Effect of Caffeine Added to the Activating Solution on Sperm Motility of Fresh and Thawed Semen of Pacu,Piaractus mesopotamicus, and Curimba,Prochilodus lineatus

Abstract

The aim was to evaluate the effect of different concentrations of caffeine added in activating solution over sperm motility in fresh and thawed semen of pacu, Piaractus mesopotamicus, and curimba, Prochilodus lineatus. The activating solutions were prepared with sodium bicarbonate solution of 0.76% (NaHCO 3 ) and caffeine was added at concentrations of 2.5, 5.0, 10.0, and 20.0 mM. As control, a solution of NaHCO 3 0.76 without caffeine was used. Eight males of pacu and 20 males of curimba were used. Aliquots of 200 μL of semen were diluted in 800 μL extender solution (DMSO 10% and BTS 5%), placed in 0.5 mL straws and cryopreserved for 7 d in a liquid nitrogen tank. There was a linear increase in sperm motility for fresh semen of pacu, and for curimba fresh and thawed semen (P < 0.05), due to the increase in the concentration of caffeine. There was a quadratic response for duration of motility for thawed semen of pacu and for fresh semen of curimba (P < 0.05), respectively. These results indicate that addition of caffeine in the activator solution can improve sperm motility parameters, however, is dependent on the species and concentration used.Pacu, Piaractus mesopotamicus, and curimba, Prochilodus lineatus, are species of migratory fish with relevant economic importance, characterized by ease of cultivation and high productivity. Moreover, due to the decline of their wild population, the interest in preservation of these species has increased considerably. The semen cryopreservation and artificial fertilization can contribute to increased productivity and preservation of these species. Both of these techniques increase the success of artificial breeding; however, semen quality is impaired either by maintenance at low temperature or by manipulation (Billard 1992).During cryopreservation spermatic cells are exposed to external conditions that are not physiologically appropriate, triggering a series 1 Corresponding author. of events that are prejudicial to sperm survival. Among these events, the energy expenditure of cells results in decreased sperm motility and, consequently, the fertilization capacity (Kopeika and Kopeika 2008). Similarly, during artificial fertilization, the addition of water for hydration of the oocyte induces rapid deterioration in spermatic cells, with rupture of the membrane and, consequently, reduction in sperm motility (Billard 1992).When sperm are exposed to the activating solution the demand for energy is very high and the activity of adenylate kinase becomes intense to hydrolyze adenosine triphosphate (ATP), which is required for flagellar beating. However, energetic consumption is much larger than the energy production, with rapid depletion of ATP levels, resulting in short duration of motility (Burness et al. 2005).