high-fat diet plus low-dose streptozotocin-induced type 2 diabetes 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耐量试验。禁食 4–6 小时；按 1–1.2 U/kg 给予胰岛素；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。

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。

基线与负荷后 15、30、60、90、120 分钟血糖时间序列；可计算血糖下降百分比或曲线下面积。

340 nm吸光度变化对应的葡萄糖浓度。

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。

Fasting 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. OGTT 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) GTT- template spreadsheet.xlsx OGTT Prepare syringes using 1cc syringe and 18G oral gavage needle. Load all syringes with calculated glucose dose and position in front of home cage. OGTT 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. OGTT 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. OGTT Begin timing from the point of successfully delivering the sterile glucose (50% dextrose) solution. OGTT Test and record the blood glucose level (see step 4) at times 15, 30, 60, 90, and 120 minutes after the initial glucose delivery. Record each value on Glucose Tolerance Test record sheet (template found on Step 2). Record condition of animal throughout and after procedure on the Glucose Tolerance Test record sheet. Extract a small amount of blood from the tail veil at 15, 30, 60 and 120 minutes as well as testing the blood glucose level. *skip blood collection at 90 minutes to ensure not to exceed 0.007 ml blood/ g body weight. OGTT Return food and environmental enrichments to cages. Plasma collection Place tubes into pre-chilled centrifuge. Centrifguge for 2 mins at 2000 rpm. 00:02:00 4 °C Plasma collection Remove the callipary-lid and dispose in biohazard bin. Place the base lid and seal the microvette (click position). Plasma collection Centrifuge at 4°C for 10 mins at 10 000 rpm. 00:10:00 4 °C Plasma collection Using a pipette, transfer the plasma (top transparent layer) to a clean and labelled tube. Store plasma samples at -20°C until assayed. Plasma collection Assay for insulin plasma on a STELLUX Chemi Rodent Insulin ELISA kit by ALPCO. See protocol at:

Fasting 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. Insulin Solution prep 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 ITT 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 ITT - template spreadsheet.xlsx ITT Prepare syringes using 1cc syringe and 26G needle. Load all syringes with calculated insulin dose and position in front of home cage. ITT 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. ITT 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. ITT Begin timing from the point of successfully delivering the insulin solution. ITT Test and record the blood glucose level (see step 5) at times 15, 30, 60, 90, and 120 minutes after the initial glucose delivery. Record each value on Insulin Tolerance Test record sheet (template found on step 2). Record condition of animal throughout and after procedure on the Insulin Tolerance Test recored sheet. ITT Return food and environmental enrichments to cages.

Calibrate Cobas for Glucose analysis by running a multi analyte standard and two control serum. Calibrate Cobas for Glucose analysis by running a multi analyte standard and two control serum. Sample Handling as performed by the Cobas Mira Plus. Sample Handling as performed by the Cobas Mira Plus. a) Pipette 3 µL of sample into cuvette. b) Absorbance is measured at 340 nm. c) Add 100 µL of Glucose liquid reagent. d) Mixture is incubated at 37ºC for 10 minutes. e) Absorbance is measured at 340 nm. Change in absorbance is calculated.

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。