Alikhani Vida, Mohebbati Reza, Hosseini Mahmoud, Khajavirad Abolfazl, Shafei Mohammad Naser
Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Applied Biomedical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Iran J Basic Med Sci. 2021 May;24(5):586-594. doi: 10.22038/ijbms.2021.53181.11978.
Periaqueductal gray (PAG) is a mesencephalic area divided into four columns including ventrolateral periaqueductal gray (vlPAG). vlPAG plays a role in cardiovascular regulation during normal and hemorrhagic (Hem) conditions. Due to presence of glutamate in this area, we evaluated the effect of glutamatergic receptors of this area on cardiovascular activity in normotensive and hypovolemic Hem rats.
Animals were divided into twelve groups: saline (vehicle), Glutamate, GYK52466 (non-NMDA receptor antagonist), and MK801 (NMDA receptor antagonist) with and without Glu microinjected into vlPAG in normal and Hem conditions. Following the femoral artery cannulating and microinjecting, changes (Δ) of heart rate (HR), systolic blood pressure (SBP), and mean arterial pressure (MAP) were recorded via a PowerLab unit.
In normotensive conditions, microinjection of Glu increased ΔMAP, ΔSBP, and ΔHR (<0.001). MK-801 and GYKI-52466 nonsignificant reduced cardiovascular responses than vehicle while their changes were significant compared with glutamate (<0.001). Co-injection of GYKI- 52466 with Glu did not significantly reduce ΔSBP and ΔMAP induced by Glu (>0.05) but co-injection of MK-801 with Glu significantly attenuate these effects(<0.01). In Hem, Glu increased ΔSBP, ΔMAP, and ΔHR (<0.05). GYKI-52466 alone did not change cardiovascular responses but MK-801 decreased ΔSBP than Hem (<0.01). Co-injection of GYKI-52466 with Glu had significant(<0.05) but MK-801 with Glu had no significant effect compared with Hem (>0.05).
The glutamatergic system of vlPAG increases cardiovascular values that are mostly mediated through the NMDA receptor. Since vlPAG is well known as an inhibitory region, it seems that glutamate does not have a noteworthy cardiovascular role in vlPAG during Hem and normal conditions.
中脑导水管周围灰质（PAG）是中脑的一个区域，分为四列，包括腹外侧中脑导水管周围灰质（vlPAG）。vlPAG在正常和出血（Hem）情况下的心血管调节中发挥作用。由于该区域存在谷氨酸，我们评估了该区域的谷氨酸能受体对正常血压和低血容量性Hem大鼠心血管活动的影响。
将动物分为十二组：生理盐水（溶剂）、谷氨酸、GYK52466（非NMDA受体拮抗剂）和MK801（NMDA受体拮抗剂），在正常和Hem条件下，分别向vlPAG注射或不注射谷氨酸。在股动脉插管和微量注射后，通过PowerLab装置记录心率（HR）、收缩压（SBP）和平均动脉压（MAP）的变化（Δ）。
在正常血压条件下，注射谷氨酸可增加ΔMAP、ΔSBP和ΔHR（<0.001）。与溶剂相比，MK-801和GYKI-52466对心血管反应的降低无显著意义，但与谷氨酸相比，它们的变化具有显著性（<0.001）。GYKI-52466与谷氨酸共同注射并未显著降低谷氨酸诱导的ΔSBP和ΔMAP（>0.05），但MK-801与谷氨酸共同注射可显著减弱这些作用（<0.01）。在Hem情况下，谷氨酸增加了ΔSBP、ΔMAP和ΔHR（<0.05）。单独使用GYKI-52466并未改变心血管反应，但MK-801使ΔSBP低于Hem组（<0.01）。与Hem组相比，GYKI-52466与谷氨酸共同注射有显著影响（<0.05），但MK-801与谷氨酸共同注射无显著影响（>0.05）。
vlPAG的谷氨酸能系统增加心血管值，这主要通过NMDA受体介导。由于vlPAG是一个众所周知的抑制区域，在Hem和正常情况下，谷氨酸在vlPAG中似乎没有显著的心血管作用。
