Progesterone Induces Hyperpolarization after a Transient Depolarization Phase in Human Spermatozoa

• Published in: Biology of reproduction Vol. 66; no. 6; pp. 1775 - 1780
• Main Authors: PATRAT, C, SERRES, C, JOUANNET, P
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.06.2002
• Subjects: Acrosome Reaction - physiology; Biological and medical sciences; Calcium - metabolism; Calcium Channels, T-Type - physiology; Chlorides - metabolism; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Humans; Male; Mammalian male genital system; Membrane Potentials - drug effects; Morphology. Physiology; Progesterone - pharmacology; Sodium - metabolism; Spectrometry, Fluorescence; Sperm Capacitation; Spermatozoa - drug effects; Spermatozoa - physiology; Spermatozoa - ultrastructure; Vertebrates: reproduction; Zona Pellucida - physiology; Depolarization; Human; Reproduction; Spermatozoa; Plasma membrane; Acrosome reaction; Progesterone; Fecundation; Sex steroid hormone; Ovarian hormone; Hyperpolarization; Progestagen
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod66.6.1775

Progesterone (P 4 ) induces a membrane depolarization and various ion fluxes (chloride efflux, sodium and calcium influxes), which are required for the human sperm acrosome reaction (AR). By use of the potentiometric fluorescent dye DiSC 3 (5) and two different technical approaches, the present study aimed to quantify and further analyze P 4 -induced modifications in membrane potential in capacitated human spermatozoa. Spectrofluorimetric analysis revealed that the mean resting membrane potential of sperm was −58 ± 2 mV (n = 12). When 10 μM P 4 was added, the sperm membrane depolarized by ∼+15 mV, partly driven by a Cl − efflux. It subsequently repolarized to reach a significant lower potential than the initial resting potential in two thirds of the tested samples. The flow cytometry analysis showed a heterogeneous resting membrane potential and revealed that the depolarization-hyperpolarization events concerned only subpopulations, between 3% and 40% of the sperm cells according to the samples (n = 7). We hypothesize that P 4 has a beneficial effect on the ability of zona pellucida to promote the AR in a sperm subpopulation by increasing the number of hyperpolarized cells presenting a membrane potential that is compatible with the opening of T-type calcium channels by subsequent zona pellucida-induced depolarization.