摘要
BACKGROUND： Some studies suggest that the long-term potentiation （LTP） of synaptic transmission may be the basis for the neural synaptic plasticity of hippocampus, but can be evoked by various factors including electroacupuncture. OBJECTIVE： To observe the effect of electroacupuncture on the activities of basic synaptic transmission in dentate gyrus of hippocampus and the changes of high frequency stimulation （HFS） induced activity of synaptic transmission in cerebral ischemic injured rats. DESIGN： A randomized control trial.SETTING： Shenzhen Hospital of Traditional Chinese Medicine affiliated to Guangzhou University of Traditional Chinese Medicine. MATERIALS： Sixty healthy male Wistar rats, weighing 150-250 g, were provided by the Experimental Animal Center of Guangzhou University of Traditional Chinese Medicine. The experiment began after adaptation of environment for 1 week under standard experimental environment. The main experimental instruments included the programming electrical acupuncture apparatus （PCEA, product of the Institute of Acupuncture and Meridians, Anhui College of Traditional Chinese Medicine） and multichannel physiologic recorder （RM-86, Nihon Konden）. METHODS： The experiment was carried out in Guangzhou University of Traditional Chinese Medicine between July 2003 and July 2004. ①Embedding of brain electrodes： In reference of the Pellegrino＇s rat brain atlas, the bipolar electrode stimulator was embedded into the perforant path （PP） anterior to the entorhinal area with location coordinates of AP 7.5 mm, L 4.2 mm and H 3.0 mm, that is, 7.5 mm posterior to the anterior fontanelle, 4.2 mm laterally on the right side and 3.0 mm under the subcortex. The subcortex recorder electrode coordinates are AP 3.8 mm, L 2.5 mm and H 3.5 mm, located in the granular cell layer of the unilateral dentate gyrus （DG） of hippocampus, at the site of which an opening with the diameter of 1.5 mm was drilled for the purpose of embedding of the stimulating and recording electrodes, and at the site by mild adjusting the positions of these electrodes where maximal population spike （PS） was recorded, fastened the electrodes at last. ② The 60 rats were randomized into two major groups, namely, fundamental stimulation （FS） group （basic group） and high frequency stimulation （HFS） group. Each group was further divided into three subgroups respectively： Sham-operated subgroup （n=10）： only exposed bilateral common carotid arteries without blocking their blood flow; Cerebral ischemia model subgroup （n=10）： exposing bilateral common carotid arteries and blocking their blood flow; Ischemia plus electroacupuncture subgroup （n=10）： blocked blood flow of bilateral common carotid arteries and received electroacupuncture. The electroacupuncture acupoints were the points of Du meridian, including Baihui （GV20）, Dazhui （GV14）, and points of Pen meridian, including Qihai （CV6） and Guanyuan （CV4）. ③ Process of electroacupuncture： All the rats underwent testing stimulation （1/30 Hz frequency and 0.1 ms breadth） at 30 minutes before modeling, PS values were recorded as the indexes of the excitation of DG granular cell population, and the data were input to computer for data analysis. During the experiment, the intensity of stimulation was kept stable by adopting 1/2 the value of stimulation intensity that could induce maximal PS amplitude. In the basic group, PS were recorded for 120 minutes after modeling, and among the rats in the electroacupuncture group, PS was recorded at 10 minutes before and 60 minutes after blocking blood flow in the carotid artery during continuous electrical acupuncture. In the HFS group, HFS was given immediately after modeling, PS were recorded for 180 minutes at 10 minutes after HFS was given in the sham-operated group and model group, rats in the electroacupuncture group were treated with electroacupuncture for 60 minutes at 30 minutes after HFS was given, and PS was recorded for 180 minutes after 10 minutes. LTP was triggered by HFS and PS values were determined and recorded through measuring stimulations respectively 0, 10, 30, 60, 120 and 180 minutes after the evokes.