Effects of weekly blood collection in C57BL/6 mice

We assessed hematologic recovery, body weight, and behavior after serial blood collection in 10- to 14-wk-old C57BL/6 mice. Male and female mice (5 to 11 mice for pilot groups, 23 to 35 mice for full study groups) had either 15%, 20%, or 25% of their estimated total blood volume (TBV) collected once weekly for 6 wk. Except for those of the 25% TBV male pilot group, the weights of all mice recovered or increased from one collection to the next. The behavior of all mice, with the exception of the 25% TBV male pilot group, appeared normal throughout the study. Erythrogram value changes from baseline were analyzed at each weekly blood collection. Recovery was defined as the return of mean hemoglobin values to within 2 SD of mean baseline values. According to this definition, mice in the 15% TBV male group and 15%, 20%, and 25% TBV female groups recovered hematologically. To support the statistical definition of recovery, we compared our data with human anemia categories to assess the clinical relevance of the mouse hemoglobin values. On the basis of these data, we conclude that as much as 25% TBV can be collected once weekly from female mice for 6 wk and as much as 15% TBV can be collected once weekly from male mice for 6 wk without producing weight loss, behavioral changes, or clinically significant anemia.     

Preleukemic expression of TL antigens in x-irradiated C57BL/6 mice

Anomalous appearance of TL (thymus-leukemia) antigens is a characteristic feature of radiation-induced leukemias of C57bl/6 mice. We now report that thymocytes of irradiated C57BL/6 mice express TL antigens long before the development of overt leukemia. Thus, TL is a marker for preleukemic changes occurring during radiation leukemogenesis. Low levels of murine leukemia virus (MuLV)-related antigens are also detected on preleukemic thymocytes. Comparative tests on individual mice show no direct correlation between TL and MuLV antigen expression.     

Vitamin E as a treatment for ulcerative dermatitis in C57BL/6 mice and strains with a C57BL/6 background.

In this study, we fed a standard NIH-31 diet fortified with vitamin E to C57BL/6 mice and strains of mice with a C57BL/6 background that had spontaneously developed ulcerative dermatitis (UD). In addition to the therapeutic response to increased levels of vitamin E, we also defined the occurrence of UD within our facility in terms of age, sex, coat color, and lesion location on the body. Mice with spontaneous UD were fed a vitamin E-fortified diet (3000 IU/kg) for a period of 8 weeks and entered the study without regard to vendor source, age, sex, coat color, or the site or number of UD lesions. We found that lesions occurred most commonly on the dorsal cervical and scapular regions and spared the ventral abdomen and thorax. No sex or coat color predilection was noted for the development of UD, however males were older than females at the time of lesion development. Of 71 mice, 32 (45%) had complete lesion re-epithelialization with hair regrowth. Complete lesion repair was not influenced by sex, age, or coat color. The average time to complete lesion repair ranged from 2 to 5 weeks, and there was no correlation with sex or coat color. The positive response to vitamin E suggests that protection from oxidative injury may play a role in the resolution of UD lesions and offers veterinarians and investigators a new treatment option with ease of compliance.     

七氟醚对C57小鼠海马基因表达的影响

目的:通过微阵列分析来研究七氟醚对小鼠海马基因表达的影响。方法:出生后第7天(P7)C57BL/6雄性小鼠12只,随机分为2组(n=6),重复七氟醚组(RS组)和空气对照组(C组),每天暴露于七氟醚(浓度为2.5%)或空气2 h,连续5 d,小鼠处死后提取海马RNA进行基因表达谱分析。结果:与C组相比,RS组共有30个基因发生了显著变化(1.5或1.5倍),其中上调基因16个(P0.05),下调基因14个(P0.05)。这些基因主要参与学习记忆、认知、细胞代谢、信号转导和通讯、结构和囊泡过程、生命物质结合和定位等过程。实验随机选择9个差异基因验证芯片结果,发现3个上调基因(Ppp1r1b、Id1和Txnip)和5个下调基因(Arc、c-Fos、Npas4、Grin2a和Kcnj2)。结论:七氟醚可引起小鼠海马中一些关键基因的改变,这些改变可能与认知功能障碍或其他神经系统疾病有关。     

