Hydroxytyrosol Ameliorates Busulfan-Induced Oligozoospermia in a Mouse Model

Objective Hydroxytyrosol (HT), a polyphenolic component identified in olive oil and leaves, represents one of the most extensively investigated natural phenol due to its diverse beneficial biological properties. Recent studies have shown that HT exhibits protective effects on reproductive function and can improve sperm quality. However, the precise effect and underlying mechanism of HT on oligozoospermia remain unclear. This study aims to investigate the effect and mechanism of HT across varying concentrations on oligozoospermia. Methods Oligozoospermia was induced in ICR male mice via intraperitoneal injection of busulfan (BUS, 30 mg/kg). The mice were randomly categorized into five groups as Normal, BUS, HT 10 mg/kg, HT 30 mg/kg and HT 50 mg/kg. The efficacy of HT on oligozoospermia was assessed through sperm concentration and motility using a computer-assisted sperm analysis system. Testicular and epididymal histology was examined via hematoxylin-eosin staining, while cytoskeletal integrity was evaluated by immunofluorescence. Hormone levels, along with reactive oxygen species (ROS) and malondialdehyde (MDA) were examined by ELISA kits. Differentially expressed genes were identified through RNA sequencing, and the expression levels of key genes were validated by qPCR. Results The results indicated that HT (50 mg/kg) significantly increased sperm concentration, promoted morphological recovery of testicular tissue, heightened the levels of serum testosterone, follicle-stimulating hormone, luteinizing hormone, as well as decreased the accumulation of ROS and MDA in mice with oligozoospermia. RNA sequencing analysis and RT-qPCR results revealed that HT could restore spermatogenesis and ameliorate oligozoospermia by up-regulating genes related to cilium organization, microtubule-based movement, and spermatid differentiation and development. Conclusions HT demonstrates therapeutic efficacy against busulfan-induced oligozoospermia. The mechanism of HT on oligozoospermia may be related to its influence on cilium and microtubule-based movement, along with the differentiation and development of spermatids. HT shows potential as a prospective therapeutic intervention for the treatment of oligozoospermia.