This preclinical systematic review and meta-analysis examined the effects of Shu Nan San, a classic traditional Chinese medicine herbal formula traditionally used to soothe liver qi stagnation, on depression-related behaviours in animal models. Researchers searched seven databases for studies published up to December 2025, ultimately including 28 studies involving 384 animals.
Three standard behavioural tests were analysed: the sucrose preference test, the forced swim test, and the tail suspension test. Across all three measures, Shu Nan San treatment was associated with meaningful improvements — animals showed greater preference for sucrose (suggesting reduced anhedonia) and spent less time immobile in both swim and suspension tests (suggesting reduced behavioural despair). These effects were accompanied by increases in monoamine neurotransmitters, reductions in hypothalamic-pituitary-adrenal axis hormones, and decreases in pro-inflammatory cytokines, pointing to plausible biological pathways.
However, the authors urge caution. The included studies showed substantial heterogeneity, notable risk of bias, and insufficient characterisation of the herbal constituents used. Publication bias was also assessed and adjusted for using statistical methods. The evidence was therefore considered hypothesis-generating rather than conclusive, and the authors stress that findings from rodent models cannot be directly extrapolated to human clinical practice without further rigorous investigation.
Conclusion: Shu Nan San demonstrates promising antidepressant-like pharmacological effects in animal models, but well-designed clinical trials are needed before any firm conclusions about human efficacy can be drawn.
Source: Wang Y, Wang Q, Xie H and colleagues. Frontiers in pharmacology (2026). View on PubMed (PMID 42922959) · doi:10.3389/fphar.2026.1818197
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