In order to stuy on the activity changes of catecholamine(CA) neurons depending on different patterns of low frequency electroacupuncture(EA) treatment, the experimental animals were divided into three groups as follows: 1) low frequency(4㎐) positive monophasic rectangular wave(M+), 2) low frequency negative monophasic rectangular wave(M-) and 3) low frequency biphasic rectangular wave(BI). The EA treatment was applied into the Zusanli point and stimulation was continued for 2 hours under light inhalation anethesia. The activities of CA neurons in brain stem indirectly evaluated by the ratio of colocalization between Fos positive neuron and tyrosine hydroxylase(TH) or dopamine beta hydroxylase(DβH) containing neurons using double immunohistochemical technique. The results have been summarized as follow:
1. TH containing neurons were distributed at dorsal raphe(DR), locus coeruleus(LC) and arcuate nucleus(Arc). In low frequency EA terated groups, activity of TH containing neuron was significantly increased by BI treatment in DR, LC and Arc as compared with that of control group. TH containing neurons were also activated by M+ treatment in DR and Arc. Moreover, M- treatment increased activity of TH containing neuron in Arc as compared with that of control group.
2. D β H containing neurons were distributed in LC, A5 and A7. At low frequency EA treatment, activity of D β H containing neuron was significantly increased by BI treatment in LC. Furthermore, both BI and M+ treatment significantly increased D β H containing neuronal activity in A5 as compared with that of control group.
The results indicate that low frequency EA treatments effectively increase the activity of CA neurons in the different manner. Furthermore, BI treatment was more potent in activating CA neurons rather than M+ or M- EA treatment. These data suggest that the analgesic effect of low frequency EA depends on the catecholaminergic pathway of endogenous pain control system. Moreover, these data can be applied to establish the effective therapeutic method of EA for pain control in the clinical field.
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