Brain 5-hydroxytryptamine and plasma testosterone in L-tryptophan treated rats.
Loading of L-tryptophan for 7 and 21 days increased brain 5-hydroxytryptamine (5-HT) level which was associated with decreased plasma testosterone level. Human chorionic gonadotropin (HCG) administration in L-tryptophan treated rats for 21 days increased the plasma testosterone level in spite of increased brain 5-HT level. These results suggest that brain 5-HT exerts an inhibitory influence on testicular steroidogenesis by modulating the gonadotropin-releasing-factor (GnRH) release and thence pituitary gonadotropins.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D006065:Gonadotropins, Pituitary / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013737:Testis / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000097:blood*; D014364:Tryptophan / Q000494:pharmacology*
D006063:Chorionic Gonadotropin; D006065:Gonadotropins, Pituitary; D012701:Serotonin; D013739:Testosterone; D014364:Tryptophan