Stotz-Potter E H, Willis L R, DiMicco J A
Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis 46202, USA.
J Neurosci. 1996 Feb 1;16(3):1173-9. doi: 10.1523/JNEUROSCI.16-03-01173.1996.
Both the dorsomedial hypothalamic nucleus (DMH) and the paraventricular hypothalamic nucleus (PVN) have been implicated in the neural control of the cardiovascular response to stress. We used the GABAA agonist muscimol to inhibit neuronal activation and attempted to identify hypothalamic nuclei required for the cardiovascular response to air stress. Chronically instrumented rats received bilateral injections of either 80 pmol of muscimol or 100 nl of saline vehicle into the DMH, the PVN, or an intermediate area (including the rostral edge of the DMH and the region between the two nuclei) and were placed immediately in a restraining tube and subjected to 20 min of air stress. In all rats, air stress after vehicle injections caused marked increases in heart rate (137 +/- 6 beats/min) and blood pressure (26 +/- 2 mmHg). Microinjection of muscimol into the DMH suppressed the heart rate and blood pressure response by 85 and 68%, respectively. Identical microinjection of muscimol into the intermediate area between the DMH and the PVN attenuated the increases in heart rate by only 46% and in blood pressure by 52%. In contrast, similar injections into the vicinity of the PVN failed to alter the cardiovascular response to air stress. These findings demonstrate that muscimol-induced inhibition of neuronal activity in the region of the DMH blocks air stress-induced increases in heart rate and arterial pressure, whereas similar treatment in the area of the PVN has no effect.
下丘脑背内侧核（DMH）和下丘脑室旁核（PVN）均参与了机体对压力的心血管反应的神经控制。我们使用GABAA激动剂蝇蕈醇抑制神经元激活，并试图确定对空气应激的心血管反应所需的下丘脑核团。长期植入仪器的大鼠在DMH、PVN或中间区域（包括DMH的头端边缘和两个核团之间的区域）接受双侧注射80 pmol蝇蕈醇或100 nl生理盐水载体，然后立即放入约束管中并承受20分钟的空气应激。在所有大鼠中，注射载体后空气应激导致心率（137±6次/分钟）和血压（26±2 mmHg）显著升高。向DMH微量注射蝇蕈醇分别使心率和血压反应抑制了85%和68%。向DMH和PVN之间的中间区域进行相同的微量注射，仅使心率升高减弱了46%，血压升高减弱了52%。相比之下，向PVN附近进行类似注射未能改变对空气应激的心血管反应。这些发现表明，蝇蕈醇诱导的DMH区域神经元活动抑制可阻断空气应激诱导的心率和动脉压升高，而在PVN区域进行类似处理则无效果。
