适量饮用贵州某食用白酒对Ⅰ型糖尿病小鼠胰岛β细胞的影响

目的:探讨摄入贵州某食用白酒对Ⅰ型糖尿病小鼠胰岛β细胞可能的影响及相关机制。方法:正常雄性C57BL/6J小鼠通过灌胃饮酒及注射链脲佐菌素建立单纯饮酒、糖尿病、糖尿病饮酒模型,测空腹血糖,通过免疫组织化学、real-time PCR、图像分析及形态计量法观察胰岛β细胞分泌胰岛素及胰岛素mRNA表达的改变。结果:糖尿病组及糖尿病饮酒组小鼠空腹血糖升高,达到小鼠糖尿病成模标准。单纯饮酒组小鼠血糖、β细胞平均光密度、面数密度、胰岛素mRNA相对表达量无明显变化。糖尿病组及糖尿病饮酒组β细胞平均光密度值短暂升高,面数密度与胰岛素mRNA相对表达量逐渐降低。结论:在本实验设定的时程和剂量内,单纯饮用该白酒对胰岛β细胞无明显影响。适量饮用该白酒并未加重Ⅰ型糖尿病小鼠胰岛β细胞的损伤。     

1型糖尿病小鼠体内树突状细胞亚群变化的初步研究北大核心CSCD

目的探讨1型糖尿病（type 1 diabetes mellitus, T1DM）发病过程中外周免疫器官DC亚群的改变。方法以尾静脉注射链脲佐菌素（streptozotocin,STZ）的方式制备糖尿病小鼠模型。在STZ处理后的不同时间,检测小鼠体重变化和血糖水平;制备脾脏和淋巴结单细胞,通过流式细胞术检测DC亚群、中性粒细胞、单核细胞、CD4＋Foxp3＋调节性T细胞（regulatory T cells, Treg）的比例。结果STZ处理可导致小鼠体重减轻、血糖升高。在STZ处理后10 d,T1DM小鼠脾脏和淋巴结中DC各亚群、中性粒细胞和单核细胞的比例均未发生显著改变;STZ处理后30 d和60 d,T1DM小鼠脾脏体积明显减少,DC各亚群的比例较正常小鼠降低,中性粒细胞和单核细胞的比例则上调;而在淋巴结中,DC各亚群、中性粒细胞和单核细胞的比例较正常对照均显著下调。同时,与正常对照相比,淋巴结中的CD4＋Foxp3＋Treg比例明显上调,但在脾脏中无明显变化。结论在STZ诱导的小鼠糖尿病模型中,DC亚群及其他炎症细胞在脾脏和淋巴结中发生明显改变,反映了T细胞的变化,提示DC亚群在T1DM发病中起重要作用。     

4-苯基丁酸抗内质网应激诱导胰岛β细胞凋亡

目的 探讨4-苯基丁酸（4-PBA）对2型糖尿病（T2DM）大鼠胰岛β细胞内质网应激（ERS）诱导的细胞凋亡的保护作用。方法 高脂饮食喂养加小剂量链脲佐菌素（STZ）腹腔注射建立SD大鼠T2DM模型,造模成功后取其中10只给予4-PBA灌胃20d。放射免疫法检测各组大鼠游离脂肪酸（FFA）、血糖及胰岛素的变化。醛品红染色观察胰岛形态改变,RT-PCR检测内质网相关蛋白（Caspase-3、GRP78、CHOP）的mRNA表达变化。结果 高脂对照组（EM> n/EM>＝10）和T2DM组（ EM>n/EM>＝8）大鼠血清FFA比正常对照组（EM>n/EM>＝10）显著增加,4-PBA治疗后显著下降（ EM>n/EM>＝8）。4-PBA治疗升高了T2DM造成的     

