生理和病理状况对小鼠肝脏SDF2L1基因表达的影响

目的确定小鼠肝脏SDF2L1基因在不同生理和病理条件下的表达情况,并构建SDF2L表达质粒,为进一步研究SDF2L1基因的功能奠定基础。方法 Real-time PCR确定SDF2L1基因在糖尿病条件下(db/db和ob/ob小鼠分别为糖尿病和肥胖模型小鼠)或不同营养状态的表达情况;设计并合成SDF2L1基因的PCR引物,以野生型C57BL/6J小鼠肝脏c DNA为模板,扩增SDF2L1编码区,PCR产物测序正确后连接到pc DNA4/myc-His表达载体,鉴定插入片段序列正确后,将构建的质粒转染293A细胞,Western blot检测SDF2L1的表达。结果糖尿病条件下或饥饿状态下小鼠肝脏中SDF2L1基因表达明显下调(P0.01);纯化质粒的相对分子质量为5.8 kb,酶切鉴定结果符合目的条带(666 bp)大小,插入的寡核苷酸序列与野生型SDF2L1基因序列完全相符,表达的融合蛋白大小为26ku。结论 SDF2L1基因可能参与机体糖脂代谢;成功构建SDF2L表达质粒。     

硫化氢在ob/ob小鼠皮肤创面愈合中的作用与调控机制

目的:观察硫化氢(H2S)对ob/ob小鼠皮肤创面愈合的影响并探讨其作用机制。方法:将ob/ob小鼠随机分为生理盐水组、胰岛素组和NaHS(H2S供体)组,C57BL/6小鼠作为对照组,构建小鼠背部皮肤创面模型。干预后检测各组H2S释放量;用Western blot检测胱硫醚γ-裂解酶(CSE)及基质金属蛋白酶-9(MMP-9)蛋白的表达差异;用RT-qPCR检测CSE的mRNA表达变化;使用免疫组织化学法检测中性粒细胞及单核/巨噬细胞的浸润数量;使用ELISA检测肿瘤坏死因子(TNF)-α和白细胞介素(IL)-6的水平;用Masson染色检测胶原沉积情况。结果:ob/ob小鼠皮肤创面肉芽组织中H2S释放及CSE蛋白、mRNA的表达水平以及胶原沉积显著低于C57BL/6小鼠(P0.05)。外源性H2S可加速ob/ob小鼠皮肤创面愈合(P0.05),增加胶原沉积。ob/ob小鼠创面中性粒细胞及单核/巨噬细胞浸润数量,TNF-α、IL-6的水平及MMP-9蛋白表达水平显著增加(P0.05),NaHS组显著降低。结论:H2S可显著改善糖尿病难愈性溃疡的愈合,作用机制可能与其抗炎作用有关。     

DHEA对不同周龄C57BL/6J小鼠超排卵效果的影响

目的研究脱氢表雄酮(DHEA)对不同周龄C57BL/6J雌鼠超排卵效果和卵母细胞质量影响及其机制。方法 4周龄、5周龄、6周龄、7周龄的C57BL/6J雌鼠每周龄各24只,随机分为对照组、低剂量处理组(2mg/kg/d)和高剂量处理组(5mg/kg/d)。超排卵前用DHEA给予灌胃1周,进行体外受精,收集卵丘细胞和卵巢组织。提取7周龄C57BL/6J对照组以及实验组卵丘细胞mRNA进行qRT-PCR检测胚胎质量相关基因Has2、Ptgs2和Vcan的mRNA水平以及凋亡相关基因Caspase3和Bcl2l10的mRNA水平。提取7周龄C57BL/6J对照组以及实验组卵巢组织mRNA检测Gdf9、Bmp15h和Fshr的mRNA表达水平。结果经过DHEA处理的雌鼠超排卵后,4周龄、5周龄、6周龄、7周龄的C57BL/6J雌鼠体外受精(IVF)显示实验组异型卵比例下降,7周龄的C57BL/6J雌鼠受精率升高。7周龄C57BL/6J实验组卵丘细胞中与胚胎质量相关基因Has2,Ptsg2和Vcan转录水平与对照组相比上调,Caspase-3的mRNA水平下调,Bcl2l10mRNA水平上调。7周龄C57BL/6J卵巢组织中Gdf9和Bmp15mRNA水平上调。结论 DHEA处理7周龄C57BL/6J后经激素超排,通过抑制卵丘细胞凋亡,提高卵母细胞的质量,提高超排卵效果。     

