title: Neuronal release of serotonin in the cerebellum of behaving rats: an in vivo microdialysis study.
abstract: Release of endogenous serotonin [5-hydroxy-tryptamine (5-HT)] in the cerebellum of awake rats was characterized using in vivo microdialysis. 5-HT output was increased (approximately 70%) by local application of KCI (100 mM) and was reduced (approximately 60%) by both tetrodotoxin (0.5 microM) and omission of Ca2+ from the perfusion fluid. 5-HT release was decreased (approximately 70%) by the selective 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (0.25 mg/kg, s.c.), and this effect was rapidly reversed by a selective 5-HT1A antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclo- hexane-carboxamide trihydrochloride (WAY-100635; 0.1 mg/kg, i.p.). These results indicate that a large portion of the measurable 5-HT output in the cerebellum is of neuronal origin, is dependent on impulse flow, and is sensitive to 5-HT1A autoreceptor activation. Further studies examined the relationship between 5-HT levels and general activity of the animals across the light-dark transition and during behavioral manipulations. Both 5-HT levels and behavioral activity were significantly elevated during the dark period, with changes in 5-HT efflux closely paralleling changes in activity. Similar increases (approximately 40%) in 5-HT output were observed during both feeding and feeding in the presence of a stressor (tail pinch). These findings suggest that behavioral state is an important factor determining neuronal 5-HT release in cerebellum under physiological conditions.
authors.affiliation: Program in Neuroscience, Princeton University, New Jersey, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mendlin
authors.forename: F J
authors.initials: FJ
authors.lastname: Martín
authors.forename: L E
authors.initials: LE
authors.lastname: Rueter
authors.forename: B L
authors.initials: BL
authors.lastname: Jacobs
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D002531:Cerebellum / Q000502:physiology*; D003624:Darkness; D005247:Feeding Behavior / Q000502:physiology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D009043:Motor Activity; D009474:Neurons / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D013312:Stress, Physiological / Q000378:metabolism; D014851:Wakefulness
chemical_list: D012701:Serotonin; D006897:Hydroxyindoleacetic Acid