脑C型利钠利尿肽的mRNA转录及其血浆表达水平在大鼠创伤性脑水肿中的改变

Changes of brain c-type natriuretic peptide mRNA transcription and its plasma level in traumatic brain edema in rats

目的:观察创伤性脑水肿对脑组织中C型利钠利尿肽(CNP)mRNA转录水平的影响及与其血浆中CNP水平的相关性。方法:35只S-D大鼠随机分入对照组、创伤组。采用冲击加速机制复制重度脑创伤。创伤后1天组的脑CNP mRNA转录水平采用逆转录-多聚酶链反应法(RT-PCR)行半定量测定。并同时采用酶免疫分析法(EIA),观测伤后多时点的体内血浆CNP水平。结果:创伤后1天脑水肿期内,挫伤皮质,同侧丘脑,对侧皮质,对侧丘脑和延髓等部位,与对照组相比,其CNP mRNA转录水平无显著改变(P>0.05)。然而,创伤后1天与3天组血浆的CNP水平均较对照组有明显升高(P<0.05)。结论:尽管CNP一直被认为是一种神经肽,但可能并未参与创伤性脑水肿的病理过程。而全身循环中升高的血浆CNP水平可能为机体对重度脑创伤的反应之一,其作用主要通过循环系统发挥。

Objective: To investigate the changes of C-type natriuretic peptide (CNP) mRNA transcription in a head injury rat model. Methods: 35 Sprague-Dawley rats were subjected to severe head injury induced by impact-accerleration mechanism and randomly divided into the designated sham and TBI groups. The transcription level of CNP mRNA in brain at 1 day post-injury was semi-quantified by reverse transcription-polymerase chain reaction (RT-PCR). Plasma CNP level was also monitored by the enzyme immunoassay (EIA) at 1 hour, 4h ours, 1 day, 2 day, 3 day and 6 days post-injury. Result: It was found that no significant change of CNP mRNA transcription levels occurred in the edema-tous brain regions when compared with the correspondent regions in the sham group. However, the significant increase of plasma CNP levels at 1 day and 3 days post-injury were detected, compared with that of the sham group (P<0. 05). Conclusion: The un-altered brain CNP mRNA transcription levels implicate that CNP, a presumed neuropeptide, may not involved in the pathogenesis of traumatic brain edema. Changes of CNP levels in the systemic circulation supports its role as an endogenous peptide mainly acting through the pathways associated with the vascular biology.