Identification of an ovarian voltage-activated Na+-channel type: Hints to involvement in luteolysis

Andreas Bulling, Frank D. Berg, Ulrike Berg, Diane M. Duffy, Richard Stouffer, Sergio Ojeda, Manfred Gratzl, Artur Mayerhofer

    Research output: Contribution to journalArticle

    41 Citations (Scopus)

    Abstract

    An endocrine type of voltage-activated sodium channel (eNaCh) was identified in the human ovary and human luteinized granulosa cells (GC). Wholecell patch-clamp studies showed that the eNaCh in GC is functional and tetrodotoxin (TTX) sensitive. The luteotrophic hormone human CG (hCG) was found to decrease the peak amplitude of the sodium current within seconds. Treatment with hCG for 24-48 h suppressed not only eNaCh mRNA levels, but also mean Na+ peak currents and resting membrane potentials. An unexpected role for eNaChs in regulating cell morphology and function was indicated after pharmacological modulation of presumed eNaCh steady-state activity in GC cultures for 24-48 h using TTX (NaCh blocker) and veratridine (NaCh activator). TTX preserved a highly differentiated cellular phenotype. Veratridine not only increased the number of secondary lysosomes but also led to a significantly reduced progesterone production. Importantly, endocrine cells of the nonhuman primate corpus luteum (CL), which represent in vivo counterparts of luteinized GC, also contain eNaCh mRNA. Although the mechanism of channel activity under physiological conditions is not clear, it may include persistent Na+ currents. As observed in GC in culture, abundant secondary lysosomes were particularly evident in the regressing CL, suggesting a functional link between eNaCh activity and this form of cellular regression in vivo. Our results identify eNaCh in ovarian endocrine cells and demonstrate that their expression is under the inhibitory control of hCG. Activation of eNaChs in luteal cells, due to loss of gonadotropin support, may initiate a cascade of events leading to decreased CL function, a process that involves lysosomal activation and autophagy. These results imply that ovarian eNaChs are involved in the physiological demise of the temporary endocrine organ CL in the primate ovary during the menstrual cycle. Because commonly used drugs, including phenytoin, target NaChs, these results may be of clinical relevance.

    Original languageEnglish (US)
    Pages (from-to)1064-1074
    Number of pages11
    JournalMolecular Endocrinology
    Volume14
    Issue number7
    DOIs
    StatePublished - 2000

    Fingerprint

    Luteolysis
    Granulosa Cells
    Corpus Luteum
    Tetrodotoxin
    Veratridine
    Endocrine Cells
    Lysosomes
    Primates
    Ovary
    Cell Culture Techniques
    Luteal Cells
    Messenger RNA
    Sodium Channels
    Autophagy
    Phenytoin
    Menstrual Cycle
    Gonadotropins
    Membrane Potentials
    Progesterone
    Sodium

    ASJC Scopus subject areas

    • Molecular Biology
    • Endocrinology, Diabetes and Metabolism

    Cite this

    Identification of an ovarian voltage-activated Na+-channel type : Hints to involvement in luteolysis. / Bulling, Andreas; Berg, Frank D.; Berg, Ulrike; Duffy, Diane M.; Stouffer, Richard; Ojeda, Sergio; Gratzl, Manfred; Mayerhofer, Artur.

    In: Molecular Endocrinology, Vol. 14, No. 7, 2000, p. 1064-1074.

    Research output: Contribution to journalArticle

    Bulling, Andreas ; Berg, Frank D. ; Berg, Ulrike ; Duffy, Diane M. ; Stouffer, Richard ; Ojeda, Sergio ; Gratzl, Manfred ; Mayerhofer, Artur. / Identification of an ovarian voltage-activated Na+-channel type : Hints to involvement in luteolysis. In: Molecular Endocrinology. 2000 ; Vol. 14, No. 7. pp. 1064-1074.
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    AU - Duffy, Diane M.

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    AU - Ojeda, Sergio

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