Bernatova Iveta, Key Mary P, Lucot James B, Morris Mariana
Department of Pharmacology and Toxicology, Wright State University School of Medicine, Dayton, Ohio 45435, USA.
Hypertension. 2002 Nov;40(5):768-73. doi: 10.1161/01.hyp.0000036405.27562.02.
The objective of this study was to determine the effect of chronic stress exposure on the circadian pattern of cardiovascular responses in mice. Using male C57BL6 mice with carotid arterial catheters, we tested the effect of 7 days of intermittent shaker stress on body weight, food intake, drinking activity, plasma corticosterone, mean arterial pressure (MAP), and heart rate. The stress was delivered automatically for 2-minute periods (150 cycles/min), 45 times/d for 7 days. Plasma corticosterone was significantly increased in acutely and chronically stressed mice, with a partial attenuation in the chronic condition. Stress increased water intake, produced no change in food intake, and significantly decreased body weight (5% change). MAP and heart rate were measured continuously on stress days 1, 3, and 7 and during the basal and recovery periods. Chronic stress did not produce a sustained increase in MAP; however, there was an increase in MAP during the first stress day and a decrease during the recovery period. There was a circadian pattern in the pressor responses, with greater increases seen during the light period (nonactive phase) than in the dark period (+24% versus +11% on stress day 3, light versus dark). The results suggest that a stress delivered during the nonactive phase represents a higher cardiovascular risk.
本研究的目的是确定慢性应激暴露对小鼠心血管反应昼夜节律模式的影响。我们使用植入颈动脉导管的雄性C57BL6小鼠，测试了7天间歇性摇晃应激对体重、食物摄入量、饮水活动、血浆皮质酮、平均动脉压（MAP）和心率的影响。应激以自动方式施加，每次2分钟（150次/分钟），每天45次，持续7天。急性和慢性应激小鼠的血浆皮质酮均显著升高，慢性应激时升高幅度有所减弱。应激增加了水的摄入量，食物摄入量无变化，体重显著下降（变化5%）。在应激第1天、第3天和第7天以及基础期和恢复期连续测量MAP和心率。慢性应激并未使MAP持续升高；然而，在应激第一天MAP升高，恢复期降低。压力反应存在昼夜节律模式，光照期（非活动期）的升高幅度大于黑暗期（应激第3天，光照期与黑暗期相比，升高幅度分别为+24%和+11%）。结果表明，在非活动期施加的应激代表更高的心血管风险。
