Research on the effects and preliminary mechanism of action of Shaoyao Gancao granule on hypothalamic-pituitary-adrenal axis and T lymphocytes in stressed alopecia areata mice.

Objective: To investigate the effect and mechanism of Shaoyao Gancao granule (SGG, ) on the hypothalamic-pituitary-adrenal (HPA) axis and immune imbalance status in stressed alopecia areata (AA) mice, and to provide an objective experimental basis for the clinical application of SGG.

Methods: Seventy female C57BL/6J mice aged 5-7 weeks were randomly divided into two groups: 10 mice in the blank control group and 60 mice in the mock group. The moulding group received topical imiquimod cream in combination with chronic unpredictable mild stress. On day 10, the moulding group was further divided into six groups: Shaoyao Gancao granule low-dose (SGL), Shaoyao Gancao granule medium-dose (SGM), Shaoyao Gancao granule high-dose (SGH), Antalarmin, and compound glycyrrhizin (CG). On day 24, overall and trichoscopic photographs of mice were taken on day 24 of the experiment; behavioral tests were completed; serum corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and cortisol levels were measured by enzyme-linked immunosorbent assay; and T helper cell (Th)1/Th2 and Th17/Treg cell differentiation in peripheral blood T lymphocyte subpopulations was detected by flow cytometry.

Results: The dorsal skin lesions of mice in all SGG groups showed faster hair growth, less dilated skin capillaries, and scaly conditions compared with those in the model group. In the open field test, compared with those of the model group, the moving distance and number of uprights and entries into the central area of the mice in the SGM and SGH groups significantly increased (P < 0.05), while in the forced swimming test, compared with the model group, the rest time of the mice in the SGL, SGM, and SGH groups significantly decreased (P < 0.05). The enzyme-linked immunosorbent assay results showed that, compared with the model group, the mice in the SGH group had significantly reduced CRH levels (P < 0.05), and the ACTH and cortisol levels in the SGM and SGH groups were significantly reduced (P < 0.05). The flow cytometry results showed that, compared with those in the model group, Th2 levels were significantly higher (P < 0.05), Th17 levels were significantly lower (P < 0.05), the Th1/Th2 ratio was significantly lower (P < 0.05), and the Th17/Treg ratio was significantly lower (P < 0.05) in the SGM and SGH groups. The Th1 and Treg cell ratios were reduced in all SGG groups, but the difference was not statistically significant.

Conclusion: SGG may exert therapeutic effects in AA by modulating the HPA axis and regulating immune imbalance.