title: In vivo measurement of hypothalamic serotonin release by intracerebral microdialysis: significant enhancement by immobilization stress in rats.
abstract: Intracerebral microdialysis was used to measure extracellular serotonin and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the hypothalamus of unanesthetized rats. Increase in the concentration of K+ in the perfusing Ringer solution (70 mM) produced a sharp increase in serotonin release, which was significantly attenuated by omitting Ca2+ from the perfusion medium. Intraperitoneal injection of 5-hydroxytryptophan, a precursor of serotonin, or local perfusion of pargyline, a monoamine oxidase inhibitor, elevated the hypothalamic serotonin. Releasers or uptake inhibitors of serotonin, such as fenfluramine, cocaine, mazindol, or imipramine, when added to the perfusion medium, significantly increased serotonin level, whereas 5-HIAA was unaffected by these substances. Immobilization-stress caused an immediate increase in both the extracellular serotonin and 5-HIAA in the hypothalamus, suggesting that the hypothalamic serotonergic system is activated during immobilization stress. The present study indicates that the brain microdialysis is useful for analysis of local changes in serotonin concentration which directly reflect neuronal transmission.
authors.affiliation: Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Shimizu
authors.forename: S
authors.initials: S
authors.lastname: Take
authors.forename: T
authors.initials: T
authors.lastname: Hori
authors.forename: Y
authors.initials: Y
authors.lastname: Oomura
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D003956:Dialysis; D004558:Electric Stimulation; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007026:Hypothalamic Area, Lateral / Q000378:metabolism / Q000502:physiology; D007031:Hypothalamus / Q000378:metabolism*; D007103:Immobilization; D008297:Male; D008832:Microchemistry; D010293:Pargyline / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011903:Raphe Nuclei / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013315:Stress, Psychological / Q000378:metabolism*; D013569:Synapses / Q000502:physiology
chemical_list: D012702:Serotonin Antagonists; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D010293:Pargyline; D006916:5-Hydroxytryptophan; D011188:Potassium; D002118:Calcium