title: Effect of prolonged exposure to milnacipran on norepinephrine transporter in cultured bovine adrenal medullary cells.
abstract: The antidepressants milnacipran and paroxetine are used clinically worldwide. In the present study, we report here the effects of treatment with milnacipran and paroxetine on the functional activity, binding sites, and mRNA of the norepinephrine (NE) transporter (NET) in cultured bovine adrenal medullary cells. In acute treatment with antidepressants for 20 min, both milnacipran and paroxetine competitively inhibited NET function in cultured adrenal medullary cells. Prolonged treatment of adrenal medullary cells with milnacipran produced time (48-96h)- and concentration (35-355 nM)-dependent increases in [3H]NE uptake and [3H]DMI binding without any increase in NET mRNA. At a high concentration (800 nM, 72 h), paroxetine suppressed [3H]NE uptake. To examine whether milnacipran-induced [3H]NE uptake is mediated by newly synthesized mRNAs or proteins, we used actinomycin D, an inhibitor of DNA-dependent RNA polymerase, and cycloheximide, an inhibitor of ribosomal protein synthesis. Cycloheximide (1 micorM, 72 h) abolished the effect of milnacipran on [3H]NE uptake, while the stimulatory effect of milnacipran was observed in actinomycin D-treated cells. The present findings suggest that prolonged exposure to milnacipran up-regulates the NET function, probably through a post-transcriptional process of NET or other proteins.
authors.affiliation: Department of Psychiatry, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Shinkai
authors.forename: Reiji
authors.initials: R
authors.lastname: Yoshimura
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Toyohira
authors.forename: Susumu
authors.initials: S
authors.lastname: Ueno
authors.forename: Masato
authors.initials: M
authors.lastname: Tsutsui
authors.forename: Jun
authors.initials: J
authors.lastname: Nakamura
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yanagihara
mesh_terms: D000313:Adrenal Medulla / Q000187:drug effects* / Q000378:metabolism; D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003521:Cyclopropanes / Q000494:pharmacology*; D003609:Dactinomycin / Q000494:pharmacology; D003891:Desipramine / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D000078764:Milnacipran; D009638:Norepinephrine / Q000378:metabolism; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D017374:Paroxetine / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D015854:Up-Regulation
chemical_list: D018759:Adrenergic Uptake Inhibitors; D003521:Cyclopropanes; D050484:Norepinephrine Plasma Membrane Transport Proteins; D012333:RNA, Messenger; D003609:Dactinomycin; D017374:Paroxetine; D003513:Cycloheximide; D000078764:Milnacipran; D003891:Desipramine; D009638:Norepinephrine