CCL20增强HBsAg的免疫应答效应

目的为探讨CCL20对HBsAg介导的免疫应答是否具有增强作用,为CCL20这一细胞因子作为新型乙肝制剂的应用研究提供理论依据。方法采用基因重组技术,构建趋化因子CCL20和表面抗原（HBsAg）的真核表达载体,将重组载体用肌肉免疫的方式分别注射正常的C57BL/6小鼠,通过ELISA方法检测C57BL/6小鼠的抗-HBs抗体水平、细胞增殖情况。结果用CCL20/HBsAg真核表达质粒共注射免疫后,100%小鼠能在第4、6周检测到教高效价的抗-HBs抗体,持续时间长达10周;同时,CCL20增强了HBsAg的细胞免疫反应。结论CCL20能增强小鼠针对HBsAg的体液和细胞免疫应答反应,这将为新型乙肝特异性免疫治疗应用研究提供依据。     

Loci predisposing to autoimmunity in MRL-Fas lpr and C57BL/6-Faslpr mice.

Background genes determine the incidence and severity of lymphoaccumulation and histopathologic manifestations of systemic autoimmunity in mice homozygous for the apoptosis-defective Faslpr mutation. By interval mapping of 274 F2 mice intercrossed between MRL-Faslpr (severe disease) and C57BL/6-Faslpr (minimal disease), four loci were identified with significant linkage to lymphadenopathy and/ or splenomegaly on chromosomes 4, 5, 7, and 10, which were named lupus in (MRL-Faslpr x B6-Faslpr)F2 cross1-4 (Lmb1-4), respectively. Lmb1, -2, and -3 were also linked to the production of anti-dsDNA antibodies, but not glomerulonephritis, whereas Lmb4 was associated with glomerulonephritis. Lmb2, -3, and -4 were inherited from the MRL background, but interestingly, Lmb1 was derived from the C57BL16-Faslpr. Nevertheless, each locus, regardless of the strain of origin, appeared to act in an additive manner, although certain combinations were more effective. Only a single suggestive locus on chromosome 1 could be correlated with arthritis. The identification of loci with highly significant linkage to disease manifestations in Faslpr strains will make it possible to map and clone new genetic defects contributing to autoimmunity.     

Telithromycin treatment of chronic Chlamydia pneumoniae infection in C57BL/6J mice

Chronic Chlamydia pneumoniae infections have been associated with atherosclerosis, but clear knowledge about how these infections should be treated is lacking. We studied the effect of a new ketolide antibiotic, telithromycin, on chronic C. pneumoniae lung infection. Female C57BL/6J mice on a 0.2% cholesterol diet were inoculated intranasally with C. pneumoniae either two or three times every fourth week. Telithromycin was given to the mice subcutaneously at 75 mg/kg of body weight once daily for 5 or 10 days, starting at 3 days after the last inoculation. Samples were taken at 4 and 12 weeks after the last inoculation. The presence of C. pneumoniae DNA in lung tissue was demonstrated by PCR and the detection of lipid accumulation in the aortic sinus by Oil-Red-O staining. C. pneumoniae DNA positivity and inflammatory reactions in the lung tissue of the mice inoculated twice were significantly affected by treatment after both inoculations or only after the second inoculation at 12 weeks. Intimal lipid accumulation in the aortic sinus was also slightly but significantly less abundant in the mice treated after both inoculations compared to the levels in those treated only after the second inoculation for 10 days (geometric means, 823 and 4,324 microm(2), respectively; P = 0.033). No differences between the infected, untreated controls and the group inoculated three times and treated for 5 days were seen. We conclude that telithromycin is effective in preventing the development of chronic C. pneumoniae infection and intimal lipid accumulation in C56BL/6J mice when the treatment is given after each inoculation.     

