繁殖季节布氏田鼠种群参数和生理特点的差异

在繁殖季节(6月份)和非繁殖季节(10月份),采集了内蒙古自治区阿尔善宝力格地区的布氏田鼠样本,比较其种群参数与生理指标,探讨了布氏田鼠社群结构和生理特征的季节性差异,并分析了原因。结果表明,布氏田鼠的年龄组成和性比存在明显的季节差异:繁殖季节洞口系数小,种群性比接近1,主要由当年新生鼠和越冬鼠组成;非繁殖季节洞口系数大,种群性比偏雄,主要由当年新生鼠组成。繁殖器官在繁殖季节显著大于非繁殖季节,保持了更高活性。非繁殖季节个体的胴重比更高,且雄鼠高于雌鼠,表明非繁殖季节个体和雄鼠具有更好的营养状态;同时,非繁殖季节个体具有更小的肾上腺和更大的脾脏,说明非繁殖季节中的布氏田鼠表现出更低的应激状态和更强的免疫能力。这些研究结果表明,布氏田鼠的种群参数和生理特点具有明显的季节性特点,这与不同季节中布氏田鼠采取的生存策略有着紧密联系。     

布氏田鼠哺乳期低温经历抑制成年期神经再生

哺乳动物在出生前后所经历的环境条件对其成年后的行为和生理等具有重要影响。环境温度是影响动物后代表型的重要因素之一。本研究将分娩当天的布氏田鼠母体和幼仔在常温（23℃±1℃）或低温（4℃±1℃）饲养,断乳（21日龄）时转至常温环境,至第63日龄时再随机将两组动物各分为常温组和低温暴露组,期间检测体重、摄食量、静止代谢率、认知能力和神经细胞增殖和存活等,以验证哺乳期的低温经历可影响成年动物的代谢生理、行为表型和相关脑区神经再生的假说。结果发现：哺乳期低温经历导致成年布氏田鼠摄食量显著降低,与代谢有关的下丘脑以及学习记忆有关的海马区细胞增殖和存活数量减少。当动物在成年期面临冷暴露时,与哺乳期常温经历的动物相比,哺乳期低温经历的动物摄食量较低,在Y迷宫新异臂中的穿梭次数和停留时间显著降低,但海马和下丘脑部分核团的细 胞增殖以及海马CA的细胞存活明显升高。这表明哺乳期低温经历对布氏田鼠的能量代谢、行为和相关脑区的成体神经再生产生了持久的抑制效应,但成年后再次面对低温时,动物的代谢能力和代谢及学习记忆相关脑区的神经细胞可塑性优于哺乳期未曾经历低温的动物。     

Different physiological roles of serum leptin in the regulation of energy intake and thermogenesis between pregnancy and lactation in primiparous Brandt's voles (Lasiopodomys brandtii)

Reproduction, especially lactation, is associated with major metabolic adaptive changes. In this study, we investigated the metabolic changes and the roles of leptin during different periods of reproduction in primiparous Brandt's voles (Lasiopodomys brandtii). Energy intake, thermogenic capacity and serum leptin levels were examined in non-reproductive, mid pregnant, late pregnant, early lactating and peak lactating voles. Voles increased body mass by nearly 70% during late pregnancy compared to the non-breeding controls. The increase in body mass was mainly due to the increase in body fat mass which increased by 56%, and the growth of the reproductive tissues and digestive organs. Lactating voles decreased body fat by nearly 27% at peak lactation compared to the controls, and 53% compared to late pregnant voles. At the same time they increased food intake significantly. Uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT) decreased significantly at peak lactation. Serum leptin increased significantly in the mid pregnancy, at a time when there was no increase in body fat, and remained at this high level in late pregnancy. Leptin levels decreased after parturition and reached a nadir at peak lactation. Serum leptin was negatively correlated with energy intake during lactation, but not during pregnancy. These data suggest that Brandt's voles adjust energy intake, thermogenic capacity and body reserves to match the high energy demands for reproduction. Hyperleptinemia, without decreased energy intake suggests a state of leptin resistance during pregnancy, and hypoleptinemia during lactation might act as a signal to stimulate energy intake.