Grippo Angela J, Moffitt Julia A, Johnson Alan Kim
Department of Psychology, University of Iowa, Iowa City, IA 52242-1407, USA.
Psychosom Med. 2008 May;70(4):435-43. doi: 10.1097/PSY.0b013e31816ff7dd.
There is a bidirectional relationship between mood disorders (e.g., depression) and altered cardiovascular regulation (e.g., heart disease); however, the precise causal and/or common mechanisms underlying this association are unclear. In previous studies, we have noted indications of altered sympathetic drive to the heart in rats that exhibit anhedonia, an operational sign of depression induced by subjecting the animals to a series of mild and unpredictable stressors (chronic mild stress (CMS) rodent model of depression). The purpose of the present study was to more fully characterize baroreceptor reflex function in rats with experimentally induced depression.
Male, Sprague-Dawley rats were exposed to either 4 weeks of mild, unpredictable stressors (CMS group) or standard housing conditions (control group). Depression-like behavior, resting hemodynamic and cardiac parameters, and baroreceptor reflex function were investigated in all animals after the CMS period.
CMS produced anhedonia, evidenced by reduced sucrose intake and sucrose preference, as well as elevated resting heart rate (HR), slightly elevated blood pressure, and reduced HR variability. These animals also exhibited significantly attenuated sympathoexcitatory responses to hypotension, and an elevation of basal sympathetic nerve activity.
These findings suggest that CMS is associated with altered sympathoexcitatory responses after baroreceptor unloading and provide further insights into potential common mechanisms underlying the association of depression and altered cardiovascular control.
情绪障碍（如抑郁症）与心血管调节改变（如心脏病）之间存在双向关系；然而，这种关联背后的确切因果和/或共同机制尚不清楚。在先前的研究中，我们注意到，在表现出快感缺失的大鼠中，其心脏的交感神经驱动发生了改变，快感缺失是通过让动物经受一系列轻度且不可预测的应激源（慢性轻度应激（CMS）抑郁症啮齿动物模型）诱导产生的抑郁的一个操作标志。本研究的目的是更全面地描述实验性诱导抑郁的大鼠的压力感受器反射功能。
将雄性Sprague-Dawley大鼠暴露于4周的轻度、不可预测的应激源（CMS组）或标准饲养条件（对照组）。在CMS期结束后，对所有动物的抑郁样行为、静息血流动力学和心脏参数以及压力感受器反射功能进行研究。
CMS导致了快感缺失，表现为蔗糖摄入量和蔗糖偏好降低，以及静息心率（HR）升高、血压略有升高和HR变异性降低。这些动物对低血压的交感兴奋反应也显著减弱，基础交感神经活动增强。
这些发现表明，CMS与压力感受器卸载后的交感兴奋反应改变有关，并为抑郁症与心血管控制改变之间潜在的共同机制提供了进一步的见解。
