The study of the spinal amino acid release and pain related response in modulating hyperalgesia

背景：周围组织损伤后的痛觉过敏可能是通过上调脊髓软木塞的突触传递来调节的。本研究旨在探讨在福尔马林实验中，PKC和N型钙通道阻断剂对脑脊液氨基酸是否有类似的痛反应调节作用。方法：在大鼠右侧下巴皮下注射5%福尔马林50μ1，于鞘内置入PE-10导管和环状微透析探头。之后，观察到与谷氨酸、牛磺酸和GABA的透析间隔10分钟有关的卡痕。结果：注射福尔马林后观察到卡口的双相增加；阶段1(最大11卡口/分钟。在1分钟。)和阶段2(在30-45分钟时最大值为18)。脑脊液谷氨酸和牛磺酸在前10min短暂升高，30min时谷氨酸升高暂时降低。结论：ω-CGTx抑制与抑制谷氨酸释放有关的第一时相，提示吗啡对这两个时相均有抑制作用，提示N型钙通道可能调节C纤维激活(急性疼痛)引起的神经递质释放。相反，星状孢子素抑制第二时相而不抑制谷氨酸的释放可能是通过激活脊髓突触后部位的PKC来维持痛觉过敏的。

Background ; Hyperalgesia following peripheral tissue injury may be mediated by up-regulated synaptic transmission of spinal cork. The present study was examined to investigate whether manipulation by inhibitors for PKC and N-type Ca cannel modulate similar pain-related response in relation to CSF amino acids in formalin test. We also compared characteristics of fasions with morphine in modulating hyperalgesia.Methods ; Tress days after intrathecal implantation of PE-10 catheter along with loop-type microdialysis probe in Sprague-Dawley rate, 50 μ1 of 5% formalin was subcutaneously injected into right chin of the rat. Thereafter, clinches were observed related to 10 min.-intervals of dialysis for glutamate, taurine and GABA by HPLC-ECD for 60min.Results ; Biphasic increases of clinches after injection of formalin were observed ; phase 1 (max.11 clinches/min. at 1 min.) and phase 2 (max.18 at 30-45 min.). CSF glutamate and taurine was transiently increased during first 10 min, and this increase of glutamate was temporary decreased at 30 min.Conclusion ; the present results clearly demonstrated than the ω-CgTx inhibits the first phase of flinches related to suppression of glu release, which referred to inhibition of both phases with morphine, suggesting N-type Ca channel may regulate neurotransmitter release evoked by C fiber activation (acute pain). In contrast, the inhibition of second phase of flinches without suppression of glutamate release by staurosporine may be that hyperalgesia may be maintained by PKC activation at postsynaptic site of spinal cord.