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Spontaneous Intracellular Calcium Oscillations and G s α Subunit Expression are Inversely Correlated with Secretory Granule Content in Pituitary Cells
Author(s) -
Chiavaroli Carlo,
Cooper Dermot M. F.,
Boyajian Christine L.,
MurrayWhelan Rosemary,
Demaurex Nicolas,
Spiegel Allen M.,
Schlegel Werner
Publication year - 1992
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.1992.tb00195.x
Subject(s) - medicine , endocrinology , adenylyl cyclase , prolactin , exocytosis , cholera toxin , glucocorticoid , stimulation , peptide hormone , biology , chemistry , hormone , secretion
Cells of the pituitary tumour cell line GH 4 C 1 were exposed to epidermal growth factor, estradiol and insulin for 5 days, a treatment which resulted in 1) increased prolactin storage in secretory granules, 2) the loss of spontaneous [Ca 2+ ] 1 oscillations, and 3) a selective reduction of the protein G s α, seen in immunoblots, cholera toxin labelling, and vasoactive intestinal peptide stimulation of adenylyl cyclase. In contrast, the glucocorticoid dexamethasone, which increases the expression of G s α, partially restored spontaneous [Ca 2+ ] 1 oscillations and decreased prolactin storage. It is concluded that G s α levels in tumoral cells result in spontaneous electrical activity which may empty prolactin stores by the continuous activation of exocytosis.