title: Influence of tumor necrosis factor alpha on intracellular Ca2+ in hen granulosa cells in vitro during follicular development.
abstract: In the present study, we have determined the influence of tumor necrosis factor alpha (TNF alpha) on both basal and carbamylcholine chloride (Cch)-induced [Ca2+]i in granulosa cells from the largest (F1) and smallest (F5,6) preovulatory follicles. TNF alpha (10 ng/ml) induced a small (51-63 nM) and delayed (approximately 1 min) transient increase in [Ca2+]i. The percentage of cells that responded to the cytokine was greater in F5,6 granulosa cells (48%; n = 48) than F1 granulosa cells (24%; n = 41). These responses were completely abolished in Ca(2+)-free media containing 5 mM EGTA and 2.5 mM Mg2+ or 1 mM Mn2+. Cch induced large increases (> 250 nM) in [Ca2+]i via mobilization of Ca2+ from intracellular stores in approximately 50% of Cch-responsive F1 granulosa cells but only about 15% of Cch-responsive F5,6 cells. Pretreatment with TNF alpha (4-5 min) increased the magnitude of the Cch response in both F1 and F5,6 granulosa cells previously incapable of producing large Cch-induced changes in [Ca2+]i. In F1 cells, the effects of TNF alpha on Cch-induced [Ca2+]i were far more extensive, such that the Cch response in the presence of TNF alpha was indistinguishable from the fast Cch-induced Ca2+ transient reported previously. Furthermore, the TNF alpha effect was reversible, as subsequent challenge with Cch in the absence of TNF alpha failed to produce the large Ca(2+)-transients observed earlier with the cytokine present. In conclusion, TNF alpha induces transient increases in [Ca2+]i by transmembrane Ca2+ flux, which are suppressed during cytodifferentiation. In addition, TNF alpha appeared to enhance Cch-induced mobilization of Ca2+ from intracellular stores.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Reproductive Biology Unit, Loeb Medical Research Institute, Ottawa Civic Hospital, Ontario, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Soboloff
authors.forename: M
authors.initials: M
authors.lastname: Désilets
authors.forename: B K
authors.initials: BK
authors.lastname: Tsang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D002645:Chickens; D005260:Female; D005456:Fluorescent Dyes; D016257:Fura-2; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D018721:Muscarinic Agonists / Q000494:pharmacology; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D005456:Fluorescent Dyes; D018721:Muscarinic Agonists; D014409:Tumor Necrosis Factor-alpha; D002217:Carbachol; D002118:Calcium; D016257:Fura-2