Effects of cryopreservation on progesterone-induced ion fluxes and acrosome reaction in human spermatozoa.
The present study evaluated the effects of cryopreservation on progesterone-induced variations of calcium ion concentration [Ca(2+)](i), plasma membrane potential and acrosome reaction in human spermatozoa. Spermatozoa from 10 fertile donors were divided in two equivalent aliquots, one used as control (fresh spermatozoa) and the other used after freezing-thawing. Measurement of spermatozoa [Ca(2+)](i) before and after freezing-thawing showed a significant reduction of basal [Ca(2+)](i) in thawed spermatozoa (P < 0.01). Progesterone induced a rise of [Ca(2+)](i) both in fresh and thawed spermatozoa with a significant reduction after freezing-thawing (P < 0.01). The monitoring of sperm plasma membrane potential demonstrated that progesterone induced plasma membrane depolarization in fresh spermatozoa that was absent in thawed spermatozoa. The inhibitory effects of freezing-thawing on progesterone induced [Ca(2+)](i) and plasma membrane potential variations in human spermatozoa were closely related to the inhibition of the acrosome reaction. In conclusion the present study demonstrates that freezing-thawing procedures reduce the responsiveness of human spermatozoa to progesterone in terms of [Ca(2+)](i) rise and completely inhibit its effects on plasma membrane potential variations, thus supporting the hypothesis that freezing-thawing procedures may differently modify the plasma membrane receptors for progesterone in human spermatozoa which are known to express at least two receptors for this steroid in their plasma membrane.
Rossato
M
M
University of Padova, Department of Medical and Surgical Sciences, Italy.
Zorzi
M
M
Ferlin
A
A
Garolla
A
A
Foresta
C
C
D020101:Acrosome Reaction / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002470:Cell Survival; D015925:Cryopreservation; D006096:Gramicidin / Q000494:pharmacology; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials; D011374:Progesterone / Q000494:pharmacology*; D013081:Sperm Motility; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*
D007476:Ionophores; D006096:Gramicidin; D011374:Progesterone; D002118:Calcium