Bisphenol Z inhibits the function of Leydig cells via upregulation of METTL3 expression in adult male rats

The use of bisphenol A has been restricted due to its toxicity. However, the impact of its substitute, bisphenol Z (BPZ), on Leydig cell function remains uncertain. We aimed to examine the associations between BPZ exposure and the disruption of Leydig cell function via upregulating Mettl3 and inducing oxidative stress. To address this, in vivo, male adult Sprague-Dawley rats received BPZ (0, 1, 10, or 100 mg/kg/d orally) for 7 days, and in vitro, purified Leydig cells were treated with BPZ (0–20 μM, 24 h). Leydig cell morphology and function were assessed. The results showed that BPZ did not alter Leydig cell quantity but notably decreased serum testosterone levels. Furthermore, it significantly downregulated the expression levels of genes and proteins (SCARB1, STAR, CYP17A1, HSD17B3, and INSL3) in Leydig cells. Concurrently, BPZ treatment led to diminished expression of antioxidant genes (Gpx1 and Cat), an upregulation in m6A related gene (Mettl3) subsequent to the enrichment of RNA methylation fragments in the testis. In vitro analysis of primary Leydig cells demonstrated that BPZ heightened oxidative stress and diminished testosterone production. In conclusion, BPZ reduces rat testosterone by downregulating steroidogenic genes (Star, Scarb1, Cyp17a1, and Hsd17b3) via METTL3-m6A-Camkk2 pathway, impairing Leydig cell function.