摘要
为了探讨下丘脑室旁核(paraventricular nucleus,PVN)内的甘氨酸在压力感受性反射中枢调节中的作用及其机制,本实验采用清醒自由活动的大鼠,采用脑部微量透析法和高效液相色谱法,观察静脉注射苯肾上腺素诱发的压力感受性反射对PVN区甘氨酸浓度的影响,并通过PVN区直接灌流甘氨酸或甘氨酸受体阻断剂士的宁,进一步探讨PVN内的甘氨酸对压力感受性反射的作用。结果显示:(1)静脉注射苯肾上腺素(0.8μg/0.04mL,3min内注射完毕)诱发压力感受性反射时,PVN区透析液中的甘氨酸浓度迅速升高到注射前的(162.9±27.3)%(P<0.05);(2)PVN区灌流甘氨酸受体阻断剂士的宁(100μmol/L),同时诱发压力感受性反射,可明显降低压力感受性反射的敏感性(P<0.001);(3)PVN区灌流甘氨酸(1mmol/L),同时诱发压力感受性反射,可明显提高压力感受性反射的敏感性(P<0.001)。上述结果提示,PVN内的甘氨酸可通过士的宁敏感的甘氨酸受体对压力感受性反射活动起易化作用。
The hypothalamic paraventricular nucleus （PVN） is a central site for integration of the endocrine system and the autonomic nervous system. Despite a number of studies have pointed out the importance of the PVN in the central regulation of cardiovascular functions, the chemical mediators in the PVN responsible for mediating baroreflex are not well understood. In the present study, we used the conscious rats to investigate the possible involvement of glycine （Gly） in PVN in the central regulation of baroreflex induced by intravenous injection of phenylephrine （0.8 μg/0.04 mL, in 3 min）. Then, the microdialysis sampling was performed in the PVN and the concentration of Gly in the microdialysate was measured by high performance liquid chromatography （HPLC） combined with electrochemical techniques, and mean arterial pressure （MAP） and heart rate （HR） were recorded simultaneously. Injection of phenyle- phrine elicited a significant increase （P〈0.01） in MAP from the baseline of （99.5±14.2） mmHg to the maximum of （149.8±19.5） mmHg and a decrease （P〈0.01） in HR from the baseline of （400.8~33.1） beats/rain to the minimum of （273.4±40.8） beats/min, respectively. Synchronously, the injection of phenylephrine increased the level of Gly in the microdialysate from the PVN to （162.9±27.3）% of the basal level （P〈0.05）. Perfusion of strychnine （100 μmol/L）, an antagonist of Gly receptor, into the PVN enhanced the pressor response and attenuated the bradycardic response during the baroreflex, resulting in a decrease in baroreflex sensitivity （P〈0.001）. Whereas, the perfusion of Gly （1 mmol/L） into the PVN did not affect the pressor response but enhanced the bradycardic response during the baroreflex, resulting in an increase in baroreflex sensitivity （P〈0.001）. These results suggest that endogenous Gly in the PVN may act via strychnine-sensitive Gly receptor to produce a facilitative effect on baroreflex.
出处
《生理学报》
CAS
CSCD
北大核心
2009年第2期155-160,共6页
Acta Physiologica Sinica
基金
supported by the National Natural Science Foundation of China (No. 30260031
30460041)
