Abstract
Two doses of 750-μg levonorgestrel at 12 h apart is one of the regimens for emergency
contraception. The mechanism of action of this regimen is not fully known. We investigated
whether levonorgestrel influences sperm functions and thereby, exerts contraceptive
activity. The motility, acrosome reaction, zona binding capacity, and oocyte fusion
capacity of human spermatozoa treated with 1, 10, and 100 ng/mL levonorgestrel for
3 h were evaluated. Levonorgestrel decreased the curvilinear velocity of the treated
spermatozoa in a dose-dependent manner. A significant decrease in straight-line velocity,
average path velocity and linearity were also found with 100 ng/mL levonorgestrel
treatment. This concentration of levonorgestrel, but not others, also marginally decreased
(p = 0.045) the zona binding capacity of the treated spermatozoa. The steroid had
no effect on acrosome reaction but had a dose-dependent inhibition on spermatozoa-oocyte
fusion. These data show that levonorgestrel affects sperm function only at high concentration
and the contribution of these effects to emergency contraception is unlikely to be
significant.
Keywords
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Article info
Publication history
Accepted:
August 2,
2002
Received in revised form:
June 11,
2002
Received:
April 15,
2002
Identification
Copyright
© 2002 Elsevier Science Inc. Published by Elsevier Inc. All rights reserved.
