Nest building in nulligravid,primigravid and primiparous C57BL/6J and DBA/2J mice (Mus musculus)

C57BL/6J (B6) and DBA/2J (D2) mice differ in maternal behavior and nest building, but previous observations on nest building appear to be contradictory. Lactating B6 females spent more time nest building than lactating D2 females [Physiol. Behav. 67 (1999) 599.]; however, pregnant D2 females have been reported to build better nests than pregnant B6 females [Physiol. Behav. 29 (1982) 153.]. To resolve this apparent discrepancy, virgin B6 and D2 females were mated, and the nest quality of nulligravid, primigravid and lactating primiparous females was compared between groups and with that of virgin females. There were no strain differences in the nest ratings of virgin or mated nulligravid females, nor did these groups differ within strains. Pregnant and lactating females of both strains built better nests than nonpregnant females. There was an increase in nest ratings in both strains on the day of parturition. The nest ratings of pregnant and lactating females were higher in B6 than D2 females. The largest strain differences were observed between pregnant B6 and D2 females. One hypothesis to account for these results is that females of these two strains differ in their levels of or sensitivity to hormones during pregnancy and parturition.     

Spontaneous central apneas occur in the C57BL/6J mouse strain

Despite the clinical significance of central apneas in a wide range of disorders little is known about their pathogenesis. Research in this field has been hindered by the lack of appropriate animal models. Our goal was to determine whether the C57BL/6J mouse strain, which has an inherited predisposition for dysrhythmic breathing, exhibits spontaneous apneas. In vivo plethysmography of unanesthetized, unrestrained adult C57BL/6J mice revealed a regular occurrence of spontaneous apneas. In situ recordings from respiratory outputs (phrenic, vagal, hypoglossal nerves) in the working heart-brainstem preparation (WHBP) also showed spontaneous central apneas accompanied by laryngeal closure as indicated by tonic vagal postinspiratory activity and increase in subglottal pressure. The apneas were further characterized by a hypoglossal discharge with delayed onset compared to the tonic vagal postinspiratory activity. We conclude that spontaneous central apneas with active laryngeal closure occur in C57BL/6J mice. This mouse strain is a useful animal model to study neuronal mechanisms that underlie the generation of spontaneous central apneas.     

8-OH-DPAT suppresses spontaneous central apneas in the C57BL/6J mouse strain

Apneas are common and prognostically relevant disorders of the central control of breathing, but pharmacological interventions are dissatisfying. The respiratory phenotype of C57BL/6J mice is characterized by the occurrence of spontaneous central apneas with laryngeal closure. In the present study we investigated the impact of the 5-HT(1A) receptor agonist 8-OH-DPAT on apneas in C57BL/6J mice, because of the important role of serotonin in the regulation of breathing and previous reports showing that serotonergic drugs can affect central apneas. Whole-body plethysmography in awake, unrestrained mice revealed that intraperitoneal application of 8-OH-DPAT (10microgkg(-1)) decreased the occurrence of spontaneous apneas from 1.91+/-0.25 to 1.05+/-0.05 apneas min(-1). The efficacy of 5-HT(1A) receptor activation was further verified in the in situ working heart-brainstem preparation. Here the apneas occurred at a frequency of 1.33+/-0.19min(-1). Intra-arterial perfusion with 1-2microM 8-OH-DPAT completely abolished spontaneous apneas. These results suggest that 5-HT(1A) receptor activation may be a potential treatment option for central apneas.     

Morphoquantitative analysis of the Ileum of C57BL/6 mice (Mus musculus) fed with a high-fat diet

