| Abstract: | Taurine and hypotaurine were examined for their efficacy in replacing sperm motility factor (SMF), prepared from bovine adrenal cortex, for in vitro fertilization in the golden hamster. Combinations of these amino acids at concentrations of 0.001, 0.01, 0.1, and 1 mM together with 16 μM isoproterenol (a catecholamine β-agonist) were added to the sperm incubations. After three hours of sperm preincubation, oviductal eggs were added to the sperm suspensions and examined for penetration and stage of fertilization after three or five hours of culture. At 0.001 mM, neither taurine or hypotaurine was capable of maintaining motility of hamster sperm for four to 4½ hours or of inducing fertilization. With all other concentrations, both amino acids were found to maintain motility of sperm as well as SMF. Hypotaurine stimulated motility to a greater extent than taurine and both required isoproterenol for the greatest motility. A low proportion of cumulus-free ova were fertilized when sperm were preincubated with either amino acid alone over the range of 0.01 to 1 mM; however, over 80% fertilization was consistently obtained when isoproterenol was also present during sperm incubation. Proportions of ova fertilized with taurine or hypotaurine present during sperm preincubation were comparable to those achieved with SMF. The possibility that taurine or hypotaurine is the sperm motility factor is discussed. After three hours of sperm/egg incubation, a lag in the early events of fertilization was observed in experimental groups treated with one of the amino acids (0.01 mM) alone compared with groups treated with isoproterenol present. However, if sperm/egg incubation was extended from three to five hours, no increase in number of eggs penetrated was found. Therefore, the delay observed at three hours was considered a function of fewer numbers of capacitated sperm present in the absence of isoproterenol rather than of the need for an extended capacitation time. |
