title: Mechanism of systemically injected interferon-alpha impeding monoamine biosynthesis in rats: role of nitric oxide as a signal crossing the blood-brain barrier.
abstract: The serious and characteristic side effects of interferon-alpha (IFN-alpha) therapy on the central nervous system, resulting in such problems as affective disorders or parkinsonism, have led us to investigate the biochemical mechanism of the effects of IFN-alpha on the monoaminergic neurotransmitter system using an animal model (rats). We first examined the concentrations of tetrahydrobiopterin (BH(4)) and monoamines in several regions of the brain after the intramuscular injection of IFN-alpha into rats; the levels of BH(4) and dopamine significantly decreased in the amygdala and raphe areas as compared with those of the controls. Based on these results, we further examined the concentrations of BH(4) and nitrite (NO(2)(-)) plus nitrate (NO(3)(-)), metabolites of nitric oxide (NO), in the amygdala and raphe areas after the intramuscular injection of IFN-alpha; the concentrations of both BH(4) and NO(2)(-)+NO(3)(-) significantly decreased as compared with the control. Furthermore, the addition of N(G)-monomethyl L-arginine, an inhibitor of NO synthase, after the injection of IFN-alpha restored the decreased levels of both NO(2)(-)+NO(3)(-) and BH(4) to control levels. As a result, nitric oxide induced by the intramuscular injection of IFN-alpha was found to cross the blood-brain barrier and suppress both tetrahydrobiopterin biosynthesis and dopamine production in the amygdala and raphe areas.
authors.affiliation: Department of Biochemistry, Nagoya University Graduate School of Medicine, Tsuruma-cho, Showa-ku, Nagoya 466, Japan. tomtsu@med.nagoya-u.ac.jp
authors.forename: Tomitsune
authors.initials: T
authors.lastname: Kitagami
authors.forename: Kiyofumi
authors.initials: K
authors.lastname: Yamada
authors.forename: Hideki
authors.initials: H
authors.lastname: Miura
authors.forename: Ryo
authors.initials: R
authors.lastname: Hashimoto
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Nabeshima
authors.forename: Tatsurou
authors.initials: T
authors.lastname: Ohta
mesh_terms: D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D001923:Brain Chemistry; D004333:Drug Administration Routes / Q000662:veterinary; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007155:Immunologic Factors / Q000494:pharmacology*; D016898:Interferon-alpha / Q000494:pharmacology*; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction / Q000502:physiology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D015306:Biogenic Monoamines; D004791:Enzyme Inhibitors; D007155:Immunologic Factors; D016898:Interferon-alpha; D001708:Biopterins; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; C003402:sapropterin