High-fat diet-fed C57BL/6J mouse

小鼠经口灌胃葡萄糖负荷的耐受试验。禁食 4–6 小时；普通饮食按 1 g/kg、高脂饮食 4 周以上按 0.5 g/kg 给予 50% 葡萄糖溶液；负荷前及负荷后 15、30、60、90、120 分钟测定血糖。不同组别与样本量按具体研究设计确定，本方案不预设实验分组。

小鼠腹腔注射胰岛素后的血糖反应检测。禁食 4–6 小时；按 1–1.2 U/kg 给予胰岛素（源方案以 100 U/mL 原液经冷 PBS 两步稀释，注射体积按体重计算）；注射前及注射后 15、30、60、90、120 分钟测定血糖。不同组别与样本量按具体研究设计确定，本方案不预设实验分组。

基线与负荷后 15、30、60、90、120 分钟血糖时间序列；可计算血糖曲线下面积。血浆胰岛素结果按所用 ELISA 的校准与量程判读。

以血糖浓度对时间作图得到完整血糖-时间曲线，并可计算曲线下面积（AUC）反映葡萄糖清除程度；当各受试对象基线血糖不同时应比较高于基线的幅度或曲线下面积，而非仅比较单一终点值。该检测反映葡萄糖负荷后的整体清除，不等同于胰岛素作用的直接测量。

基线与注射后 15、30、60、90、120 分钟血糖时间序列；可计算血糖下降幅度或曲线下面积。结果反映外源胰岛素负荷后的整体血糖反应，不单独等同于组织特异性胰岛素敏感性。

获得可供光学显微镜观察的 H&E 染色组织切片：细胞核蓝紫色、细胞质与结缔组织纤维粉红色，用于观察组织中细胞的整体结构与形态细节。本方案本身不产出病理评分数值，也不提供特定分子标志物的定量结果。

禁食 Fasting begins first thing in the morning (around 9am). Fast mice for 4-6 hours before OGTT begins. Transfer mice to clean cage and wire top. Keep water bottles during the fasting period. 1. If using High Fat diet (HFD), save food to give back at the end of the OGTT. 1. mark tails with a sharpie for easier identification during OGTT. 口服葡萄糖负荷 Weigh mouse to obtain body weight for dose calculations. Calculate bolus dose of glucose (**1g/kg**). Weight of mouse (g) x 2 = ul sterile glucose (50% dextrose) solution *If using HFD for 4 weeks or more, use 0.5g/kg (weight of mouse (g) x 1 = ul sterile glucose (50% dextrose) solution) 口服葡萄糖负荷 Prepare syringes using 1cc syringe and 18G oral gavage needle. Load all syringes with calculated glucose dose and position in front of home cage. 口服葡萄糖负荷 Prior to the delivery of the sterile glucose (50% dextrose) solution, a time “zero” blood glucose level must be measured. Restrain mouse and clean tail with 70% ethanol/gauze. Extract a small amount of blood from the tail vein onto One Touch Ultra blood glucose strips used with the One Touch Ultra 2 blood glucose monitoring system. Blood can be collected into microvette tubes that can be used to extract plasma which can be assayed for plasma insulin (see step 9 for plasma collection). Microvette tubes are blood collection tubes with a capillary. Tap tube until all the blood is collected in the tube. Place on ice until plasma collection. 口服葡萄糖负荷 Administer the correct dose of sterile glucose (50% dextrose) solution using the syringe and gavage needle. - Restraint of the Mouse, avoiding an excessively tight grip of the mouse, as this will induce a panic response. Ensure that the mouse cannot bite you and cannot move its head. - Gravity alone should be used to move the cannula down the esophagus. While gliding the cannula, rotate slightly as the cannula goes past the epiglottis and into the esophagus.The mouse should swallow the cannula, and this can be observed. - Inject the fluid slowly. - The cannula is then gently removed and the animal is returned to its cage. 口服葡萄糖负荷 Begin timing from the point of successfully delivering the sterile glucose (50% dextrose) solution. 口服葡萄糖负荷 Test and record the blood glucose level (see step 4) at 15, 30, 60, 90 and 120 minutes after the initial glucose delivery. Record each value and the condition of the animal on the Glucose Tolerance Test record sheet. Extract a small amount of blood from the tail vein at 15, 30, 60 and 120 minutes for plasma; skip blood collection at 90 minutes to ensure not to exceed 0.007 ml blood/ g body weight. 口服葡萄糖负荷 Return food and environmental enrichments to cages. 血浆采集 Place tubes into pre-chilled centrifuge. Centrifguge for 2 mins at 2000 rpm. 00:02:00 4 °C 血浆采集 Remove the callipary-lid and dispose in biohazard bin. Place the base lid and seal the microvette (click position). 血浆采集 Centrifuge at 4°C for 10 mins at 10 000 rpm. 00:10:00 4 °C 血浆采集 Using a pipette, transfer the plasma (top transparent layer) to a clean and labelled tube. Store plasma samples at -20°C until assayed. 血浆胰岛素测定 Assay plasma insulin with the STELLUX Chemi Rodent Insulin ELISA kit (ALPCO #80-INSMR-CH01) according to the manufacturer's protocol. Include the kit standards and quality controls in each assay and read the plate by the kit's chemiluminescence procedure.

