[Electroacupuncture alleviates facial nerve injury-induced anxiety-like behavior by raising the excitability of glutamatergic neurons in the anterior cingulate cortex of mice].

Abstract

Objectives: To investigate the effect and mechanism of electroacupuncture (EA) at "Siguan" acupoints (bilateral Hegu [LI4] and bilateral Taichong [LR3]) in ameliorating facial nerve injury-induced anxiety-like behavior in mice.

Methods: Thirty male C57BL/6J mice were randomly divided into control, model (unilateral facial nerve injury), and EA groups, with 10 mice in each group. The facial nerve injury model was established by lightly clamping the isolated facial nerve for about 30 s, twice altogether after operation. The mice of the EA group were subjected to EA stimulation (2 Hz, 0.5 mA) of bilateral LI4 and bilateral LR3 for 30 min, once per day for consecutive 7 d. The anxiety-like behavior of mice was evaluated by light-dark chamber (LDC) and elevated plus maze (EPM) tests after EA intervention. The calcium activity of glutamatergic neurons in the anterior cingulate cortex (ACC) was analyzed by fiber photometry. The intrinsic excitability level of ACC glutamatergic neurons was estimated by using whole-cell patch clamp recording.

Results: Compared with the control group, the dwell time in the light chamber and the number of entries into the light chamber of LDC tests, and the dwell time in the open arms and the number of entries into the open arms of the EPM tests were significantly decreased in the model group (P<0.01). In comparison with the model group, the dwell time in the light chamber and the number of entries into the light chamber, and the dwell time in the open arms and the number of entries into the open arms were significantly increased in the EA group (P<0.01, P<0.05). Results of fiber photometry showed a decreased activity of ACC glutamatergic neurons when the mice moved from the closed arm to the open arm in an EPM, a decrease of input resistance and the number of discharge spikes induced by 300 pA current injection in the model group (P<0.05, P<0.01). Compared with the model group, the excitability of the glutamatergic neurons, input resistance and the number of discharge spikes (induced by 300 pA current injection) were considerably increased in the EA group (P<0.05).

Conclusions: EA of "Siguan" acupoints alleviates the facial nerve injury-induced anxiety-like behavior, probably by decreasing the excitability of glutamatergic neurons in the ACC.