Expression profiling of the effect of high-fat diet, low-fat diet, CR and exercise on mice liver

Dietary interventions are effective ways to extend or shorten lifespan. By examining midlife hepatic gene expressions in mice under different dietary conditions, which resulted in different lifespans and aging-related phenotypes, we were able to identify genes and pathways that modulate the aging process. We found that pathways transcriptionally correlated with diet-modulated lifespan and physiological changes were enriched for lifespan-modifying genes. Male C57BL/6J mice at 4 weeks of age were purchased from Shanghai Animal Co, Ltd. Mice were maintained under a 12-hour dark/light cycle (lights on at 6:30 am) at a temperature of 22 ± 3 °C in accredited animal facilities. Prior to the start of experiment, mice were maintained on a low-fat diet (Research Diets Inc., New Brunswick, NJ) for one week. At the age of 5 weeks, animals were randomly assigned to one of the 6 intervention groups (n = 30 for each group): feeding of a low-fat diet (10% fat, D12450B, Research Diets) ad libitum (LF) or with 30% calorie restriction (LF+CR) or with voluntary running exercise (LF+Ex), feeding of a high-fat diet (60% fat, D12492, Research Diets) ad libitum (HF) or with 30% calorie restriction (HF+CR) or with voluntary running exercise (HF+Ex). All mice were housed individually during the study. The daily consumption of food in LF and HF groups was recorded over a week and averaged to determine the amount of food for the following week for the LF+CR and HF+CR groups, respectively. After 1 week acclimation in cage with the locked running wheels, mice in the LF+Ex and HF+Ex groups were allowed free access to a running wheel, and the running distance and time were recorded automatically by the equipment. The hepatic transcriptional level for 3 mice from each intervention group at 62 weeks of age was analyzed using Affymetrix Mouse Genome 430 2.0 Arrays.

饮食干预是调控寿命长短的有效手段。本研究通过分析不同饮食干预条件下中年小鼠的肝脏基因表达谱——这些干预手段可带来不同的寿命时长及衰老相关表型，得以筛选出可调控衰老进程的基因与信号通路。研究发现，与饮食调控的寿命及生理变化存在转录相关性的信号通路，显著富集了寿命调控相关基因。本研究使用的4周龄雄性C57BL/6J小鼠购自Shanghai Animal Co, Ltd.。所有小鼠于资质认证的动物实验设施中饲养，环境条件为：12小时明暗循环（早6:30开灯），饲养温度22±3℃。实验开始前，小鼠先以低脂饲料（Research Diets Inc., 新泽西州新不伦瑞克市）适应饲养1周。小鼠5周龄时被随机分为6组干预组（每组n=30）：① 自由采食低脂饲料（脂肪供能比10%，货号D12450B，Research Diets）（LF组）；② 低脂饲料配合30%热量限制（LF+CR组）；③ 低脂饲料配合自愿跑轮运动（LF+Ex组）；④ 自由采食高脂饲料（脂肪供能比60%，货号D12492，Research Diets）（HF组）；⑤ 高脂饲料配合30%热量限制（HF+CR组）；⑥ 高脂饲料配合自愿跑轮运动（HF+Ex组）。实验全程所有小鼠均单笼饲养。LF组与HF组的每日摄食量连续记录一周并取平均值，以此分别确定LF+CR组与HF+CR组后续一周的饲喂量。LF+Ex与HF+Ex组小鼠先在安装了锁定跑轮的笼中适应1周后，方可自由使用跑轮，其运动距离与时长由设备自动记录。实验结束时（小鼠62周龄），从每个干预组中选取3只小鼠，利用Affymetrix Mouse Genome 430 2.0 基因芯片分析其肝脏组织的转录水平。