随机限食与重喂食小鼠的能量代谢和行为的可塑性

分别测定了随机限食和重喂食驯化的雌性KM小鼠的体重、摄食量、基础代谢率(BMR)、行为活动、身体脂肪和性腺重量.随机限食使摄食量增加、BMR和活动行为降低,生长发育迟缓,但对身体脂肪无显著影响.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变化.结果表明,动物通过能量摄入和支出的权衡策略适应难以预测的食物资源变化,能量代谢和活动行为的可塑性调节在能量代谢的权衡策略中发挥重要作用.     

随机限食和重喂食小鼠能量收支和生长发育的可塑性

为阐明能量收支和生长发育的可塑性对动物适应食物资源变化的作用和意义,将断乳后的雄性KM小鼠40只随机限食4周,再重喂食4周。采用封闭式流体压力呼吸计测定基础代谢率(BMR)。限食使摄食量显著增加,BMR和活动行为降低,胴体和生殖腺重量显著降低。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变化。结果表明,KM小鼠能通过摄食量、BMR、活动行为和身体组成的可塑性调节以适应难以预测的食物资源变化。     

剃毛和增加胎仔数对KM 小鼠哺乳期能量收支的影响

为探讨最大持续能量收支限制的因素和生理机理,本文测定了增加胎仔数和背部剃毛的KM 小鼠的哺乳
期摄食量和繁殖输出。基础代谢率(BMR)以封闭式流体压力呼吸计测定。结果发现,增加胎仔数对哺乳期体
重、摄食量、热传导率、BMR 和胎仔重的影响不显著;与非剃毛对照组相比,剃毛使哺乳高峰期日平均摄食量
增加了13.8% (P<0.001)、BMR 增加了18.1% (P< 0.01)、热传导增加了30.8% (P< 0.01),但剃毛对体
重、胎仔数和胎仔重的影响不显著;胎仔数与断乳时胎仔重显著正相关,与幼体平均体重显著负相关。BMR 与
母体体重和胎仔重显著正相关。这些结果表明,KM 小鼠哺乳期能量收支受到了限制,剃毛显著增强了KM 小鼠
的散热能力,但未影响繁殖输出;支持“外周限制假说”,不符合“热耗散限制假说”。     

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。     

随机限食和重喂食对小鼠体重、能量收支及瘦素的影响

为阐明限食和重喂食(SFR-Re)诱导的体重"补偿性增长"生理机制,该文测定了SFR-Re驯化的KM小鼠能量摄入与支出、身体成分以及血清瘦素水平。结果显示,随机限食使体重显著降低,重喂食后体重增加至对照组水平。驯化结束后,SFR-Re驯化小鼠基础代谢率增加,产热降低,褐色脂肪组织(BAT)细胞色素c氧化酶(COX)活性和解偶联蛋白1(UCP1)水平显著降低,摄入能、消化率和脂肪重量均显著高于自由取食的对照组小鼠,但血清瘦素水平组间差异不显著。即在食物资源丰富的条件下,经历食物短缺的动物将增加能量摄入和消化吸收效率以及脂肪组织能量贮存,从而导致体重的"补偿性增长",同时,血清瘦素可能在该过程中发挥重要作用。     

黑线仓鼠的BMR个体差异及其应对高脂食物的能量学对策

为探讨高脂食物对小型哺乳动物能量代谢的影响及其与基础代谢率(Basal metabolic rate, BMR)的关系,将成年雌性黑线仓鼠(Cricetulus barabensis)分为高、低BMR组,每组再随机分为低脂、高脂食物组,驯化6周后,测定体重、摄入能和代谢率,以及消化酶活力、褐色脂肪组织(Brown adipose tissue, BAT)和主要内脏器官与肌肉的细胞色素c氧化酶(Cytochrome c oxidase, COX)活性、解偶联蛋白(Uncoupling protein, UCP) mRNA表达等。结果显示,高脂食物对高、低BMR组动物体重均无显著影响。与低脂食物组相比,高脂食物组的摄食量、摄入能和消化能显著下降,小肠脂肪酶活力显著增强,消化率明显增加,但高、低BMR组的组间差异不显著。夜间代谢水平显著高于昼间,高脂食物使高BMR组的夜间代谢率显著升高。BAT、肌肉和内脏器官COX活性不受高脂食物的影响,高、低BMR组的组间差异也不显著。高脂食物组仅肝脏UCP2表达显著上调。结果表明,能量摄入和消化系统形态及功能的可塑性调节是黑线仓鼠应对高脂食物的主要策略;黑线仓鼠的代谢率具有显著的昼夜节律,既受高脂食物的影响,也与动物自身的BMR水平有关,但UCP表达具有组织特异性,这可能不是导致BMR个体差异的因素。     