Due to the increase in overweight and obesity in humans, various studies have been conducted in recent years that demonstrate the detrimental effects on tissues and organs. The aim of this study was to assess the morphoquantitative changes produced in the ileum of mice, associated with high-fat diets. Fourteen male C57BL/6 mice, 5 months old, were fed two types of diets for 14 weeks. The control group (C) was fed a standard diet (10% fat, AIN-93M) and the experimental group (E) was fed a high-fat diet (42% fat, AIN-93M-AG). The assessments included: body weight, calorie consumption, food efficiency, biochemical analysis of plasma lipids, diameter, total wall thickness, thickness of the tunica mucosa and tunica muscularis, length and width of the intestinal villi, depth of the intestinal crypts and number of goblet cells per mm^-2 (N_A). For the statistical analysis the Student’s t-test was used, considering a P value less than 0.05. The mice in the E group presented greater weight gain (P = 0.028), higher levels of total and LDL cholesterol (P = 0.03 and P = 0.01, respectively), and length of the intestinal villi (P = 0.000). The width of the intestinal villi and the NA of PAS-positive goblet cells presented significantly lower values (P = 0.037 and P = 0.039, respectively) than the C group. The observed changes could be related to the higher demand for fat absorption and to possible alterations in the intestinal microflora and inflammation by action of high-fat diets.     

应用环磷酰胺构建C57BL/6J小鼠免疫抑制模型

背景：在免疫增强剂的研究中,常用到免疫抑制模型,如何建立免疫抑制模型成为免疫增强剂作用评价的关键。 目的：应用环磷酰胺构建C57BL/6J小鼠免疫抑制模型。 方法：将小鼠随机分为正常对照组、环磷酰胺50 mg/kg 5 d组,环磷酰胺80 mg/kg 3 d组,环磷酰胺80 mg/kg 5 d组,环磷酰胺100 mg/kg 5 d组和环磷酰胺100 mg/kg隔天给药组。正常对照组小鼠腹腔注射生理盐水0.1 mL,连续5 d。环磷酰胺50 mg/kg 5 d组,环磷酰胺80 mg/kg 3 d组,环磷酰胺80 mg/kg 5 d组和环磷酰胺100 mg/kg 5 d组小鼠分别以环磷酰胺50,80,80,100 mg/kg腹腔注射连续5,3,5,5 d。环磷酰胺100 mg/kg隔天给药组小鼠腹腔注射100 mg/kg环磷酰胺,隔天1次,共注射3次。 结果与结论：与正常对照组比较,腹腔注射环磷酰胺可导致小鼠外周血中CD3⁺T,CD3⁺CD4⁺T及CD3⁺CD8⁺T细胞明显下降(P < 0. 05);谷丙转氨酶(除环磷酰胺50 mg/kg 5 d、80 mg/kg 3 d组)、谷草转氨酶、尿素显著升高(P < 0.05),其中环磷酰胺80 mg/kg 5 d组、环磷酰胺100 mg/kg 5 d组和环磷酰胺100 mg/kg隔天给药组对肝肾功能的影响更为明显。提示腹腔注射环磷酰胺可建立CD3⁺T,CD3⁺CD4⁺T及CD3⁺CD8⁺T细胞明显下降的免疫抑制模型,其中以环磷酰胺50 mg/kg 5 d和80 mg/kg 3 d方式对肝肾功能的损伤较小。     

Genomic copy number and expression variation within the C57BL/6J inbred mouse strain

The C57BL/6J strain is one of the most widely used animal models for biomedical research, and individual mice within the strain are often assumed to be genetically identical after more than 70 yr of inbreeding. Using a single nucleotide polymorphism (SNP) genotyping panel, we assessed if copy number variations (CNVs) could be detected within the C57BL/6J strain by comparing relative allele frequencies in first generation (F(1)) progeny of C57BL/6J mice. Sequencing, quantitative PCR, breeding, and array comparative genomic hybridization (CGH) together confirmed the presence of two CNVs. Both CNVs span genes encoded on chromosome 19, and quantitative RT-PCR demonstrated that they result in altered expression of the insulin-degrading enzyme (Ide) and fibroblast growth factor binding protein 3 (Fgfbp3) genes. Analysis of 39 different C57BL/6J breeders revealed that 64% of mice from the Jackson Laboratory colony were heterozygous for the CNV spanning Ide. Homozygotes with and without the duplication were present in concordance with Hardy-Weinberg equilibrium (13% and 23%, respectively), and analysis of archived samples from the C57BL/6J colony suggests that the duplication has rapidly reached a high frequency in the colony since 1994. The identification of two CNVs in the small portion of the genome screened demonstrates that individual mice of highly inbred strains are not isogenic and suggests other CNVs may be segregating within C57BL/6J as well as other carefully maintained inbred strains. These differences can influence interpretations of physiological, biomedical, and behavioral experiments and can be exploited to model CNVs apparent in the human genome.     