2型糖尿病KKAy模型小鼠肾脏中TGF-β及其受体和细胞外基质蛋白表达的关系

探讨2型糖尿病动物模型KKAy小鼠肾脏细胞外基质蓄积的原因和TGF-β及其受体的关系.15只KKAy小鼠和18只C57BL/J小鼠,分成3组,分别于16、20和24周处死动物,常规测体重、肾功能、血脂和尿蛋白,取肾皮质常规切片、染色,观察肾脏病理改变.用免疫组化和免疫印迹法检测不同周龄的KKAy小鼠及参照组C57BL/J小鼠肾皮质TGF-β1及TGF-βⅠ、Ⅱ型受体的表达,并用RT-PCR方法检测肾皮质细胞外基质Ⅳ型胶原和纤维连接蛋白(fibronectin, FN)mRNA水平.KKAy小鼠16周龄以后便开始出现明显的肥胖、高血糖、高胰岛素血症和蛋白尿,符合2型糖尿病早期肾病特点.其FN和Ⅳ型胶原mRNA表达都比同龄参照组C57BL/J小鼠高2～4倍,其中以16周时最为显著, FN为1.53±0.46比较0.63±0.16(P＜0.001); Ⅳ型胶原为5.08±1.92比较1.21±0.25(P＜0.01).KKAy小鼠肾小球内TGF-β1及TGF-βⅠ型受体的水平明显低于C57BL/J小鼠,而Ⅱ型受体表达却高于C57BL/J小鼠.2型糖尿病KKAy小鼠早期肾病时,肾皮质细胞外基质合成增加,与TGF-βⅡ型受体表达增加有关.     

S6K1 shRNA基因重组腺病毒的构建及对基因沉默效果的研究

目的 构建S6K1 shRNA基因重组腺病毒(S6K1Ax)并在细胞及小鼠肝脏验证对S6K1基因的沉默效果.方法 设计3种S6K1 shRNA序列,通过在pcPUR质粒与pcDNA3.1质粒、cosmid质粒之间的拼接将S6K1 shRNA转染进腺病毒,筛选沉默效果最佳的S6K1Ax并在293细胞扩增纯化得到高效价的S6K1Ax.感染来源于小鼠的肝脏、肌肉、脂肪细胞系,在Western blot水平评价其对S6K1蛋白表达的抑制效果.将S6K1Ax注射进C57BL/6J小鼠尾静脉,6 d后处死小鼠取肝脏,逆转录-聚合酶链反应和Western blot观察小鼠肝脏S6K1在mRNA和蛋白水平的表达.检测注射S6K1Ax前后小鼠血清丙氨酸氨基转移酶(ALT)变化.结果 Western blot证实制备的S6K1 Ax可抑制来源于小鼠的肝脏、肌肉、脂肪3种细胞系和小鼠C57BL/6J肝脏S6K1的蛋白表达.小鼠肝脏S6K1 mRNA结果显示:对照组为1.39±0.21,实验组为0.63±0.09,t=6.132,P<0.01,差异有统计学意义.S6K1Ax注射小鼠,ALT水平注射前为(15.15±4.43)U/L,注射后为(17.32±4.22)U/L,t=1.451,P>0.05,差异没有统计学意义.结论 构建的S6K1Ax可将来源于小鼠的细胞系及C57BL/6J小鼠肝脏S6K1基因沉默,为研究S6K1的基因功能提供了适合的实验工具.     