Partial medial meniscectomy produces osteoarthritis pain-related behaviour in female C57BL/6 mice

Murine models of osteoarthritis (OA) provide a potentially powerful tool to elucidate mechanisms responsible for OA pain. However, few studies have examined pain behaviours in relevant OA models in mice. We have therefore characterized the time course and pharmacological sensitivities of pain-related behaviours in a model of OA in C57Bl/6 mice induced by partial medial meniscectomy. Progressive degenerative joint damage developed in a time-dependent manner and was first detected 4 weeks after surgery. Pain was assessed by monitoring weight bearing, mechanical hyperalgesia, cold allodynia, mechanical allodynia and vocalisation in response to knee compression for 12 weeks postsurgery. No significant weight-bearing deficits were observed during the course of the study. Significant mechanical allodynia was present in the ipsilateral hind limb from 9 weeks after surgery. Hind limb mechanical hyperalgesia and cold allodynia, and increased vocalisation in response to knee compression developed in the ipsilateral limb in 2 phases. An early phase of hypersensitivities lasted for up to 3 weeks and was reversed by treatment with a nonsteroidal anti-inflammatory drug (NSAID), diclofenac. Pain then resolved for several weeks, followed by a second phase of NSAID-insensitive pain after 7 weeks postsurgery. During this phase, all pain behaviours could be reversed by morphine. In contrast, other analgesic drugs (paracetamol, gabapentin, and tramadol) had selective effects on only 1 or 2 modalities. Pain levels fluctuated during the second phase, with transient periods of reduced pain. At these times, underlying hypersensitivities could be unmasked by administration of naloxone, indicating that reduced pain was due to endogenous opioids.     

不同浓度顺铂对C57BL/6小鼠卵巢功能的影响

目的:通过研究不同浓度顺铂对C57BL/6小鼠卵巢功能的影响,探讨能够引起C57BL/6小鼠卵巢早衰的最低有效浓度,从而为临床研究提供一种安全、可靠、便捷的早发性卵巢功能不全(POI)模型构建方案。方法:随机选择SPF级雌性C57BL/6小鼠(6~8周)60只,随机分为对照组、剂量1.0组(1 mg/kg)、剂量1.5组(1.5 mg/kg)、剂量2.0组(2 mg/kg),给药组均连续腹腔注射7 d顺铂。结果:1.0组小鼠卵巢受损较轻,卵巢组织形态、卵泡计数及血清激素水平与对照组相比,变化程度较小,无法用于建模;1.5组小鼠卵巢受损较重,体质量下降平稳,一般状态好,死亡率低,动情周期恢复率低,卵巢组织形态、卵泡计数及血清激素水平与对照组差异均有统计学意义(P<0.05),但变化较为平缓,适宜建立POI模型;2.0组小鼠卵巢受损严重,体质量下降明显,全身状况差,出现持续的动情间期,卵巢组织形态、卵泡计数及血清激素水平与对照组差异均有统计学意义(P<0.05),但变化大,不利于实验研究。结论:1.5 mg/kg为建立C57BL/6小鼠POI模型的合适有效浓度,采用该给药方案建立的模型,卵巢组织损伤较为稳定,能够较好地模拟POI患者的激素水平变化,动物耐受性好,有利于治疗研究的开展,适用于POI治疗方案的评价。     

Treatment of acute Chlamydia pneumoniae infection with telithromycin in C57BL/6J mice

