Extracts of Rhizoma Polygonati Odorati Prevent High-Fat Diet-Induced Metabolic Disorders in C57BL/6 Mice

Polygonatum odoratum (Mill.) Druce belongs to the genus Polygonatum family of plants. In traditional Chinese medicine, the root of Polygonatum odoratum, Rhizoma Polygonati Odorati, is used both for food and medicine to prevent and treat metabolic disorders such as hyperlipidemia, hyperglycemia, obesity and cardiovascular disease. However, there is no solid experimental evidence to support these applications, and the underlying mechanism is also needed to be elucidated. Here, we examined the effect of the extract of Rhizoma Polygonati Odorati (ER) on metabolic disorders in diet-induced C57BL/6 obese mice. In the preventive experiment, the ER blocked body weight gain, and lowered serum total cholesterol (TC), triglyceride (TG) and fasting blood glucose, improved glucose tolerance test (GTT) and insulin tolerance test (ITT), reduced the levels of serum insulin and leptin, and increased serum adiponectin levels in mice fed with a high-fat diet significantly. In the therapeutic study, we induced obesity in the mice and treated the obese mice with ER for two weeks. We found that ER treatments reduced serum TG and fasting blood glucose, and improved glucose tolerance in the mice. Gene expression analysis showed that ER increased the mRNA levels of peroxisome proliferator-activated receptors (PPAR) γ and α and their downstream target genes in mice livers, adipose tissues and HepG2 cells. Our data suggest that ER ameliorates metabolic disorders and enhances the mRNA expression of PPARs in obese C57BL/6 mice induced by high-fat diet.     

Perinatal Exposure to Low-Dose Methoxychlor Impairs Testicular Development in C57BL/6 Mice

Methoxychlor (MXC), an organochlorine pesticide, has adverse effects on male reproduction at toxicological doses. Humans and wild animals are exposed to MXC mostly through contaminated dietary intake. Higher concentrations of MXC have been found in human milk, raising the demand for the risk assessment of offspring after maternal exposure to low doses of MXC. In this study, pregnant mice (F0) were given intraperitoneal daily evening injections of 1 mg/kg/d MXC during their gestational (embryonic day 0.5, E0.5) and lactational periods (postnatal day 21.5, P21.5), and the F1 males were assessed. F1 testes were collected at P0.5, P21.5 and P45.5. Maternal exposure to MXC disturbed the testicular development. Serum testosterone levels decreased, whereas estradiol levels increased. To understand the molecular mechanisms of exposure to MXC in male reproduction, the F1 testes were examined for changes in the expression of steroidogenesis- and spermatogenesis- related genes. RT-PCR analysis demonstrated that MXC significantly decreased Cyp11a1 and increased Cyp19a1; furthermore, it downregulated certain spermatogenic genes (Dazl, Boll, Rarg, Stra8 and Cyclin-a1). In summary, perinatal exposure to low-dose MXC disturbs the testicular development in mice. This animal study of exposure to low-dose MXC in F1 males suggests similar dysfunctional effects on male reproduction in humans.     

High-Efficient FLPo Deleter Mice in C57BL/6J Background

Conditional gene manipulation in mice becomes a routine for genetic studies of mammalian gene functions. Additional site-specific recombinases such as FLP or φ31 provide one more level of gene manipulation flexibility. The recombination activity of the currently available FLP deleter mice remains low. We generated a new FLP deleter mouse line with the mouse codon-optimized FLPo gene in C57BJ/6 background, which showed superior recombination efficacy in comparison to FLPe deleter mice. 100% complete removal of FRT-flanked Neo cassette was observed in all F1 progeny mice carrying both FLPo and Neo cassette, which can be transmitted to F2 generation independent of FLPo activity. Our new FLPo transgenic mice (on pure C57BJ/6 background) will largely facilitate the gene targeting process and is valuable for conditional gene manipulation.     