γ射线对C57BL/6J和C3H/HeN小鼠肺成纤维细胞生物学行为影响的比较研究

目的比较C57BL/6J和C3H/HeN两种小鼠肺成纤维细胞以不同剂量的60Coγ射线照射后生物学行为的异同。方法原代分离培养C57BL/6J和C3H/HeN两种小鼠肺成纤维细胞(LF),应用2、4、6和8Gy的60Coγ射线照射后,通过MTT比色法、流式细胞术、AgNOR染色和免疫荧光细胞化学染色法,检测照射后两种LF的增殖活力、细胞周期以及a-平滑肌肌动蛋白(a-SMA)、基质金属蛋白酶-1(MMP-1)和金属蛋白酶组织抑制剂-1(TIMP-1)表达的变化。结果以2~8Gy照射后,C57BL/6J和C3H/HeN小鼠的LF增殖活力与正常对照组相比较未见明显增强。照射后,C57BL/6J小鼠的LF非整倍体增多,a-SMA高表达,MMP-1的表达呈弱阳性,TIMP-1的表达呈增强趋势。照射后,C3H/HeN小鼠的LF出现G2-M期阻滞,a-SMA的表达减弱至消失,MMP-1和TIMP-1的表达均呈增强趋势。结论以60Coγ射线照射后,C57BL/6J和C3H/HeN两种小鼠的LF生物学行为不同,C57BL/6J小鼠的LF呈“活化”状态,为该种小鼠易发生肺纤维化的细胞学基础提供了实验依据。     

三氧化二砷对MRL/lpr狼疮鼠IFN-γ基因表达的调控

目的: 探讨三氧化二砷(ATO)调控MRL/lpr狼疮鼠干扰素γ(IFN-γ)基因表达的机制。方法: 将20周龄MRL/lpr狼疮鼠和正常C57BL/6J小鼠无菌条件下取出脾脏,制成脾脏淋巴细胞悬液。体外经植物血球凝集素P(PHA-P,终浓度20 mg/L)和白细胞介素-2(IL-2,终浓度10⁶ IU/L)常规刺激48 h后,随机分为PBS组(空白对照)和 ATO(1.0 μmol/L)组,继续培养24 h。酶联免疫吸附法(ELISA)测定各组培养上清液IFN-γ的表达量,采用实时荧光定量PCR(Q-PCR)检测各组IFN-γ mRNA的表达情况,应用基于半定量PCR和Q-PCR的染色质免疫共沉淀(ChIP)技术检测各组细胞 IFN-γ 启动子区乙酰化组蛋白H3、H4(acH3, acH4)及启动子区结合RNA聚合酶Ⅱ(RNAPⅡ)的水平。结果: (1)MRL/lpr狼疮鼠PBS组IFN-γ的分泌和IFN-γ mRNA的表达均高于C57BL/6J小鼠PBS组(分别P<0.01和 P<0.05),并且 IFN-γ 启动子区acH3、acH4的水平及启动子区域富集RNAPⅡ水平高于C57BL/6J小鼠PBS组(均P<0.01)。(2)在MRL/lpr狼疮鼠中,与PBS组相比,ATO组IFN-γ的分泌和IFN-γ mRNA的表达下降(分别P<0.01, P<0.05),IFN-γ基因启动子区域acH3、acH4的水平及启动子区域富集RNAPⅡ水平也下降(均P<0.01)。(3)在C57BL/6J小鼠中,PBS组和ATO组之间以上指标均无差异。结论: ATO下调MRL/lpr狼疮鼠IFN-γ的分泌和IFN-γ mRNA的表达可能是通过降低基因启动子区域acH3、acH4的水平减弱了RNAPⅡ依赖的转录,而ATO对正常C57BL/6J小鼠无明显影响。     

