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目的:研究脑内P物质(substance P,SP)的心血管反应与去甲肾上腺素能系统的关系。方法:家兔脑室注射6-羟基多巴胺(6-hydroxydopamine,6-OHDA)10天后注射SP,记录平均动脉血压和心率的变化;放射受体测定法测定下丘脑及腹侧延髓中SP受体的密度和亲和力。结果:6-OHDA预处理后,下丘脑及腹侧延髓内NA的含量分别降低86.7％和77.0％,侧脑室注射SP的升压反应显著减弱。6-OHDA组下丘脑和腹侧延髓突触小体膜上SP受体总数B_(max)分别为(42±18)和(20±5)pmol·g~(-1)protein,显著低于对照组(108±5)和(35.9±2.2)pmol·g~(-1)protein,而6-OHDA组[~(125)I]SP对SP受体的平衡解离常数K_d[(0.029±0.001),(0.015±0.003)nmol·L~(-1)]显著高于对照组[(0.015±0.004),(0.014±0.006)nmol·L~(-1)]。结论:中枢去甲肾上腺素神经通路参与侧脑室注射SP的心血管反应。
Objective: To investigate the relationship between cardiovascular reactions and noradrenergic system of substance P (SP) in the brain. Methods: The ventricular injection of 6-hydroxydopamine (6-OHDA) in rabbits was performed 10 days after injection of SP, and the changes of mean arterial pressure and heart rate were recorded. The levels of SP receptor in the hypothalamus and ventral medulla oblongata were measured by radioimmunoassay Density and affinity. Results: After pretreatment with 6-OHDA, the content of NA in the hypothalamus and ventral medulla decreased by 86.7% and 77.0%, respectively. The antihypertensive response to lateral ventricle injection of SP was significantly attenuated. The total number of SP receptors in the hypothalamus and ventral medulla oblongata synovial membrane in the 6-OHDA group was (42 ± 18) and (20 ± 5) pmol · g -1 protein, respectively, which was significantly lower than (108 ± 5) and (35.9 ± 2.2) pmol · g -1 protein in the control group, while the [~ (125) I] 0.001), (0.015 ± 0.003) nmol·L -1] was significantly higher than that of the control group [(0.015 ± 0.004), (0.014 ± 0.006) nmol·L -1]. CONCLUSIONS: Central norepinephrine neural pathways are involved in the cardiovascular responses to intracerebroventricular injection of SP.