链脲佐菌素诱导小鼠B细胞可抑制MIN-6细胞分泌胰岛素并促进胰岛素自身抗体的产生

目的探讨链脲佐菌素(STZ)诱导小鼠后B淋巴细胞对自身免疫性糖尿病发展的作用。方法以低剂量STZ诱导ICR小鼠,建立小鼠自身免疫性糖尿病模型,采用放射免疫法和ELISA分别检测胰岛素和胰岛素自身抗体,判断模型的诱导情况;以CD19磁珠分选STZ诱导的小鼠以及正常小鼠外周血B淋巴细胞,通过流式细胞术检测磁珠分选情况;以PBS处理的MIN-6细胞为空白对照组(A组),以正常小鼠B细胞和MIN-6细胞共培养为B组,以经20μg/m L脂多糖(LPS)预处理的正常小鼠B细胞和MIN-6细胞共培养为C组,以STZ诱导小鼠后的B细胞与MIN-6细胞共培养为D组,通过SYBRGreen染料实时荧光定量PCR(qRT-PCR)、放射免疫法分别检测处理后的胰岛素mRNA及其蛋白表达情况,并通过ELISA检测胰岛素自身抗体水平以及转化生长因子β(TGF-β)水平。结果与A组相比,STZ诱导组小鼠体质量减少、血糖升高、血清中胰岛素含量降低、胰岛素自身抗体升高;通过免疫磁珠分选,以流式细胞仪检测的结果显示,CD19+B细胞所占比例达到98%;与A组及B相比,C组和D组中MIN-6细胞胰岛素mRNA水平以及共培养上清中胰岛素水平均降低,并且胰岛素自身抗体和TGF-β的表达均增加。结论 STZ诱导的自身免疫性糖尿病小鼠模型的B淋巴细胞可能通过增加胰岛素自身抗体的产生来抑制胰岛MIN-6细胞产生胰岛素。     

胰岛表面涂抹诱导性多能干细胞对小鼠1型糖尿病的治疗作用

<正>本研究旨在探讨在胰腺表面涂抹正常或缺氧预处理的诱导性多能干细胞(iP SC)对1型糖尿病(T1DM)小鼠的治疗作用。腹腔注射链脲佐菌素(STZ)建立小鼠1型糖尿病模型。将8周龄C57雄性正常小鼠随机分为5组:PBS组、iP SC组、STZ(链脲佐菌素注射造模)组、STZ+iP SC组和STZ+hpc-iP SC(STZ注射造模后给予缺氧预处理iP SC)组,每组10只。细胞在涂抹于胰     

黄芪和山药配伍治疗MLD-STZ诱导糖尿病小鼠的实验研究

目的探讨黄芪、山药配伍对小剂量多次链脲佐菌素（MLD—STZ）诱导糖尿病小鼠的治疗作用及相应机制。方法以低剂量链脲佐菌素多次腹腔注射,建立糖尿病小鼠模型,将制备好模型小鼠分为山药组（1．4g·kg^-1·d^-1）、黄芪组（2．8g·kg^-1·d^-1）、配伍组（山药加黄芪4．2g·kg^-1·d^-1）及模型组（等量蒸馏水进行灌胃）,同时设立正常对照组,每周测定小鼠空腹血糖及体质量,4周后处死小鼠。形态学方法观察胰岛病理结构变化,TUNEL检测胰岛细胞凋亡,化学比色法测定血清中超氧化物歧化酶（SOD）、一氧化氮（NO）的含量;MTF测定脾细胞对刀豆蛋白A（ConA）的增殖反应,以酶联免疫吸附法（ELISA）检测脾细胞白细胞介素-4（IL-4）和γ-干扰素（IFN-γ）的分泌。结果与模型组比较,各药物处理组对血糖的升高均有显著的抑制作用,对体质量的降低也有改善作用。胰岛病理结构显示各药物处理组均能改善胰岛病理损伤,对胰岛细胞凋亡有保护作用,其中配伍组效果明显。各药物处理组对NO均有明显的抑制作用;山药组、配伍组明显上调SOD表达;黄芪组、配伍组脾细胞对ConA的增殖能力明显减弱,同时Th1／Th2分泌因子比值下调。结论黄芪、山药配伍能有效防治糖尿病,其机制是通过抗氧化及免疫调节共同发挥作用。     

