title: Glutamate in the parabrachial nucleus of rats during conditioned taste aversion.
abstract: Brain microdialysis combined with HPLC and spectroscopic detection was used to monitor extracellular glutamate in the parabrachial nucleus (PBN) of rats during acquisition of a conditioned taste aversion (CTA). Microdialysis fractions taken every 20 min were used to assess the effects of presentation of the conditioned stimulus alone (CS, consumption of 0.1% saccharin), the unconditioned stimulus alone (US, intraperitoneal injection of 0.15 M LiCl, 2% b.w. induced malaise after water drinking) as well as that of CS-US pairing. After 15 min of saccharin drinking, the glutamate concentration in the eluate (20 microl/20 min) reached 80% above the baseline but returned to the basal value in the next fraction. LiCl alone (applied 1 h after 15 min drinking of water) increased glutamate only following some delay, i.e. in the second and third post-lithium fraction by 90 and 67%, respectively. However, when LiCl was injected 1 h after the onset of saccharin intake, the glutamate concentration rose significantly (by 95%) already in the first post-LiCl fraction and by 120% in the second one. It appears, therefore, that the 'saccharin trace' facilitates the effect of lithium on extracellular concentration of glutamate in PBN during acquisition of CTA.
authors.affiliation: Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: E
authors.initials: E
authors.lastname: Bielavska
authors.forename: I
authors.initials: I
authors.lastname: Miksik
authors.forename: J
authors.initials: J
authors.lastname: Krivanek
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D003216:Conditioning, Operant; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D017551:Microdialysis; D011149:Pons / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012439:Saccharin; D013649:Taste
chemical_list: D018698:Glutamic Acid; D012439:Saccharin