Mechanisms of Circadian Blood Pressure and Activity Rhythms

昼夜血压和活动节律的机制

• 批准号: 8148786
• 负责人: Jurgen Schnermann
• 金额: $ 35.37万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8148786
• 关键词: Affect; Age; Animals; Autonomic nervous system; Baroreflex; Behavior; Biological Clocks; Blood Pressure; Circadian Rhythms; Cues; Defect; Diabetes Mellitus; Diabetic Nephropathy; Diastolic blood pressure; Diet; Disease; Eating; Employee Strikes; Excretory function; Failure; Feeding Patterns; Food; Genes; Goals; Heart Rate; Hour; Human; Hypertension; Injection of therapeutic agent; Insulin-Dependent Diabetes Mellitus; Inulin; Kidney; Length; Light; Liver; Messenger RNA; Metabolic; Motor Activity; Mus; Mutation; Neurons; Organ; Pattern; Periodicity; Peripheral; Phase; Process; Protocols documentation; Reducing diet; Renal function; Renin; Role; Running; Sodium Chloride; System; Telemetry; Time; Urine; Variant; Water; Wild Type Mouse; diabetic; flame photometry; improved; peripheral blood; salt intake; urinary

1. Mice heterozygous for an Ins2 mutation (Akita mice) develop severe insulin-dependent diabetes mellitus and have been used by us and others as a mouse model to study diabetic nephropathy. Because of the critical role of blood pressure in causing end-organ damage we determined long-term blood pressure (MAP) and heart rate (HR) levels, their circadian variability, and their regulation by changes in salt intake in diabetic Akita and wild type mice by using the radiotelemetry system in unrestrained animals at about 12 weeks of age. Akita mice demonstrated robust circadian rhythms of mean arterial, systolic and diastolic blood pressure, heart rate and locomotor activity without significant differences in the mesor, amplitude, and acrophase of the rhythms compared with C57BL/6J mice. However, 24-h mean heart rate was significantly lower in Akita mice compared with C57BL/6J mice (527 10 vs. 581 14 bpm; p=0.008), especially in the dark period. After obtaining baseline values the mice were placed on diets with either a high (8.0%) or low (0.04%) NaCl content in a random order. All diets were provided for a 1-wk period prior to the 7 day telemetry study. Both Akita and C57BL/6J mice adapted to the low NaCl diet without significant changes of the rhythm parameters and the mean values of blood pressure and locomotor activity although blood pressure tended to be lower in Akita reaching significance for systolic pressure values. On the high NaCl diet, Akita mice showed a striking further reduction in heart rate in both light and dark phases (489 12 vs. 571 10 bpm, p=0.001), and the appearance of a second heart rate and blood pressure minimum at 2 AM. We conclude that circadian patterns of blood pressure, heart rate and locomotor activity are not dramatically altered in 12-week old Akita diabetic mice with established diabetes mellitus. However, reduced heart rates in response to a high salt diet and reduced blood pressures during low NaCl diet suggest a regulatory impairment in type 1 diabetes, presumably at the level of the autonomic nervous system and baroreflex functions. 2. Light is well known to serve as the strongest input for the entrainment of circadian rhythms of locomotor activity, body temperature, and cardiovascular functions. However, food intake has also been shown to independently entrain locomotor activity, but less is known whether food also affects blood pressure rhythmicity. We have therefore assessed the ability of the food cue to determine circadian variations of renal and cardiovascular functions. In experiments in wild type mice food was offered during the daytime (between 10 AM and 2 PM) for 6 consecutive days under 12 hr light (6 to 18 hr):12 hr dark conditions (18 to 6 hr). During ad libitum feeding (AL) food was always available. Blood pressure and heart rate were determined by radiotelemetry for 20 consecutive days (7 day AL, 6 days RF, 7 days AL). Urine was collected in metabolic cages in 4 hr periods; urinary Na and K were determined with flame photometry. GFR was measured by single injection FITC inulin clearance at two time points (12 and 24 hr). On the normal ad libitum feeding pattern, blood pressure, heart rate and activity peaks occurred during the active night period (acrophases at 0:050:05, 23:100:21 and 22:440:17, respectively). Restricted daytime feeding caused a dramatic phase shift to the light period (acrophases at 14:380:43, 13:400:33 and 16:310:33, respectively; p<0.01). During AL peaks of water, Na and K excretion were seen between 19 and 23 hrs (49296 l/4h, 9419 mEq/4h, 15733 mEq/4h). After 6 days of restricted feeding, peaks of water and K excretion occurred in the period 11-15 hrs (737109 l/4h, 17028 mmol/4h) while the urinary Na peak was observed in the 15-19 hr period (1069 mmol/4h; p<0.001). During AL GFR at midnight and noontime were not significantly different (39332l/min vs 36110 l/min, p=0.204). After 6 days of RF, GFR at midnight was significantly lower at noontime (23341l/min vs. 39332l/min, p=0.0193). Clock genes (Bmal1, Per1, Cry1, Clock) in both liver and kidney showed a significant phase shift with the restricted daytime feeding protocol. Expression of NHE3, AQP2, V1aR, renin and NKCC1 mRNA showed circadian variation (one way ANOVA, p<0.01), and a phase advance after 6 days of daytime feeding (p<0.01, two way ANOVA). Expression of Oct1, Oct2, NKCC2, NCC and ENac did not show significant circadian variations, and RF did not change expression levels. We conclude that food intake causes a marked and rapid adaptation of cardiovascular and renal circadian variations. The resetting of expression of clock genes and clock-controlled genes in the kidney during daytime feeding may be related to the temporal resetting of kidney function.