A multimodal, multidimensional atlas of the C57BL/6J mouse brain

Strains of mice, through breeding or the disruption of normal genetic pathways, are widely used to model human diseases. Atlases are an invaluable aid in understanding the impact of such manipulations by providing a standard for comparison. We have developed a digital atlas of the adult C57BL/6J mouse brain as a comprehensive framework for storing and accessing the myriad types of information about the mouse brain. Our implementation was constructed using several different imaging techniques: magnetic resonance microscopy, blockface imaging, classical histology and immunohistochemistry. Along with raw and annotated images, it contains database management systems and a set of tools for comparing information from different techniques. The framework allows facile correlation of results from different animals, investigators or laboratories by establishing a canonical representation of the mouse brain and providing the tools for the insertion of independent data into the same space as the atlas. This tool will aid in managing the increasingly complex and voluminous amounts of information about the mammalian brain. It provides a framework that encompasses genetic information in the context of anatomical imaging and holds tremendous promise for producing new insights into the relationship between genotype and phenotype. We describe a suite of tools that enables the independent entry of other types of data, facile retrieval of information and straightforward display of images. Thus, the atlas becomes a framework for managing complex genetic and epigenetic information about the mouse brain. The atlas and associated tools may be accessed at http://www.loni.ucla.edu/MAP.     

Identification of a group of Mus dunni endogenous virus-like endogenous retroviruses from the C57BL/6J mouse genome: proviral genomes, strain distribution, expression characteristics, and genomic integration profile

About 10 % of the mouse genome is occupied by sequences associated with endogenous retroviruses (ERVs). However, a comprehensive profile of the mouse ERVs and related elements has not been established yet. In this study, we identified a group of ERVs from the mouse genome and characterized their biological properties. Using a custom ERV mining protocol, 191 ERVs (159 loci reported previously and 32 new loci), tentatively named Mus dunni endogenous virus (MDEV)-like ERVs (MDL-ERVs), were mapped on the C57BL/6J mouse genome. Seven of them retained putative full coding potentials for three retroviral polypeptides (gag, pol, and env). Among the 57 mouse strains examined, all but the Mus pahari/Ei strain had PCR amplicons corresponding to a conserved MDL-ERV region. Interestingly, the Mus caroli/EiJ??s amplicon was somewhat larger than the others, coinciding with a substantial phylogenetic distance between the MDL-ERV populations of M. caroli/EiJ and C57BL/6J strains. MDL-ERVs were highly expressed in the lung, spleen, and thymus of C57BL/6J mice compared to the brain, heart, kidney, and liver. Seven MDL-ERVs were mapped in the introns of six annotated genes. Of interest, some MDL-ERVs were mapped periodically on three clusters in chromosome X. The finding that these MDL-ERVs were one of several types of retroelements, which form mosaic-repeat units of tandem arrays, suggests that the formation of the mosaic-repeat unit preceded the tandem arrangement event. Further studies are warranted to understand the biological roles of MDL-ERVs in both normal and pathologic conditions.     

Standard atlas space for C57BL/6J neonatal mouse brain

A standard atlas space with stereotaxic co-ordinates for the postnatal day 0 (P0) C57BL/6J mouse brain was constructed from the average of eight individual co-registered MR image volumes. Accuracy of registration and morphometric variations in structures between subjects were analyzed statistically. We also applied this atlas coordinate system to data acquired using different imaging protocols as well as to a high-resolution histological atlas obtained from separate animals. Mapping accuracy in the atlas space was examined to determine the applicability of this atlas framework. The results show that the atlas space defined here provides a stable framework for image registration for P0 normal mouse brains. With an appropriate feature-based co-registration strategy, the probability atlas can also provide an accurate anatomical map for images acquired using invasive imaging methods. The atlas templates and the probability map of the anatomical labels are available at .     

