Effects of Electroacupuncture at Auricular Concha Region on the Depressive Status of Unpredictable Chronic Mild Stress Rat Models

To explore new noninvasive treatment options for depression, this study investigated the effects of electroacupuncture (EA) at the auricular concha region (ACR) of depression rat models. Depression in rats was induced by unpredictable chronic mild stress (UCMS) combined with isolation for 21 days. Eighty male Wistar rats were randomly assigned into four groups: normal, UCMS alone, UCMS with EA-ACR treatment, and UCMS with EA-ear-tip treatment. Rats under inhaled anesthesia were treated once daily for 14 days. The results showed that blood pressure and heart rate were significantly reduced in the EA-ACR group than in the UCMS alone group or the EA-ear-tip group. The open-field test scores significantly decreased in the UCMS alone and EA-ear-tip groups but not in the EA-ACR group. Both EA treatments downregulated levels of plasma cortisol and ACTH in UCMS rats back to normal levels. The present study suggested that EA-ACR can elicit similar cardioinhibitory effects as vagus nerve stimulation (VNS), and EA-ACR significantly antagonized UCMS-induced depressive status in UCMS rats. The antidepressant effect of EA-ACR is possibly mediated via the normalization of the hypothalamic-pituitary-adrenal (HPA) axis hyperactivity.