OBJECTIVES: The efficacy of telithromycin, a new ketolide antibiotic, was investigated in the treatment of acute Chlamydia pneumoniae infection in a mouse model. METHODS: C57BL/6J mice were inoculated intranasally, and the effects of three different doses of telithromycin (25, 50 and 100 mg/kg) were assessed after 5 and 10 days of treatment. Lungs for culture, PCR, histopathology, and blood for serum samples were collected immediately after each treatment period and at 3 weeks post-inoculation. C. pneumoniae-specific antibodies were analysed, and the effect of treatment was assessed by culture, detection of C. pneumoniae DNA and determination of histopathological inflammatory changes in mouse lungs. RESULTS: Culture negativity in the lungs was achieved with the higher doses, 50 and 100 mg/kg, after 10 days of treatment. C. pneumoniae DNA was not totally eradicated with the treatments, but the groups treated with 50 and 100 mg/kg doses for 10 days had the lowest DNA positivity rates (10%) 3 weeks after the inoculation. In lung histopathology, the efficacy of telithromycin on inflammatory changes was also dose-dependent: higher doses were more effective in reducing the inflammatory reaction. Overall, the 25 mg/kg dose had a weaker effect compared with the others. CONCLUSIONS: Telithromycin had both time- and dose-dependent effects on the eradication of chlamydia and on reducing infection-induced inflammatory changes in mouse lungs.     

Effect of prior intragastric antigen administration on primary and secondary anti-ovalbumin responses of C57BL/6 and NZB mice

We evaluated the effect of antigen feeding on the subsequent primary and secondary anti-ovalbumin (OVA) responses of C57BL/6 and NZB mice. When C57BL/6 mice were given a single 20-mg dose of OVA intragastrically, profound tolerance was observed after challenge, 7 d later, with 125 micrograms of OVA in complete adjuvant or after two injections of 5 micrograms of OVA adsorbed to alum given 7 and 21 d after antigen feeding. OVA-fed NZB mice failed to become tolerant to a primary challenge with OVA in complete adjuvant, but showed a degree of tolerance similar to that of C57BL/6 mice when challenged two or three times with OVA in alum. These studies demonstrate that NZB mice fail to show tolerance at the level of the primary response after antigen feeding; however, they are normally tolerant when a secondary response to a lower dose of antigen is evaluated. This study suggests that, after antigen feeding, different mechanisms of tolerance may be involved in the regulation of primary and secondary responses.     

链脲佐菌素诱导C57BL/6小鼠糖尿病瘙痒模型的建立

[目的]探讨链脲佐菌素(streptozotocin , STZ)诱导C57BL/6小鼠糖尿病瘙痒模型的最佳剂量.[方法]24只雄性8周C57BL/6野生型小鼠,体重20～28 g,随机分为四组: A组(对照组)单次腹腔注射等剂量柠檬酸钠溶液 10 mL/kg,pH=4.5;B组STZ单次大剂量腹腔注射STZ 160 mg/kg;C组STZ腹腔注射40 mg/kg,连续注射5 d,每次给药时间间隔24 h;D组STZ两次中剂量注射,腹腔注射STZ 85 mg/kg+65 mg/kg,两次间隔时间24 h.从给药前4周开始,A组正常饮食,B、C、D组高脂饮食喂养至实验结束.注射STZ前1 d、注射STZ后1、2、3、4周测定动物的空腹血糖(FBG)、体重,采用录像记录30 min搔抓次数.[结果]与A组相比,B、C、D组造模后血糖升高并在不同时间点达到糖尿病标准(>200 mg/dL)(P<0.05),B组体重较A、C、D组下降(P<0.05),D组在STZ注射后第2、3周搔抓次数较A、B、C增多(P<0.05).[结论]腹腔分两次、间隔24 h注射STZ 85 mg/kg+65 mg/kg并配合高脂饮食是建立糖尿病并发瘙痒小鼠模型的合适方法.     

