Serotonin and dopamine in the parabrachial nucleus of rats during conditioned taste aversion learning.
A microdialysis technique was used to monitor changes in serotonin (5-HT), 5-hydroxyindole acetic acid (5-HIAA) and dopamine (DA) in the extracellular space of the parabrachial nucleus (PBN) of rats to estimate the contribution of these neurotransmitter systems to the acquisition of conditioned taste aversion (CTA). A significant (280%) enhancement of 5-HT was found immediately after saccharin drinking (CS). I.p. injection of unconditioned stimulus LiCl alone (after water drinking) also increased level of 5-HT (200%). However, when saccharin intake was followed by injection of LiCl (CS-US pairing), no change in 5-HT was observed. 5-HIAA and DA were unaffected by any of the above treatments. Thus in spite of elevation of 5-HT in PBN following saccharin consumption alone (CS) or LiCl administration alone (US) no changes in 5-HT occurred after pairing of both stimuli (CS-US). Our work demonstrates that participation of 5-HT in acquisition of CTA appears to be unlikely, and also DA appears not to be engaged in this acquisition at all. At the level of the PBN 5-HT participates mainly in CS and/or US stimuli processing, where this phenomenon has close relationship to other important physiological mechanisms, involved in behavioral control. Such as anxiety, alimentation intake.
Zach
Petr
P
Institute of Anatomy, Third Medical Faculty, Czech Republic; Social and Health Faculty, South-Bohemian University, Czech Republic.
Petr
Zach
Z
Krivanek
Jiri
J
Jiri
Krivanek
K
Vales
Karel
K
Karel
Vales
V
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003216:Conditioning, Operant / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism*; D005518:Food Preferences / Q000502:physiology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis / Q000379:methods; D011149:Pons / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012701:Serotonin / Q000378:metabolism*; D013649:Taste
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D004298:Dopamine