[Effects of progesterone on intracellular free Ca2+ concentration in the spermatozoa of fertile men and patients with unexplained infertility].
OBJECTIVE
To investigate the difference in the responsiveness of intracellular free Ca2+ concentration ([Ca2+]i) to progesterone in the spermatozoa of normal fertile men and patients with unexplained infertility.


METHODS
Nine normal fertile men and 10 patients with unexplained infertility were selected in this study. After swim-up separation of the motile fraction and 2-hour in vitro capacitation, the spermatozoa were loaded with the fluorescent calcium indicator Fluo-3/AM (8.85 micromol/L) for 40 minutes away from the light, and then the sperm suspension was mixed with equal amount of 20% gelatin to immobilize the spermatozoa. The basal intracellular free [Ca2+]i and that induced by 10 micromol/L progesterone in the individual sperm were assessed by laser scanning confocal microscopy.


RESULTS
The infertile patients had a significantly lower basal level of [Ca2+]i in the capacitated sperm than the fertile men (P < 0.01). The sperm from the normal controls responded to progesterone by exhibiting a rapid but transient rise in [Ca2+]i, with the peak level significantly higher than the basal level (P < 0.05), while those from the infertile patients by showing a slight increase, with no significant difference between the peak and basal levels (P > 0.05). Both the peak of the progesterone-induced [Ca2+]i and its increase amplitude expressed as the difference between the peak and basal levels were significantly higher in the normal fertile group than in the infertile patients (P < 0.01).


CONCLUSIONS
The responsiveness of [Ca2+]i to progesterone is reduced in the spermatozoa of patients with unexplained infertility, which suggests a functional defect in the non-genomic sperm membrane progesterone receptor responsible for calcium influx.
Huo
Yong-Wei
YW
Research Center of Reproductive Medicine, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China. hyw301@mail.xjtu.edu.cn
Wang
Li-Rong
LR
Tian
Hong
H
Xu
Yong-Jun
YJ
Zhao
Xiao-Ge
XG
Qiu
Shu-Dong
SD
D020101:Acrosome Reaction / Q000187:drug effects*; D000328:Adult; D002118:Calcium / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007248:Infertility, Male / Q000503:physiopathology*; D008297:Male; D011374:Progesterone / Q000494:pharmacology*; D013094:Spermatozoa / Q000187:drug effects*; D055815:Young Adult
D011374:Progesterone; D002118:Calcium