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。

FFPE 肾组织切片的 PAS 染色流程，按源方案 FFPE 分支执行脱蜡、复水、氧化、Schiff 显色、苏木素复染、脱水透明和封片。具体切片厚度、视野与定量方法按研究设计确定。

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。

肾小球基底膜、系膜基质和糖蛋白呈 PAS 阳性（品红/紫红色），细胞核呈蓝色；按研究设计进行肾小球系膜扩张或病变范围判读。

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.

Start with FFPE here: Allow PAS “kit” to come to room temperature on the bench. Start with FFPE here: For paraffin sections, deparaffinize in xylene, two changes, 00:03:00 each. Start with FFPE here: Hydrate through graded alcohols, 00:01:00 each: 100%, 100%, 95%, 70%, water Start with FFPE here: Rinse well in distilled water by holding finger over slides, pouring water into sink and adding water. Do this 5 times. Start Frozen samples here: Place in 0.5% Periodic acid for 00:10:00 (to oxidize). Start Frozen samples here: Rinse well in distilled water (follow Step 4). Start Frozen samples here: Pour Schiff’s reagent into Coplin jar containing slides. Allow to sit 15-30 minutes at room temperature (kidney samples ~30 minutes). Start Frozen samples here: Rinse in running warm (~40 °C) distilled or tap water (follow Step 4). The tissue should appear pink after rinsing with warm water. Start Frozen samples here: Place slides in movable gray slide holder. Start Frozen samples here: Counterstain in Hematoxylin (staining line) for 00:01:00. Start Frozen samples here: Rinse well in distilled water, starting with blue container next to hematoxylin (follow Step 4). Start Frozen samples here: Quickly dip slides into “Bluing” agent (0.5% ammonium hydroxide). Start Frozen samples here: Rinse 1 minute in distilled water until pink color is visible (follow Step 4). Start Frozen samples here: Dehydrate through graded alcohols, 10 short dips in each: 95%, 95%, 100%, 100% If the last 100% ethanol rinse is colored by residual stain, additional washing in new 100% ethanol solution should be performed. Start Frozen samples here: Fix in 2 rounds of xylenes, 00:01:00 each (in the hood). Start Frozen samples here: Coverslip slides: - Place coverslip on paper towel - Add 2-3 drops of cytoseal to edge (depending on size) - Dip slide into xylenes, take out and roll the xylene lengthwise on slide - Line up slide and cover slip and slowly place the slide on the coverslip - If needed, use dissecting tool to remove bubbles Start Frozen samples here: Image slides using a Leica brightfield scanner, AxioScan Z1 slide scanner (or equivalent) at 20x (~1 µm spatial resolution) and save as.tiff or.jpg file.