C57BL/6J-HBV转基因小鼠的繁育与检测

目的　摸清C57BL 6J -HBV转基因小鼠的繁育规律 ,建立可靠的HBsAg表达检测方法。方法　对C57BL 6J-HBV转基因小鼠两种不同交配方式的繁殖性能和HBsAg的表达情况进行比较研究 ;应用免疫组化的方法证实血清学诊断HBsAg的准确性并用激光扫描共聚焦显微镜确定HBsAg在肝细胞中的表达部位。结果与结论　从繁殖性能来看 ,两种交配方式窝产仔数差异不显著 (P >0 .0 5 ) ,而离乳数差异具有显著性 ( 0 .0 1

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Diet-Induced Obesity in Male C57BL/6 Mice Decreases Fertility as a Consequence of Disrupted Blood-Testis Barrier

Obesity is a complex metabolic disease that is a serious detriment to both children and adult health, which induces a variety of diseases, such as cardiovascular disease, type II diabetes, hypertension and cancer. Although adverse effects of obesity on female reproduction or oocyte development have been well recognized, its harmfulness to male fertility is still unclear because of reported conflicting results. The aim of this study was to determine whether diet-induced obesity impairs male fertility and furthermore to uncover its underlying mechanisms. Thus, male C57BL/6 mice fed a high-fat diet (HFD) for 10 weeks served as a model of diet-induced obesity. The results clearly show that the percentage of sperm motility and progressive motility significantly decreased, whereas the proportion of teratozoospermia dramatically increased in HFD mice compared to those in normal diet fed controls. Besides, the sperm acrosome reaction fell accompanied by a decline in testosterone level and an increase in estradiol level in the HFD group. This alteration of sperm function parameters strongly indicated that the fertility of HFD mice was indeed impaired, which was also validated by a low pregnancy rate in their mated normal female. Moreover, testicular morphological analyses revealed that seminiferous epithelia were severely atrophic, and cell adhesions between spermatogenic cells and Sertoli cells were loosely arranged in HFD mice. Meanwhile, the integrity of the blood-testis barrier was severely interrupted consistent with declines in the tight junction related proteins, occludin, ZO-1 and androgen receptor, but instead endocytic vesicle-associated protein, clathrin rose. Taken together, obesity can impair male fertility through declines in the sperm function parameters, sex hormone level, whereas during spermatogenesis damage to the blood-testis barrier (BTB) integrity may be one of the crucial underlying factors accounting for this change.     

Embryonic stem cells derived from C57BL/6J and C57BL/6N mice

Mouse embryonic stem (ES) cells with the C57BL/6 genetic background allow the generation of knockout mice without the need to backcross to C57BL/6. However, C57BL/6 ES cells whose pluripotency after homologous recombination has been confirmed are not yet available from public cell banks. To facilitate the use of ES cells derived from C57BL/6 sublines in both biologic and medical research, we demonstrated that the use of knockout serum replacement as a medium supplement and 8-cell blastomeres as recipient embryos allowed establishment of ES cells and production of germline chimeric mice, respectively. Under effective conditions, a large number of ES cell lines were established from C57BL/6J and C57BL/6N blastocysts. The majority of ES cells in many cell lines obtained from both strains showed a normal chromosome number. Germline chimeric mice were generated from C57BL/6J and C57BL/6N ES cells. Finally, the ES cell line B6J-S1UTR, derived from C57BL/6J, was used for successful production of gene knockout mice. C57BL/6J ES (B6J-S1UTR and B6J-23UTR) and C57BL/6N ES (B6N-22UTR) cells are available from the cell bank of the BioResource Center at RIKEN Tsukuba Institute (http://www.brc.riken.jp/lab/cell/english/).     

Differences in anxiety-related behavior between apolipoprotein E-deficient C57BL/6 and wild type C57BL/6 mice

The influence of ApoE gene deletion on the anxiety state has not been previously investigated. The elevated plus maze was used in this study to determine differences in anxiety-related behavior between apoE-deficient and wild type C57BL/6 mice. The apoE-deficient mice demonstrated less anxiety on the elevated plus maze by spending more time in the open arms of the elevated plus maze compared to wild type mice (p<0.001). Additionally, female apoE-deficient mice visited the open arm of the maze more often than their apoE-deficient male counterpart (p<0.05). The anxiety state and/or sex are possible variables to be considered when designing physiological and/or behavioral studies involving mice that are apoE-deficient.     

