Diosgenin reduces bone loss through the regulation of gut microbiota in ovariectomized rats

Diosgenin (DIO) is an aglycone of steroid saponins acquired from plants, including Dioscorea alata, Smilax China, and Trigonella foenum graecum, acting as an anti-osteoporosis, anti-diabetic, anti-hyperlipidemic, anti-inflammatory. Recent studies have demonstrated that DIO reduces bone loss. This study aimed to investigate the effects of DIO on the gut microbiota (GM) of ovariectomized (OVX) osteoporotic rats. Female Sprague-Dawley rats were randomly divided into sham operation (sham + vehicle group) or ovariectomy. For 12 weeks, OVX rats were treated using a vehicle (OVX + vehicle group) and DIO (OVX + DIO group). Subsequently, ELISA was conducted to determine serum estradiol levels, micro-CT scanning was performed to evaluate bone quality, and feces were collected for metagenomics sequencing to examine the structure and function of GM. Raw reads were filtered to remove chimera sequences. Operational taxonomic units (OTUs) were clustered in the filtered reads. A Venn diagram analysis was conducted to study the common and unique OTUs in the sham + vehicle, OVX + vehicle, and OVX + DIO groups. LEfSe analysis was conducted to evaluate the specific GM of the three groups. The GM functions were analyzed using the KEGG and CAZy databases. After a 12-week treatment, DIO administration prevented OVX-induced weight gain and increased the estradiol levels. DIO treatment improved the bone microstructure and structural parameters of rat tibias. Metagenomics sequencing results identified 1139, 1207, and 1235 operational taxonomic units (OTUs) in the sham + vehicle, OVX + vehicle, and OVX + DIO groups, respectively. The percentage of common OTUs was 41.2%. Treatment with DIO restored the composition of GM in OVX rats by increasing the abundance of Coriobacteriia Adlercreutzia, Romboutsia, and Romboutsia_idealis and reducing the abundance of Betaproteobacteria, Gammaproteobacteria, Methanobacteria, Bacteroides, Phocaeicola, Alistipes, Bacteroids_uniformis, Bacteroids_xylanisolvens. The anti-osteoporosis effect of DIO can be regulated through environmental information processing, organismal Systems, Cellular Processes, human diseases, metabolism, and genetic information processing. Meanwhile, treatment with DIO improved GM homeostasis by increasing the metabolism of carbohydrates, other amino acids, and glycans and reducing translation, energy metabolism, and nucleotide metabolism. DIO can reduce bone loss by regulating the structural composition and function of GM, a novel strategy for preventing osteoporosis.