脊髓损伤后自主神经反射异常大鼠心脏和肠系膜前动脉α-肾上腺素能受体的表达

Expression changes of alpha adrenergic receptors in heart and mesenteric artery in autonomic dysreflexia rats after spinal cord transection

目的:观察高位脊髓横切(spinal cord transection,SCT)慢性期自主神经反射异常(autonomic dysreflexia,AD)大鼠心脏和肠系膜前动脉α-肾上腺素能受体(-αAR)各亚型mRNA表达量,探讨AD的可能机制。方法:暴露大鼠脊髓,横切T4节段,术后4周用自制导管刺激直肠,观察升压反应,挑选发生AD的大鼠(AD组,n=16),取其心脏和肠系膜前动脉及其分支,实时定量PCR测定α1A-,α1B-,α1D-,α2A-,α2B-,α2C-AR mRNA的表达量,与只暴露脊髓、不进行横切的大鼠(假手术组,n=16)进行比较。结果:与假手术组相比,AD组大鼠心脏α1A-AR mRNA(P<0.05)、α1B-AR mRNA(P<0.01)表达下调,而α1D-ARmRNA表达量未见明显改变;肠系膜前动脉α1A、-α1D、-α2B-AR mRNA(P<0.01)、α2C-AR mRNA(P<0.05)表达上调,而α1B-、α2A-AR mRNA表达量未见明显改变。结论:大鼠SCT慢性期AD的发生可能与心脏α1A-、α1B-AR,肠系膜前动脉α1A-、α1D-、α2B-、α2C-AR的异常表达有关。

Objective：To investigate the changes of alpha adrenergic receptors （α-AR） mRNA expression in heart and mesenteric artery in autonomic dysreflexia （AD） rats after spinal cord transection, so as to explore the possible mechanism of AD. Methods： The spinal cord of rats was exposed and the fourth thoracic spinal cord was transected;4 weeks later, rats＇ rectum was stimulated by self-made catheter and those with a mean arterial blood pressure increased by more than 15 mmHg （1 mmHg= 0. 133 kPa） were chosen as AD group （n=16）. Heart and mesenteric arteries along with their branches were harvested, mRNA expression of α1A^-,α1B^-,α1D^-,α2A^-, α2B^- and α2C^- AR was quantified by real time PCR and the result was compared with that in sham-operated group （the fourth thoracic spinal cord was exposed hut not transected）. Results： Compared with sham-operated group, rats in AD group had a lower expression of α1A^-AR mRNA（P〈0.05） and α1B^-AR mRNA（P〈0.01） in their heart, but the expression of α1D^-AR mRNA had no obvious change. Also,rats in AD group had a higer expression of α1A^-,α1D^-,α2B^-AR mRNA （all P〈0.01） and α2c^-AR mRNA（P〈0.05） in their mesentric artery,but α1B^- and α2A-AR mRNA expression had no obvious change. Conclusion： AD may occur in the chronic stage of spinal cord transection in rats. The abnormal expression of α1A^- and α1B^- AR mRNA in the heart and α1A^- ,α1D^-,α2B^- and α2c^-AR mRNA in the mesenteric artery may be related to AD.