实验性蛛网膜下腔出血大鼠儿茶酚胺氧位甲基转移酶表达的变化及意义

目的观察实验性蛛网膜下腔出血(SAH)后早期大鼠儿茶酚胺氧位甲基转移酶(catechol-O-methyltrans-ferase,COMT)mRNA和蛋白表达、血浆儿茶酚胺(catecholamine)含量、基底动脉管径和管壁厚度的变化规律,探讨SAH后早期大鼠COMT表达变化的意义。方法以视交叉前池单次注血法构建大鼠SAH模型。采用RT-PCR、Western blot法检测大鼠SAH后早期各个时相点(SAH后6、12、24、48、72 h)纹状体组织内COMT mRNA和蛋白表达。采用高效液相色谱法测定大鼠相应时相点血浆CA含量。HE染色后测量大鼠相应时相点基底动脉管径和管壁厚度。结果与健康对照组和假手术组比较,SAH组大鼠在建模后6 h见COMT mRNA和蛋白表达开始增高(P<0.01),12 h时达到高峰(P<0.01),24 h后开始下降(P<0.01),48 h时仍高于健康对照组和假手术组相应时相点水平(P<0.01),至建模后72 h时接近正常水平(P>0.05)。SAH组大鼠在建模后6 h即见血浆CA含量升高,24 h时达到峰值,24 h后开始下降,至72 h后仍高于健康对照组和假手术组相应时相点水平。SAH组大鼠在建模后12 h基底动脉的管径明显缩小和管壁明显增厚(P<0.01),至建模后24 h最明显(P<0.01)并持续至建模后48 h(P<0.01);建模后72 h,基底动脉的管径和管壁厚度已接近正常大小(P>0.05)。结论实验性SAH可以诱导SAH后早期大鼠纹状体COMT表达增高;SAH后早期CA含量明显升高并伴有CVS发生;SAH后早期CVS和血浆CA含量增高可能与SAH后早期COMT表达增高不够充分和持久有关。

Expression profile of catechol-O-methyltransferase in rats after subarachnoid hemorrhage

Objective To investigate the expression pattern of mRNA and protein of catechol-O-methy-ltransferase(COMT),plasma content of catecholamine(CA),diameter and wall thickness of basilar artery in early period after subarachnoid hemorrhage(SAH) in rats,and to investigate the significance of COMT expression in early period after SAH.Methods Rat SAH model was established by single blood injection to prechiasmatic cistern.RT-PCR and Western blotting were adopted to detect mRNA and protein expression of COMT respectively in the striatum corpora at 6,12,24,48,and 72 h after SAH.Plasma content of CA was determined by high performance liquid chromatography,and the diameter and wall thickness of basilar artery in rats were measured after SAH in corresponding time points.Results Compared with the control group,COMT expression in rats in SAH group began to rise at 6 h,reached peak at 12 h,then decreased continually at 24 h and 48 h,and finally returned close to the level of control group at 72 h.The expression of COMT at 6,12,24 and 48 h after SAH was significantly higher than that of control group(P<0.01) and that of sham group at corresponding time points(P<0.01).After SAH modeling,CA content in SAH group began to rise 6 h after SAH and reached peak at 24 h,and decreased after 24 h to 72 h.The contents in each time points were higher than that in control group and those in sham operation group at corresponding time points(P<0.01).The caliber constriction and wall thickening aggravated obviously 12 h after modeling(P<0.01),reached the peak at 24 h(P<0.01) and last to 48 h(P<0.01).The caliber and wall thickness of basilar artery reached nearly normal size 72 h after SAH modeling(P>0.05).Conclusion Experimental SAH induces COMT upregulation in early stage after injury.And plasma CA content is increased obviously accompanied with cerebral vasospasm(CVS),which may be associated with insufficient elevated expression of COMT in early stage after experimental SAH.