实时FQ-PCR检测链脲佐菌素诱导糖尿病小鼠模型胰腺survivin基因的表达

目的：研究链脲佐菌素（STZ）诱导的糖尿病小鼠胰腺survivin基因mRNA表达，了解其在胰岛损伤中的作用。 方法： 小剂量多次注射STZ的方法建立糖尿病小鼠模型，每周测定体重及血糖，并采用实时荧光PCR方法检测胰腺survivin基因mRNA表达水平。 结果： 正常BALB/c小鼠胰腺有survivin基因表达。STZ组体重在4周内无明显改变；血糖在第1周即明显升高；survivin表达水平在3、4周显著升高。对照组体重持续增加，血糖及survivin表达水平各周间无显著差异。 结论： 正常小鼠胰腺有survivin基因表达，STZ注射后survivin表达水平显著升高，可能与胰岛恢复有关。     

亨廷顿蛋白相关蛋白1基因沉默对小鼠胰岛β细胞系NIT细胞凋亡的影响

目的探讨沉默亨廷顿蛋白相关蛋白1(HAP1)基因表达对小鼠胰岛β细胞株-NIT细胞凋亡的影响。方法化学合成针对小鼠HAP1基因的siRNA,转染NIT细胞,观察干扰效果;通过膜联蛋白V/碘化丙啶(AnnexinⅤ/PI)染色和原位末端核苷酸标记法(TUNEL),检测沉默HAP1表达后NIT细胞的凋亡;通过AnnexinⅤ/PI染色检测沉默HAP1表达后,链脲佐菌素(STZ)所诱导的NIT细胞凋亡。结果靶向HAP1的siRNA能有效抑制NIT细胞HAP1的表达;HAP1 siRNA实验组,NIT细胞凋亡数增多,凋亡率显著高于空白对照组(P0.01);STZ可明显诱导NIT细胞的凋亡,沉默HAP1的表达能增加STZ所诱导的NIT细胞凋亡。结论沉默HAP1的表达可以增加小鼠胰岛β细胞株NIT细胞的凋亡,同时也能促进凋亡诱导剂(STZ)所诱导的胰岛NIT细胞的凋亡。     

替米沙坦通过抑制胰岛内质网应激减少STZ致长期高脂喂养大鼠糖尿病的发生

目的:研究肾素血管紧张素Ⅱ受体阻断剂替米沙坦对长期高脂喂养大鼠链脲佐菌素(STZ)致糖尿病的发病率和胰岛β细胞功能的影响及其作用机制。方法:以高脂高热量饮食饲养Wistar大鼠,16周后以替米沙坦干预,24周后1次性给予小剂量STZ,注射STZ1周后行静脉胰岛素释放实验检测胰岛β细胞功能;采用反转录-聚合酶链反应及免疫组化法检测胰岛内质网应激因子及胰岛素的表达。结果:与高脂+STZ组相比,高脂+替米沙坦+STZ组大鼠糖尿病发病率明显下降,胰岛素最大分泌量增加了56.9%,早期胰岛素分泌指数(EISI)及急性胰岛素分泌反应(AIR)升高了1.98倍和0.88倍,β细胞内胰岛素表达量及胰岛素阳性表达细胞密度明显增加,胰岛β细胞内质网应激凋亡相关分子免疫球蛋白结合蛋白、C/EBP同源蛋白基因表达及Bax蛋白表达均显著下降。结论:肾素血管紧张素系统(RAS)阻断可以增强长期高脂喂养大鼠对STZ性糖尿病的抵抗性,减少β细胞内质网应激介导的凋亡因子的表达。减弱胰岛内质网应激可能是RAS阻断而改善β细胞功能、减少糖尿病发生的重要机制之一。     