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。     

饥饿对中华倒刺鲃幼鱼代谢、个性和集群的影响

在自然界中,环境变化、季节更替和人为因素造成食物资源时空分布的不均一性,导致鱼类经常面临食物资源短缺的环境胁迫,对其能量代谢和行为造成一定影响。为考察食物资源短缺下暖水性鲤科鱼类能量代谢、个性与集群行为的应对策略及其可能的内在关联,选取中华倒刺鲃(Spinibarbus sinensis)幼鱼为实验对象,分别测定饥饿组(2周)和对照组(维持日粮)在处理前后实验鱼的标准代谢率(Standard metabolic rate,SMR)、个性行为(勇敢性、探索性和活跃性)以及实验处理后的集群行为(凝聚力和协调性)。研究发现:(1)饥饿组和对照组实验过程中实验鱼SMR均显著下降,但仅饥饿组实验鱼SMR具有重复性;(2)饥饿导致中华倒刺鲃幼鱼勇敢性、探索性、活跃性均显著增加;(3)饥饿导致群体成员间距离缩短,游泳速度及其同步性上升。研究表明:饥饿后的中华倒刺鲃不仅适应性降低SMR以减少能量消耗,而且呈现出更高的勇敢性、探索性和活跃性以利于获取食物资源;饥饿迫使中华倒刺鲃群体提高凝聚力和协调性,可能有助于提高群体的生存能力。     

限食及重喂食对雄性长爪沙鼠生理指标的影响

限食通常会显著影响鼠类的营养及内分泌等生理指标,但限食后重喂食其生理指标是否能得以恢复尚不
清楚。本文采取70% 的限食水平,研究了限食及重喂食对雄性长爪沙鼠生理指标的影响。将雄性长爪沙鼠分为
限食组、重喂食组和对照组。限食组先自由饮食4 周,后70% 限食4 周;重喂食组先70% 限食4 周,后恢复自
由饮食4 周。对照组自由饮食8 周。实验结束时,检测各组肥满度及血清白蛋白和总蛋白含量、血清甲状腺素
T3 和T4 水平、睾酮和皮质醇含量等各项生理指标的变化。研究结果表明,4 周限食显著降低了雄性长爪沙鼠的肥满度和血清甲状腺素T4 含量,显著升高了其血液皮质醇含量;限食后重喂食4 周后可使上述指标恢复或接近正常,但血清白蛋白含量比对照组低,其他指标与对照组无明显差异,长爪沙鼠的一些生理指标在限食重喂食
后能得以恢复,但其内分泌调节可能存在新的变化,值得进一步研究。     

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。     

Effects of stochastic food deprivation on energy budget,body mass and activity in Swiss mice

When small animals are faced with an unpredictable food supply,they can adapt by altering different components of their energy budget such as energy intake,metabolic rate,rate of non-shivering thermogenesis(NST)or behaviour.The present study examined the effect of stochastic food deprivation(FD)on body mass,food intake,resting metabolic rate(RMR),NST and behaviour in male Swiss mice.During a period of 4 weeks' FD,animals were fed ad libitum for a randomly assigned 4 days each week,but were deprived of food ...     

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。     

Body mass and behavior in Swiss mice subjected to continuous or discontinuous food restriction and refeeding

Food restriction (FR) is hypothesized to decrease body fat content of an animal and thus prevent obesity. However, the response of energy budget to a continuous (CFR) or discontinuous FR (DFR) remains inconsistent. In the present study, effects of CFR or DFR and refeeding on energy budget and behavior were examined in male Swiss mice. CFR significantly decreased the energy expenditure associated with basal metabolic rate (BMR) and activity behavior, but not sufficiently to compensate for energy deficit and thus resulted in lower body mass and fat content. DFR mice had a significantly higher food intake on ad libitum days and showed increases in BMR and activity after 4 weeks’ DFR, which might resulted in lower body mass and less body fat than controls. After being refed ad libitum, both CFR and DFR mice had similar body mass, BMR, and behavioral patterns to controls but had 95% and 75% higher fat content. This suggested that not only CFR but also DFR would be a significant factor in the process of obesity for animals that were refed ad libitum. It also indicated that food restriction interrupted many times by periods of ad libitum feeding had the same long-term effects like continuous underfeeding.     

Trade-off between energy budget, thermogenesis and behavior in Swiss mice under stochastic food deprivation

(1) The role of metabolic rate, thermogenesis and behavior in trade-off strategy was examined in Swiss mice under stochastic food deprivation (FD).

(2) For the mice under severe FD, food intake on feeding days increased, and basal metabolic rate (BMR) and nonshivering thermogenesis decreased significantly. The duration of activity decreased but resting behavior increased significantly on feeding days.

