Department of Physiology, Shiraz University of Medical Sciences, Shiraz, Iran; Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Department of Physiology, Isfahan University of Medical Sciences, Isfahan, Iran.
Brain Res. 2023 Mar 1;1802:148218. doi: 10.1016/j.brainres.2022.148218. Epub 2022 Dec 23.
The hypothalamic paraventricular nucleus (PVN) is an important brain region involved in control of the cardiovascular system. Direct injection of angiotensin II (AngII) into the PVN produces a short or long pressor response. This study was performed in anesthetized rats to find whether the parvocellular part of the paraventricular nucleus (PVNp) affects the baroreflex. And if so, what is the effect of AngII injected into the PVNp on the baroreflex? Drugs were microinjected into the PVNp while blood pressure and heart rate were recorded continuously. We found that microinjection of AT1 and AT2 receptor antagonists into the PVNp region did not affect the baseline mean arterial pressure (MAP) and heart rate (HR) indicating that under normal conditions AngII may not provide tonic activity, at least in anaesthetized animals. Bilateral microinjections of a synaptic blocker (CoCl) into the PVNp attenuated the baroreflex gains in responses to loading and unloading of baroreceptors, indicating that PVNp is involved in the baroreflex rate component. Microinjection of AngII into the PVNp increased MAP and HR. However, AngII slightly attenuated the baroreflex rate component using its two receptors AT1 and AT2. Collectively, these findings suggest that the PVNp as a whole is involved in the baroreflex. But AngII attenuates the heart rate response of the baroreflex through AT1 and AT2 receptors.
下丘脑室旁核（PVN）是参与心血管系统控制的重要脑区。将血管紧张素 II（AngII）直接注射到 PVN 中会产生短或长的升压反应。本研究在麻醉大鼠中进行，以确定室旁核的小细胞部分（PVNp）是否影响血压反射。如果是这样，那么将 AngII 注射到 PVNp 中对血压反射有什么影响？当血压和心率连续记录时，将药物微注射到 PVNp 中。我们发现，将 AT1 和 AT2 受体拮抗剂微注射到 PVNp 区域不会影响基础平均动脉压（MAP）和心率（HR），表明在正常情况下，AngII 可能不会提供紧张性活动，至少在麻醉动物中不会。将突触阻滞剂（CoCl）双侧微注射到 PVNp 会减弱对压力感受器加载和卸载的血压反射增益，表明 PVNp 参与了血压反射率成分。将 AngII 微注射到 PVNp 中会增加 MAP 和 HR。然而，AngII 通过其两个受体 AT1 和 AT2 略微减弱了血压反射率成分。总之，这些发现表明，整个 PVNp 参与了血压反射。但是，AngII 通过 AT1 和 AT2 受体减弱了血压反射的心率反应。
