title: Melatonin biosynthesis and metabolism in peripheral blood mononuclear leucocytes.
abstract: Cultured human peripheral blood mononuclear leucocytes (PBML) were able to synthesize indoleamines, including melatonin, and were also able to convert melatonin taken up from the incubation medium into N-acetyl-5-hydroxytryptamine (NAHT) and 5-hydroxytryptamine (5-HT). These compounds were analysed by h.p.l.c., and melatonin was additionally characterized by two-dimensional t.l.c., mass spectrometry and radioimmunoassay. Only hydroxyindoles were detected by h.p.l.c. in unstimulated PBML culture. Sustained stimulation by melatonin or interferon-gamma (IFN-gamma) increased markedly the basal production of 5-HT. IFN-gamma- or 5-HT-stimulated (but not resting) cells produced NAHT and melatonin. Furthermore, the addition of melatonin to the culture medium strongly enhanced NAHT and 5-HT production without affecting tryptophan hydroxylation, suggesting the possibility of direct or indirect transformation of melatonin into NAHT and 5-HT.
authors.affiliation: Laboratorio de Sustancias Vasoactives, Universidad de Buenos Aires, Argentina.
authors.forename: L M
authors.initials: LM
authors.lastname: Finocchiaro
authors.forename: V E
authors.initials: VE
authors.lastname: Nahmod
authors.forename: J M
authors.initials: JM
authors.lastname: Launay
mesh_terms: D002478:Cells, Cultured; D006801:Humans; D007211:Indoles / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism*; D008550:Melatonin / Q000096:biosynthesis* / Q000276:immunology; D011863:Radioimmunoassay; D012701:Serotonin / Q000378:metabolism*; D014365:Tryptophan Hydroxylase / Q000378:metabolism
chemical_list: D007211:Indoles; D012701:Serotonin; D007371:Interferon-gamma; D014365:Tryptophan Hydroxylase; D008550:Melatonin