完全脾切除增加了小鼠胰岛对STZ的敏感性

目的: 探讨脾脏对链脲菌素(STZ)损伤胰岛β细胞是否具有保护作用。方法: 以外科手术切除小鼠全脾。60只脾切除小鼠随机分为3组,分别以80 mg/kg、160 mg/kg STZ给小鼠腹腔注射,另一组腹腔注射生理盐水。60只正常小鼠做同样分组及处理。1周后,测定各组小鼠空腹血糖、血清胰岛素水平,免疫组化分析各组胰岛β细胞总量,ELISA法分析胰岛细胞凋亡,Luminol化学发光法测定各组胰腺活性氧簇(ROS)水平。结果: 80 mg/kg STZ处理脾切除组空腹血糖浓度显著升高,血清胰岛素显著降低;同剂量STZ处理的正常小鼠血糖及胰岛素水平则正常;此外, 80 mg/kg STZ处理的脾切除小鼠β细胞总量、胰岛凋亡细胞核小体聚集值及胰腺组织ROS的产生与同剂量STZ处理的正常小鼠相比均有显著差异。结论: 脾可以阻止低剂量STZ对正常小鼠胰岛β细胞的破坏作用。完全脾切除增加了胰岛对STZ的敏感性,这一作用与胰腺组织ROS增加相关。     

吡咯烷二硫代氨基甲酸酯减轻2型糖尿病大鼠胰岛β细胞氧化损伤

 目的 探讨吡咯烷二硫代氨基甲酸酯（PDTC）对2型糖尿病大鼠胰岛β细胞氧化损伤的影响及其机制。方法 用长期高脂饮食加小剂量链脲佐菌素（STZ,27mg/kg体重）建立2型糖尿病大鼠模型。PDTC治疗组大鼠每天腹腔注射PDTC（50mg/kg）1次,1周后取血浆检测血糖。取胰腺组织匀浆测定丙二醛（MDA）、超氧化物歧化酶（SOD）及谷胱甘肽过氧化物酶（GSH-PX）的含量;应用免疫组化和Western blot等检测胰腺组织中诱生型一氧化氮合酶（iNOS）的表达及硝基化酪氨酸（NT）的水平;流式细胞术检测胰岛β细胞凋亡百分率。结果 糖尿病大鼠血糖、MDA水平均显著高于对照组（P﹤0.01）;SOD和GSH-PX水平明显低于对照组（P﹤0.01）;胰岛组织中iNOS表达水平（0.37±0.06）和NT生成量（0.24±0.01）均较对照组（0.11±0.01）和（0.12±0.01）明显增多（P<0.01）。PDTC治疗后血糖明显降低,MDA明显减少（P＜0.01）;而SOD、GSH-PX水平明显升高（P＜0.05,P＜0.01）;胰岛组织中iNOS表达及NT生成均明显减少（P＜0.01）;胰岛β细胞凋亡率明显降低（P＜0.05）。结论 PDTC可以降低血糖,减轻大鼠体内氧化应激反应,减少糖尿病大鼠胰岛β细胞的凋亡。     

R6/2型亨廷顿病转基因小鼠胰岛β细胞功能损伤

目的：研究R6/2型亨廷顿病(HD) 转基因小鼠胰岛β细胞的功能,揭示HD转基因小鼠继发糖尿病的机制。方法：利用R6/2 型HD转基因小鼠模型,检测正常和HD小鼠空腹血糖以及血清胰岛素水平;并应用HE染色和免疫荧光技术分析正常和HD小鼠胰岛形态学差异。结果：与正常小鼠相比,R6/2 型HD小鼠空腹血糖显著增高,血清胰岛素水平明显降低,胰岛萎缩,β细胞数量减少,细胞功能指数降低,而胰岛素抵抗指数正常。结论：胰岛β细胞功能损伤是引起R6/2 HD转基因小鼠继发糖尿病发生的主要因素。     

