Mechanism of the traditional Chinese medicine SMBJ alleviates diabetes mellitus-induced Leydig cell dysfunction in rats testes

Simiao Biejia Decoction (SMBJ), a traditional Chinese herbal formula, has been clinically applied to treat diabetes mellitus (DM)-induced male dysfunction due to its kidney-tonifying, heat-clearing, and blood-enriching properties. However, the precise molecular mechanisms and therapeutic targets through which SMBJ confers protection against DM-induced testicular damage remain to be fully elucidated. Goto-Kakizaki (GK) and wild-type rats were randomly assigned to the wild-type, GK model, and SMBJ low-, medium-, and high-dose groups. SMBJ was administered at low, medium, and high doses (2.44, 4.88, and 9.76 g/kg/day) by gavage for 4 weeks. Serum testosterone, blood glucose, and oxidative stress levels were measured using ELISA and colorimetric assays. Histopathological staining was performed to evaluate testicular damage. In vitro experiments were conducted using the R2C cell line subjected to high-glucose conditions, with intervention using SMBJ-containing serum. RT-qPCR, Western blotting, immunofluorescence, MeRIP-qPCR, RNA stability were employed to elucidate the underlying mechanisms. SMBJ alleviates oxidative stress injury, thereby reducing apoptosis and enhancing testosterone secretion in the interstitial tissue and in high glucose-stimulated R2C cell of diabetic rats. METTL3 expression was downregulated in the testes of diabetic rat and in R2C cell exposed to high glucose. METTL3 knockdown mimicked the effects of high glucose, underscoring its protective role in Leydig cells. Si-METTL3 decreased the stability of PI3K/AKT mRNAs, whereas SMBJ upregulated METTL3 expression, modulating the PI3K/AKT pathway, reversing high glucose-induced damage in R2C cell, and highlighting its therapeutic potential in Leydig cell protection. SMBJ may upregulates METTL3 expression alongside PI3K/AKT activation to ameliorate diabetes mellitus-induced Leydig cell dysfunction. The potential regulatory role of m6A modification in diabetes-induced testicular injury was further elucidated.