提前一周单笼饲养 实验前一周将小鼠改为单笼饲养。 称量体重 逐只称量小鼠体重，用于按体重计算给糖体积。 禁食6小时 禁食六小时（06:00:00）。 测定基线血糖 禁食结束后，先用血糖仪测定血糖作为基线。 腹腔注射葡萄糖 按2 g/kg体重腹腔注射葡萄糖：将2 g D-葡萄糖溶于10 ml生理盐水配成20%葡萄糖贮备液，按每克体重10 ul给予。 系列采血测定血糖 于注射葡萄糖后15、30、45、60、90和120分钟采集血样，用血糖仪测定血糖。

禁食 Fasting begins first thing in the morning (around 9am). Fast mice for 4-6 hours before ITT begins. Transfer mice to clean cage and wire top. Keep water bottles during the fasting period. 1. If using High Fat diet (HFD), save food to give back at the end of the ITT. 1. Mark tails with a sharpie for easier identification during ITT. 胰岛素溶液配制 Stock 1: 50ul of 100U/ml Humulin R into 4950ul of cold sterile 1X PBS. Invert solution 3-4 times to mix. Stock 2: 1ml of Stock 1 into 9ml of cold sterile 1X PBS. Invert solution 3-4 times to mix. Keep on ice until use 胰岛素负荷 Weigh mouse to obtain body weight for dose calculations. Calculate bolus dose of insulin (**1-1.2 units/kg**). Weight of mouse (g) x 10 = ul insulin stock 2 solution 胰岛素负荷 Prepare syringes using 1cc syringe and 26G needle. Load all syringes with calculated insulin dose and position in front of home cage. 胰岛素负荷 Prior to the delivery of the insulin solution, a time “zero” blood glucose level must be measured. Restrain mouse and clean tail with 70% ethanol/gauze. Extract a small amount of blood from the tail vein onto One Touch Ultra blood glucose strips used with the One Touch Ultra 2 blood glucose monitoring system. 胰岛素负荷 Administer the correct dose of Insulin solution using an IP (intraperitoneal) injection method. - Restrain the mouse. Then place the mouse is in dorsal recumbency with the head down allowing the viscera to move cranially. - Using the bend of the knee and the ventral abdominal midline as landmarks, the needle is inserted half way between the midline and lateral side of the animal at the natural bend of the knee. Insert the needle at a 30 to 45 degree angle into either the left or right lower abdominal quadrant. - Prior to injection, aspirate to make sure the needle has not penetrated a blood vessel, the intestines or the urinary bladder. When aspirating the syringe, you should see an air bubble in the hub of the needle, and not any form of fluid. - Inject and return mouse to cage. 胰岛素负荷 Begin timing from the point of successfully delivering the insulin solution. 胰岛素负荷 Test and record the blood glucose level at 15, 30, 60, 90, and 120 minutes after the insulin injection. Record each value and the condition of the animal on the Insulin Tolerance Test record sheet. 胰岛素负荷 Return food and environmental enrichments to cages.

脱蜡（Dewaxing） 石蜡切片置于二甲苯中脱蜡 3 次，每次 00:03:00。 复水（Rehydration） 石蜡切片依次置于 100% 乙醇中 3 次、每次 00:03:00，再置于 95% 乙醇中 1 次、00:03:00，随后用水漂洗。 苏木素核染色（Hematoxylin staining） 石蜡切片以苏木素染液染色 00:00:20，随后在流水下冲洗 00:01:00。 分化与返蓝（Differentiation and bluing） 石蜡切片置于返蓝液中 00:01:00，随后在流水下冲洗 00:01:00；此步使细胞核呈现蓝色。 伊红染色（Eosin staining） 石蜡切片以伊红复染 00:00:10；此步使细胞质成分与结缔组织纤维呈现粉红色。 脱水与透明（Dehydration and Clearing） 石蜡切片依次置于 95% 乙醇中 00:02:00、100% 乙醇中 2 次、每次 00:02:00，随后置于二甲苯中 2 次、每次 00:02:00。 封片（Mounting） 石蜡切片以 Permount 封片介质加盖玻片封固。