Baldi E, Casano R, Falsetti C, Krausz C, Maggi M, Forti G
Department of Clinical Pathophysiology, University of Florence, Italy.
J Androl. 1991 Sep-Oct;12(5):323-30.
Progesterone induced a rapid, long-lasting, dose-dependent increase of intracellular free calcium concentration ([Ca2+]i) in human sperm capacitated overnight. This effect was not counteracted by the cytosolic progesterone receptor antagonist RU486 (1 mumol/L) nor by the GABA-A receptor antagonists bicuculline (10 mumol/L) and picrotoxin (50 mumol/L). Also, the rank order of potency of several progestative steroids on [Ca2+]i differed from that previously reported for uterine intracellular progesterone receptor or for P-GABA interaction in the central nervous system, indicating a different pathway for progesterone stimulation of human sperm. Modifications of basal and progesterone-stimulated [Ca2+]i during sperm capacitation were also studied. A progressive, parallel increase of basal and progesterone-stimulated [Ca2+]i in capacitating spermatozoa was found. In particular, progesterone-stimulated [Ca2+]i increased from a basal concentration of 147% +/- 17% at 10 minutes to 327% +/- 65% after 120 minutes of incubation in capacitating medium. This increase was well correlated with basal [Ca2+]i (r = 0.93). In contrast, basal and progesterone-stimulated [Ca2+]i concentrations were constantly low in spermatozoa incubated in noncapacitating medium. In capacitated spermatozoa, initial responsiveness to progesterone and basal [Ca2+]i was higher than in capacitating and noncapacitated samples, and remained constant throughout the duration of the experiment. The progressive, parallel increase of [Ca2+]i and response to progesterone observed during in vitro capacitation of human spermatozoa might be physiologically relevant in vivo during capacitation of sperm in the female genital tract.
孕酮可使过夜获能的人类精子细胞内游离钙浓度（[Ca2+]i）迅速、持久且呈剂量依赖性增加。这种效应既未被胞质孕酮受体拮抗剂RU486（1 μmol/L）抵消，也未被GABA-A受体拮抗剂荷包牡丹碱（10 μmol/L）和苦味毒（50 μmol/L）抵消。此外，几种孕激素对[Ca2+]i的作用强度顺序与先前报道的子宫细胞内孕酮受体或中枢神经系统中P-GABA相互作用的顺序不同，这表明孕酮刺激人类精子的途径不同。还研究了精子获能过程中基础[Ca2+]i和孕酮刺激的[Ca2+]i的变化。发现在获能精子中，基础[Ca2+]i和孕酮刺激的[Ca2+]i呈平行递增。特别是，在获能培养基中孵育120分钟后，孕酮刺激的[Ca 2+]i从10分钟时的基础浓度147%±17%增加到327%±65%。这种增加与基础[Ca2+]i密切相关（r = 0.93）。相反，在非获能培养基中孵育的精子中，基础[Ca2+]i和孕酮刺激的[Ca2+]i浓度一直较低。在获能精子中，对孕酮的初始反应性和基础[Ca2+]i高于正在获能和未获能的样本，并且在整个实验过程中保持恒定。在人类精子体外获能过程中观察到的[Ca2+]i的平行递增以及对孕酮的反应可能在体内女性生殖道中精子获能期间具有生理相关性。
