title: Acute suppression of endogenous testosterone levels by exogenous testosterone in normal men.
abstract: The effect of exogenous testosterone on endogenous plasma testosterone was studied in normal men. Intramuscularly administered testosterone-19,19,19-d3 rapidly appeared in the systemic circulation in large amounts. Endogenous plasma testosterone was suppressed to near-castrate levels. The suppressed level began to rise between 6 and 10 h, and reached a preinjection level at 24 h after the injection. Plasma LH decreased with a concomitant decrease in endogenous testosterone and began to rise as soon as plasma total testosterone returned to physiological levels.
mesh_terms: D000328:Adult; D003864:Depression, Chemical; D005246:Feedback; D006801:Humans; D007273:Injections, Intramuscular; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D012636:Secretory Rate / Q000187:drug effects; D013737:Testis / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D013739:Testosterone; D007986:Luteinizing Hormone