强啡肽A及其受体拮抗剂对大鼠脊髓损伤后脊髓血流量的影响

Effects of dynorphin A and its receptor antagonist on spinal cord blood flow after spinal cord injury to rats

目的：探讨强啡肽Ａ在脊髓损伤（ＳＣＩ）中的作用。方法：采用Ａｌｌｅｎ打击法复制大鼠ＳＣＩ模型，应用强啡肽Ａ放免检测技术和氢清除法分别测定伤段脊髓组织２４ｈ内强啡肽Ａ含量和脊髓血流量（ＳＣＢＦ）的变化，并观察脊髓蛛网膜下腔注射强啡肽Ａ及其受体拮抗剂ｎｏｒ－ＢＮＩ对ＳＣＢＦ的影响。结果：ＳＣＢＦ在伤后１０ｍｉｎ即有明显下降、２ｂ较１ｈ略有回升，４～８ｈ又进一步下降，两次下降相差显著；ＳＣＩ后脊髓蛛网膜下腔注射强啡肽Ａ可明显加剧脊髓缺血，而注射强啡肽受体拮抗剂ｎｏｒ－ＢＮＩ则可显著减轻脊髓缺血。脊髓强啡肽Ａ含量在伤后１０ｍｉｎ明显升高，１～２ｈ有所下降，但仍高于对照组，４，８ｈ较２ｈ略增加。强啡肽Ａ含量与ＳＣＢＦ的变化，两者呈显著相关性。结论：ＳＣＩ后强啡肽Ａ的过度释放是ＳＣＩ后继发性损伤的重要因素。

Objective: To probe into the effect of dynorphin A in spinal cord injury(SCI). Methods: The alteration of spinal cord blood flow (SCBF) and dynorphin A in the injury site were studied using a rat SCI model induced by Allen's weight drop method (50 g/cm) , and dynorphin A and its receptor antagonist nor-binaltorphimine(nor-BNI) were infused into the spinal subrachnoid space adjacent to the trauma site.Results: After SCI,the SCBF were significantly reduced at 10 min and further reduced at4～8 h. Administration of dynorphin A significantly accentuated the reduced SCBF while administration of its receptor antagonist nor-BNI significantly diminished the reduced SCBF. Dynorptin A level was significantly increased at 10 min. The dynorphin A was decreased in 1, 4 and 8 h as compared with 10 min, but it was increased as compared with control group. The significant correlation between SCBF and dynorphin A concentration was found. Conclusion: The increased dynorphin A postinjury could be the cause of microcirculatory disturbance and secondary damage in SCI.