摘要
目的 探讨中枢α1和α2 肾上腺素受体 (α1 AR ,α2 AR)在脑室注射 (icv)组胺 (HA)对颈动脉窦压力感受性反射 (CSR)重调定中的作用。方法 孤离麻醉SD大鼠的双侧颈动脉窦区 ,将不同窦内压 (ISP)与其对应的平均动脉压(MAP)值进行Logistic五参数曲线拟合 ,求得ISP MAP关系曲线及其特征参数 ,观察icvHA以及预先在蓝斑 (LC)或孤束核 (NTS)微量注射α1或α2 AR拮抗剂对CSR的影响。结果 icvHA (6 0 μmol·L-1,5 μl)导致ISP MAP关系曲线后半程明显上移 (P <0 0 5 ) ,ISP和增益关系曲线中部明显下移 (P <0 0 5 ) ,反射参数MAP反射变动范围及反射最大增益减小 (P <0 0 5 ) ;预先向LC注射选择性的α1 AR拮抗剂酚苄明 (PBZ ,3μmol·L-1,5 0 0nl)或α2 AR拮抗剂育亨宾 (YOH ,2 5 μmol·L-1,5 0 0nl) ,均能明显加强HA的上述效应 ,PBZ的这种加强作用不如YOH的显著 (P <0 0 5 ) ;预先向NTS注射相同剂量、容积的PBZ或YOH ,对HA效应的影响与LC注射后的相类似 ,但NTS注射YOH后icvHA所致的阈压变化进一步明显升高 (P <0 0 5 )。结论 脑室给HA使CSR产生快速重调定 ,反射敏感性下降 ;LC与NTS处的α1、α2 AR作用可减弱icvHA对CSR的重调定 ;LC、尤为NTS处的α2
AIM To investigate the effects of α 1 and α 2 adrenoceptors (α 1 AR, α 2 AR) in the nucleus tractus solitarius (NTS) and locus ceruleus (LC) on carotid sinus baroreceptor reflex (CSR) resetting induced by intracerebroventricular injection (icv) of histamine (HA). METHODS The left and right carotid sinus regions were isolated from the systemic circulation in 45 Sprague Dawley rats anesthetized with pentobarbital sodium. The intracarotid sinus pressure (ISP) was altered in a stepwise manner. ISP mean arterial pressure (MAP) relationship curve and its characteristic parameters were constructed by fitting to the logistic function with five parameters. The changes in CSR performance induced by icv HA and the effects of pretreatment with α 1 AR or α 2 AR antagonist into the NTS or LC on the responses of CSR to HA were examined. RESULTS icv microinjection of HA (60 μmol·L -1 in 5 μl) significantly shifted the ISP MAP relationship curve upwards ( P <0 05) and moved the middle part of ISP Gain relationship curve downwards ( P <0 05), and reduced the MAP range and maximum gain ( P <0 05). The pretreatment with phenoxybenzamine (PBZ, a selective antagonist of α 1 AR, 3 μmol·L -1 in 500 nl) or yohimbine (YOH, a selective antagonist of α 2 AR, 2 5 μmol·L -1 in 500 nl) into the LC could obviously intensify the above mentioned changes in CSR performance induced by HA, but the intensive effect of PBZ was less remarkable than that of YOH ( P <0 05). After microinjection of PBZ or YOH into the NTS with the respectively corresponding dose and volume, the responses of CSR to HA were similar to those after microinjection of PBZ or YOH into the LC, but after microinjection of YOH into the NTS, the change in the threshold pressure resulted from HA was significantly increased ( P <0 05). CONCLUSION The intracerebroventricular administration of HA results in a rapid resetting of CSR and a decrease in reflex sensitivity, and the functions of both α 1 AR and α 2 AR in the LC and NTS may attenuate CSR resetting induced by icv microinjection of HA. Furthermore, α 2 AR in the LC, especially in NTS might play an important role in mediating the responses of CSR to HA.
出处
《中国药理学通报》
CAS
CSCD
北大核心
2003年第9期1037-1042,共6页
Chinese Pharmacological Bulletin
基金
苏州大学青年教师研究基金项目资助课题 NoQ3 13 40 44
关键词
颈动脉窦反射重调定
组胺
脑室注射
中枢α1-肾上腺素受体
中枢α2-肾上腺素受体
孤束核
蓝斑
平均动脉压
carotid sinus baroreceptor reflex resetting
histamine
intracerebroventricular injection
α 1 adrenoceptor
α 2 adrenoceptor
nucleus tractus solitarius
locus ceruleus
mean arterial pressure
