| Ischemic cerebrovascular disease, causing the highest incidence, mortality and mutilation, leads to hypoxic-ischemic neuronal damage and neurologic impairment. Acute cerebral ischemic areas generally contain severe central area and peripheral penumbra area where pathological characteristics are cell apoptosis. Neuron apoptosis after ischemia-reperfusion involves different mechanisms mainly including the exitotoxicity of excitatory amino acids, calcium overload, oxygen-derived free radicals and nitric oxidate . Among these mechanisms exitotoxicity is the most capital link. However, excitatory amino acids (glutamicacid chiefly) act only through the activation of the excitatory amino acids receptors on postsynaptic membrane. Therefore the core of exitotoxicity is the activation of the excitatory amino acids receptors. In the brain of rats, ionic type excitatory amino acids receptors that are also called ligand gating include AMPA, KA and NMDA receptors. In some studies, NMDAR1(subunit of NMDA receptor) and GluR-2 (subunit of AMPA receptor) play an importance role in cell apoptosis. The brain injury mediated by increase of NR1 and decrease of GluR-2 are characterized by the intra-flow of Ca2 +, which may last from several hours to several days and thereby the treatment time is much longer. Penumbra area may converse into normal perfusion area under some anti-apoptosis factors. The most widely applied ischemic model is middle cerebral artery occlusion (MCAO) of rats, which is similar to embolism of human beings on pathological changes and behavior. Electroacupuncture (EA) is a tradional therapeutic method in China. In some studies, while EA stimulation was applied at the anatomical points of"Shuigou"and"baihui", it has been shown to exert such therapeutic effects as reduction of speech retardment, improvement of locomotion and enhancement of memory on patients subjected to stroke. In this study, we proposed to investigate the thereputic effect of EA on the brain ischemia of rat MCAO model, and estimate the results by use of immuno- histochemistry, western-blot and the technique of RT-PCR.Experimental esults were as follow: (1) The result of praxiology: According to Longa's neurological deficits score system, no neurological impairment was found in Sham group and control group; Rats in MCAO group showed the symptome of neurological deficits such as failure to extend left forepaw fully, circling to the left, falling to the left and without spontaneous walk. The neurological deficit score of EA group is significantly lower than that of MCAO group (P<0.01); (2) Result of immuno-histochemistry: the number of GluR2 immuno-positive neurons were not changing in CA1 area of rat hippocampus of sham and control groups(P>0.05), but was decreased in that of ischemia group ( P<0.05 ) . The number of GluR2 immuno-positive neurons was increased in CA1 area of rat hippocampus of acupuncture group, but it was less than that of sham group(P<0.05); On other hand, The number of NR1 immuno-positive neurons was not changed in CA1 area of rat hippocampus of sham group and control group(P>0.05), but increased in that of ischemia group(P<0.05). The number of NR1 immuno-positive neurons was decreased in CA1 area of rat hippocampus of acupuncture group, but it is still more than that of sham group(P<0.05). (3) Results of western-blot and RT-PCR: They were basically coincident with the results of immunohistochemistry.In summing up, the result of this study suggests that the mechanisms involved in the neuroprotection by EA in cerebral ischemia may be due to the up-regulation of GluR2 and down-regulation NR1 expression, which may protect the neurons of hippocampus of rat from glutamate neurotoxicity. |
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