Endpoint Refinement for Total Body Irradiation of C57BL/6 Mice

Acute radiation syndrome is a life-threatening condition that has the potential to affect large populations of humans. Although several animal models of this syndrome are available, the total-body–irradiated mouse has emerged as an important tool to evaluate the efficacy of prospective prophylaxis, mitigation, and treatment compounds. Despite the widespread use of this model, humane endpoints have not been clearly identified. To address this issue, we developed a cageside observation-based scoring system specifically for total-body–irradiated mice to assess the progression of clinical signs associated with acute radiation syndrome. Male C57BL/6 mice (n = 175; age, 8 to 9 wk) received an anticipated LD₅₀ dose of radiation and were observed for progression of clinical signs of acute radiation syndrome for 30 d. All mice were scored individually through cageside observation of their body posture (score, 0 to 3), eye appearance (0 to 3), and activity level (0 to 3). Retrospective analysis of the score data indicated that death could be predicted accurately by using increasing cumulative scores (0 to 9). Total scores of 6, 7, 8, and 9 were associated with mortality rates of 78.6%, 86.4%, 93.3%, and 100%, respectively. Furthermore, scores of 6, 7, and 8 predicted death within 3, 1.5, and 0.5 d, respectively. The use of this scoring system provides investigators and IACUCs with predictive humane, surrogate endpoints for total-body–irradiated mice. This system allows preemptive euthanasia of mice before they become moribund, thereby minimizing pain and distress associated with acute radiation syndrome and improving animal welfare.Abbreviations: ARS, acute radiation syndrome; LD_50/30, the dose of radiation that is lethal for 50% of the test subjects within 30 d; TBI, total body irradiationAcute radiation syndrome (ARS) due to either accidental radiation exposure or nuclear attack is a life-threatening condition that has the potential to affect a large population of people. The severity of ARS is dependent on the overall dose, dose rate, radiation quality, and proportion of the body that is irradiated. ARS typically progresses through 4 clinical phases: prodrome, latency, illness, and either recovery or death.^1,7 The prodromal period is characterized by nausea, vomiting, and fatigue and can include autonomic instability and loss of consciousness at high doses in humans.¹ After the latent phase, which can be absent with high doses of radiation, the illness phase manifests in various organ systems as particular syndromes of the hematopoietic, gastrointestinal, skin, and neurovascular systems.^1,8 The hematopoietic system is the most sensitive to radiation, and decreased blood cell counts can be detected even in asymptomatic patients.¹ Increasing radiation doses cause complete destruction of bone marrow, sloughing of the mucosal layer of the gastrointestinal system, skin burns, and breakdown of the neurologic and cardiovascular systems, ultimately resulting in death.^1,8Preparatory planning for the medical management of ARS is essential and requires the use of total body irradiation (TBI) models in animals to evaluate the efficacy of prospective prophylaxis, mitigation, and treatment compounds.^8,28 The 2 body systems most sensitive to TBI are the hematopoietic and gastrointestinal systems, and mice are an excellent model for both; the C57BL/6 and C3H/He strains are used most often.²⁸ To study the hematopoietic syndrome, the most widely used TBI condition for acute radiation damage is the LD₅₀, because of the temporal predictability of the development of subsequent clinical signs. The temporal sequence and outcome of the hematopoietic syndrome occur considerably more rapidly in mice than in humans, and the experimental outcome is defined as the LD_50/30 (50% population death within 30 d of irradiation) in mouse models.²⁸ In addition, because mice have been deemed an appropriate species for testing radioprotectors or mitigators, the clinical efficacy of various drugs can be evaluated easily in a mouse TBI model.²⁸Although mice are an exceedingly common model for ARS, there are currently no established humane endpoint criteria for these types of studies. Similar to sepsis models, TBI and ARS studies typically use LD_50/30 as the standard of comparison, and this practice has resulted in the frequent and widespread use of death or moribund state as the experimental endpoint.^5,7,18,26 The moribund condition, an unresponsive and immobile animal, is a commonly used endpoint for a variety of research protocols associated with high mortality or progressive and severe disease states.^23,24 Using this criterion requires the animal to progress through all potential phases of pain and distress associated with the chosen model to a near-death state before the animal is euthanized.¹⁷The ability to predict death with a high probability and high accuracy in TBI studies would allow for preemptive euthanasia, with the intent to (1) ameliorate terminal pain and distress associated with ARS and (2) improve animal welfare. To this end, the current study sought to establish an observation-based scoring system to assess the health status of irradiated mice. Specifically, mice that received a targeted LD_50/30 TBI dose were evaluated by using daily cageside observational scoring of body posture, eye appearance, and activity level. This observation-based study was performed in conjunction with an approved IACUC study of the effects of synthetic parathyroid hormone in irradiated mice. The results were analyzed to identify the predictive nature of these criteria of impending death, with the goal of establishing useful endpoint criteria for future TBI studies.     

