Shenling Kaixin granules attenuate depression via multi-target mechanisms: evidence from CSDS model and cellular...

Major depressive disorder (MDD) is a highly prevalent, disabling psychiatric illness with multifactorial pathogenesis-including neurotransmitter imbalance, neuroinflammation, oxidative stress, and impaired neuroplasticity. Current pharmacotherapies have limited efficacy and are often accompanied by adverse effects, underscoring the need for safer, more effective interventions.

We evaluated the effects of Shenling Kaixin Granules (SLKX) on CSDS-induced depression-like behaviors in mice and systematically elucidated underlying mechanisms using complementary in vivo and in vitro approaches.

A CSDS mouse model was used to model depression-like behavior. Mice received various doses of SLKX for 28 days. Behavioral assessments, biochemical measurements, and molecular assays were performed to define pharmacological effects and implicated pathways. In addition, a corticosterone (CORT)-induced SH-SY5Y injury model was established, and the PI3K inhibitor LY294002 was applied to test the causal involvement of pathways identified in vivo.

The chemical profile of SLKX was characterized by UPLC-MS. Depression-like phenotypes were assessed via the sucrose preference, social interaction, elevated plus maze, light-dark box, and open field tests. Hippocampal neurotransmitters, cytokines, and oxidative-stress markers were quantified by ELISA. Western blot analyses measured key proteins in the PI3K/AKT/CREB-BDNF, TLR4/NF-κB, Nrf2/HO-1, and apoptotic cascades. Neuroinflammation, apoptosis, and hippocampal ultrastructure were evaluated by immunofluorescence, TUNEL staining, and transmission electron microscopy. Serum metabolite profiles were obtained by untargeted metabolomics. Furthermore, the CORT-induced SH-SY5Y model with LY294002 intervention was used to substantiate key pathways in vitro.

UPLC-MS identified 26 constituents in SLKX that may underlie its pharmacological activity. SLKX significantly attenuated weight loss and depression-like behaviors (anhedonia, social avoidance, anxiety-like behavior, and reduced exploration) and restored hippocampal neurotransmitter balance in CSDS mice. Mechanistically, SLKX activated Nrf2/HO-1 signaling and enhanced antioxidant capacity; inhibited TLR4/MyD88/NF-κB signaling and suppressed inflammatory cytokine release; blocked mitochondria-mediated apoptosis; promoted PI3K/AKT/CREB-BDNF activation and enhanced neuroplasticity; and corrected CSDS-induced serum metabolic disturbances. In vitro, SLKX-containing serum significantly ameliorated CORT-induced SH-SY5Y injury. Its antioxidant and neurotrophic actions depended on PI3K/AKT-mediated Nrf2 activation and enhancement of CREB/BDNF signaling, providing causal evidence.

SLKX exerts antidepressant effects by synergistically modulating neural-immune-endocrine-metabolic networks through multitarget mechanisms. Convergent findings from animal and cell studies support the core mechanisms of SLKX and lay an experimental foundation for its potential clinical application in depression.