β淀粉样蛋白及代谢酶类在阿尔茨海默病和糖尿病模型小鼠脑内的表达

目的观察阿尔茨海默病(AD)和糖尿病模型小鼠脑内β淀粉样蛋白(Aβ)及代谢相关酶类的表达情况,以便从分子水平找到糖尿病并发AD的实验室依据。方法 5月龄双转基因痴呆症模型小鼠(APP/PS1双转基因小鼠)、ob/ob T2DM肥胖模型小鼠和野生型C57BL/6J小鼠为对照,分别用免疫组化染色、ELISA和Western blot检测脑内老年斑(SP)、Aβ含量及Aβ代谢酶类的表达情况。结果 APP/PS1小鼠大脑皮质及海马均可见一定数量的SP;ob/ob小鼠大脑皮质内偶可见SP,而对照组未见SP。与对照小鼠相比,APP/PS1与ob/ob小鼠脑内Aβ40、Aβ42的含量明显升高(P0.05);但APP/PS1小鼠脑内Aβ水平显著高于ob/ob小鼠(P0.05)。APP在APP/PS1小鼠脑内的表达显著高于其他两组小鼠;在ob/ob小鼠脑内的表达要强于对照小鼠(P0.05)。Aβ生成的关键酶BACE1在APP/PS1与ob/ob小鼠脑内的表达显著高于对照小鼠(P0.05),但其在APP/PS1小鼠脑内的表达要强于ob/ob小鼠(P0.05)。Aβ降解的关键酶IDE在APP/PS1与ob/ob小鼠脑内的表达显著低于对照小鼠(P0.05),且在ob/ob小鼠脑内表达最低。结论 Aβ生成与降解的异常以及其异常聚集沉积不仅发生在早期AD脑内,同时也发生在T2DM脑内,提示Aβ过表达可能是促进2型糖尿病并发AD的重要原因之一。     

FIZZ1在ApoE基因敲除小鼠动脉粥样硬化斑块内的表达

目的:探讨FIZZ1在ApoE基因敲除小鼠粥样斑块内的表达。方法:C57BL/6JApoE基因敲除鼠及C57BL/6J野生型小鼠各9只,分别喂食高脂饲料及普通饲料,24周后处死,自主动脉根部至腹主动脉离断整支血管,石蜡包埋后作连续切片,行HE染色及FIZZ1免疫组化,检测血管斑块内FIZZ1表达情况,RT-PCR检测斑块内FIZZ1mRNA表达。结果:ApoE基因敲除鼠高脂饲养24周后,主动脉根部动脉粥样硬化明显,斑块体积较大,免疫组化及其RT-PCR可见FIZZ1及其mRNA在粥样硬化斑块内明显表达,同龄野生型C57BL/6J鼠血管壁内未见FIZZ1及其mRNA表达。结论:FIZZ1能在动脉粥样硬化斑块内表达。     

胰腺衍生因子（PANDER）在糖尿病小鼠胰腺中的表达变化

 目的 探讨PANDER蛋白在1型和2型糖尿病小鼠胰岛中的表达变化及其与胰岛素抵抗和高血糖的相关性。方法 以STZ诱导和自发性Akita 1型糖尿病小鼠及2型糖尿病db/db小鼠为动物模型,用实时定量PCR,免疫组化和Western Blot的方法检测胰腺中PANDER mRNA和蛋白指标。结果 相较于正常C57BL/6小鼠,STZ诱导和Akita 1型糖尿病小鼠胰腺组织中PANDER mRNA（STZ：1.00±0.17 vs. 0.25±0.06,P<0.01;Akita：1.00±0.19 vs.0.17±0.04,P<0.001）和蛋白（免疫组化灰度扫描STZ：1.00±0.18 vs. 0.16±0.11）水平均明显降低;相较于db/m小鼠,db/db小鼠胰腺组织中PANDER mRNA（1.00±0.05 vs. 2.13±0.46,P<0.05）和蛋白（1.00±0.28 vs. 3.58±0.36,P<0.01）水平均明显升高;罗格列酮灌胃db/db小鼠一个月后,胰岛肥大、胰岛素抵抗及高血糖症状得以缓解,同时胰腺中PANDER mRNA（1.00±0.13 vs. 0.28±0.06,P<0.01）和蛋白水平明显降低。结论 1型糖尿病小鼠胰腺组织中PANDER表达显著减少;2型糖尿病小鼠胰腺组织中PANDER明显升高。     

高脂高糖食诱导的糖尿病小鼠肝脏清道夫受体B1的表达

目的：探讨糖尿病小鼠肝脏SR-B1表达变化，及其与血脂的关系。 方法： 进正常食C57BL/6J小鼠10只、进高脂高糖食8周小鼠5只、进高脂高糖食16周小鼠10只，测定血脂、血清胰岛素（INS）、空腹血糖（FBG），及肝脏SR-B1蛋白表达。 结果： ① 高脂高糖食16周的小鼠血清甘油三酯（TC）、FBG明显高于正常小鼠（P＜0.05)，其胰岛素水平与正常小鼠无显著差异（P＞0.05）。② 高脂高糖食小鼠肝脏SB-B1表达高于正常动物，16周强于8周的小鼠。 结论： 糖尿病小鼠肝脏SR-B1表达高于正常小鼠，血清HDL-C降低可能与肝脏的SR-B1蛋白表达增高有关。     

Mice bearing the ob/ob mutation have impaired immunity.