不同方法建立C57BL/6J小鼠抑郁症模型的探讨

目的用不同方法建立C57BL/6J小鼠抑郁症模型,为探讨GalR蛋白对小鼠抑郁症的治疗作用打下基础。方法 C57BL/6J小鼠经体重、敞箱实验及反抗抓获实验初筛后,随机分为4组:Ⅰ.CUMS组,Ⅱ.CUMS+CORT组,Ⅲ.CORT组,Ⅳ.正常对照组。每天记录小鼠体重及摄食量。28d后进行液体消耗及强迫游泳实验测试。结果小鼠抑郁模型在第28d建立成功。Ⅱ组小鼠短期内体重迅速下降并死亡。与Ⅰ组小鼠相比,Ⅲ组小鼠液体消耗和强迫游泳实验指标改变更明显。结论成功建立C57BL/6J小鼠抑郁症模型。CUMS和CORT模型结合,小鼠不能耐受,短期内死亡。单独CORT模型造模效果要优于CUMS模型。在后续试验中,将用CORT法建立C57BL/6J小鼠抑郁症模型。     

Repetitive Glucose Spikes Accelerate Atherosclerotic Lesion Formation in C57BL/6 Mice

Background

A number of epidemiological studies demonstrated that postprandial hyperglycemia is a risk factor for cardiovascular disease in individuals with impaired glucose tolerance. Although several laboratory studies have addressed the plausible causal role of postprandial acute hyperglycemia (glucose spikes) in the development of atherosclerosis, there is little convincing evidence in vivo whether the atherosclerotic lesion formation can be accelerated solely by glucose spikes. Here, we assessed the effect of repetitive glucose spikes on atherosclerotic lesion formation in mice.

Methods

Female C57BL/6 mice were fed an atherogenic diet from 8 to 28 weeks of age. During the atherogenic diet feeding period, the mice orally received a glucose solution (50 mg glucose/mouse; G group) or water (W group) twice daily, 6 days a week. Atherosclerotic lesion formation in the aortic sinus was quantitatively analyzed in serial cross-sections by oil red O staining.

Results

G group mice showed transient increases in blood glucose level (~5 mmol/L above W group), and the levels returned to levels similar to those in W group mice within 60 min. No significant differences in glucose tolerance, insulin sensitivity, and plasma lipid profiles were observed after the 20-week repetitive administration between the 2 groups. G group mice showed an approximately 4-fold greater atherosclerotic lesion size in the aortic sinus than W group mice. Gene expression levels of Cd68 and Icam1 in the thoracic aorta were higher in G group mice than in W group mice.

Conclusions

These results indicate that glucose spikes can accelerate atherosclerotic lesion formation, with little influence on other metabolic disorders. Repetitive glucose administration in wild-type mice may serve as a simple and useful approach to better understanding the causal role of glycemic spikes in the development of atherosclerosis.     

Bisphenol A Impairs Hepatic Glucose Sensing in C57BL/6 Male Mice

Aims/Hypothesis

Glucose sensing (eg. glucokinase activity) becomes impaired in the development of type 2 diabetes, the etiology of which is unclear. Estrogen can stimulate glucokinase activity, whereas the pervasive environmental pollutant bisphenol A (BPA) can inhibit estrogen action, hence we aimed to determine the effect of BPA on glucokinase activity directly.

Methods

To evaluate a potential acute effect on hepatic glucokinase activity, BPA in water (n = 5) vs. water alone (n = 5) was administered at the EPA’s purported “safe dose” (50 µg/kg) by gavage to lean 6-month old male C57BL/6 mice. Two hours later, animals were euthanized and hepatic glucokinase activity measured over glucose levels from 1–20 mmol/l in liver homogenate. To determine the effect of chronic BPA exposure on hepatic glucokinase activity, lean 6-month old male C57BL/6 mice were provided with water (n = 15) or water with 1.75 mM BPA (∼50 µg/kg/day; n = 14) for 2 weeks. Following the 2-week exposure, animals were euthanized and glucokinase activity measured as above.

Results

Hepatic glucokinase activity was signficantly suppressed after 2 hours in animals given an oral BPA bolus compared to those who received only water (p = 0.002–0.029 at glucose 5–20 mmol/l; overall treatment effect p<0.001). Exposure to BPA over 2 weeks also suppressed hepatic glucokinase activity in exposed vs. unexposed mice (overall treatment effect, p = 0.003). In both experiments, the Hill coefficient was higher and Vmax lower in mice treated with BPA.

Conclusions/Interpretation

Both acute and chronic exposure to BPA significantly impair hepatic glucokinase activity and function. These findings identify a potential mechanism for how BPA may increase risk for diabetes.     

