scholarly journals Polyphosphoinositide breakdown and subsequent exocytosis in the Ca2+/ionophore-induced acrosome reaction of mammalian spermatozoa

1989 ◽  
Vol 259 (2) ◽  
pp. 397-406 ◽  
Author(s):  
E R S Roldan ◽  
R A P Harrison
Keyword(s):  
Acrosome Reaction ◽  
Fertilization In Vitro ◽  
Ionophore A23187 ◽  
Bivalent Cation ◽  
Phosphoinositide Breakdown ◽  
Phosphoinositide Cycle ◽  
Phosphatidylinositol 4 ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

An investigation was made of the modifications in phospholipids that occur during the exocytotic event known as the ‘sperm acrosome reaction’. Phospholipids were prelabelled with 32P, and exocytosis was induced with Ca2+ and the ionophore A23187. When incubated with [32P]Pi in various media suitable for supporting sperm survival or fertilization in vitro, spermatozoa from all five species examined (ram, boar, guinea pig, mouse and human) incorporated 32P rapidly into the components of the phosphoinositide cycle. There were differences both between species and between media with respect to the actual rate of incorporation of label, and also between species with respect to other phospholipids labelled. Treatment of spermatozoa with Ca2+ and A23187 to induce the acrosome reaction resulted in a rapid breakdown of phosphatidylinositol 4, 5-bisphosphate and phosphatidylinositol 4-phosphate, which was complete within 3 min; there was also a great increase in labelling of phosphatidate. Occurrence of acrosome reactions in the sperm population was only observed after 5-10 min and reached a maximum response of greater than 90% after more than 30 min. The phosphoinositide breakdown was related to subsequent exocytosis: after EGTA/ionophore treatment, neither inositide breakdown nor exocytosis took place; however, later addition of Ca2+ resulted in immediate inositide breakdown, and exocytosis followed, with a delay relative to Ca2+ addition exactly similar to that following standard Ca2+/ionophore treatment. Neomycin inhibited both inositide breakdown and subsequent exocytosis provided it was added together with Ca2+ and ionophore; however, if the drug was added 3 min after Ca2+ and ionophore (by which time inositide breakdown was already complete), exocytosis was not inhibited. Ca2+ seemed to have several consecutive roles in the acrosome reaction. Low (micromolar) levels of free Ca2+ were needed both for phosphoinositide breakdown and for an event downstream of this breakdown; no other bivalent cation could substitute for Ca2+ in either event, and inositide breakdown was actually inhibited by Mg2+. In addition, millimolar levels of Ca2+ were needed for later stages of exocytosis, although this requirement could be satisfied by Sr2+. We conclude that breakdown of polyphosphoinositides is an essential early process after Ca2+ entry in the chain of events that lead to exocytosis in the mammalian sperm acrosome reaction.

scholarly journals Neurotensin stimulates the sperm acrosome reaction and alters percentages of fertilization in vitro

2019 ◽  
Vol 112 (3) ◽  
pp. e202
Author(s):  
Genevieve E. Campbell ◽  
Estella L. Jones ◽  
Pierre Comizzoli ◽  
Diane M. Duffy
Keyword(s):  
Acrosome Reaction ◽  
Fertilization In Vitro ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

scholarly journals Neurotensin stimulates the sperm acrosome reaction and reduces percentages of fertilization in vitro

F&S Science ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 27-35
Author(s):  
Genevieve E. Campbell ◽  
Estella L. Jones ◽  
Pierre Comizzoli ◽  
Diane M. Duffy
Keyword(s):  
Acrosome Reaction ◽  
Fertilization In Vitro ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

scholarly journals Mouse gamete interactions during fertilization in vitro. Chlortetracycline as a fluorescent probe for the mouse sperm acrosome reaction.