Diverse effects of stanozolol in C57BL/6J and A/J mouse strains

Although skeletal muscle is the principal target for androgenic anabolic steroids (AAS) other physiological and behavioral processes are also affected. Wide variations in response to AAS are known to exist in individuals but the genetic basis of this has hardly been explored. Female mice from the A/J and C57BL/6J strains were divided into four experimental groups: CTRL-Sham, housed in a regular mouse cage and subjected to a sham operation mimicking implantation of steroids; CTRL-AAS, mice similarly housed and implanted with a pellet containing stanozolol (release rate, 4.6 mg/kg/day); EX-Sham, sham operated mice housed in a cage with two towers which required mice to climb 1 m to obtain food or water; EX-AAS, mice similarly housed and implanted with a stanozolol pellet. The experimental treatment was initiated at 10 weeks of age and lasted for 7 weeks. Body weight was assessed periodically during the experiment (time effect), systolic blood pressure (BP) and heart rate (HR) were measured after 6 weeks of treatment, and weights of gastrocnemius (GAST), soleus, tibialis anterior (TA), extensor digitorum longus (EDL), quadriceps femoris (QF) and biceps brachii (BB) muscles, heart, liver, kidney and abdominal fat were measured after 7 weeks of treatment. AAS treatment significantly increased weight of GAST (P ≪ 0.001), TA (P < 0.01), EDL (P < 0.01) and QF (P ≪ 0.001) muscles in both of the strains. Several of the measured indices were differentially affected in the two strains by AAS (body weight, Time × Strain × AAS P < 0.02; BP and HR, Strain × AAS P < 0.03 and P < 0.01, respectively). These findings encourage the view that recombinant inbred strains and chromosome substitution strains derived from the A/J and C57BL/6J mice can be utilized to explore the genetic architecture of these interactions in order to elucidate the mechanism underlying both the positive and negative health-related effects of AAS.     

Limiting dilution analysis of ontogeny of self- and allo-reactive thymocytes of C57BL/6J mouse

In the present study, functional development of mouse fetal through neonatal to adult thymocytes was analyzed by limiting dilution assay (LDA) in terms of allo-reactivity and self-reactivity. Self-reactive PTL-p were always much less than those of allo-reactive PTL-p at all ages examined in this study. These results imply that thymocyte proliferation is not predominantly driven by responses to self antigens in the thymus, and that self-reactive thymocytes do not develop prior to allo-reactive thymocytes during thymic ontogeny. It is unlikely that most of such proliferating, murine early fetal thymocytes are self-reactive; allo-reactive cells are unlikely to have been derived from self-reactive cells during T cell development.     

Development of inferior colliculus response properties in C57BL/6J mouse pups

Summary Response properties of inferior colliculus (IC) neurons were studied in tranquilized C57BL/6J mice during a period of rapid auditory system development between 12 and 17 days of age. In IC units of the youngest mice, spontaneous activity was absent, a disproportionate number of onset responses was observed, and many units were not securely driven by sound. Frequency response ranges were restricted to relatively low frequencies, sharpness of tuning was poor, and thresholds at best frequencies (BFs) were quite high. Dynamic intensity ranges were restricted, but nonmonotonic functions were observed. By 15–17 days of age, spontaneous activity was appreciable, incidences of response patterns were near adult proportions, and most units in the ventrolateral nucleus were securely driven by tones. Response ranges had expanded markedly to include high frequencies, sharpness of tuning increased, and thresholds had decreased. Dynamic intensity ranges and intensity functions were similar to those observed in adult mice.     

Susceptibility of heat shock protein 70.1-deficient C57BL/6 J,wild-type C57BL/6 J and A/J mice to Trypanosoma congolense infection

Toxoplasma gondii is a protozoan parasite with a worldwide distribution. In both sheep and humans, if the parasite is encountered during pregnancy, fetal infection and abortion can occur. Therefore, Toxoplasma infection in sheep has a major economic impact upon sheep farming. Clinically, there is a need to distinguish recent (acute) infections from longstanding (chronic) infections. However, current serological techniques, such as detection of anti-T. gondii IgG, cannot discriminate between acute and chronic infections. Increasing immunoglobulin avidity is a good determining factor of how recent an infection is. In this study, we describe the application and validation of a T. gondii IgG avidity ELISA, based on the use of an affinity-purified, native T. gondii P30 antigen. The assay was used to examine sera from eight sheep experimentally infected with T. gondii and found that all seroconverted within 21 days post-infection (p.i.), beginning with avidities that were initially low but that increased over time, with all sheep reaching high IgG avidity within 10 weeks p.i. In addition, sera from clinically healthy but T. gondii-seropositive lambs and ewes and seropositive ewes with a history of abortion were also subjected to a preliminary serological investigation. High IgG avidities were found in 80% of the seropositive lambs, in 90% of the clinically healthy ewes and in 97% of the ewes with abortion problems. These findings indicate that the animals had most likely contacted the parasite a longer time ago.     

