Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Department of Physiology, School of Medicine, Sabzevar University of Medical Sciences, Sabzevar, Iran.
Basic Clin Pharmacol Toxicol. 2024 Oct;135(4):441-450. doi: 10.1111/bcpt.14070. Epub 2024 Sep 1.
The midbrain dorsomedial periaqueductal grey column (dmPAG) is involved in the regulation of cardiovascular responses. Due to the presence of Gamma-Aminobutyric acid (GABA) receptors in the dmPAG, this study aimed to investigate the role of GABA receptors in the dmPAG on cardiovascular parameters and its possible peripheral mechanisms. The left femoral artery was cannulated, and systolic arterial pressure (SAP), mean arterial pressure (MAP) and heart rate (HR) were recorded using a Power lab system. Microinjection of saline, muscimol and bicuculline (BIC) was done using a stereotaxic device. Also, the peripheral mechanisms dependent on GABA receptors in the dmPAG were evaluated by intravenous (i.v.) injection of hexamethonium (Hexa) and atropine (Atr) 5 min before the BIC. Results showed that BIC significantly increased ∆SAP, ∆MAP and ∆HR than the control group, but muscimol had no significant effect. Injection of Hex significantly attenuates the effect of BIC on ∆SAP and ∆MAP. Atr (i.v) significantly increased the ∆HR, and when injected before BIC microinjection, it did not affect the cardiovascular responses induced by BIC. These findings show that GABA receptors of the dmPAG have inhibitory effects on the cardiovascular system, which are mostly mediated by the sympathetic system.
中脑背内侧水管周围灰质柱（dmPAG）参与心血管反应的调节。由于 dmPAG 中存在γ-氨基丁酸（GABA）受体，本研究旨在探讨 dmPAG 中 GABA 受体在心血管参数及其可能的外周机制中的作用。通过立体定向设备进行左股动脉插管，使用 Powerlab 系统记录收缩压（SAP）、平均动脉压（MAP）和心率（HR）。通过立体定向设备进行生理盐水、muscimol 和bicuculline（BIC）的微注射。此外，通过在 BIC 前 5 分钟静脉注射六烃季铵（Hexa）和阿托品（Atr）来评估 dmPAG 中 GABA 受体的外周机制。结果表明，BIC 显著增加了 ∆SAP、∆MAP 和 ∆HR，而 muscimol 则没有显著影响。Hex 的注射显著减弱了 BIC 对 ∆SAP 和 ∆MAP 的影响。Atr（iv）显著增加了 ∆HR，当在 BIC 微注射前注射时，它不会影响 BIC 引起的心血管反应。这些发现表明，dmPAG 中的 GABA 受体对心血管系统具有抑制作用，主要通过交感神经系统介导。