Differential expression of an equivalent clonotype among BALB/c and C57BL/6 mice

The primary anti-phosphorylcholine (PC) response in BALB/c, C57BL/6, and congenic and recombinant inbred strains of these parental types has been examined in the splenic focus system. The frequencies of PC-specific precursors were shown to vary among these strains from 2 to 20 precursors per 10(6) splenic B cells. The distribution of these frequencies suggests that elements closely linked to or within the major histocompatibility complex may play a role in the determination of this parameter, although additional experiments are necessary to adequately assess this possibility. Moreover, all strains tested, regardless of immunoglobulin allotype, expressed monoclonal antibodies indistinguishable from the TEPC 15 myeloma protein (T15) clonotype. Further, the frequency of this clonotype in a given strain did not appear related to allotype, since both high and low T15 frequencies were found among strains of either the BALB/c (a(1)) or C57BL/6 (a(2)) allotype. The examination of normal serum for the T15 idiotype, however, revealed that only mice of the BALB/c allotype (a(1)) expressed the T15 idiotype in detectable quantities. After immunization with Diplococcus pneumoniae, sera from mice of the a(1) allotype consistently contained large quantities of the T15 idiotype, whereas sera from mice of the a(2) allotype exhibited various degrees of cross-reactivity with anti-T15 antibody. These results suggest that: (a) the allotype of an individual, although closely related to serum levels of an idiotype, is unrelated to the proportion of the precursor population which expresses that idiotype and; (b) the serum expression of a given idiotype may reflect regulatory processes, which act either during or before antigenic stimulation, rather than the actual clonotype representation in the repertoire. These findings indicate that distinctions must be made between the expression of idiotypic determinants within precursor B-cell populations and elements which regulate the subsequent appearance of those idiotypes in serum antibodies.     

Attenuation of the alcohol preference of C57BL/6 mice during chronic renal failure

The C57BL/6 inbred mouse strain is known for its strong, genetically determined preference for alcohol over water. In this study we examined the voluntary alcohol consumption (VAC) of C57BL/6 mice during chronic renal failure (CRF). Two weeks after the surgical induction of renal failure, CRF mice, together with normal and sham-operated control mice, were submitted to a standard 24-day VAC protocol. The mice were offered water for the first 6 days (period of acclimatization), alcohol (10% ethanol solution) for the next 4 days (period of forced alcohol exposure), and a choice between water and alcohol for the last 14 days (VAC period). The results (mean +/- SEM) obtained from the last 8 days of the VAC period were significantly different (P <.05) between CRF mice and the 2 control groups. As expected, CRF mice had a higher total fluid intake than did normal and sham-operated controls (9.5 +/- 0.2 vs 5.4 +/- 0.2 and 5.4 +/- 0.2 g/d). Surprisingly, despite their increased total fluid consumption, CRF mice nearly abolished their absolute alcohol intake compared with that of both control groups (3.2 +/- 0.5 vs 13.1 +/- 0.8 and 14.2 +/- 1.1 g alcohol/kg body wt/d). The resulting alcohol preference ratio (g alcohol/g total fluid) was markedly decreased in the CRF mice compared with that in both control groups (0.09 +/- 0.01 vs 0.62 +/- 0.03 and 0.64 +/- 0.05). We conclude that the innate alcohol preference of C57BL/6 mice is nearly abolished during CRF. Additional studies to clarify the mechanism of this striking change in drinking pattern are required, with special emphasis on the possible role of angiotensin II, which is involved in thirst regulation and known to reduce the alcohol consumption of normal alcohol-preferring rats.     