Methionine-Restricted C57BL/6J Mice Are Resistant to Diet-Induced Obesity and Insulin Resistance but Have Low Bone Density

Dietary methionine restriction (MR) extends lifespan, an effect associated with reduction of body weight gain, and improvement of insulin sensitivity in mice and rats as a result of metabolic adaptations in liver, adipose tissue and skeletal muscle. To test whether MR confers resistance to adiposity and insulin resistance, C57BL/6J mice were fed a high fat diet (HFD) containing either 0.86% methionine (control fed; CF) or 0.12% methionine (methionine-restricted; MR). MR mice on HFD had lower body weight gain despite increased food intake and absorption efficiency compared to their CF counterparts. MR mice on HFD were more glucose tolerant and insulin sensitive with reduced accumulation of hepatic triglycerides. In plasma, MR mice on HFD had higher levels of adiponectin and FGF21 while leptin and IGF-1 levels were reduced. Hepatic gene expression showed the downregulation of Scd1 while Pparg, Atgl, Cd36, Jak2 and Fgf21 were upregulated in MR mice on HFD. Restriction of growth rate in MR mice on HFD was also associated with lower bone mass and increased plasma levels of the collagen degradation marker C-terminal telopeptide of type 1 collagen (CTX-1). It is concluded that MR mice on HFD are metabolically healthy compared to CF mice on HFD but have decreased bone mass. These effects could be associated with the observed increase in FGF21 levels.     

Indomethacin Treatment Prevents High Fat Diet-induced Obesity and Insulin Resistance but Not Glucose Intolerance in C57BL/6J Mice

Chronic low grade inflammation is closely linked to obesity-associated insulin resistance. To examine how administration of the anti-inflammatory compound indomethacin, a general cyclooxygenase inhibitor, affected obesity development and insulin sensitivity, we fed obesity-prone male C57BL/6J mice a high fat/high sucrose (HF/HS) diet or a regular diet supplemented or not with indomethacin (±INDO) for 7 weeks. Development of obesity, insulin resistance, and glucose intolerance was monitored, and the effect of indomethacin on glucose-stimulated insulin secretion (GSIS) was measured in vivo and in vitro using MIN6 β-cells. We found that supplementation with indomethacin prevented HF/HS-induced obesity and diet-induced changes in systemic insulin sensitivity. Thus, HF/HS+INDO-fed mice remained insulin-sensitive. However, mice fed HF/HS+INDO exhibited pronounced glucose intolerance. Hepatic glucose output was significantly increased. Indomethacin had no effect on adipose tissue mass, glucose tolerance, or GSIS when included in a regular diet. Indomethacin administration to obese mice did not reduce adipose tissue mass, and the compensatory increase in GSIS observed in obese mice was not affected by treatment with indomethacin. We demonstrate that indomethacin did not inhibit GSIS per se, but activation of GPR40 in the presence of indomethacin inhibited glucose-dependent insulin secretion in MIN6 cells. We conclude that constitutive high hepatic glucose output combined with impaired GSIS in response to activation of GPR40-dependent signaling in the HF/HS+INDO-fed mice contributed to the impaired glucose clearance during a glucose challenge and that the resulting lower levels of plasma insulin prevented the obesogenic action of the HF/HS diet.     

C57BL/6小鼠PD-1基因敲除后炎症与心房电重构的关系研究

目的:研究C57BL/6小鼠在PD-1基因敲除后体内炎症升高对房颤发病易感性的影响。方法:对两组动物进行了观察:C57BL/6小鼠和C57BL/6-PD-1基因敲除小鼠(各组均为15只,雄性,6-8周龄)。应用流式细胞仪微球芯片捕获技术对比了实验组与对照组的血清炎性细胞因子表达水平,应用多导电生理记录仪检测了实验组与对照组心房有效不应期和有效不应期离散度。结果:和对照组相比较,C57BL/6-PD-1-/-小鼠血清炎性细胞因子水平明显升高,C57BL/6-PD-1-/-小鼠心房肌有效不应期较对照组减低,而有效不应期离散度则明显升高。结论:PD-1基因敲除后出现的机体内炎性细胞因子水平的升高导致了C57BL/6小鼠的心房电重构,并由此使得C57BL/6-PD-1-/-小鼠心房纤颤发病易感性升高。     

