Showing papers by "Csilla Krausz published in 1995"
TL;DR: The results indicate that [Ca2+]i and acrosome reaction increases in response to progesterone can be of value in the prediction of sperm fertilizing ability.
Abstract: In this study we have investigated responsiveness to progesterone in spermatozoa from a group of unselected male partners of couples undergoing in-vitro fertilization (IVF). We evaluated progesterone-stimulated intracellular Ca2+ ([Ca2+]i) and percentage increase in acrosome reaction in the same sperm sample used for oocyte inseminations. [Ca2+]i was measured with a fluorimetric method, while the acrosome reaction was assessed using a fluorescent probe (fluorescein isothiocyanate-labelled peanut lectin). The average percentage [Ca2+]i as well as the rate of increase in the frequency of acrosome reaction following progesterone challenge were significantly lower (P < 0.005) in the group of patients with a fertilization rate < 50%. In addition, significant correlations between the fertilization rate and the progesterone-stimulated [Ca2+]i and acrosome reaction increases (r = 0.78 and r = 0.79 respectively) were observed. Furthermore, in cases of fertilization failure, no increase of [Ca2+]i or acrosome reaction was observed in response to progesterone with the exception of one case. Our results indicate that [Ca2+]i and acrosome reaction increases in response to progesterone can be of value in the prediction of sperm fertilizing ability. As the two parameters were significantly correlated to each other (r = 0.86), the two assays have similar IVF predictive value and might be used interchangeably as a diagnostic tool in the assignment of male patients to the different kinds of assisted fertilization techniques.
102 citations
TL;DR: A role for tyrosine kinase(s) in the mechanism of capacitation and activation of human spermatozoa by PAF and progesterone is suggested.
98 citations
TL;DR: Responsibility to P is significantly reduced in oligozoospermic men as well as in subjects with reduced fertilization rate and these studies indicate that a biochemical alteration of sperm in their capacity to respond to P might be responsible for reduced fertilizing ability.
44 citations
TL;DR: Recent studies suggest the possibility that the sperm's response to P may be functionally related to their fertilizing ability, thus opening new perspectives in the possible development of a predictive test in the assisted reproductive techniques.
Abstract: Progesterone's (P) stimulatory actions on human spermatozoa have been known for many years. P indeed appears to be the main sperm stimulator present in women's biological fluids, particularly the follicular fluid. The nongenomic nature of the biological effects of P on human spermatozoa has been demonstrated only recently. P and 17-α-hydroxy P have been shown to increase sperm intracellular calcium, phosphatidylinositide hydrolysis, and tyrosine phosphorylation of proteins, and to induce the acrosome reaction (AR), through a rapid, nongenomic mechanism. The effect on calcium is due to influx of the ion from the extracellular medium, as it is inhibited by the calcium chelator EGTA and appears to be mediated by P-binding sites present on the sperm surface, particularly at the head level. The nature of such binding sites has not been addressed so far, but the lack of inhibition of P action by the potent antiprogestin RU486 strongly suggests a biochemical difference from the genomic ones. Evidence exists for involvement of the phospholipid platelet-activating factor (PAF), polyamines, tyrosine kinase activation, proteases, and other factors in P-mediated calcium increase and acrosome reaction. Recent studies suggest the possibility that the sperm's response to P may be functionally related to their fertilizing ability, thus opening new perspectives in the possible development of a predictive test in the assisted reproductive techniques.
35 citations