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Extracellular ATP is a trigger for the acrosome reaction in human spermatozoa
C Foresta1, M Rossato, F Di Virgilio
1University of Padova, III Cattedra di Patologia Medica, Italy.
Abstract:
We tested the effect of extracellular adenosine 5'-triphosphate (ATPo) on the activation of human spermatozoa. ATPo, in a concentration range from 50 microM to 5 mM, induced the acrosome reaction, which, at the optimal concentration of 2.5 mM, was maximal (30-35% of spermatozoa activated) within 60 min of the addition of the nucleotide. At the end of this incubation in the presence of ATPo no decrease in cell motility and viability was observed. Among other purine/pyrimidine nucleotides only the ATP analogue adeny-5'-lyl imidodiphosphate was effective (70% of ATP); a weak (10% of ATP) effect was also observed with CTP and the ATP analogues adenosine 5'-(beta gamma-methylene)triphosphate and adenosine 5'-O-(thiotriphosphate). ATPo did not cause Ca2+ release from intracellular stores, nor it caused Ca2+ influx from the extracellular milieu; on the contrary, it caused a clear, albeit slow, plasma membrane depolarization. ATPo-activated spermatozoa showed a nearly 100% success rate in the standard hamster egg fertilization test. Our results describe a new effect of ATPo in human spermatozoa with relevant potential applications in fertility studies.
Insights
Extracellular adenosine 5'-triphosphate (ATPo) effectively triggers the acrosome reaction in human spermatozoa without compromising motility or viability. This finding has significant implications for fertility research and applications.
Area of Science:
- Reproductive Biology
- Cell Signaling
- Biochemistry
Background:
- Human sperm activation is crucial for fertilization.
- Extracellular nucleotides can influence sperm function.
- The specific role of adenosine 5 omino-triphosphate (ATPo) in human sperm activation requires further elucidation.
Purpose of the Study:
- To investigate the effect of extracellular adenosine 5 omino-triphosphate (ATPo) on human spermatozoa activation.
- To determine the optimal concentration and time course for ATPo-induced acrosome reaction.
- To explore the underlying mechanisms of ATPo action and its impact on sperm function and fertilization potential.
Main Methods:
- Human spermatozoa were incubated with varying concentrations of ATPo (50 microM to 5 mM).
- Acrosome reaction, motility, and viability were assessed.
- Intracellular calcium levels and plasma membrane potential were monitored.
- Fertilization capacity was evaluated using the hamster egg penetration assay.
Main Results:
- ATPo induced the acrosome reaction in a concentration-dependent manner, with maximal effect (30-35%) at 2.5 mM within 60 minutes.
- No significant decrease in sperm motility or viability was observed.
- ATPo caused plasma membrane depolarization but not intracellular Ca2+ release or influx.
- ATPo-activated spermatozoa demonstrated a nearly 100% success rate in the hamster egg fertilization test.
Conclusions:
- Extracellular adenosine 5 omino-triphosphate (ATPo) is a potent inducer of the acrosome reaction in human spermatozoa.
- ATPo activates sperm through plasma membrane depolarization, independent of intracellular Ca2+ changes.
- These findings highlight a novel role for ATPo in human reproduction with potential applications in fertility treatments and diagnostics.