Behavioral and Neural Correlates of Acute and Scheduled Hunger in C57BL/6 Mice

In rodents, daily feeding schedules induce food anticipatory activity (FAA) rhythms with formal properties suggesting mediation by food-entrained circadian oscillators (FEOs). The search for the neuronal substrate of FEOs responsible for FAA is an active area of research, but studies spanning several decades have yet to identify unequivocally a brain region required for FAA. Variability of results across studies leads to questions about underlying biology versus methodology. Here we describe in C57BL/6 male mice the effects of varying the ‘dose’ of caloric restriction (0%, 60%, 80%, 110%) on the expression of FAA as measured by a video-based analysis system, and on the induction of c-Fos in brain regions that have been implicated in FAA. We determined that more severe caloric restriction (60%) leads to a faster onset of FAA with increased magnitude. Using the 60% caloric restriction, we found little evidence for unique signatures of neuronal activation in the brains of mice anticipating a daily mealtime compared to mice that were fasted acutely or fed ad-libitum–even in regions such as the dorsomedial and ventrolateral hypothalamus, nucleus accumbens, and cerebellum that have previously been implicated in FAA. These results underscore the importance of feeding schedule parameters in determining quantitative features of FAA in mice, and demonstrate dissociations between behavioral FAA and neural activity in brain areas thought to harbor FEOs or participate in their entrainment or output.     

A comparative phenotypic and genomic analysis of C57BL/6J and C57BL/6N mouse strains

Background

The mouse inbred line C57BL/6J is widely used in mouse genetics and its genome has been incorporated into many genetic reference populations. More recently large initiatives such as the International Knockout Mouse Consortium (IKMC) are using the C57BL/6N mouse strain to generate null alleles for all mouse genes. Hence both strains are now widely used in mouse genetics studies. Here we perform a comprehensive genomic and phenotypic analysis of the two strains to identify differences that may influence their underlying genetic mechanisms.

Results

We undertake genome sequence comparisons of C57BL/6J and C57BL/6N to identify SNPs, indels and structural variants, with a focus on identifying all coding variants. We annotate 34 SNPs and 2 indels that distinguish C57BL/6J and C57BL/6N coding sequences, as well as 15 structural variants that overlap a gene. In parallel we assess the comparative phenotypes of the two inbred lines utilizing the EMPReSSslim phenotyping pipeline, a broad based assessment encompassing diverse biological systems. We perform additional secondary phenotyping assessments to explore other phenotype domains and to elaborate phenotype differences identified in the primary assessment. We uncover significant phenotypic differences between the two lines, replicated across multiple centers, in a number of physiological, biochemical and behavioral systems.

Conclusions

Comparison of C57BL/6J and C57BL/6N demonstrates a range of phenotypic differences that have the potential to impact upon penetrance and expressivity of mutational effects in these strains. Moreover, the sequence variants we identify provide a set of candidate genes for the phenotypic differences observed between the two strains.     

Electron Microscopy Analysis of Sciatic Nerve Fibers in C57BL/6 Transgenic Mice

Neurophysiology - Hereditary Charcot–Marie–Tooth (CMT) motor/sensory neuropathy is a known disease in the group of polyneuropathies. It is characterized, in particular, by the process...     

Mild Calorie Restriction Induces Fat Accumulation in Female C57BL/6J Mice

This study investigated the effects of mild calorie restriction (CR) (5%) on body weight, body composition, energy expenditure, feeding behavior, and locomotor activity in female C57BL/6J mice. Mice were subjected to a 5% reduction of food intake relative to baseline intake of ad libitum (AL) mice for 3 or 4 weeks. In experiment 1, body weight was monitored weekly and body composition (fat and lean mass) was determined at weeks 0, 2, and 4 by dual energy X‐ray absorptiometry. In experiment 2, body weight was measured every 3 days and body composition was determined by quantitative magnetic resonance weekly, and energy expenditure, feeding behavior, and locomotor activity were determined over 3 weeks in a metabolic chamber. At the end of both experiments, CR mice had greater fat mass (P < 0.01) and less lean mass (P < 0.01) compared with AL mice. Total energy expenditure (P < 0.05) and resting energy expenditure (P < 0.05) were significantly decreased in CR mice compared with AL mice over 3 weeks. CR mice ate significantly more food than AL mice immediately following daily food provisioning at 1600 hours (P < 0.01). These findings showed that mild CR caused increased fat mass, decreased lean mass and energy expenditure, and altered feeding behavior in female C57BL/6J mice. Locomotor activity or brown adipose tissue (BAT) thermogenic capacity did not appear to contribute to the decrease in energy expenditure. The increase in fat mass and decrease in lean mass may be a stress response to the uncertainty of food availability.