title: Sensitivity of human peripheral blood mononuclear leukocytes to visible light.
abstract: Overnight light exposure of cultured human peripheral blood mononuclear leukocytes [PBML], significantly increased basal [3H]thymidine incorporation and upon stimulation with phytohemagglutinin [PHA]. Melatonin (10(-9) to 10(-5) M) enhanced the light-induced increase of [3H]thymidine incorporation, while serotonin (10(-9) to 10(-7) M) stimulated [3H]thymidine incorporation in the dark. The wavelengths responsible of this effect were restricted to the blue-green zone of the spectrum. The stimulatory effect of visible light on PHA-induced DNA replication had a circannual rhythm, being maximal during winter. In winter, white light also reduced melatonin and serotonin binding to PBML membranes and switched the PBML indole metabolism towards serotonin and 5-hydroxy-indole-acetic acid [HIAA] synthesis, with a concomitant decrease of melatonin production.
authors.affiliation: Laboratorio de Sustancias Vasoactivas, Instituto de Investigaciones Médicas, Universidad de Buenos Aires, Argentina.
authors.forename: L M
authors.initials: LM
authors.lastname: Finocchiaro
authors.forename: E
authors.initials: E
authors.lastname: Polack
authors.forename: V E
authors.initials: VE
authors.lastname: Nahmod
authors.forename: G C
authors.initials: GC
authors.lastname: Glikin
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D017931:DNA Primers / Q000737:chemistry; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000528:radiation effects*; D008027:Light; D008550:Melatonin / Q000378:metabolism; D008969:Molecular Sequence Data; D017299:Rod Opsins / Q000235:genetics; D012701:Serotonin / Q000378:metabolism
chemical_list: D017931:DNA Primers; D007211:Indoles; D017299:Rod Opsins; D012701:Serotonin; D004247:DNA; D008550:Melatonin