脐带间充质干细胞源外泌小体减轻糖尿病模型小鼠心肌纤维化

目的:探讨脐带间充质干细胞外泌小体对糖尿病模型小鼠心肌纤维化的保护作用。方法:6~8周C57BL/6雄性小鼠随机分为3组:对照组、糖尿病模型组和糖尿病+外泌小体组。采用高脂饮食连续喂养5周后,联合小剂量多次(45 mg/kg,每周1次,连续5周)腹腔注射链脲佐菌素的方法诱导糖尿病(血糖≥16.7 mmol/L)模型。糖尿病+外泌小体组在糖尿病造模后,经尾静脉每周注射1次外泌小体,连续注射4周;对照组和糖尿病组予等体积的生理盐水连续注射4周。利用小动物彩色多普勒超声诊断仪检测小鼠心功能指标;然后取腹主动脉血,用生化比色法检测葡萄糖和游离脂肪酸的含量;同时取心脏组织,HE染色观察心肌纤维的结构变化;Masson染色观察心肌纤维化水平。结果:超声心动图结果显示,与对照组相比,糖尿病组较对照组的左心室舒张末期内径和左心室收缩末期内径增大(分别P0.05和P0.01),射血分数和室壁缩短率下降(P0.01);糖尿病+外泌小体组较糖尿病组的左心室收缩末期内径减小,心室扩张减小,射血分数和室壁缩短率提高(P0.01)。生化比色法检测血糖及血浆游离脂肪酸结果显示,与对照组相比,糖尿病组血糖及血浆游离脂肪酸水平显著增高,差异有统计学意义(P0.01);糖尿病+外泌小体组可显著降低血糖及游离脂肪酸水平,差异有统计学意义(P0.01)。HE染色结果显示,对照组心肌细胞完整,排列整齐;糖尿病组心肌细胞出现肥大、断裂;糖尿病+外泌小体组心肌细胞较完整,排列较整齐。Masson染色结果显示,与对照组相比,糖尿病组纤维化面积显著增大,差异有统计学意义(P0.01);与糖尿病组比较,糖尿病+外泌小体组纤维化面积减小,差异有统计学意义(P0.01)。结论:局部注射人脐带间充质干细胞外泌小体可以减轻糖尿病小鼠心肌纤维化,并改善心脏功能。     

Insulin downregulates the expression of the Ca2+-activated nonselective cation channel TRPM5 in pancreatic islets from leptin-deficient mouse models

We recently proposed that the transient receptor potential melastatin 5 (TRPM5) cation channel contributes to glucose-induced electrical activity of the β cell and positively influences glucose-induced insulin release and glucose homeostasis. In this study, we investigated Trpm5 expression and function in pancreatic islets from mouse models of type II diabetes. Gene expression analysis revealed a strong reduction of Trpm5 mRNA levels in pancreatic islets of db/db and ob/ob mice. The glucose-induced Ca²⁺ oscillation pattern in db/db and ob/ob islets mimicked those of Trpm5 ^?/? islets. Leptin treatment of ob/ob mice not only reversed the diabetic phenotype seen in these mice but also upregulated Trpm5 expression. Leptin treatment had no additional effect on Trpm5 expression levels when plasma insulin levels were comparable to those of the vehicle-injected control group. In murine β cell line, MIN6, insulin downregulated TRPM5 expression in a dose-dependent manner, unlike glucose or leptin. In conclusion, our data show that increased plasma insulin levels downregulate TRPM5 expression in pancreatic islets from leptin-deficient mouse models of type 2 diabetes.     

CCR7 directs the recruitment of T cells into inflamed pancreatic islets of nonobese diabetic (NOD) mice

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease characterized by the destruction of insulin-producing β cells in the pancreatic islets. The migration of T cells from blood vessels into pancreas is critical for the development of islet inflammation and β cell destruction in T1D. To define the roles of C–C chemokine receptor type 7 (CCR7) in recruitment of T cells into islets, we used laser capture microdissection to isolate tissue from inflamed islets of nonobese diabetic (NOD) mice and uninflamed islets of BALB/c and young NOD mice. RT–PCR analyses detected mRNAs for CCR7 and its chemokine ligands CCL19 (ELC; MIP-3β) and CCL21 (SLC) in captures from inflamed, but not from uninflamed, islets. Immunohistology studies revealed that high endothelial venules in inflamed islets co-express CCL21 protein and MAdCAM-1 (an adhesion molecule that recruits lymphocytes into islets). Desensitization of lymphocyte CCR7 blocked about 75 % of T cell migration from the bloodstream into inflamed islets, but had no effect on B cell migration into islets. These results indicate that CCR7 and its ligands are important in the recruitment of T cells into inflamed islets and thus in the pathogenesis of T1D.     