近交系C57BL/6J小鼠的脱毛特征

目的了解近交系C57BL/6J小鼠脱毛的性质和脱毛的特征。方法在各代鼠详细观察记录脱毛出现的时间、状况和缓解情况;利用对照组2对来自不同父母鼠的F1雌雄鼠进行交配实验和回盒饲养实验,观察脱毛和脱毛缓解的特征,在F2小鼠观察脱毛特征的遗传性,对脱毛区域皮肤进行病理分析。结果脱毛(头、颈或背部)多出现在3～6只同养的雌性鼠中(对照组32.4%,实验组16.3%),脱毛-新毛生长的过程交替进行,交配有缓解脱毛的作用并能维持新毛的生长状态,脱毛的特征可以遗传。皮肤病理显示皮肤各层结构、毛囊和毛囊球上皮无明显病理性改变。结论脱毛可能是本品系在特定饲养条件下适应环境压力失败及缺乏生理活动的一种表现,具有经过良性、可缓解、特征可遗传等特点。     

Age-dependent and tissue-specific structural changes in the C57BL/6J mouse genome

We tested the hypothesis that structural changes in the genome parallel age- and organ-specific phenotypes in conjunction with the differential transposition activities of retroelements. The genomes of the liver from C57BL/6J mice were larger than other organs, coinciding with an increase in genomic copies of certain retroelements. In addition, there were differential increments in the genome size of the liver with increasing age, which peaked at 5 weeks. The findings that the genome structure of an individual is variable depending on age and organ type in association with the transposition of retroelements may have broad implications in understanding biologic phenomena.     

Age and brightness discrimination learning by C57BL/6J mice

Groups of 20–34 C577BL/6J mice, aged 75, 225, 375, and 525 days, learned a brightness discrimination for water. The error scores of the 75- and 525-day groups were almost identical, and both made significantly more errors than the 225-day-old mice. Both immature and older mice appear to be deficient in learning ability compared to young adults.     

IGF-1 as selected growth factor multi-response to antidepressant-like substances activity in C57BL/6J mouse testis model

Insulin-like growth factor (IGF-1) affects almost all cells in the body. Extremely important functions of this growth factor have been demonstrated in the brain and the reproductive system of both, females and males. Also, it is considered as a pro-inflammatory cytokine adjusting tissue homeostasis. However, it seems to play a special role in the male reproductive system and it may be disturbed by the application of antidepressants with different mechanisms of drug action during therapy. To date, the effect of antidepressant-like substances (ALS) on the course of physiological processes in male testicular cells is poorly understood. Therefore, the purpose of the research was to determine the presence, localizationof IGF-1R (insulin-like growth factor 1 β receptor) and mRNA gene expression of IGF-1R and IGF-1 after administration of 3-[(2-methyl-1,3-tiazol-4-yl)ethynyl]-pyridine (MTEP) and N-[2-(Cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS-398) in the different scheme in the testis of mice. Imipramine was used as a reference drug having a documented interaction with the mGluR5 receptors. The immunohistochemical analyses showed the localization of IGF-1R in Sertoli, Leydig, and germinal cells after all used substances. Differences in receptor localization were observed depending on the drugs applied and the type of analyzed cells. In contrast, there was a significant increase in IGF-1 gene expression after IMI + NS-398 and in IGF-1R after MTEP + NS-398 and IMI + NS-398 administration. It can, therefore, be assumed that the use of a combination of NS-398 with some ALS may run different mechanisms of action and affect the regulation of reproductive function in mouse testis through maintaining homeostasis at the molecular and immunological levels related to IGF.     

