Electroacupuncture to point Baihui confers anxiolytic effects by promoting oxytocin release from PVN in Mice

BACKGROUND: Anxiety disorders-including generalized anxiety disorder, posttraumatic stress disorder, and social anxiety disorder-are highly prevalent psychiatric conditions that impose substantial clinical and social burdens. Preclinical and clinical studies have shown that electroacupuncture (EA) can effectively alleviate anxiety-like behaviors; however, the specific neural circuits and molecular mechanisms underlying EA's therapeutic effects remain incompletely elucidated. METHODS: We first assessed the impacts of EA at four classical acupoints-Zusanli (ST36), Neiguan (PC6), Tianshu (ST25), and Baihui (GV20)-delivered with distinct stimulation waveforms on anxiety-like behaviors in conventionally housed mice, using the elevated plus maze and open field test paradigms. To identify the neural circuit underlying the behavioral effects of Baihui (GV20) EA, we employed pseudorabies virus expressing enhanced green fluorescent protein (PRV-EGFP) for retrograde tracing from Baihui (GV20) and quantified c-Fos expression across the whole brain as a marker of neuronal activation. ELISA was utilized to measure plasma oxytocin (OXT) levels following EA at Baihui (GV20). Furthermore, a selective pharmacological antagonist of the oxytocin receptor (OXT-R) was administered to verify the critical role of OXT signaling in mediating the anxiolytic benefits of Baihui (GV20) EA. RESULTS: EA at GV20 using intermittent electrical wave stimulation exhibited the most robust anxiolytic effects compared to EA at other acupoints or alternative stimulation parameters. Retrograde virus tracing from GV20 revealed a direct neuronal connection between the PVN and the GV20 acupoint region. Further experiments showed that GV20 EA significantly increased the activation of OXT-synthesizing neurons in the PVN and elevated peripheral OXT concentrations in mouse plasma. Critically, intraperitoneal injection of an OXTR antagonist completely abrogated the anxiolytic effects of GV20 EA, confirming that OXT signaling is indispensable for this therapeutic action. CONCLUSIONS: Intermittent 1.5 mA EA at Baihui (GV20) mitigates anxiety-like behavior in mice via a PVN-derived, OXT-dependent pathway. This work clarifies the anatomical and molecular mechanisms underlying EA-mediated anxiety relief and provides a basis for further exploring functional connections between specific acupoints and brain regions.