1. The sperm acrosome reaction response to progesterone associated with sperm DNA damage has a better predicting value for IVF than that response to the ionophore Jian yuan Jin, MS Wenzhou, China (2007)

2. Introduction and Aims
Sperm acrosome reaction (AR), a highly Ca2+ influx dependent event, is essential for the fertilizing ability and can be induced by several kinds of molecule in vivo or in vitro.
Progesterone (P4) have been widely known as a physiological stimulator of sperm AR. Along with the importance of the CatSper calcium channel, a major receptor of P4 in human sperm, being identified and well elaborated, the interaction between the fertilizing spermatozoon and P4 triggered AR activity probably should be further elucidated.
The sperm DNA fragmentation (SDF), recognized as one of the most important reflections of sperm quality, may relate to the alters of cellular functions, such as sperm motility and sperm AR.
This study aimed to evidence the correlation between P4-induced AR and SDF and to determine the predictive value of P4-induced AR for in vitro fertilization (IVF).

3. Methods
Design: The spontaneous or induced (response to P4 or A23187) sperm AR were assessed in 129 patients including a subgroup of 47 who underwent IVF treatment
— female with or without simple tubal factors
— male with a semen concentration ≥10×106/ml and sperm progressive motility ≥20%).
Methods:
— Conventional semen analysis was performed using CASA system or according to the WHO laboratory manual.
— Sperm AR was evaluated by using fluorescein-conjugated Pisum sativum agglutinin (FITC-PSA).
— SDF was analyzed by the Sperm Chromatin Structure Assay (SCSA).
— The multivariate linear regressions were performed to detect the correlations between P4-induced AR and sperm motility, normal morphology, SDF and the fertilization rate of IVF.
— Receiver operating characteristic (ROC) curve analysis was used to determine the prognostic accuracy of P4-induced AR as well as the cutoff point for predicting “50% fertilization rate

4. Results
1.The correlation between sperm AR and SDF : Sperm AR response to P4 and A23187 were correlated significantly to the percentage of SDF. While the spontaneous AR rate had a positive correlation with SDF.

5. Results
2. The effect of P4-induced AR on the fertilization rate and its predictive value for IVF The results of the multivariate linear regressions suggested that P4-induced AR, as well as SDF was significantly correlated to the fertilization rate in IVF. And the ROC analyses indicated that P4-induced AR was a better prognostic predictor for the fertilization rate compared with the SDF. A cutoff value for P4- induced AR to predict “50% fertilization rate” was 23.4% with sensitivity and specificity of 63.3% and 88.2%, respectively.

6. Results of univariate and multivariate linear regression analyses aiming to investigate the associations with spontaneous or induced AR for fertilization rate in IVF (n=47).

7. Conclusions
— Induced sperm AR is negatively correlated with sperm DNA damage, further direct evidence need to be provided for interpreting the relationship. — The assessment of P4-induced AR of capacitated sperm may be a more sensitive indicator for fertilization rate in vitro compared with A23187-induced AR.