GGPPS‐mediated Rab27A geranylgeranylation regulates β cell dysfunction during type 2 diabetes development by affecting insulin granule docked pool formation

Loss of first‐phase insulin secretion associated with β cell dysfunction is an independent predictor of type 2 diabetes mellitus (T2DM) onset. Here we found that a critical enzyme involved in protein prenylation, geranylgeranyl pyrophosphate synthase (GGPPS), is required to maintain first‐phase insulin secretion. GGPPS shows a biphasic expression pattern in islets of db/db mice during the progression of T2DM: GGPPS is increased during the insulin compensatory period, followed by a decrease during β cell dysfunction. Ggpps deletion in β cells results in typical T2DM β cell dysfunction, with blunted glucose‐stimulated insulin secretion and consequent insulin secretion insufficiency. However, the number and size of islets and insulin biosynthesis are unaltered. Transmission electron microscopy shows a reduced number of insulin granules adjacent to the cellular membrane, suggesting a defect in docked granule pool formation, while the reserve pool is unaffected. Ggpps ablation depletes GGPP and impairs Rab27A geranylgeranylation, which is responsible for the docked pool deficiency in Ggpps‐null mice. Moreover, GGPPS re‐expression or GGPP administration restore glucose‐stimulated insulin secretion in Ggpps‐null islets. These results suggest that GGPPS‐controlled protein geranylgeranylation, which regulates formation of the insulin granule docked pool, is critical for β cell function and insulin release during the development of T2DM. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Macrophage migration inhibitory factor deficiency protects pancreatic islets from cytokine-induced apoptosis in vitro

During pathogenesis of diabetes, pancreatic islets are exposed to high levels of cytokines and other inflammatory mediators that induce deterioration of insulin-producing beta cells. Macrophage migration inhibitory factor (MIF) plays a key role in the onset and development of several immunoinflammatory diseases and also controls apoptotic cell death. Because the occurrence of apoptosis plays a pathogenetic role in beta cell death during type 1 diabetes development and MIF is expressed in beta cells, we explored the influence of MIF deficiency on cytokine-induced apoptosis in pancreatic islets. The results indicated clearly that elevated MIF secretion preceded C57BL/6 pancreatic islets death induced by interferon (IFN)-γ + tumour necrosis factor (TNF)-α + interleukin (IL)-1β. Consequently, MIF-deficient [MIF-knock-out (KO)] pancreatic islets or islet cells showed significant resistance to cytokine-induced death than those isolated from C57BL/6 mice. Furthermore, upon exposure to cytokines pancreatic islets from MIF-KO mice maintained normal insulin expression and produced less cyclooxygenase-2 (COX-2) than those from wild-type C57BL6 mice. The final outcome of cytokine-induced islet apoptosis in islets from wild-type mice was the activation of mitochondrial membrane pore-forming protein Bcl-2-associated X protein and effector caspase 3. In contrast, these apoptotic mediators remained at normal levels in islets from MIF-KO mice suggesting that MIF absence prevented initiation of the mitochondrial apoptotic pathway. Additionally, the protection from apoptosis was also mediated by up-regulation of prosurvival kinase extracellular-regulated kinase 1/2 in MIF-KO islets. These data indicate that MIF is involved in the propagation of pancreatic islets apoptosis probably via nuclear factor-κB and mitochondria-related proteins.     

黄芪多糖对链唑脲霉素诱导的2型糖尿病大鼠肾脏TGF-β_1表达的影响

目的:探讨黄芪多糖(APS)对链唑脲霉素(STZ)诱导的2型糖尿病(T2DM)大鼠早期肾脏病理改变的治疗作用及其机制。方法:雄性SPF级SD大鼠随机分为正常对照组(C组)、APS对照组(CA组)、T2DM组(DM组)及APS治疗组(DA组),每组8只。观察治疗前后各组大鼠血糖、葡萄糖耐量变化,肾脏组织形态学和转化生长因子β1(TGF-β1)表达等的变化。结果:DM组大鼠血糖显著高于C组,同时伴有明显的糖耐量异常(P<0.01),经APS治疗8周后,DA组血糖降低,糖耐量改善(P<0.01)。DM组大鼠的肾小球面积较正常大鼠大、系膜基质增加,肾小管管腔扩大,管壁变薄,肾小球基底膜(GBM)增厚,可见蛋白管型,APS治疗可减轻T2DM大鼠肾脏病理改变,降低TGF-β1的表达水平。结论:APS能够降低血糖,增强机体胰岛素敏感性,减轻DM肾脏病理损害。其机制与APS降低T2DM大鼠肾脏TGF-β1表达有关。     

