title: Chloride efflux in unstimulated Leydig cells causes autonomous cAMP production and stimulatory/inhibitory steroidogenesis with an efflux inhibitor.
abstract: Gonadotropins cause immediate chloride secretion in Leydig cells, which still have an unknown physiological. Thyroid and Leydig cells produce more cAMP and steroids, respectively, under low or chloride-free conditions. Here, we show that chloride efflux mediated by incubation of Mouse Leydig Tumor cells (MLTC-1) in hypotonic or chloride-free isotonic buffers results in more cAMP production without any gonadotropic stimulation. MLTC-1 cells incubated with 0.5mM diphenylamine-2-carboxylate (DPC), a chloride efflux inhibitor, produced increased amounts of testosterone as chloride ions were substituted by gluconate or sulphate ions under isotonic conditions. There was also an up-regulation of steroidogenic acute regulatory protein and 3beta-hydroxysteroid dehydrogenase/isomerase type I mRNAs, without human chorionic gonadotropin. With the exception of cAMP production, 2mM DPC inhibited all of the above, including the transcription of constitutively expressed cholesterol side-chain cleavage enzyme and the L19 house-keeping gene. Although it was speculated that gonadotropin mediated chloride secretion could aid steroid hormone release, we conclude that the real reason for chloride secretion in Leydig cells may be to "kick start" cAMP production.
authors.affiliation: Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Whales Hospital, 1/F Clinical Sciences Building, 30-32 Ngan Shing Street, Shatin, New Territories, Hong Kong SAR, PR China. nspanesar@cuhk.edu
authors.forename: Nirmal S
authors.initials: NS
authors.lastname: Panesar
authors.forename: Kam W
authors.initials: KW
authors.lastname: Chan
mesh_terms: D000818:Animals; D002021:Buffers; D045744:Cell Line, Tumor; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism* / Q000494:pharmacology; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D005942:Gluconates / Q000494:pharmacology; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D009097:Multienzyme Complexes / Q000235:genetics; D010750:Phosphoproteins / Q000235:genetics; D011375:Progesterone Reductase / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D013251:Steroid Isomerases / Q000235:genetics; D013256:Steroids / Q000096:biosynthesis*; D013431:Sulfates / Q000494:pharmacology; D013739:Testosterone / Q000096:biosynthesis; D062367:ortho-Aminobenzoates / Q000494:pharmacology*; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: C021425:3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase; D002021:Buffers; D018118:Chloride Channels; D002712:Chlorides; D006063:Chorionic Gonadotropin; D005942:Gluconates; D009097:Multienzyme Complexes; D010750:Phosphoproteins; D012269:Ribosomal Proteins; D013256:Steroids; D013431:Sulfates; D062367:ortho-Aminobenzoates; D000098682:Steroidogenic Acute Regulatory Protein; C050482:Rpl19 protein, rat; D013739:Testosterone; C001209:fenamic acid; D000242:Cyclic AMP; D011375:Progesterone Reductase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D013251:Steroid Isomerases; C030691:gluconic acid