1979 ◽  
Vol 83 (3) ◽  
pp. 544-555 ◽  
Author(s):  
P M Saling ◽  
B T Storey
Keyword(s):  
Plasma Membrane ◽  
Fluorescent Probe ◽  
Zona Pellucida ◽  
Acrosome Reaction ◽  
Sperm Head ◽  
Fertilization In Vitro ◽  
Ionophore A23187 ◽  
Mouse Sperm ◽  
Sperm Acrosome

We have developed an assay for detecting the acrosome reaction in mouse sperm using chlortetracycline (CTC) as a fluorescent probe. Sperm known to be intact with nonreacted acrosomes show CTC fluorescence in the presence of Ca2+ over the anterior portion of the sperm head on the plasma membrane covering the acrosome. Sperm which have undergone the acrosome reaction do not show fluorescence on the sperm head. Mouse sperm bind to zonae pellucidae of cumulus-free eggs in vitro in a Ca2+-dependent reaction; these sperm are intact by the CTC assay. Intact sperm bind to mechanically isolated zonae under the same conditions: the egg is apparently unnecessary for this inital reaction. Sperm suspensions, in which greater than 50% of the motile population had completed the acrosome reaction, were prepared by incubation in hyperosmolal medium followed by treatment with the divalent cation ionophore, A23187. Cumulus-free eggs challenged with such sperm suspensions preferentially bind intact sperm; acrosome-reacted sperm do not bind. We conclude that the plasma membrane of the mouse sperm is responsible for recognition of the egg's zona pellucida and that the obligatory sequence of reactions leading to fusion of mouse gametes is binding of the intact sperm to the zona pellucida, followed by the acrosome reaction at the zona surface, followed in turn by sperm penetration of the zona.

Dynamics of human sperm acrosome reaction: relation with in vitro fertilization

1991 ◽  
Vol 55 (5) ◽  
pp. 994-999 ◽  
Author(s):  
Patrick Fénichel ◽  
Michèle Donzeau ◽  
Dariush Farahifar ◽  
Bernard Basteris ◽  
Noël Ayraud ◽  
...  
Keyword(s):  
In Vitro Fertilization ◽  
Acrosome Reaction ◽  
Human Sperm ◽  
Vitro Fertilization ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

scholarly journals Potassium ion influx and Na+,K+-ATPase activity are required for the hamster sperm acrosome reaction.

1981 ◽  
Vol 91 (1) ◽  
pp. 77-82 ◽  
Author(s):  
R J Mrsny ◽  
S Meizel
Keyword(s):  
Atpase Activity ◽  
Acrosome Reaction ◽  
Atpase Inhibitor ◽  
Mammalian Sperm ◽  
Ion Influx ◽  
K 12 ◽  
Low K ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

The role of a K+ ion influx and Na+,K+-ATPase activity in the hamster sperm acrosome reaction (AR) was examined, using a range of concentrations of K+,K+ ionophores and a Na+,K+-ATPase inhibitor. Washed epididymal hamster sperm, capacitated in vitro in an artificial medium containing 2 mM Ca2+, 147 mM Na+, and 3, 6, 12, 18, or 24 mM K+, began undergoing the AR after 3 h of incubation. Sperm incubated in low K+ (0.9 mM) failed to undergo the AR even after 5 h of incubation. Sperm in 0.9 mM K+ could be induced to undergo the AR when either K+ (12 mM) alone or K+ (12 mM) with 0.1 microM nigericin was added after 3.5 h of incubation. The addition of K+ alone stimulated the AR in 30 min, whereas nigericin plus K+ stimulated the AR 15 min after addition. Neither nigericin added alone (0.9 mM K+) nor nigericin plus 12 mM K+ added to a low Ca2+ (0.35 mM) system resulted in acrosome reactions. Valinomycin (1 nM) did not stimulate the AR when added together with K+ (3-24 mM) to sperm incubated in 0.9 mM K+ for 3.5 h but markedly decreased sperm motility. Micromolar levels of ouabain blocked the AR when added between t = 0--3 h to sperm incubated with 3-24 mM K+. Inhibition of AR by the addition of 1 microM ouabain to sperm incubated with 3 mM K+ was completely reversed by the addition of 0.1 microM nigericin at t = 3.5 h. These results suggest that Na+,K+-ATPase activity and the resulting K+ influx are important for the mammalian sperm AR. Some similarities between requirements for the hamster sperm AR and secretory granule exocytosis are discussed.

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