Adrenomedullin gene delivery rescues estrogen production in Leydig cells via the inhibition of TGF-β1/Smads signaling pathway.

Our previous findings demonstrated that adrenomedullin (ADM) protects against the reduction in testosterone production and apoptosis of Leydig cells both in vitro and in vivo. In this study, we investigated whether ADM could preserve estrogen production in Leydig cells by suppressing the transforming growth factor-β1 (TGF-β1) / Smads signaling pathway. Leydig cells were treated with lipopolysaccharide (LPS) and recombinant adenovirus ADM (Ad-ADM), an adeno-associated viral vector expressing ADM. Cell viability and cytochrome P450 aromatase (P450arom) activity were assessed. Estrogen, testosterone, and TGF-β1 concentrations in the culture medium were measured. Additionally, the gene expression and protein levels of CYP19, TGF-β1, and Smads were evaluated. The results indicated that Ad-ADM mitigated the reductions in Leydig cell viability and testosterone production, counteracted the decreases in P450arom activity, and restored CYP19 gene expression and protein levels in LPS-treated cells. Moreover, Ad-ADM reduced the elevated gene expression and protein levels of Smads and TGF-β1 induced by LPS. Based on these findings, we propose that ADM safeguards estrogen production in Leydig cells by inhibiting the TGF-β1/Smads signaling pathway.