④ Methods for expressing the level of synaptic transmission： Each testing stimulus provoked one PS, and 10 successive amplitude values （V/mV） were averaged relevant to a certain time cut. The averaged PS of 6 time cuts at 30 minutes before modeling was made as basal synaptic transmission level as control. Synaptic transmission at each time cut was expressed as： p=（ Vdifferentime cut / Vbasal） × 100%. MAIN OUTCOME MEASURES： The differences of synaptic transmission level were compared among the subgroups in the basic group after models also among the subgroups in the HFS group after HFS.RESULTS： All the 60 rats were involved in the analysis of results. ① Comparison of synaptic transmission level at different time cut after modeling and the effect of electroacupuncture in the subgroups of the basic group： The synaptic transmission level in the sham-operated subgroup had no significant change within 120 minutes （P 〉 0.05）. The synaptic transmission levels at 10, 30 and 60 minutes in the model subgroup were obviously lower than those in the sham-operated group [（60±7）%, （90±3）%, （93±4）%; （100±5）%, （102±6）%, （105±7）%, P 〈 0.05-0.01]. With the prolongation of time for ischemia/reperfusion, the synaptic transmission level gradually ascended to the normal level, and those at 90 and 120 minutes were close to those in the sham-operated group （P 〉 0.05）. In the subgroup of electroacupuncture, the synaptic transmission levels at 10, 30, 60, 90 and 120 minutes were obviously higher than those in the model subgroup [（93±5）%, （106±10）%, （123±16）%, （145±20）%, （168±25）%; （96±7）%, （98±8）%, P 〈 0.05-0.01].② Comparison of synaptic transmission level at different time cut after HFS and the effect of electroacupuncture in the groups： In the sham-operated group, the synaptic transmission level after HFS increased significantly, and maintained without decrease within 180 minutes. In the model group, the synaptic transmission level at 0, 10, 30, 60, 120 and 180 minutes after HFS were obviously lower than those in the sham-operated group [（60±7）%, （95±9）%, （138±11）%, （141±13）%, （140±13）%, （138±15）%; （100±6）%, （182±21）%, （179±18）%, （177±18）%, （175±23）%, （178±24）%, P 〈 0.01]. The synaptic transmission level at 60, 120 and 180 minutes after HFS in the electroacupuncture group were close to those in the sham-operated group （P 〉 0.05）, those at 120 and 180 minutes after HFS in the electroacupuncture group were obviously higher than those in the model group [（171±22）%, （181±25）%, P 〈 0.05-0.01]. CONCLUSION： Electroacupuncture could enhance the basic activity of synaptic transmission in the dentate gyros of hippocampus in cerebral ischemic injury in rats. Electroacupuncture has obvious LTP effect on the activity of synaptic transmission induced by HFS.
BACKGROUND： Some studies suggest that the long-term potentiation （LTP） of synaptic transmission may be the basis for the neural synaptic plasticity of hippocampus, but can be evoked by various factors including electroacupuncture. OBJECTIVE： To observe the effect of electroacupuncture on the activities of basic synaptic transmission in dentate gyrus of hippocampus and the changes of high frequency stimulation （HFS） induced activity of synaptic transmission in cerebral ischemic injured rats. DESIGN： A randomized control trial.SETTING： Shenzhen Hospital of Traditional Chinese Medicine affiliated to Guangzhou University of Traditional Chinese Medicine. MATERIALS： Sixty healthy male Wistar rats, weighing 150-250 g, were provided by the Experimental Animal Center of Guangzhou University of Traditional Chinese Medicine. The experiment began after adaptation of environment for 1 week under standard experimental environment. The main experimental instruments included the programming electrical acupuncture apparatus （PCEA, product of the Institute of Acupuncture and Meridians, Anhui College of Traditional Chinese Medicine） and multichannel physiologic recorder （RM-86, Nihon Konden）. METHODS： The experiment was carried out in Guangzhou University of Traditional Chinese Medicine between July 2003 and July 2004. ①Embedding of brain electrodes： In reference of the Pellegrino＇s rat brain atlas, the bipolar electrode stimulator was embedded into the perforant path （PP） anterior to the entorhinal area with location coordinates of AP 7.5 mm, L 4.2 mm and H 3.0 mm, that is, 7.5 mm posterior to the anterior fontanelle, 4.2 mm laterally on the right side and 3.0 mm under the subcortex. The subcortex recorder electrode coordinates are AP 3.8 mm, L 2.5 mm and H 3.5 mm, located in the granular cell layer of the unilateral dentate gyrus （DG） of hippocampus, at the site of which an opening with the diameter of 1.5 mm was drilled for the purpose of embedding of the stimulating and recording electrodes, and at the site by mild adjusting the positions of these electrodes where maximal population spike （PS） was recorded, fastened the electrodes at last. ② The 60 rats were randomized into two major groups, namely, fundamental stimulation （FS） group （basic group） and high frequency stimulation （HFS） group. Each group was further divided into three subgroups respectively： Sham-operated subgroup （n=10）： only exposed bilateral common carotid arteries without blocking their blood flow; Cerebral ischemia model subgroup （n=10）： exposing bilateral common carotid arteries and blocking their blood flow; Ischemia plus electroacupuncture subgroup （n=10）： blocked blood flow of bilateral common carotid arteries and received electroacupuncture. The electroacupuncture acupoints were the points of Du meridian, including Baihui （GV20）, Dazhui （GV14）, and points of Pen meridian, including Qihai （CV6） and Guanyuan （CV4）. ③ Process of electroacupuncture： All the rats underwent testing stimulation （1/30 Hz frequency and 0.1 ms breadth） at 30 minutes before modeling, PS values were recorded as the indexes of the excitation of DG granular cell population, and the data were input to computer for data analysis. During the experiment, the intensity of stimulation was kept stable by adopting 1/2 the value of stimulation intensity that could induce maximal PS amplitude. In the basic group, PS were recorded for 120 minutes after modeling, and among the rats in the electroacupuncture group, PS was recorded at 10 minutes before and 60 minutes after blocking blood flow in the carotid artery during continuous electrical acupuncture. In the HFS group, HFS was given immediately after modeling, PS were recorded for 180 minutes at 10 minutes after HFS was given in the sham-operated group and model group, rats in the electroacupuncture group were treated with electroacupuncture for 60 minutes at 30 minutes after HFS was given, and PS was recorded for 180 minutes after 10 minutes. LTP was triggered by HFS and PS values were determined and recorded through measuring stimulations respectively 0, 10, 30, 60, 120 and 180 minutes after the evokes.④ Methods for expressing the level of synaptic transmission： Each testing stimulus provoked one PS, and 10 successive amplitude values （V/mV） were averaged relevant to a certain time cut. The averaged PS of 6 time cuts at 30 minutes before modeling was made as basal synaptic transmission level as control. Synaptic transmission at each time cut was expressed as： p=（ Vdifferentime cut / Vbasal） × 100%. MAIN OUTCOME MEASURES： The differences of synaptic transmission level were compared among the subgroups in the basic group after models also among the subgroups in the HFS group after HFS.RESULTS： All the 60 rats were involved in the analysis of results. ① Comparison of synaptic transmission level at different time cut after modeling and the effect of electroacupuncture in the subgroups of the basic group： The synaptic transmission level in the sham-operated subgroup had no significant change within 120 minutes （P 〉 0.05）. The synaptic transmission levels at 10, 30 and 60 minutes in the model subgroup were obviously lower than those in the sham-operated group [（60±7）%, （90±3）%, （93±4）%; （100±5）%, （102±6）%, （105±7）%, P 〈 0.05-0.01]. With the prolongation of time for ischemia/reperfusion, the synaptic transmission level gradually ascended to the normal level, and those at 90 and 120 minutes were close to those in the sham-operated group （P 〉 0.05）. In the subgroup of electroacupuncture, the synaptic transmission levels at 10, 30, 60, 90 and 120 minutes were obviously higher than those in the model subgroup [（93±5）%, （106±10）%, （123±16）%, （145±20）%, （168±25）%; （96±7）%, （98±8）%, P 〈 0.05-0.01].② Comparison of synaptic transmission level at different time cut after HFS and the effect of electroacupuncture in the groups： In the sham-operated group, the synaptic transmission level after HFS increased significantly, and maintained without decrease within 180 minutes. In the model group, the synaptic transmission level at 0, 10, 30, 60, 120 and 180 minutes after HFS were obviously lower than those in the sham-operated group [（60±7）%, （95±9）%, （138±11）%, （141±13）%, （140±13）%, （138±15）%; （100±6）%, （182±21）%, （179±18）%, （177±18）%, （175±23）%, （178±24）%, P 〈 0.01]. The synaptic transmission level at 60, 120 and 180 minutes after HFS in the electroacupuncture group were close to those in the sham-operated group （P 〉 0.05）, those at 120 and 180 minutes after HFS in the electroacupuncture group were obviously higher than those in the model group [（171±22）%, （181±25）%, P 〈 0.05-0.01]. CONCLUSION： Electroacupuncture could enhance the basic activity of synaptic transmission in the dentate gyros of hippocampus in cerebral ischemic injury in rats. Electroacupuncture has obvious LTP effect on the activity of synaptic transmission induced by HFS.