1。用于INS2突变（Akita小鼠）的杂合小鼠会产生严重的胰岛素依赖性糖尿病，并已被我们和其他人用作研究糖尿病性肾病的小鼠模型。由于血压在引起最终器官损害中的关键作用，因此我们确定了长期血压（MAP）和心率（HR）水平，它们的昼夜节律变异性以及它们通过在约12周时在不受欢迎的动物中使用Radiotelemetry System在糖尿病Akita和野生型小鼠中通过盐摄入的变化来调节。 Akita小鼠表现出均匀的动脉，收缩压和舒张压，心率和运动活性的圆润节奏，与C57BL/6J小鼠相比，节奏的中孔，振幅和尖顶均没有显着差异。但是，与C57BL/6J小鼠相比，Akita小鼠的平均心率显着降低（527 10 vs. 581 14 bpm； P = 0.008），尤其是在黑暗时期。获得基线值后，将小鼠放在饮食上，其含量高（8.0％）或低（0.04％）的NaCl含量随机顺序。所有饮食均在7天遥测研究之前的1周期间提供。 Akita和C57BL/6J小鼠均适合低NaCl饮食，而节奏参数的显着变化以及血压和运动活性的平均值，尽管血压在Akita中倾向于较低，但对基质压力值的显着性较低。在高NaCl饮食上，秋田小鼠在光和黑暗相（489 12 vs. 571 10 bpm，p = 0.001）中的心率进一步降低，第二次心脏速率和血压最低的出现在2 AM。我们得出的结论是，患有糖尿病已建立的糖尿病的12周糖尿病小鼠，血压，心率和运动活性的昼夜节律模式不会发生明显改变。然而，低盐饮食的响应降低心率和低NaCl饮食期间的血压降低表明1型糖尿病的调节性损害大概是在自主神经系统水平和巴雷诺反射功能的水平上。 2。众所周知，光是运动活性，体温和心血管功能的昼夜节律节奏的最强输入。然而，食物摄入也已显示出独立夹带运动活性，但鲜为人知的食物是否还会影响血压的节奏性。因此，我们已经评估了食品提示确定肾脏和心血管功能的昼夜节律变化的能力。在野生型小鼠的实验中，在白天（凌晨10点至下午2点之间）提供了6个小时的光线（6至18小时）：12小时的黑暗条件（18至6小时）。在随意进食期间（AL）食物始终可用。血压和心率连续20天（7天AL，6天RF，7天AL）确定。在4个小时的时间内收集尿液在代谢笼中；用火焰光度法确定尿Na和K。通过在两个时间点（12和24小时）的单个注射FITC侵蚀蛋白清除率测量GFR。在正常的自发进食模式下，血压，心率和活动峰发生在活动夜晚（分别为0：050：05：05：05，23：100：21和22：440：17）。日常喂养受限导致急剧转移到光周期（分别为14：380：43，13：400：33和16：310：33； p <0.01）。 在水的峰值期间，可以看到19至23小时（49296 L/4H，9419 MEQ/4H，15733 MEQ/4H）之间的Na和K排泄。经过6天的限制喂养后，在11-15小时（737109 L/4H，17028 mmol/4H）的周期中发生了水和K排泄峰，而在15-19小时（1069 mmol/4H; p <0.001）中观察到尿Na峰。 在午夜的Al GFR期间，中午没有显着差异（39332L/min vs 36110 L/min，p = 0.204）。 RF 6天后，午夜时期的GFR在中午（23341L/min vs. 39332L/min，p = 0.0193）明显降低。肝脏和肾脏中的时钟基因（BMAL1，PER1，CRY1，时钟）均与日常喂养方案受到限制的相移。 NHE3，AQP2，V1AR，Renin和NKCC1 mRNA的表达表现出昼夜节律变化（ANOVA，P <0.01），白天喂养6天后（P <0.01，两道ANOVA）后阶段进步。 OCT1，OCT2，NKCC2，NCC和ENAC的表达没有显示出明显的昼夜节律变化，RF没有改变表达水平。我们得出的结论是，食物摄入会引起心血管和肾脏昼夜节律变化的明显和快速适应。白天喂养中时钟基因和时钟控制基因表达的重置可能与肾功能的时间重置有关。