# The Mechanism of Action of Stigmasterol in Bone Formation in Osteoporosis

## TL;DR

Stigmasterol improves bone formation in osteoporosis by activating a key signaling pathway that enhances osteoblast differentiation.

## Contribution

This study identifies the JAK2/STAT3 pathway as a novel mechanism through which stigmasterol promotes osteogenic differentiation and bone protection.

## Key findings

- Stigmasterol improved bone microarchitecture in ovariectomized rats and increased osteogenic marker expression.
- Stigmasterol promoted osteogenic differentiation of MC3T3-E1 cells in a dose-dependent manner.
- Network pharmacology and mechanistic studies revealed JAK2/STAT3 activation as the key pathway involved in stigmasterol's effects.

## Abstract

Osteoporosis (OP) is a metabolic bone disease characterized by reduced bone mass and impaired bone microarchitecture, significantly impacting patients’ quality of life. Stigmasterol (STG), a natural plant sterol, has been reported to possess multiple biological activities. However, its effects on OP bone formation and underlying molecular mechanisms remain unclear. The effects of STG on OP bone formation and potential mechanisms were investigated through in vivo and in vitro experiments combined with network pharmacology analysis. An OP model was established in ovariectomized (OVX) rats, and the bone-protective effects of STG were evaluated via micro-CT analysis and histological staining. In vitro experiments, MC3T3-E1 pre-osteoblasts were used to assess STG’s influence on osteogenic differentiation through Western blot analysis and ALP/ARS staining. Network pharmacology methods were used to predict potential targets and signaling pathways for STG in OP treatment, followed by mechanism validation. STG significantly improved bone microarchitecture in OVX rats, increased key osteogenic marker expression, and promoted MC3T3-E1 osteogenic differentiation in a dose-dependent manner. Network pharmacology analysis predicted 278 potential targets for STG in treating OP, with pathway enrichment analysis indicating significant involvement of the JAK/STAT pathway. Mechanistic studies revealed that STG promotes osteogenic differentiation by activating the JAK2/STAT3 signaling cascade. As an osteogenic promoter, STG effectively alleviates bone loss and enhances osteoblast differentiation by activating the JAK2/STAT3 signaling pathway.