The role of chloride ions in the regulation of steroidogenesis in rat Leydig cells and adrenal cells.
The role of chloride ions in the regulation of steroidogenesis in rat Leydig cells and adrenal cells has been investigated. It was found that the chloride channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) inhibited LH but not dibutyryl cAMP (dbcAMP)-stimulated steroidogenesis in the Leydig cells. This was found to be via an inhibition of cAMP production, because both LH- and forskolin-stimulated cAMP productions were inhibited by DIDS. The exclusion of chloride ions enhanced steroidogenesis during incubation of Leydig cells and adrenal cells with dbcAMP. The adrenal cells were found to be more sensitive to dbcAMP than Leydig cells and the enhancing effects of chloride removal were higher. In the presence of chloride ions, near maximum steroidogenesis was achieved with approximately 60 microM and 1 mM dbcAMP in the adrenal and Leydig cells, respectively. In the absence of chloride ions the concentrations required decreased approximately 50-fold and 10-fold, respectively. It is concluded that although LH may regulate DIDS sensitive chloride channels, the enhanced stimulation of cAMP-mediated steroidogenesis by chloride exclusion is not mediated via these channels. We propose a model based on the present and previous studies [1] with Leydig tumour (MA10) cells i.e. that intracellular chloride ion depletion enhances the action of cAMP on protein synthesis which results in increased synthesis of the Steroidogenic Acute Regulator (StAR) protein and consequently increased steroidogenesis.
Department of Biochemistry and Molecular Biology, Royal Free Hospital School of Medicine, London, UK. bacooke@rfhsm.ac.uk
B A
BA
Cooke
L
L
Ashford
D R
DR
Abayasekara
M
M
Choi
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000311:Adrenal Glands / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002712:Chlorides / Q000502:physiology*; D000242:Cyclic AMP / Q000096:biosynthesis; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D013739:Testosterone / Q000096:biosynthesis*
D002121:Calcium Channel Blockers; D002712:Chlorides; D013739:Testosterone; D000242:Cyclic AMP; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid