Objective To observe the effect of electroacupuncture(EA)stimulation of"Shenmen"(HT 7)-"Tongli"(HT 5)segment of the Heart Meridian on neuronal electrical activities of hypothalamic paraventricular nucleus(PVN)in rats with myocardial ischemia(MI)

so as to investigate its possible mechanism underlying improvement of MI.Methods Thirty-two SD rats were randomly divided into sham control

model

HT 7-HT 5 and"Taiyuan"(LU 9)-"Lieque"(LU 7)groups(n=8 in each group).EA preconditioning(2 Hz

1 V

20 min)was applied to bilateral HT 7-HT 5 and bilateral LU 9-LU 7

respectively

once everyday for 7 days.The electrical activities of the right PVN region were recorded by the implanted microelectrode array(2×4)and Plexon multi-channel acquisition system.Cluster analysis of neuronal signals was carried out by Offline Sorter software.The discharge waveforms

autocorrelation and cross-correlation of neuronal activities were analyzed by using Neuro Explorer software.Results Cluster analysis of neuronal signals showed that 2

2

1 and 1 interneuron in the sham

model

HT 7-HT 5

and LU 9-LU 7 groups

and 3 pyramidal neurons in the HT 7-HT 5 were acquired.Cross correlation analysis showed that the SPK 02 aand SPK 02 bneurons of the HT 7-HT 5 group had an inhibitory relationship.The total discharge frequency was significantly increased in the model group relevant to the sham group(P<0.01)

and was markedly lower in the HT 7-HT 5 group than in the model group and LU 9-LU 7 group(P<0.01).Real-time spectrum analysis showed that the local field potential spectrum energy of the HT 7-HT 5 group was significantly lower than that of the model group and the LU 9-LU 7 group.Conclusion EA of HT 7-HT 5 segment of the Heart Meridian can inhibit the electrical activity of interneuron and activate the electrical activity of pyramidal neuron in PVN region

and an inhibitory relationship exists between the interneuron and pyramidal neuron in MI rats

which may be a mechanism of EA in regulating activities of the ischemic heart.