Astragaloside Ⅳ ameliorates C-band electromagnetic radiation-induced anxiety-like behavior in mice by targeting microglial CCL2/CCR2 signaling axis

To investigate the neuroinflammatory mechanism underlying C-band electromagnetic radiation (EMR)-induced anxiety-like behavior in mice and the protective effect of Astragaloside Ⅳ (AS-Ⅳ).

A mouse model of electromagnetic exposure was established using a 10 mW/cm² C-band EMR source. Anxiety-like behaviors were assessed using the open field test and the elevated plus maze test. The expression levels of the M1-type pro-inflammatory factor C-C motif chemokine ligand 2 (CCL2), C-C chemokine receptor 2 (CCR2), and the transcription factor early growth response protein 1 (EGR-1) in the mouse cortex and BV2 microglial cells were detected by RT-PCR and Western blotting. Bioinformatics analysis was conducted to predict potential binding sites for transcription factor EGR-1 in the promoter regions of the CCL2 and CCR2 genes while siRNA knockdown was used to verify the regulatory role of EGR-1 inCCL2/CCR2 expression. Different doses of AS-Ⅳ were administered prophylactically to mice for 14 days prior to EMR to find out whether it could antagonize EMR-induced anxiety-like behavior and suppress the activation of the EGR-1/CCL2/CCR2 pathway.

C-band EMR exposure induced anxiety-like behavior in mice, as evidenced by significantly reduced entries into and time spent in the center zone of the open field test and the open arms of the elevated plus maze (vs. control). Compared with the control group, the mRNA and protein levels of CCL2 and CCR2 in the mouse cortex were significantly upregulated 24 hours after EMR exposure while EGR-1 expression levels in the mouse cortex and BV2 cells were significantly increased 3 hours after EMR exposure. Knockdown of EGR-1 expression significantly suppressed the upregulation of CCL2 and CCR2 in the BV2 cell line. Prophylactic administration of medium and high doses of AS-Ⅳ significantly ameliorated anxiety-like behavior in EMR-exposed mice and restored the expression levels of EGR-1, CCL2, and CCR2 in the cortex to near-normal levels.

C-band electromagnetic radiation can activate the transcription factor EGR-1, which upregulates the CCL2/CCR2 signaling axis and induces cortical neuroinflammation, ultimately mediating anxiety-like behavior in mice. Astragaloside Ⅳ (AS-Ⅳ) exerts anti-inflammatory and anxiolytic effects by antagonizing the activation of the EGR-1/CCL2/CCR2 pathway.