[Alteration of monoamine contents in microdialysate following droperidol enhanced electroacupuncture]

The monoamine contents in microdialysate from rat brain before and after droperidol (DRO), a dopamine (DA) antagonist, enhanced electroacupuncture-induced analgesia (EA) were measured using techniques of in vivo microdialysis and high performance liquid chromatography with electrochemical detection (HPLC-EC), so as to investigate the monoamine mechanism of the potentiating effect of DRO on acupuncture analgesia (AA). The results showed that the levels of DA and its metabolites homovanillic acid (HVA) in perfusate increased after EA (P < 0.05 or 0.01), and further increased after DRO + EA (P < 0.05 and 0.01, vs EA treatment). A significant decrease in norepinephrine (NE) content after EA (P < 0.01) was observed, but no further change after DRO + EA (P > 0.05, vs EA treatment). The contents of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) we elevated after EA treatment, and a further elevation in 5-HT and 5-HIAA contents induced by DRO + EA was noted. The results in the present study suggest that DRO potentiated AA not only via antagonizing the activity of dopaminergic system, but also by coordinating the activities of other monoamines in the brain.