title: A lateral hypothalamic D1 dopaminergic mechanism in conditioned taste aversion.
abstract: The aim of this study was to elucidate the role of the neuropil located in the LHA in the acquisition of the association between a taste (conditioned stimulus = saccharin) and a visceral distress (unconditioned stimulus = lithium chloride) leading to long delayed learning of a conditioned taste aversion (CTA). In 82 male rats guide-cannulae were directed bilaterally into the basolateral LHA where bilateral microinjections were made after the conditioned stimulus and before the unconditioned stimulus. We found that: (1) tetrodotoxin, a non-specific blocker of neuronal activity disrupted the acquisition of the CTA; (2) SCH 23390, a specific D1 receptor blocker also disrupted learning of the CTA, while sulpiride, a D2 receptor blocker, did not; (3) neither the specific blockade of D1 nor of D2 receptors could prevent the visceral distress-induced decrease in water intake, showing that the visceral distress was actually experienced; and (4) the sham taste aversion learning (i.e. without visceral distress) revealed that neither the D1 nor the D2 receptors blockade induced by themselves either a taste preference or a taste aversion towards saccharin, indicating that the impaired acquisition of the CTA was not due to a superimposed taste preference that could have been induced by the intra-LHA D1 receptors blockade. It is concluded that the neuropil in the LHA is necessary in the process of the acquisition of long delayed learning and that it uses a D1 receptor specific mechanism.
authors.affiliation: Neurobiologie des Régulations, CNRS URA 1860, Collège de France, Paris, France. caulliez@bisance.citi2.fr
authors.forename: R
authors.initials: R
authors.lastname: Caulliez
authors.forename: M J
authors.initials: MJ
authors.lastname: Meile
authors.forename: S
authors.initials: S
authors.lastname: Nicolaidis
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D004326:Drinking / Q000187:drug effects; D007031:Hypothalamus / Q000502:physiology*; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000502:physiology*; D012439:Saccharin / Q000494:pharmacology; D013649:Taste / Q000502:physiology*
chemical_list: D017447:Receptors, Dopamine D1; D012439:Saccharin; D018021:Lithium Chloride