title: Isoflurane anesthesia induces biphasic effect on dopamine release in the rat striatum.
abstract: The effect of isoflurane anesthesia on changes in the extracellular concentrations of dopamine (DA) and its metabolites (3-methoxytyramine (3-MT), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA)) modulated by pargyline, monoamine oxidase inhibitor, was studied using in vivo microdialysis techniques. A microdialysis probe was implanted into the right striatum of male SD rats. Each rat (n=5-6) was given saline or the same volume of 30 or 75 mg kg(-1) pargyline intraperitoneally with or without 1 h isoflurane anesthesia (1 or 3%). Isoflurane anesthesia increased the extracellular concentration of DA in high dose (3%) and increased the metabolite concentrations in a dose-dependent manner. Pargyline administration increased the extracellular concentration of DA and 3-MT, and decreased that of other metabolites. After 30 mg kg(-1) pargyline treatment, 1% isoflurane-induced DA release and increasing of 3-MT were preserved, whereas high dose isoflurane (3%) decreased the concentration of metabolites (DOPAC and HVA), despite of the increase by low dose isoflurane (DOPAC). When 75 mg kg(-1) pargyline was administered, isoflurane anesthesia decreased the concentration of DA and DOPAC. The isoflurane-induced 3-MT increase was preserved in all experiments. Our results suggest that isoflurane anesthesia induced biphasic effect on DA regulation probably by the potentiation of DA release and the inhibition of DA synthesis. Isoflurane might modulate DA homeostasis presynaptically.
authors.affiliation: Medical Clinic of Hamamatsu Base, Japan Air Self Defense Force, Hamamatsu City, Shizuoka 432-8551, Japan. yuadachi@poppy.ocn.ne.jp
authors.forename: Yushi U
authors.initials: YU
authors.lastname: Adachi
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yamada
authors.forename: Maiko
authors.initials: M
authors.lastname: Satomoto
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Higuchi
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Watanabe
authors.forename: Tomiei
authors.initials: T
authors.lastname: Kazama
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003342:Corpus Striatum / Q000187:drug effects*; D004298:Dopamine / Q000031:analogs & derivatives / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis / Q000379:methods; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018685:Anesthetics, Inhalation; D008996:Monoamine Oxidase Inhibitors; D015102:3,4-Dihydroxyphenylacetic Acid; D010293:Pargyline; D007530:Isoflurane; C001746:3-methoxytyramine; D004298:Dopamine