限制性摄食对小鼠血中β羟丁酸水平及大脑皮质脂蛋白脂酶表达的影响

Effect of restricted feeding on serum beta-hydroxybutyrate level and lipoprotein lipase expression in cerebral cortex in mice

目的探讨限制性摄食对小鼠血中β羟丁酸(beta-hydroxybutyrate,βOHB)水平及大脑皮质脂蛋白脂酶(lipoprotein lipase,LPL)表达的影响。方法 50只健康成年C57BL/6J小鼠按体重随机分为5组,每组10只,分别于禁食0、8、12、16 h和24 h后采血,采用ELISA法测定βOHB的水平。另取20只小鼠按体重随机分为禁食组和对照组,每组10只,禁食组小鼠采用隔日禁食的方式连续处理4周,对照组小鼠自由摄食,实验末期称重并分析体脂比(体脂肪含量占体重的百分比),再分别采用Real-time RT-PCR法和Western bolt法检测大脑皮质LPL mRNA及其蛋白表达水平。结果小鼠血中βOHB水平随着禁食时间的延长而逐渐升高,禁食0、8、12、16和24 h后的小鼠血中βOHB水平(mmol/L)分别为(0.93±0.13)、(0.95±0.37)、(1.33±0.26)、(1.68±0.13)、(1.74±0.27);与禁食0 h比较,禁食12、16及24 h的小鼠血中βOHB水平均明显升高(P<0.05);禁食16 h和24 h的小鼠血中βOHB水平差异无统计学意义(P>0.05),但二者均明显高于禁食12 h的小鼠血中βOHB水平(P<0.05)。在整个实验期间隔日禁食组及对照组小鼠均未见异常表现,两组小鼠体重及体脂肪含量差异无统计学意义(P>0.05)。隔日禁食组小鼠大脑皮质LPL mRNA水平及蛋白表达均高于对照组(P<0.01;P<0.05)。结论禁食12～24 h的小鼠血中βOHB水平明显升高;隔日禁食处理4周可上调小鼠大脑皮质LPL mRNA及其蛋白表达水平。

Objective To explore the effect of restricted feeding on the serum beta-hydroxybutyrate βOHB level and lipoprotein lipase （ LPL） expression in cerebral cortex in mice. Methods Based on their body weight, 50 healthy adult C57BL/6J mice were randomly divided into 5 groups （ each n= 10） , and blood was respectively collected at 0, 8, 12, 16 and 24 h after fasting for detection of serum βOHB by ELISA. Additionally, the other 20 mice were randomly divided into 2 groups（ each n = 10）, the fasting group and control group. The mice in the fasting group received alternate-day fasting diet for 4 consecutive weeks, while those in the control group were fed ad libitum. The body weight and the percentage of body fat were measured at the end of the experiment. Moreover, the expression of LPL mRNA and protein in the cerebral cortex of mice were detected by real-time RT-PCR and Western blot respectively. Results The serum βOHB level in mice was gradually increased with the extension of fasting time, with （0.93±0.13） nmol/L, （0.95 ±0.37） nmol/L, （1.33 ±0.26） nmol/L, （1.68±0.13） nmol/L and （1.74 ±0.27） nmol/L at 0, 8, 12, 16 and 24 h after fasting respectively. Compared with the serum βOHB level at 0 h, the βOHB levels at 12, 16 and 24 h after fasting were significantly increased （ all P〈0.05 ）. No significant difference was found between the serum βOHB levels at 16 and 24 h after fasting （P〉0.05 ）, but both were remarkably higher than that at 12 h （P〈0.05）. During the experiment, no abnormal manifestations were found in the mice of the alternate-day fasting group and the control group; moreover, their body weight and percentage of body fat showed no statistieally significant differenee （ P〉0.05）. Compared with the control group,the expression of LPL mRNA and protein in the cerebral cortex of the mice in the alternate-day fasting group was remarkably upregulated（P〈0.01 ; P〈0.05）. Conclusions The serum βOHB level in mice is significantly increased during 12-24 h after fasting, and alternate-day fasting for 4 weeks can up-regulate the expression of LPL mRNA and protein in the cerebral cortex of mice.