Taurine and Hypotaurine: Their Effects on Motility, Capacitation and the Acrosome Reaction of Hamster Sperm in Vitro and Their Presence in Sperm and Reproductive Tract Fluids of Several Mammals

Previous work from this laboratory has shown that the β-amino acid taurine can support and stimulate hamster sperm motility during in vitro capacitation in the presence or absence of epinephrine. The present report describes in vitro results which demonstrate that hypotaurine, a precursor of taurine, can also support and stimulate motility under these conditions and that a higher number of acrosome reactions occur in the presence of taurine as compared to hypotaurine (both in the presence and absence of epinephrine). In all cases, the greates percentage of acrosome reactions occurs in the presence of epinephrine. Whether these β-amino acids act independently of epinephrine of in a synergistic manner with it remains to be determined. In addition to these in vitro studies, we report that hypotaurine and taurine are present at high levels in bovine follicular fluid, rabbit uterine and ampullar oviductal fluid (11 hr after mating, i.e., 1 hr after ovulation), monkey oviductal fluid, bovine adrenal cortex "motility factor" preparation and human, guinea pig and hamster sperm preparations. Based on these results, we suggest the possibility that taurine and hypotaurine may have roles in vivo in the maintenance and stimulation of sperm motility and stimulation of capacitation and/or acrosome reactions.