Dual energy metabolism-dependent effect of Ureaplasma urealyticum infection on sperm activity

Genital Ureaplasma urealyticum infection is considered a sexually transmitt ed infection. It has long been debated whether the presence of U urealyticu m in semen may be a possible cause of infertility. Long-term incubation (4 hours or overnight) of sperm cells with U urealyticum in vitro resulted in a significant inhibition of sperm motility and membrane alteration whereas a short incubation (45 minutes) of sperm cells with ureaplasmas resulted in an acceleration of sperm velocity. The aim of this study was to understand these contradictory reports of U urealyticum infection on sperm motility. Spermatozoa from fresh ejaculates of normozoospermic Semen of men who were referred to the university Male Fertility laboratory for semen analysis, wi th no history of genital tract infection, and from normal Assaf breed rams were infected in vitro with U urealyticum serotype 8, at different pHs and O-2 concentrations. Sperm viability and motility and changes in extracellul ar pH were evaluated. A significant (16%-43%) increase in sperm activity wa s observed upon infection at alkaline pH (7.8) under aerobic or hypoxic con ditions, and a 58% increase was observed under anaerobic conditions and pH 7.2. When the infection was conducted under aerobic conditions and acidic p H (6.3), or under hypoxic conditions at neutral pH (7.2), an 8%-25% inhibit ion of sperm activity was observed. These results indicate that when sperm activity depends on mitochondrial oxidative phosphorylation, usually at low pHs, U urealyticum competes with mitochondrial energy production and there fore reduces sperm motility and viability. However, when sperm energy metab olism depends on glycolysis, usually at higher pHs, U urealyticum stimulate s glycolysis and sperm activity.