Sucrose preference is restored by electro-acupuncture combined with chlorimipramine in the depression-model rats

The present study was to investigate the effect of electroacupuncture (EA) combined with chlorimipramine on the sucrose preference of depressive rats induced by chronic mild stress (CMS). Rats were exposed chronically (1st - 4th week) to a variety of mild unpredictable stresses. The tricyclic antidepressant chlorimipramine and EA were administrated on these depressive rats for 6 weeks (5th - 11th week). EA was applied at points of "Bai-Hui" (Du 20) and "An-Mian" (EX 17) (right side), by EA apparatus (Model 6805-2, Shanghai). Dense (60Hz/5sec)-sparse (4Hz/2.5sec) frequency of the wave was selected and the current intensity (< or = 1mA) was adjusted to provoke slight twitches of the rat's ear. The preference for 1% sucrose solution and the immobility time in the forced swimming test were measured as the symptoms of anhedonia and depressed mood, which were central features of major depression. The preference for 1% sucrose solution was reduced by CMS, but could be restored to normal level after 6 weeks treatment with chlorimipramine at 5mg/kg or EA combined with chlorimipramine at 2.5mg/kg. In the forced swimming test, the immobility time of depressive rats was decreased in both groups. However, the preference for sucrose and the immobility time in the depressive rats were not significantly changed by the treatment with only EA or chlorimipramine at 2.5 mg/kg. The results suggested that EA could potentiate the antidepressant effect of chlorimipramine in low dose, and EA combined with antidepressant might be a better method in treating depression.