Background: Management of diabetes mellitus induced-erectile dysfunction (DMED) is challenging because of its poor responses to phosphodiesterase type 5 inhibitors. Increasingly important roles of 12-lipoxygenase (12-LOX) have been proven in diabetes mellitus. Aim: To investigate 12-LOX activity and therapeutic effect of its inhibitor, baicalein (BE), on DMED. Methods: Intraperitoneal streptozotocin injection was used to induce type I DM, and an apomorphine test was used to evaluate erectile function. In experiment A, we assessed 12-LOX expression alteration in the corpus cavernosum (CC) of rats with DMED of different levels of severity. In experiment B, rats with DMED were intraperitoneally injected with BE for 4 weeks, and control rats were injected with vehicles. The erectile function was tested by cavernous nerve stimulation before penile tissue was harvested. We performed Western blot, immunohistochemistry, immunofluorescence, Masson trichrome staining, and enzyme-linked immunosorbent assays to measure related proteins in CC. Main Outcome Measure: The main outcome measures included rectile response, histologic examination, and expression alteration of related proteins. Results: 12-LOX upregulation was associated with the progression of type I DMED. After 4 weeks treatment, compared with the DMED group, the DMED + BE group showed better erectile responses to cavernous nerve stimulation. In the DMED + BE group, significantly enhanced endothelial nitric oxide synthase/nitric oxide/cyclic guanosine monophosphate pathway, reduced 12-LOX expression, and inhibited p38 mitogen-activated protein kinase/arginase II/L-arginine pathway were showed in CC relative to the DMED group. In addition, overactivated oxidative stress and fibrosis in the DMED group were both partially ameliorated in the DMED + BE group. Clinical Implications: BE may be considered as an effective therapy for DMED, but needs to be verified in future human investigations. Strengths & Limitations: The role of 12-LOX and its inhibitor, BE, is firstly demonstrated in rats with type I DMED. However, the experimental data are derived from animal models with without evidences from cellular-based experiments. Conclusion: 12-LOX might serve as an important factor in the pathogenesis of type I DMED. BE alleviated erectile dysfunction in rats with type I DMED probably by inhibiting 12-LOX expression, ameliorating endothelial nitric oxide synthase dysfunction, as well as suppressing oxidative stress and fibrosis.

Backgrounds: Erectile dysfunction (ED) is a common andrological disorder that tends to afflict diabetic patients, among others. Pharmacological therapy of diabetes mellitus‐induced ED (DMED) is ineffective, as it is linked with smooth muscle cell loss in the corpus cavernosum. Ferroptosis is a recently identified kind of cell death evoked by lipid peroxidation, and it is connected with a number of diabetic complications.Objectives: To investigate the role of ferroptosis in DMED.Materials and methods: We established the rat model of DMED and conducted a combined analysis of RNA sequencing (RNA‐seq) and Gene Expression Omnibus (GEO) data to identify differentially expressed genes (DEGs). Next, DMED disease targets were determined by cross‐referencing DEGs and DMED‐related genes in the DisGeNET, GenCLiP3, and GeneCards databases. Additionally, these targets were analyzed using “clusterProfiler” in R utilizing Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations. Immunohistochemistry (IHC) staining of rat penile tissues was used to validate several targets. Notably, the Cell Counting Kit‐8 assay, Western blotting, oxidative stress (OS) level, and iron concentration were tested in corpus cavernosum smooth muscle cells (CCSMCs) stimulated with high glucose (HG), and treated with Ferrostatin‐1 (Fer‐1).Results: Sixty‐nine disease targets of DMED were identified. According to KEGG analysis, these targets were primarily enriched in the ferroptosis pathway. Additionally, IHC results revealed that the expression of GPX4, SLC7A11, and ACSL4 was deregulated in the DMED group compared to the control group. Significantly, HG decreased cell viability and increased OS and iron levels in CCSMCs, which could be reversed by Fer‐1 treatment.Discussion and conclusion: Our study revealed that ferroptosis may indeed exist in DMED. GPX4, SLC7A11, and ACSL4 all have a role in controlling the viability of CCSMCs, making them potential therapeutic targets.