(3) It suggested that a trade-off between increased food intake and decreased energy expenditure related to lower BMR, thermogenesis and activity might be employed to meet reduced calorie intake caused by unpredictable FD.

Effect of food restriction on energy intake and thermogenesis in Yunnan red-backed vole (Eothenomys miletus) with different metabolic levels

Shortage of food resources has significant effects on many physiological parameters of animals. The aim of the present study was to examine the relationship between the energetics countermeasures in response to food restriction and the levels of metabolism in Eothenomy miletus. Survival rate, body mass, basal metabolic rate (BMR), nonshivering thermogenesis (NST), body fat mass, serum leptin levels and other physiological parameters were measured. Animals were divided into high-BMR (hBMR) and low-BMR (lBMR) group. The two groups were restricted to 70% of ad libitum food intake for 4 weeks. The data showed that food intake increased by 24.5% in hBMR group than that in lBMR group before the experiment. Body mass, body fat mass, BMR and NST with hBMR or lBMR group significantly decreased after food restricting. Eighty percent of E. miletus survived with hBMR group, but 60% of E. miletus survived with lBMR group. Serum leptin levels were positively correlated with body mass, BMR and NST. The results suggested that E. miletus could apply physiological adjustments to adapt the period of food shortage by reducing energy metabolism, providing the support for the “metabolism switch hypothesis”. E. miletus with hBMR had decreased energy expenditure to maintain the normal physiological function. However, lBMR group could not decrease energy expenditure to meet the stress of available energy resource, which led to body mass decreased and mortality rate increased. Serum leptin levels may be involved in the regulation of energy balance and body mass in E. miletus during the food restriction.     

Effects of photoperiod and food availability on growth, leptin, sexual maturation and maintenance in the Mongolian gerbils (Meriones unguiculatus)

Reproductive activity of Mongolian gerbils is regulated by photoperiod nevertheless body weight regulation is controlled without ambient photoperiod. Food intake is a major factor affecting rodent reproductive efficiency. Leptin is a hormone secreted by adipose tissue and modulates food intake, energy expenditure and body fat stores. In this study we studied the interaction of photoperiod and food availability on growth, sexual maturation and leptin concentration in the male and female gerbils. Gerbils were gestated and reared in either 14L:10D or 2L:22D. At weaning, gerbils were housed individually and divided into three groups: fed ad libitum, fed 80% of ad libitum or fed 60% of ad libitum. Body weights were recorded at weaning and every week thereafter. After twelve weeks of treatment, animals were sacrificed and testes and uterine weights were determined and blood was collected for leptin measurement. Food restriction reduced body weight and inhibited reproductive development. Absolute paired testis weights were similar in ad lib and 80% of ad lib groups but significantly different compared with the 60% of ad lib group in both photoperiods. Body weights were also directly dependent upon the level of food restriction. Uterine mass was only affected in the 60% of ad lib group in 14L but both food restriction levels significantly affected the uterine weights in 2L. Significant variations were found in leptin profiles. Leptin concentration was highest in ad lib and 80% of ad lib groups and lowest in 60% of ad lib groups. These results suggest that the reproductive activity of Mongolian gerbils is sensitive to food intake and multiple potential environmental cues (e.g., food availability, temperature) can be utilized.     

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。     

Photoperiod influences the critical caloric intake necessary to maintain reproduction among male deer mice (Peromyscus maniculatus).

The concept of critical day length is well established among rodents; reproductive function is maintained when day lengths are greater than some specific threshold. In addition to day length cues, seasonal breeding in deer mice can also be regulated by food availability. The caloric threshold necessary to support reproduction remains unspecified for seasonally breeding rodents. The present study examined the interaction between photoperiod and food availability on reproductive function in adult male deer mice (Peromyscus maniculatus). A critical caloric intake profile was constructed in long (16L:8D) and short (8L:16D) photoperiods; groups of deer mice in both photoperiods either received food ad libitum or 90, 80, or 70% of their individual ad libitum food intake for 10 wk. At autopsy, paired testes, epididymides, and seminal vesicles were removed and weighed. Body mass, total body fat, and total body water contents were also obtained. Short, as compared to long, day lengths inhibited the reproductive systems of male deer mice. However, food consumption interacted with photoperiod to affect reproductive function. Significant reductions in reproductive organ size as well as spermatogenic activity were observed among short-day mice after a 10% reduction in ad libitum food intake. Long-day animals required a 20% reduction in caloric intake to depress reproductive function. Body mass and total body water content were generally unaffected by either photoperiod or food consumption. Total body fat content was reduced in short- as compared to long-day mice. Individual reproductive responsiveness to short days increased as food availability decreased.(ABSTRACT TRUNCATED AT 250 WORDS)