title: Aging in the AXC/SSh rat: diminished prostate L-ornithine decarboxylase (ODC) activity reflects diminished prostate ODC protein and transcript content.
abstract: Immunotitration of L-ornithine decarboxylase (ODC) activity in ventral prostates of young mature (6-month-old) and aged (26-month-old) AXC/SSh rats established that the relation between enzyme activity and prostate ODC mass content was age invariant, demonstrating that the 4-fold diminution in prostate ODC activity in aged subjects represents decreased ODC protein content. Testosterone treatment of aged rats increased prostate ODC activity 2-fold and did not affect prostate ODC half-life. These latter findings and the preceding observation established that the testosterone-mediated increase in prostate ODC activity in aged individuals reflected increased ODC mass content. The half-life of prostate S-adenosyl-L-methionine decarboxylase, another prominent enzyme of polyamine biosynthesis, also was not altered by testosterone treatment of 26-month-old animals. The age-related diminution and testosterone-mediated increase in ventral prostate ODC activity occurred in concert with comparable quantitative changes in ventral prostate ODC transcript content. Because plasma testosterone content was age invariant between 3 and 18 months, the age span during which much of the reduction in prostate ODC activity occurs, and then declined by 50% at 26 months, our studies suggest that age-related diminutions in prostate ODC activity and transcript content reflect altered prostate sensitivity to androgen rather than response to diminished plasma testosterone content. Our data imply that age-related alterations in androgen regulation of androgen-responsive genes may be characteristic of the prostate during aging.
mesh_terms: D012437:Adenosylmethionine Decarboxylase / Q000378:metabolism; D000375:Aging / Q000378:metabolism*; D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D007158:Immunologic Techniques; D008297:Male; D009955:Ornithine Decarboxylase / Q000235:genetics / Q000378:metabolism*; D011467:Prostate / Q000187:drug effects / Q000201:enzymology*; D012313:RNA / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000097:blood / Q000494:pharmacology; D014158:Transcription, Genetic
chemical_list: D013739:Testosterone; D012313:RNA; D003513:Cycloheximide; D009955:Ornithine Decarboxylase; D012437:Adenosylmethionine Decarboxylase