肾脏局部生物钟系统与水盐排泄昼夜节律的时相关系

Temporally Relationship between Renal Local Clock System and Circadian Rhythm of the Water Electrolyte Excretion

目的观察大鼠水盐排泄昼夜节律以及肾脏局部生物钟系统的钟基因及下游与水盐转运相关的钟控基因的昼夜节律表达的关系。方法饲养正常成年SD雄性大鼠,分别于授时时间(ZT)00∶00-ZT12∶00(开灯后,即日间)及ZT12∶00-24∶00(关灯后,即夜间)留取尿液,比较日夜间尿量及尿钠、尿钾、尿氯的排泄率,然后分别于ZT2∶00、6∶00、10∶00、14∶00、18∶00及22∶00处死大鼠并取肾脏组织,应用实时定量PCR方法检测6个钟基因CLOCK、BMAL1、Per1、Per2、Cry1和Cry2及6个钟控基因NHE3、αENa C、NCC、Ptges、V1aR和V2R的mRNA表达。应用部分傅里叶分析合并逐步回归的分析方法对基因表达进行节律分析。结果正常大鼠尿量及尿钾排泄率呈夜高日低的昼夜节律(P<0.05),而尿钠及尿氯排泄率也表现为夜间高于日间的趋势,但差异无统计学意义。与其同步的肾脏组织内6个钟基因CLOCK、BMAL1、Per1、Per2、Cry1、Cry2(P均<0.05)及6个钟控基因NHE3、αENa C、NCC、Ptges、V1aR、V2R(P均<0.05)均表现昼夜节律,其峰值均处于大鼠夜间活动期。结论大鼠水钠排泄节律与肾脏局部生物钟系统的钟基因及钟控基因表达的昼夜节律具有时相协同性。

Objective To investigate the relationship of the circadian rhythm of the urine volume and urine electrolytes excretion rate and the daily expression pattern of the clock genes and clock-controlled genes with the water electrolyte transportation circadian pattern in rat kidneys. Methods Male adult SD rats were exposed to in a light∶ dark（ 12∶ 12） cycles. We collected two period urine from zeitgeber time（ ZT） 00 ∶ 00-ZT12 ∶ 00（ light time,rest period） and ZT12∶ 00-24∶ 00（ dark time,activity period） and then compared the urinary excretion rates of volume,sodium,potassium,and chloride at light time with those at dark time. Rats were sacrificed every 4 hours throughout a 24-hour day-night cycle. Circadian clock gene CLOCK,BMAL1,Per1,Per2,Cry1,Cry2 and kidney specific clock-controlled gene NHE3,αENa C、NCC,Ptges,V1 aR,V2R expression were profiled by real-time quantitative polymerase chain reaction. Data were analysed by a partial Fourier analysis and a stepwise regression technique. Results Urine volume and urine potassium excretion rate displayed highlevel at dark time and low at light time in SD rats（ P〈0. 05）,and urine sodium and chloride excretion rate also showed the trend（ P〉0. 05）. Clock gene CLOCK,BMAL1,Per1,Per2,Cry1,Cry2（ P〈0. 05） and kidney specific clock-controlled gene NHE3,αENa C,NCC,Ptges,V1 aR,V2R（ P〈0. 05） mRNA expression showed circadian pattern,and the peak times of the genes were in the dark time. Conclusion Urine volume and urine electrolyte excretion rate which displayed circadian pattern were temporally coupled with the rhythm of expression of clock and clock-controlled genes associated with water electrolyte transportation in rats kidney.