长期小强度跑台运动对C57BL/6J小鼠突触可塑性的影响

目的:本研究观察长期小强度跑台运动对C57BL/6J小鼠突触可塑性的影响,探讨运动提高学习和记忆能力的细胞机制。方法:3月龄雌性C57BL/6J小鼠随机分为运动组(12只)和对照组(12只)。运动组小鼠进行5个月小强度跑台训练,运动训练结束后进行Morris水迷宫检测学习和记忆行为学改变,1周后采用电生理学方法在体记录海马齿状回(DG)的群体峰电位(PS)和场兴奋性突触后电位(f-EPSP)的变化。电生理学测试后制备小鼠脑石蜡切片,采用免疫组织化学方法检测海马DG区突触素(SYP)的蛋白表达情况,并取海马组织利用Western blot方法检测SYP的蛋白表达。结果:电生理学结果显示,高频刺激后运动组小鼠PS幅值和f-EPSP斜率百分数均高于对照组,差异具有显著性(P0.05);运动组小鼠海马组织突触素蛋白表达水平明显高于对照组,差异具有显著性(P0.05);运动组小鼠海马齿状回突触素阳性反应产物的整合光密度值明显高于对照组,差异具有显著性(P0.05)。结论:5个月小强度跑台运动可增强C57BL/6J小鼠的突触结构和功能可塑性。     

载脂蛋白E基因缺乏对C57BL/6小鼠狼疮早期抗体产生的影响

目的 用两种不同狼疮造模方法研究载脂蛋白E基因缺乏(apoE-/-)对C57BL/6(B6)小鼠系统性红斑狼疮发病早期抗体产生的影响.方法 将36只apoE-/- C57BL/6雌性小鼠分为降植烷对照组,降植烷模型组,脂多糖对照组,脂多糖模型组;同时将34只普通B6雌性小鼠亦分为降植烷对照组,降植烷模型组,脂多糖对照组,脂多糖模型组;降植烷对照组一次性腹腔注射生理盐水0.5 mL,降植烷模型组一次性腹腔注射降植烷0.5 mL,脂多糖对照组1周2次注射生理盐水,每次0.2 mL,脂多糖模型组1周2次注射脂多糖溶液0.2 mL,浓度为250 mg/L;3周后采血测定血清中抗核抗体(ANA)、抗dsDNA抗体、抗可溶性抗原(ENA)抗体水平,并比较各组间的差异.结果 ANA各模型组均较对照组升高,且apoE-/-的降植烷模型组较普通B6降植烷模型组升高;抗dsDNA抗体仅apoE-/-的降植烷模型组较对照组升高;抗ENA抗体apoE-/-的脂多糖模型组较对照组及普通B6脂多糖模型组升高.结论 在降植烷诱导的模型早期,apoE-/-可促进雌性B6小鼠ANA及抗dsDNA抗体的产生;在脂多糖诱导的模型早期,apoE-/-可促进雌性B6小鼠抗ENA抗体的产生.     

Effects of buprenorphine on a cecal ligation and puncture model in C57BL/6 mice

Sepsis research relies heavily on animal models. One of the most frequently used models, cecal ligation and puncture (CLP), involves surgery, and animal use committees may require the use of analgesics after CLP. However, some analgesics are immunomodulatory and may affect research outcomes. In addition, both septic inflammation and responses to opioids may vary with the sex of the subject. Therefore, we investigated the effects of buprenorphine in inbred mice of both sexes undergoing CLP. We hypothesized that buprenorphine would not significantly change the outcome or patterns of inflammation in C57BL/6 mice after CLP. Male and female C57BL/6 mice underwent CLP surgery and were randomized into 2 groups to receive either buprenorphine or saline. Three-week survival studies were performed (n = 20 per group). Survival did not differ between groups of female mice, but male mice that received buprenorphine had decreased survival compared with that of controls. Reducing the dose of buprenorphine in male mice ameliorated the difference in survival. To examine inflammation, mice (n = 10 per group) were euthanized at 12, 24, or 48 h after CLP. Cell counts and cytokines were measured in the blood and peritoneal lavage fluid. In female and male C57BL/6 mice, buprenorphine treatment resulted in few differences in inflammatory parameters, although peripheral neutrophil counts were decreased transiently in male mice. The findings suggest that the effects of buprenorphine on sepsis models in C57BL/6 mice may be sex-specific. Consequently the use of analgesics must be assessed on a study-by-study basis, and investigators should define analgesic regimens when publishing sepsis studies.