The obese mutant mouse C57BL/6J ob/ob showed impaired ability to reject skin grafts or react to a contact-sensitising agent in comparison with littermate controls (either +/ob or +/+). Ability of spleen cells from mice bearing the ob/ob mutation to produce a graft-versus-host reaction in C57BL/6J X DBA/2J F1 hybrid mice was not impaired.     

高糖应激促脂肪变性肝细胞凋亡的线粒体机制

目的:探讨高糖应激对脂肪变性肝细胞凋亡的作用及其可能机制。方法:C57BL/6J小鼠饲喂高脂饲料6周后,采用肝脏原位灌注技术分离得到脂肪变性原代肝细胞,在含有35 mmol/L葡萄糖的高糖DMEM培养基中孵育12 h,以正常DMEM培养基(添加30 mmol/L甘露醇)孵育的细胞作为对照,观察高糖处理对脂肪变性肝细胞活力、线粒体膜电位、凋亡蛋白酶caspase活性及凋亡相关信号通路的影响。结果:高糖应激使脂肪变性肝细胞活力下降,凋亡显著增加,而等渗甘露醇处理的对照细胞没有明显变化。高糖组细胞出现较为严重的线粒体去极化,导致线粒体膜电位降低,细胞色素C释放增多。线粒体介导凋亡关键酶caspase-9和caspase-3活性在高糖组有显著升高,抑制凋亡因子Bcl-2和Bcl-x L表达量明显降低,促凋亡蛋白Bax水平显著升高,而感受外源性凋亡信号的caspase-8的活性没有明显变化。结论:高糖应激会导致脂肪变性肝细胞线粒体膜电位下降,启动线粒体介导的内源性凋亡途径,引起肝细胞凋亡。这可能是高血糖加速非酒精性脂肪性肝病病程进展的一个重要原因。     

Cytochemical analysis of pancreatic islet hypercytolipidemia following diabetes (db/db) and obese (ob/ob) mutation expression: influence of genomic background.

Both diabetes (db/db) and obese (ob/ob) genotype mutations induce a hyperglycemic-hyperinsulinemic endometabolic state in C57BL mice, manifesting a type II NIDDM diabetes-obesity syndrome (DOS) in these leptin ligand/receptor-deficient models. The severity of the DOS induced by these single gene, homozygous-recessive mutations may be moderated by the background genome on which the mutation is expressed. The current studies define the phenotypic, systemic, cytochemical and cellular metabolic responses to db/db and ob/ob mutation expression when modified by /KsJ (severe DOS expression) or /6 (modified DOS expression) background strain influences as compared to littermate control (+/?) indices. Both db/db and ob/ob mutations induced dramatic increases in body weights, blood glucose and serum insulin concentrations relative to +/? indices when expressed on either the C57BL/KsJ (-/KsJ) or C57BL/6 (-/6) backgrounds. However, the -/KsJ background enhanced the severity of expression of these DOS indices relative to the -/6 strain. Similarly, the -/KsJ genome suppressed cellular glucose uptake rates, pancreatic tissue weights and insulin concentrations in both db/db and ob/ob mutants relative to /6 background strain influences or +/? indices. Concurrent enhancement of tissue and cellular lipogenic metabolism and islet cytolipid depositions were exaggerated when the mutations were expressed on the -/KsJ background relative to the -/6 genome. Pancreatic islet B-cell lipodeposition was markedly enhanced in ob/ob and db/db mutants expressed on either the -/KsJ or -/6 background. In both ob/ob and db/db models, B-cell insulin granulation was prominent in mildly hypertrophic pancreatic islets when the mutations were expressed on the -/6 background. In contrast, the severity of the DOS state expressed on the -/KsJ background resulted in pronounced B-cell atrophy, characterized by insulin degranulation, cellular hypertrophy and hypercytolipidemia associated with tissue involution, in both ob/ob and db/db mutants. Dramatic alterations in tissue norephinephrine (NE) and alpha-1-receptor populations in ob/ob and db/db mutants were exaggerated by the -/KsJ genome as compared to -/6 or control indices. The influences of the -/KsJ genome on the progressive expression of tissue NE counter-regulatory responses to enhanced cytolipidemic indices were inversely related, with cytochemical lipodeposition occurring under conditions of diminished adrenergic responses to the DOS indices. The results of these studies indicate that the severity of the type-II diabetes endometabolic syndrome induced by the ob/ob or db/db genotypic mutations is modified by the existing genome on which the mutations are expressed. These data suggest that the severity of genomic mutation expression may be modified depending on the capability of the background genome to counter-regulate the systemic, cellular or metabolic consequences of these mutations.     

