title: Luteinizing hormone and cyclic AMP-mediated induction of microsomal cytochrome P-450 enzymes in cultured mouse Leydig cells.
abstract: Treatment of mouse Leydig cell cultures with luteinizing hormone (LH) or with 8-bromo-cAMP (8-Br-cAMP) for 5 days elicited a dose- and time-dependent increase in the microsomal cytochrome P-450 enzyme activities. 17 alpha-Hydroxylase and C17-20 lyase as well as a parallel increase in testosterone production. Reduction of the oxygen tension from 19 to 1% resulted in a greater increase in enzyme activity. Induction of microsomal cytochrome P-450 activities was 35 to 50% greater with 8-Br-cAMP than with LH and the increase in C17-20 lyase activity was 4-fold greater than that of 17 alpha-hydroxylase. Maximal induction of P-450 enzyme activities was observed between 3 and 5 days of continual treatment with 8-Br-cAMP or LH. Removal of 8-Br-cAMP from the culture medium inhibited any further increase in C17-20 lyase activity and testosterone production. The role of protein synthesis in the induction process was investigated by incubating Leydig cell cultures with and without cycloheximide between 24 and 48 h of treatment with 8-Br-cAMP. Cycloheximide completely inhibited the induction of C17-20 lyase activity and the increase in testosterone production. After removal of the inhibitor, cultures responded in a manner that paralleled induction in cultures that had not been treated with cycloheximide. In both cases, a 24-h lag period occurred prior to an increase in cytochrome P-450 activity. These data suggest that the increase in microsomal cytochrome P-450 activities represents an increase in enzyme synthesis and, furthermore, that reduction of oxygen tension decreases degradation of newly synthesized Leydig cell microsomal cytochrome P-450 activities as recently reported (Quinn, P.G., and Payne, A.H. (1984) J. Biol. Chem. 259, 4130-4135).
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000446:Aldehyde-Lyases / Q000096:biosynthesis*; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D007985:Leydig Cells / Q000187:drug effects / Q000201:enzymology*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008861:Microsomes / Q000201:enzymology; D010100:Oxygen; D013254:Steroid 17-alpha-Hydroxylase / Q000096:biosynthesis*; D013250:Steroid Hydroxylases / Q000096:biosynthesis*; D013739:Testosterone / Q000096:biosynthesis
chemical_list: D015124:8-Bromo Cyclic Adenosine Monophosphate; D013739:Testosterone; D007986:Luteinizing Hormone; D003513:Cycloheximide; D000242:Cyclic AMP; D013250:Steroid Hydroxylases; D013254:Steroid 17-alpha-Hydroxylase; D000446:Aldehyde-Lyases; D010100:Oxygen