Betulinic acid ameliorates cavernous nerve injury-induced erectile dysfunction through Nrf2/HO-1 pathway activation and inhibition of mitochondrial damage-dependent corpus cavernosum smooth muscle cells apoptosis.

The most prevalent complication of radical prostatectomy is erectile dysfunction (ED) resulting from cavernous nerve injury (CNI), which is primarily characterized by corporal apoptosis. Betulinic acid (BA) is an active pentacyclic triterpenoid with significant anti-apoptosis properties. Nevertheless, whether BA can improve CNI-induced ED remains unclear. A total of 20 male Sprague-Dawley rats randomized into Sham, bilateral CNI (BCNI), BCNI + low-dose BA, and BCNI + high-dose BA groups. Four weeks after daily intragastric administration of phosphate-buffered saline (PBS) or BA, electrical stimulation of the cavernous nerves was performed for erectile function assessment, followed by collection of penile tissues for histological analysis. An apoptotic model of corpus cavernosum smooth muscle cells (CCSMCs) was established using H2O2. Both low- and high-dose BA treatment improved ED and alleviated cavernous tissue damage in BCNI rats, accompanied by upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Additionally, BA alleviated H2O2-induced oxidative stress, mitochondrial damage, and apoptosis in CCSMCs. This protection was associated with coordinated decreases in reactive oxygen species, mitochondrial superoxide, mitochondrial permeability transition pore opening, and caspase3 levels, along with increased mitochondrial membrane potential, activated Nrf2/HO-1 signaling pathway, and improved mitochondrial morphology. However, this protective effect was partially attenuated by the Nrf2 inhibitor ML385. Overall, BA ameliorated ED and alleviated cavernosal damage in BCNI rats, primarily through Nrf2/HO-1-mediated protection against mitochondrial damage-dependent apoptosis in CCSMCs.