Dept. of Environmental Health, Life Science and Human Technology, Nara Women's Univ., Kita-Uoya Nishimachi, Nara, Japan.
Am J Physiol Regul Integr Comp Physiol. 2010 Oct;299(4):R1114-20. doi: 10.1152/ajpregu.00831.2009. Epub 2010 Aug 11.
The present study was designed to document changes in sympathetic nerve activity and cardiovascular function when conscious rats were challenged with a noise stressor to induce freezing behavior. The potential contribution of the arterial baroreceptors in regulating sympathetic nerve activity and cardiovascular adjustments during the freezing behavior was then examined. Wistar male rats were assigned to sham-operated (SO) and sinoaortic-denervated (SAD) groups and instrumented chronically with electrodes for measurements of renal (RSNA) and lumbar (LSNA) sympathetic nerve activity, electroencephalogram, electromyogram, and electrocardiogram and catheters for measurements of systemic arterial and central venous pressure. Both SO and SAD rats were exposed to 90 dB of white noise for 10 min, causing freezing behavior in both groups. In SO rats, freezing behavior was associated with an immediate and significant (P < 0.05) increase in RSNA, no changes in LSNA or mean arterial pressure, and a significant (P < 0.05) decrease in heart rate. SAD attenuated the magnitude of the immediate increase in RSNA and had no influence on the response in LSNA during freezing behavior compared with SO rats. Moreover, in SAD rats, mean arterial pressure increased significantly (P < 0.05) while heart rate did not change during the freezing behavior. These data indicate that freezing behavior evokes regionally different changes in sympathetic outflows, which may be involved in generating the patterned responses of cardiovascular function to stressful or threatening sensory stimulation. Moreover, it is suggested that the arterial baroreceptors are involved in generating the differential changes in RSNA and LSNA and thus the patterned changes in cardiovascular functions observed during freezing behavior in conscious rats.
本研究旨在记录当意识清醒的大鼠受到噪声应激源挑战以诱导冻结行为时，交感神经活动和心血管功能的变化。然后检查动脉压力感受器在调节交感神经活动和冻结行为期间心血管调节中的潜在贡献。雄性 Wistar 大鼠被分配到假手术（SO）和去窦神经（SAD）组，并接受慢性电极植入，用于测量肾（RSNA）和腰（LSNA）交感神经活动、脑电图、肌电图和心电图以及用于测量全身动脉和中心静脉压的导管。SO 和 SAD 大鼠均暴露于 90 dB 的白噪声 10 分钟，导致两组均出现冻结行为。在 SO 大鼠中，冻结行为伴随着 RSNA 的即刻显著增加（P < 0.05），LSNA 或平均动脉压无变化，心率显著降低（P < 0.05）。与 SO 大鼠相比，SAD 减弱了 RSNA 即刻增加的幅度，并且在冻结行为期间对 LSNA 的反应没有影响。此外，在 SAD 大鼠中，平均动脉压显著增加（P < 0.05），而心率在冻结行为期间没有变化。这些数据表明，冻结行为引起交感神经输出的区域不同变化，这可能涉及到对压力或威胁性感觉刺激的心血管功能的模式反应的产生。此外，建议动脉压力感受器参与产生 RSNA 和 LSNA 的差异变化，从而产生在意识清醒的大鼠的冻结行为期间观察到的心血管功能的模式变化。
