Effects of glucose and fructose on motility patterns of dog spermatozoa from fresh ejaculates

This study was performed to gain insight about how fructose and glucose mod ulate dog spermatozoa motility in the absence of other motility-modulating factors. Incubation of dog spermatozoa from fresh ejaculates in a basal med ium without sugars for 60 min at 37 degreesC induced a progressive decrease in the percentage of motile spermatozoa and in some mean motility paramete rs, such as mean velocity (VAP), linear coefficient (LIN) and dance (DNC), and an increase in the mean frequency of head displacement (BCF). This indi cates a progressive loss of linearity and an increase in oscillatory moveme nt. Addition of 10 mM fructose prevented these effects. Incubation in a bas al medium with 10 mM glucose for 60 min at 37 degreesC provoked a fast and intense decrease of LIN and a slight increase of DNC, inducing a less linea r and more oscillatory mean movement. Neither fructose nor glucose modified the percentage of motile spermatozoa. The response to both sugars was dose -dependent, with differences appearing at concentrations as low as I mM. An analysis of the spermatozoa subpopulation placed above the 95(th) percenti le of the whole population and a factorial analysis of the data indicated t hat the changes in the mean values of the motility parameters were mainly d ue to a specific motile subpopulation that had a strong reaction to the two sugars. Our results indicate that fructose, at concentrations from I to 10 mM, induced a more linear and less oscillatory motility pattern than gluco se. Moreover, from our results we suggest the presence of motile dog sperm subpopulations with an increased sensitivity to fructose and glucose. (C) 2 001 by Elsevier Science Inc.