Human spermatozoa capacitated with progesterone or a long incubation show accelerated internalization by an alkyl ether lysophospholipid.
OBJECTIVE
To evaluate changes that occur in sperm plasma membranes during capacitation, the internalization of [(3)H]lyso-platelet activating factor ([(3)H]lyso-PAF) across the plasma membrane of human spermatozoa was measured as a function of incubation time or exposure to progesterone (P).


METHODS
In vitro cell culture study using human spermatozoa.


METHODS
Department of Obstetrics and Gynecology, School of Medicine, the University of Tokushima, Japan.


METHODS
Semen were obtained from three fertile healthy volunteers.


METHODS
The internalization of [(3)H]lyso-PAF across the plasma membranes of human spermatozoa that were incubated for an extended period or exposed to P was measured at 5, 20, 60, and 120 minutes after the addition of the phospholipid probe using the modified albumin back-exchange method.


METHODS
The percentage of capacitated and acrosome-reacted sperm and the proportion of internalization of lyso-PAF across the plasma membrane.


RESULTS
A 6-hour incubation period significantly increased the percentage of capacitated spermatozoa and the proportion of internalization of [(3)H]lyso-PAF across the plasma membrane of human spermatozoa compared with controls (capacitated spermatozoa, 20.3 +/- 10.6% vs. 8.5 +/- 1.8%; internalization 120 minutes after the addition of the phospholipid probe, 25.6 +/- 2.5% vs. 11.6 +/- 3.0%) (mean +/- SEM). Exposure to P significantly increased the percentage of capacitated spermatozoa compared with controls (19.6 +/- 6.8% vs. 11.0 +/- 2.4%) and also significantly accelerated the internalization of [(3)H]lyso-PAF compared with controls (internalization 120 minutes after the addition of the phospholipid probe, 26.2 +/- 1.8% vs. 21.4 +/- 1.1%).


CONCLUSIONS
The administration of P or a long incubation increased the proportion of internalization and consequently induced capacitation in human spermatozoa.
Yamano
Shuji
S
Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Tokushima, Japan.
Yamazaki
Jun
J
Irahara
Minoru
M
Tokumura
Akira
A
Nakagawa
Koji
K
Saito
Hidekazu
H
D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D008297:Male; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*; D011374:Progesterone / Q000494:pharmacology*; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology*; D013997:Time Factors
C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D011374:Progesterone