Classically conditioned enhancement of hyperinsulinemia in the ob/ob mouse

The obese (C57BL/6J ob/ob) mouse is a commonly used animal model of non-insulin-dependent diabetes mellitus. Recent experiments have shown that stress hyperglycemia can be classically conditioned in the obese but not in the lean mouse. In the present study, classical conditioning of insulin secretion was attempted in C57BL/6J obese and lean animals. For 21 days, obese and lean mice were exposed to a conditioned olfactory stimulus prior to and during eating. On the 22nd day, blood was sampled for all animals following presentation of the conditioned stimulus; testing was repeated 2 weeks later following an additional 4 days of conditioning. Results indicated an effect of conditioning, with significantly greater plasma insulin for trained than for untrained obese mice. That insulin secretion can be more easily conditioned in the obese mouse suggests that a cholinergic mechanism may be involved in the hyperinsulinemia characteristic of this animal.     

Effects of intermittent feeding upon body weight and lifespan in inbred mice: interaction of genotype and age

Beginning at either 1.5, 6 or 10 months of age, male mice from the A/J and C57BL/6J strains and their F1 hybrid, B6AF1/J were fed a diet (4.2 kcal/g) either ad libitum every day or in a restricted fashion by ad libitum feeding every other day. Relative to estimates for ad libitum controls, the body weights of the intermittently-fed restricted C57BL/6J and hybrid mice were reduced and mean and maximum life span were incremented when the every-other-day regimen was initiated at 1.5 or 6 months of age. When every-other-day feeding was introduced at 10 months of age, again both these genotypes lost body weight relative to controls; however, mean life span was not significantly affected although maximum life span was increased. Among A/J mice, intermittent feeding did not reduce body weight relative to ad libitum controls when introduced at 1.5 or 10 months of age; however, this treatment did increase mean and maximum life span when begun at 1.5 months, while it decreased mean and maximum life span when begun at 10 months. When restricted feeding was introduced to this genotype at 6 months of age, body weight reduction compared to control values was apparent at some ages, but the treatment had no significant effects on mean or maximum life span. These results illustrate that the effects of particular regimens of dietary restriction on body weight and life span are greatly dependent upon the genotype and age of initiation. Moreover, when examining the relationship of body weight to life span both between and within the various groups, it was clear that the complexity of this relationship made it difficult to predict that lower body weight would induce life span increment.     

T cells with a quiescent phenotype (CD45RA+) are overabundant in the blood and involuted lymphoid tissues in wasting protein and energy deficiencies

