Open AccessCalcium-dependent increase in adenosine 3′,5′-monophosphate and induction of the acrosome reaction in guinea pig spermatozoa
Author(s) -
Ross V. Hyne,
David L. Garbers
Publication year - 1979
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.76.11.5699
Subject(s) - capacitation , acrosome reaction , calcium , sperm , chemistry , guinea pig , extracellular , adenosine , acrosome , cyclic adenosine monophosphate , endocrinology , medicine , andrology , biochemistry , biology , receptor , organic chemistry
Experiments were designed to determine the interrelationship between cyclic AMP and Ca2+ during the processes of sperm capacitation and the acrosome reaction. In minimal culture media containing pyruvate and lactate as substrates, guinea pig spermatozoa required a minimum of 1.0-1.5 hr to capacitate in the presence of 1.7 mM Ca2+ and a minimum of 0.5-1.0 hr to capacitate in the absence of added Ca2+ . Sperm cyclic AMP concentrations were increased by as much as 30-fold within 0.5 min after addition of cells to various media containing Ca2+ , and the concentrations then remained increased for up to 4 hr. When the cells were added to several Ca2+ -deficient media, however, cyclic AMP concentrations increased only about 3-fold within 0.5 min and then returned to basal concentrations within 2 min. D-600, a calcium transport antagonist, completely blocked the Ca2+ -induced increase in sperm cyclic AMP concentrations. In contrast to capacitation, the acrosome reaction failed to occur in the absence of extracellular Ca2+ . After capacitation of spermatozoa in a Ca2+ -free medium, addition of Ca2+ caused an increase in sperm cyclic AMP concentrations within 1 min and a maximal number of spermatozoa showing an acrosome reaction within 10 min. The addition of 1-methyl-3-isobutylxanthine along with Ca2+ had a synergistic effect on the increase in cyclic AMP. Neither 1-methyl-3-isobutylxanthine nor 8-Br cyclic AMP induced an acrosome reaction in capacitated spermatozoa in the absence of Ca2+ , but both significantly decreased the time required for maximal expression of the acrosome reaction in the presence of Ca2+ . These results suggest that the sperm acrosome reaction is associated with both a primary transport of Ca2+ and a Ca2+ -dependent increase in sperm cyclic AMP concentrations. Because a cyclic AMP analogue did not induce an acrosome reaction in the absence of added Ca2+ , the increase in sperm cyclic AMP concentrations induced by Ca2+ probably reflects one of a number of Ca2+ -dependent events associated with the acrosome reaction.