The effect of electroacupuncture (EA) on TRPM7 mRNA expression of focal cerebral ischemia in rats and further the role of EA in the relationship between TRPM7 and trkA pathway was investigated. Thirty SD rats were randomly divided into 5 groups : normal group, ischemia/reperfusion group, EA treated group (ischemic rats with EA treatment), TE infusion group (ischemic rats with EA treatment and TE buffer infusion),AS-ODN group (ischemic rats with EA treatment and antisense trkA oligonucleotide infusion). The stroke animal model was established by the modified method of middle cerebral artery occlusion. Antisense trkA oligonucleotide that blocked NGF’s effects was injected into cerebroventricle before EA. The TRPM7 mRNA was detected by RT-PCR method. The results showed that there were low TRPM7 mRNA levels in cortex and hippocampus in normal group. Compared with normal group, TRPM7 mRNA expression was increased significantly in ischemia/reperfusion group (P<0.05). A significant reduction in the expression of TRPM7 mRNA was found in EA treated group in contrast to ischemia/reperfusion group (P<0.05). The expression of TRPM7 mRNA in AS-ODN group was remarkably increased compared with EA treated group and TE infusion group (P<0.05). The results indicated that TRPM7 channels in the ischemic cortex and hippocampus in rats might play a key role in ischemic brain injury. EA could reverse the overexpression of TRPM7 in cerebral ischemia/reperfusion rats. And the inhibitory effect of EA on TRPM7 channels might be through trkA pathway.
To study the protective effect of rosuvastatin on ischemic brain injury and its mechanism, focal cerebral ischemia/reperfusion was induced by occlusion of the middle cerebral artery (MCA) using the intra-luminal filament technique. The cerebral blood flow was monitored with la-ser-Doppler flowmetry (LDF). The slices of brain tissue were stained with cresyl-violet. The cerebral volume of infarction and edema were quantified with ImageJ software. The expressions of endothe-lial NO synthase (eNOS) and activated caspase-3 were detected with Western blot. The inducible NO synthase (iNOS) positive cells were immunohistochemically observed. The results demonstrated that rosuvastatin (20 mg/kg) could remarkably decrease infarct volume and cerebral edema after MCAO 90 min/reperfusion 24 h. Western blots showed that the expression of eNOS in cerebral cortex be-fore and after ischemia was (100±43.3) %, (1668.9±112.2) % respectively (P<0.001), rosuvastatin significantly up-regulated the expression of eNOS in non-ischemic cortex (P<0.001), whereas in ischemic cortex of rosuvastatin group the expression of eNOS was (1678.8±121.3) % . There was no expression of activated caspase-3 in non-ischemic cortex,nonetheless the expression of activated caspase-3 increased after ischemia, and rosuvastatin significantly diminished it (P<0.01). Immuno-histochemistry revealed no iNOS-positive cells in non-ischemic brain area, while in ischemic brain area the number of iNOS positive cells went up,and rosuvastatin could significantly reduced them. Consequently, the mechanisms of rosuvastatin’s neural protection on ischemic brain injury are to en-hance expression of eNOS, to inhibit expression of iNOS and activated caspase-3.
To investigate whether glutamate and voltage-gated calcium channels-independent calcium influx exists during acute anoxic neuronal damage and its possible relationship to neuronal protective function of NGF. In in vitro model of acute anoxia, hippocampal cultures from newborn rats were exposed to 3 mmol/L KCN. Changes of intracellular Ca2+ concentration ([Ca2+]i) were monitored by con-focal imaging and cell viability was assayed by PI and cFDA staining. The results showed that after treatment with primary hippocampal cultures with 3 mmol/L KCN for 15 min, [Ca2+]i was significantly increased 6.27-fold compared to pre-anoxia level and 73.3% of the cells died. When combination of 20 μmol/L MK-801 (glutamate receptor antagonist), 40 μmol/L CNQX (AMPA receptor antagonist) and 5 μmol/L nimodipine (voltage-gated calcium channel antagonist) (hereafter denoted as MCN) were administrated to hippocampal cultures, levels of [Ca2+]i and cell death rate induced by KCN were partially reduced by 35.9% and 47.5% respectively. However, Gd3+ (10 μmol/L) almost completely blocked KCN-mediated [Ca2+]i elevation by 81.9% and reduced neuronal death by 88.8% in the presence of MCN. It is noteworthy that NGF, used in combination with MCN, inhibited KCN-induced [Ca2+]i increase by 77.4% and reduced cell death by 87.1%. Only PLC in- hibitor U73122 (10 μmol/L) abolished NGF effects. It is concluded that Gd3+-sensitive calcium influx, which is NMDA (glutamate receptor) and voltage-gated calcium channels-independent, is responsible for acute anoxic neuronal death. NGF can inhibit Gd3+-sensitive calcium influx and reduce anoxic neuronal death through activating PLC pathway.
