Activation of Cl− Channels by Human Chorionic Gonadotropin in Luteinized Granulosa Cells of the Human Ovary Modulates Progesterone Biosynthesis

Abstract

Chloride permeability pathways and progesterone (P4) secretion elicited by human chorionic gonadotropin (hCG) in human granulosa cells were studied by electrophysiological techniques and single-cell volume, membrane potential and Ca2+i measurements. Reduction in extracellular Cl(-) and equimolar substitution by the membrane-impermeant anions glutamate or gluconate significantly increased hCG-stimulated P4 accumulation. A similar result was achieved by exposing the cells to hCG in the presence of a hypotonic extracellular solution. Conversely, P4 accumulation was drastically reduced in cells challenged with hCG exposed to a hypertonic solution. Furthermore, conventional Cl(-) channel inhibitors abolished hCG-mediated P4 secretion. In contrast, 25-hydroxycholesterol-mediated P4 accumulation was unaffected by Cl(-) channel blockers. In human granulosa cells, hCG triggered the activation of a tamoxifen-sensitive outwardly rectifying Cl(-) current comparable to the volume-sensitive outwardly rectifying Cl(-) current. Exposure of human granulosa cells to hCG induced a rapid 4,4'-diisothiocyanatostilbene-2,2-disulphonic acid-sensitive cell membrane depolarization that was paralleled with an approximately 20% decrease in cell volume. Treatment with hCG evoked oscillatory and nonoscillatory intracellular Ca2+ signals in human granulosa cells. Extracellular Ca2+ removal and 4,4'-diisothiocyanatostilbene-2,2-disulphonic acid abolished the nonoscillatory component while leaving the Ca2+ oscillations unaffected. It is concluded that human granulosa cells express functional the volume-sensitive outwardly rectifying Cl(-) channels that are activated by hCG, which are critical for plasma membrane potential changes, Ca2+ influx, and P4 production.

Transient Receptor Potential Vanilloid 1 Expression Mediates Capsaicin-Induced Cell Death

“…Cell cultures were equilibrated using DiBAC 4 (3) [Molecular Probes, Eugene, OR, United States] as described previously ( Kunz et al, 2006 ). This anionic fluorescent dye is distributed across the plasma membrane relative to the membrane potential following Nernst’s equation ( Olivero et al, 2008 ). DiBAC 4 (3) (200 nM) was applied extracellularly for approximately 20 min to ensure dye distribution across the cell membrane.…”

Transcriptome Display During Testicular Differentiation of Channel Catfish (Ictalurus punctatus) as Revealed by RNA-Seq Analysis

“…Several members of fatty acid-binding proteins are localized in Leydig cells and Sertoli cells and are implicated in steroidogenesis with a stage-specific manner [19,[56][57][58]. Fxyd1 encodes an ion channel regulator protein [59,60] and is evoked by gonadotropins in steroidogenesis [61]. Plac8 was first found in trophectoderm of preimplantation embryos and spongiotrophoblast of developing placenta [62].…”

2-Methoxyestradiol in the human corpus luteum throughout the luteal phase and its influence on lutein cell steroidogenesis and angiogenic activity

“…The red blood cells and detritus were eliminated in Histopaque gradient. Macrophages were eliminated by additional plating of the cells for 30 minutes at 37 C. The GCs were cultured for 76 hours in growth medium M-199 with 10% heat-treated fetal calf serum and 24 hours in serumfree M-199 supplemented with 0.1 % BSA (12). Cultures were treated for 24 hours with different compounds.…”