The objective of this investigation was to determine the influence of distinct forms of acute weight loss on the expression of the quiescence marker, CD45RA, by T cells in several lymphoid compartments including the blood. Male and female weanling mice, CBA/J and C57BL/6J strains, were allocated to the following groups: ad libitum intake of a complete purified diet; restricted intake of the complete diet; and ad libitum intake of an isocaloric low-protein diet. The restricted intake protocol produced weight loss through energy deficiency (marasmic-type malnutrition), whereas the low-protein diet caused wasting through inadequate protein nitrogen and induced a condition mimicking incipient kwashiorkor. In one experiment, weanling mice of both strains were maintained for 14 days according to each of these dietary protocols and, in a supplementary study, C57BL/6J weanlings consumed either the complete diet or the low-protein diet ad libitum for 21 days. Zero-time control groups (19-days old and 23-days old in C57BL/6J and CBA/J strains, respectively) were included in the first experiment to control for ontogeny-related change. Expression of CD45RA was assessed by two-colour flow cytometry in CD4+ and CD8+ T cells from the spleen, mesenteric lymph nodes and blood. Within 14 days, energy-restricted mice exhibited a high percentage of CD4+ T cells expressing CD45RA in all three lymphoid compartments in both mouse strains (an average of 50% CD45RA+ versus 9% in well-nourished controls), and a similar outcome was apparent in the CD8+ subset (93% CD45RA+ versus 63%). Mice fed the low-protein diet required up to 21 days to exhibit the same imbalance within the CD4+ T-cell subset (33% CD45RA+ versus 4% in well-nourished controls). A shift toward a quiescent phenotype occurs throughout the peripheral T-cell system in acute wasting disease. Consequently, the quiescence-activation phenotype of blood T cells reflects the same index in secondary lymphoid organs in such pathologies. Naive-type quiescence among T cells is implicated as a component of depressed adaptive immunocompetence in the advanced stages of diverse forms of acute weight loss.     

Difference in glucose intolerance between C57BL/6J and ICR strain mice with streptozotocin/nicotinamide-induced diabetes

Blood glucose and plasma insulin levels between C57BL/6J and ICR strain mice with nicotinamide (NA) and streptozotocin (STZ)-induced diabetes were compared to establish a suitable strain of the experimental diabetic mouse model. The mice were intraperitoneally treated twice with STZ (100 mg/kg) 15 min after injection of NA (120 mg/kg) at a 1-day interval, and non-fasting blood glucose level was then weekly monitored for 5 weeks. The blood glucose level in ICR mice gradually increased and was about 2-times higher than that in C57BL/6J mice at the end of the observation. The plasma insulin level in ICR mice was comparatively low, compared with that in C57BL/6J mice. ICR mice were also markedly glucose-intolerant when oral glucose tolerance test was performed. These results indicate that ICR strain is more sensitive than C57BL/6J strain as a mouse model with NA/STZ-induced mild diabetes.     

Naltrexone potentiates glycemic responses during stress and epinephrine challenge in genetically obese mice

The genetically obese mouse (C57BL/6J ob/ob) is a commonly used animal model of non-insulin-dependent diabetes mellitus. These mice show exaggerated glycemic responses during behavioral stress and adrenergic stimulation, but the precise glucoregulatory mechanisms are not well characterized. The ob/ob mice have multiple endocrine abnormalities, including elevated pituitary and circulating beta-endorphin levels; and a relationship between hyperglycemia and altered opioid function has been suspected. We now report that opiate antagonism with naltrexone potentiates hyperglycemic responses during stress and epinephrine challenge in obese mice. This effect of opioid blockade suggests that endogenous opioids inhibit stress- and epinephrine-induced hyperglycemia in the genetically obese mouse.     

Humoral immune response in hereditary and overt diabetes mellitus

The inbred diabetic mutant mouse, C57BL/KsJ db +/db + (db +/db +), spontaneously develops diabetes mellitus when allowed food ad libitum. However, restriction of food intake prevents the expression of this genetic predisposition for diabetes. This experimental design has been used previously to demonstrate a deficient neutralizing antibody response to coxsackievirus B4 (CB4) in mutants with the genetic predisposition only. These observations demonstrate that in the genetically predisposed diabetic mutant, deficient humoral immunity extends further to a general impairment in both total IgM and IgG production after CB4 infection. Furthermore, these mice are unable to produce a virus-specific IgG response but do show a high level of nonspecific antibody suggesting a polyclonal activation following CB4 challenge. In addition, we observed an increase in the number of spleen IgM antibody-forming cells to sheep erythrocytes (SRBC) in the overtly diabetic animal following CB4 infection with little change apparent in the genetically predisposed animal after infection. These results were identical to the changes seen in total spleen cell numbers. Our animal model provides an opportunity to distinguish between the genetic predisposition to diabetes and the overt disease and suggests that some of the immune impairment found prior to diabetes onset may be partially diminished afterwards.