Toxic effects of mercury chloride on silver catfish (Rhamdia quelen) spermatozoa

摘要

Heavy metals are highly toxic elements that are present in the environment, especially in water. Mercury chloride (HgCl2) stands out among these compounds because of its strong ability to induce damage to any tissue with which it comes into contact. The gametes of spawning aquatic animals, such as fish, are susceptible to such damage. Thus, our objective was to evaluate the toxic potential of HgCl2 in the capacitation and activation of Rhamdia quelen sperm. Semen was collected from seven males and activated in 58 mM sodium chloride (NaCl) containing O (control), 4(-10), 7(-10), 7(-9), and 7(-8) M HgCl2. The evaluated variables included motility, vigor, motility time, morphology, membrane integrity, membrane fluidity, mitochondrial functionality, production of reactive oxygen species (ROS), and DNA fragmentation. All evaluated HgCl2 concentrations increased primary pathologies and reduced motility, vigor and motility time. Damage to membrane integrity and fluidity began occurring at a concentration of 7(-10) M HgCl2. These results indicate that HgCl2 has a toxic effect on different sites of fish spermatozoa and that sperm motility decreases after exposure to HgCl2, impairing sperm capacitation and activation.