The effect of lesions of the sympathoadrenal system on training induced adaptations in adipocytes and pancreatic islets in rats

Physical training increases insulin stimulated glucose uptake in adipocytes and decreases insulin secretion from pancreatic islets. The mechanism behind these adaptations is not known. Because in acute exercise adrenergic activity influences both adipocytes and pancreatic islets, the sympathetic nervous system was examined as the possible mediator. Rats were either adrenodemedullated or sham adrenodemedullated and underwent either unilateral abdominal sympathectomy or were sham sympathectomized. Resting plasma adrenaline concentration in adrenodemedullated rats was 32% of the concentration in sham adrenodemedullated rats (P<0.0001) and muscle noradrenaline content in sympathectomized leg was 9% of content in sham sympathectomized leg (P<0.0001). After operations rats were either swim trained for 10 weeks or remained sedentary. Insulin stimulated 3-O-[¹⁴C]methylglucose transport was measured in adipocytes from epididymal fat pads, and insulin secretion and glucose metabolism were measured in glucose stimulated pancreatic islets. Training increased insulin stimulated glucose transport in adipocytes (P<0.0001) and decreased their size (P<0.0001), but neither adrenodemedullation nor sympathetic denervation affected these parameters significantly. Training decreased insulin secretion (P<0.01) and increased glucose oxidation (P=0.02) and utilization (P=0.08) in pancreatic islets, but none of these parameters was affected significantly by adrenodemedullation. It is concluded that adrenergic activity is not important for the training induced decrease in size and increase in insulin stimulated glucose transport of adipocytes. Neither is an intact adrenal medulla necessary for training-induced adaptations in pancreatic beta cell function. Finally, in response to training, β cell insulin secretion and glucose metabolism changed in opposite directions.     

Reduction in insulitis following administration of IFN-gamma and TNF-alpha in the NOD mouse

In insulin dependent diabetes mellitis (IDDM) beta cell destruction is associated with infiltration of the pancreatic islets by T lymphocytes and macrophages. Cytokine products from the infiltrating immunocytes not only have powerful immunoregulatory actions but also are capable of impairing islet cell functions and have thus been postulated to assume a central role in mediating anti-beta cell immunity and beta cell destruction. In an effort to explore further the role of cytokines in the pathogenesis of IDDM, we examined clinical, metabolic and pathological features of NOD/Wehi mice injected intraperitoneally with multiple doses of IFN-gamma and/or TNF-alpha. Blood glucose profiles were not significantly altered by injection of cytokines alone or in combination. Except for a hypoglycaemic rebound in mice injected with TNF-alpha, arginine stimulation tests revealed no disturbances in islet secretory function in cytokine injected mice. Compared with vehicle and cytokines alone, injection of IFN-gamma + TNF-alpha was associated with a variety of clinical and pathological changes including abdominal distention, piloerection, ascites, oedema, thymic atrophy, splenic enlargement and pancreatic distention. Histological examination of the pancreas in these mice revealed moderate to severe pancreatitis which included focal haemorrhagic necrosis, oedema and polymorphonuclear and mononuclear cell infiltration. The islets in these mice appeared normal morphologically and when stained for insulin. The injection of IFN-gamma + TNF-alpha, and to a lesser extent TNF-alpha alone, was associated with a significant reduction in the severity of insulitis. Examination of pancreatic MHC-class I and class II molecule expression revealed in mice given IFN-gamma + TNF-alpha, as compared with controls, significant and uniform induction of both these molecules on ductal and acinar cells; low level MHC-class II expression was also detectable on beta cells in these mice. MHC-class I molecules which were expressed at high levels by beta cells in control mice did not appear to change following administration of the cytokines alone or in combination. We conclude that despite their immunostimulatory actions in vitro and in other models in vivo, systemic administration of the cytokines IFN-gamma and/or TNF-alpha to NOD/Wehi mice does not activate or enhance, and may actually suppress, anti-beta cell immunity in this model.