Shonis C A, Peano C A, Dillon G H, Waldrop T G
Department of Physiology and Biophysics, College of Medicine, University of Illinois, Urbana 61801.
Brain Res Bull. 1993;31(5):493-9. doi: 10.1016/0361-9230(93)90115-r.
Previous studies have suggested that a decreased inhibitory input onto neurons within the posterior hypothalamus (PH), a known pressor area, may contribute to hypertension in the spontaneously hypertensive rat (SHR). Recent experiments from this laboratory have shown that neurons in the PH of the SHR have an altered and elevated discharge frequency compared to those in the normotensive rat. In addition, biochemical studies have reported that there is a decreased concentration of the inhibitory neurotransmitter, GABA, in the hypothalamus of the SHR. The objective of the present study was to assess any variations in GABAergic modulation of cardiovascular activity in SHRs compared to normotensive Wistar-Kyoto (WKY) rats and Sprague-Dawley (SD) rats. Arterial pressure and heart rate responses to microinjections of the GABA synthesis inhibitor 3-mercaptopropionic acid (3-MP) into the posterior hypothalamic area of anesthetized young (6-8 weeks) and mature (11-16 weeks) hypertensive and normotensive rats were recorded. Microinjection of 3-MP elicited increases in arterial pressure of 17.4 +/- 3.9 mmHg, 18.1 +/- 7.8 mmHg, 16.9 +/- 6.4 mmHg, and 10.4 +/- 3.5 mmHg in the mature WKY, mature SD, young WKY, and young SHR, respectively. In addition, heart rate was elevated by 33.2 +/- 21.9 beats/min, 70.0 +/- 25.3 beats/min, 56.3 +/- 15.0 beats/min and, 45.9 +/- 10 beats/min in the mature WKY, adult SD, young WKY, and young SHR groups, respectively. In contrast, microinjection of 3-MP into the posterior hypothalamus of adult SHRs produced no significant change in arterial pressure (-5.0 +/- 1.8 mmHg) or heart rate (+5.3 +/- 6.1 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)
以往研究表明，已知的升压区域——下丘脑后部（PH）内神经元的抑制性输入减少，可能导致自发性高血压大鼠（SHR）出现高血压。该实验室最近的实验表明，与正常血压大鼠相比，SHR的PH神经元放电频率发生改变且升高。此外，生化研究报告称，SHR下丘脑内抑制性神经递质γ-氨基丁酸（GABA）的浓度降低。本研究的目的是评估与正常血压的Wistar-Kyoto（WKY）大鼠和Sprague-Dawley（SD）大鼠相比，SHR心血管活动的GABA能调节是否存在任何差异。记录了麻醉的年轻（6 - 8周）和成熟（11 - 16周）高血压和正常血压大鼠下丘脑后部区域微量注射GABA合成抑制剂3-巯基丙酸（3-MP）后动脉血压和心率的反应。在成熟WKY、成熟SD、年轻WKY和年轻SHR中，微量注射3-MP分别使动脉血压升高17.4±3.9 mmHg、18.1±7.8 mmHg、16.9±6.4 mmHg和10.4±3.5 mmHg。此外，成熟WKY、成年SD、年轻WKY和年轻SHR组的心率分别升高33.2±21.9次/分钟、70.0±25.3次/分钟、56.3±15.0次/分钟和45.9±10次/分钟。相比之下，向成年SHR下丘脑后部微量注射3-MP，动脉血压（-5.0±1.8 mmHg）和心率（+5.3±6.1次/分钟）无显著变化。（摘要截断于250字）
