Cadmium toxicity at low concentration on rabbit spermatozoa motility, morphology and membrane integrity in vitro

In this study the effect of cadmium on various parameters of spermatozoa motility, morphology as well as on the spermatozoa membrane integrity in rabbits was analyzed in vitro, experimental concentrations ranging from 0.62 to 0.98 micro g CdCl(2)/mL. Pooled rabbit (n = 5) semen was cultured in vitro with cadmium and subsequently diluted to various experimental concentrations apart from control which received no cadmium exposure. Using computer assisted semen analysis method (CASA) we detected decrease of total motility with in the higher concentration range at Time 0. However, with increasing time (after 1 and 2 h of culture), cadmium exerted deleterious effect leading to significant motility reduction in comparison to control. A similar trend was exhibited in case of progressive motility, too. Most of the spermatozoa distance and velocity parameters detected no significant change in comparison to control at the beginning of culture (Time 0), although the toxic effect became significant (P < 0.05) with the passage of culture time (Times 1 and 2 h) in all concentrations. Analysis of spermatozoa morphology detected significant (P < 0.05) alterations at higher concentrations. At higher concentrations acrosomal changes, head without flagellum/separated flagellum, broken flagellum and other abnormalities were significantly higher (P < 0.05), while knob-twisted flagellum and small heads differed significantly (P < 0.05) in comparison to control at all concentrations. In regards to flagellum torso, flagellum ball and retention of cytoplasmic drop statistically higher values (P < 0.05) were noted at the maxium experimental concentration only. Annexin analysis for detection of spermatozoa with disordered membranes revealed higher occurrence of positive spermatozoa in cadmium exposed groups. Annexin-positive reactions suggested alterations in anterior part of head (acrosome) and in flagellum (mitochondrial segment) of spermatozoa. This paper underlines that cadmium is highly toxic for rabbit spermatozoa, as visualized by the toxic effects on parameters of spermatozoa motility, morphology and membrane integrity. The toxic effect is more drastic at higher concentrations. This study also indicates that cadmium requires a minimum one hour incubation time to exert its deletorious effects on various parameters of spermatozoa, particularly at low concentrations.