Icariin ameliorates sarcopenia via activation of the estrogen receptor α/fatty acid transport protein 1 pathway.

BACKGROUND

Sarcopenia is a prevalent disorder among postmenopausal women, representing a debilitating condition with limited treatment options. Icariin (ICA), a prenylated flavonol glycoside, is commonly used in conditions associated with estrogen deficiency; however, its efficacy and mechanism in postmenopausal sarcopenia remain undefined.

PURPOSE: This study aimed to evaluate the therapeutic effect of ICA on postmenopausal sarcopenia and to elucidate its underlying mechanism, with a focus on the estrogen receptor α/fatty acid transport protein 1 (ERα/FATP1) pathway.

STUDY

DESIGN

An integrated approach was employed, combining in vivo pharmacological evaluation, multi-omics analyses, and in vitro mechanistic validation.

METHODS

The in vivo therapeutic effect of oral ICA was assessed by evaluating muscle function, histology, and senescence markers. Human muscle transcriptome datasets and mouse single-cell RNA sequencing data were analyzed. In vitro validation was performed in D-galactose-induced senescent C2C12 myoblasts. Target engagement was confirmed by molecular docking, cellular thermal shift assay, and surface plasmon resonance, and mechanistic validation was performed via FATP1 knockdown.

RESULTS

Oral administration of ICA significantly improved muscle mass, function, and fiber cross-sectional area, while attenuating lipid deposition and cellular senescence. Single-cell RNA sequencing revealed a diminished myoblast pool with downregulated ERα in aged muscle. This finding aligns with human transcriptome data, linking reduced ERα/FATP1 signaling and dysregulated fatty acid metabolism to sarcopenia. Metabolomic analysis identified FATP1 as a critical transporter of eicosapentaenoic acid and docosapentaenoic acid, which activated the protein kinase B/ mammalian target of rapamycin pathway to promote myogenesis. Importantly, ICA functioned as a dual-target agonist, directly binding to and upregulating both ERα and FATP1, thereby elevating eicosapentaenoic/ docosapentaenoic acid levels and reactivating the protein kinase B/ mammalian target of rapamycin/ myogenic differentiation 1 axis. The specificity of this pathway was confirmed, as FATP1 knockdown completely abrogated the protective effects of ICA.

CONCLUSION

This study identifies the ERα/FATP1 axis as a pivotal therapeutic target for sarcopenia. ICA, acting as a first-in-class dual agonist of this pathway, represents a promising candidate for sarcopenia treatment by synchronously modulating estrogen signaling and fatty acid metabolism.