Experimental Research On Modulation Of Acupuncture On Extracellular Neuronal [Ca～(2+)]i Signal Transduction Mechanism In Rat Hippocampal CA1 Region During Cerebral Ischemia Reperfusion

Objective:To study the dynamic changes and extracellular signal transduction on hippocampus CA1 neuron [Ca²⁺]i during cerebral ischemia reperfusion, and the "XNKQ " acupuncture's intervention influence on it in MCAO rats.Methods :We examined the dynamic changes of the content of intracellular calcium during cerebral ischemia reperfusion and observed the intervention effect of acupuncture on the modultion of ischemic calcium accumulation , via using "XNKQ" acupuncture as an intervention method , technique of confocal laser scanning microscope(CLSM) and double fluorescent labeling, and established acute cerebral ischemia reperfusin rat model via middle cerebral artery occlusion by nylon suture as research object. We also used CLSM to examine the changes of [Ca²⁺]i during cerebral ischemia reperfusion in the brain slice of hippocampal CA1 region after intracerebroventricular injection of different membrane calcium channels antagonists, so as to indicate the extracellular calcium signal transduction and effects of acupuncture on it.Results:1. Compared with the control group, sham operated group has no difference (P>0.05). The neuron [Ca²⁺]i of hippocampus CA1 regions in the rat began to increase after ischemia 1h, and sustained to elevate after reperfusion , at 6h of ischemia reperfusion time course the [Ca²⁺]i elevated at the highest level. Then the [Ca²⁺]i became to decrease, however is still higher than that before CIR. While at 24h of CIR time course the [Ca²⁺]i elevated at the second peak of calcium accumulation, but is lower than 6h time course.2. Compared with the model group, there's no difference between non-acupoint group and model group at the same time point (P>0.05). Both "XNKQ" acupunctureand traditional acupuncture could decrease the ischemic accumulation of calcium of any time course during cerebral ischemia reperfusion (P<0. 01, P<0. 05). But the inhibitory effect to Ca2+overloading of "XNKQ" acupuncture is obviously better than that of traditional acupuncture and non-acupoint gruop (P<0. 05, P<0. 01) .3. After inhibit different membrane calcium channels: [Ca2+]j in hippocamal neurons in both sham operated and XNKQ groups have no sigmficantly changes before and after medication (P>0.05), voltage-gated calcium channel and receptor-gated channels of glutamate respectively, except for GYKI 52466, compare with control group, intracellular Ca2+ fluorescent intensity of model group are significantly decreased, however, still higher than sham operation group; L-VGCC antagonist (Nitrendipine) and NMD A receptor antagonist(MK-801) can significantly inhibited the ischemic Ca2+ accumulation in the CA1 region (P<0.01) . Nitrendipine and MK-801 have greater effect to decrease the calcium indensity than MPCG (P<0.05). At the same time, though non-competitve AMPA antagonist GYKI 52466 can reduce the level of calcium, but the difference have no significance compared to vehicle. The [Ca2+]; of acupuncture is sigmficantly lower than that of the model group after ICV administration (PO.05).Conclusion:1. The [Ca2+];had increased sustainedly during cerebral ischemia reperfusion, at 6h of CIR, the Ca2+ elevated at the peak level.2.The "XNKQ" acupuncture could regulate the content of intracellular calcium of the region of ischemia and reperfusion, inhibited Ca + overloading, and maintained the calcium homeostasis, so as to protect neurons from injury of brain ischemia reperfusion.3. The inhibitory effect to Ca2+ overloading of "XNKQ" acupuncture is better than that of traditional acupuncture.4.The enhanced ischemia-induced Ca2+ accumulation of neuron cells in the hippocampal CA1 region is mediated mainly via activation f both VGCC and NMDA receptors. And activation of mGluRs also participated in the pathological...