title: Hormonal regulation of rat Leydig cell cytochrome P-45017 alpha mRNA levels and characterization of a partial length rat P-45017 alpha cDNA.
abstract: We have isolated and characterized a P-45017 alpha cDNA fragment from a rat testis library. The partial length rat P-45017 alpha cDNA (1Kb) has high overall nucleotide and deduced amino acid similarity with human and bovine P-45017 alpha cDNA's and contains the conserved tridecapeptide and heme regions, the termination codon and polyadenylation site. Using this rat testis cDNA probe we measured P-45017 alpha mRNA levels of rat Leydig cells from animals treated with hCG. Temporal studies with a low hCG dose showed an early increase in mRNA levels returning to control values at later times, while a higher desensitizing dose caused a marked reduction in the mRNA (24 h) and a small recovery at 48 h. Fetal rat Leydig cells maintained in the presence of LH treated with estradiol showed a 70% decrease in P-45017 alpha mRNA levels and testosterone production followed closely the changes in P-45017 alpha mRNA. These studies suggest that gonadotropin stimulation and desensitization of P-45017 alpha dependent enzymes in the adult rat testis as well as estradiol induced desensitization in fetal Leydig cells are related to levels P-45017 alpha mRNA.
authors.affiliation: Section on Molecular Endocrinology, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
authors.forename: M
authors.initials: M
authors.lastname: Nishihara
authors.forename: C A
authors.initials: CA
authors.lastname: Winters
authors.forename: E
authors.initials: E
authors.lastname: Buzko
authors.forename: M R
authors.initials: MR
authors.lastname: Waterman
authors.forename: M L
authors.initials: ML
authors.lastname: Dufau
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D005796:Genes / Q000187:drug effects*; D007700:Kinetics; D007985:Leydig Cells / Q000187:drug effects / Q000201:enzymology*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D012016:Reference Values; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; D007986:Luteinizing Hormone; D004247:DNA; D013250:Steroid Hydroxylases; D013254:Steroid 17-alpha-Hydroxylase