Morphological evidence of exocrine function in coagulating gland renin of mouse strain C57BL/6

Background: Renin is classically secreted from juxtaglomerular cells of the kidney by endocrine or paracrine mechanisms. In a previous report, intense renin immunoreactivity was observed in the coagulating gland (CG), a new source for renin in mice. In the present study, immunoelectron microscopical analysis for renin was carried out to clarify the secretory site of CGs. Methods: Five adult male C57BL/6 mice were used in this study. The CGs were fixed with an ice-cold 2% glutaraldehyde and 2% paraformaldehyde mixture and embedded in Lowicryl K4M. Ultrathin sections were treated with antimouse renin antiserum and colloidal gold (15 nm)-labeled protein A complex. Results: In immunoelectron microscopical observation, renin was first detected at the Golgi vacuoles just budding from the lamellae, although it was not demonstrated in all Golgi vacuoles. In the production series of exocrine granules, renin immunoreactivity was observed in some granules that were distributed in the supranuclear region. Both renin-positive and negative exocrine granules were secreted from the apical cell membrane by exocytosis. The lysosomal granules also showed stronger renin immunoreactivity and contained homogeneous or heterogeneous materials. In the supranuclear region, it was observed that exocrine granules were fused with irregular lysosomal granules. At the apical region, such lysosomal granules were closely associated with cell membrane. At the basolateral region, immunoreactivity for renin was localized in electron dense granules. Conclusions: These results suggest that part of the renin in the CGs is released by exocrine secretion into the genital tract. © 1995 Wiley-Liss, Inc.     

白藜芦醇通过调节iNOS抑制C57BL/6J小鼠动脉粥样硬化的机制探讨

目的:探讨白藜芦醇(resveratrol,RES)对卵巢切除小鼠血脂四项总胆固醇(CHOL)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)以及血清一氧化氮(nitric oxide,NO)含量、胸主动脉的过氧亚硝基阴离子(peroxynitrite anion,ONOO-)及诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)蛋白表达水平的影响。方法:雌性C57小鼠经卵巢切除建立去势模型后,分为假手术组、单纯去势组、假手术高脂组、模型高脂组和RES组。单纯去势组和假手术组给予普通饲料,其余给予高脂饲料。14周后,收集血清检测各组血清的CHOL、TG、LDL-C和HDL-C水平,硝酸还原酶法测血浆NO水平,油红O染色观察动脉粥样硬化(atherosclerosis,AS)情况,DAB染色测定血管ONOO-及iNOS水平,免疫印迹测定血管组织的iNOS表达。结果:模型高脂组血清CHOL、TG、LDL-C和NO较正常对照组升高(P0.05);与模型高脂组相比,RES组可降低小鼠血清的TC、TG、LDL-C和NO(P0.05);14周后,AS模型成功建立,模型高脂组有明显的AS病理改变,单纯去势组无明显AS斑块,RES组AS病变明显减轻;高脂喂养14周后,模型高脂组血管组织的iNOS及ONOO–表达也较正常对照组明显提高(P0.05);与模型高脂组相比,RES组可降低小鼠胸主动脉的iNOS表达(P0.05),与此同时,血管ONOO-含量较模型高脂组降低。结论:RES可以抑制iNOS表达,减少NO生成,防治动脉粥样硬化。     

Histamine H2 receptors mediate morphine-induced locomotor hyperactivity of the C57BL/6J mouse

Morphine-induced locomotor hyperactivity of the C57BL/6J mouse was challenged with intracranial injections of antihistamines or the opiate antagonist naloxone. When cimetidine (H2 receptor blocker) was injected into the nucleus accumbens/stria terminalis, it significantly reduced opiate-stimulated locomotion. However, ventricular injections of cimetidine did not significantly alter either morphine or amphetamine hyperactivity, nor did cimetidine depress spontaneous locomotion. Although naloxone eliminated morphine-induced locomotion when injected into either the nucleus accumbens or the ventricles, chlorpheniramine (H1 receptor blocker) failed to reduce this behavior. These data suggest that opiate-stimulated locomotion of the C57BL/6J mouse may be partially mediated by histamine H2 receptors of the nucleus accumbens or closely adjacent structures.