title: Intra-amygdalar okadaic acid enhances conditioned taste aversion learning and CREB phosphorylation in rats.
abstract: Protein phosphatases (PPs) regulate many substrates implicated in learning and memory. Conditioned taste aversion (CTA) learning, in which animals associate a novel taste paired with a toxin and subsequently avoid the taste, is dependent on several serine/threonine phosphatase substrates and the PP1-binding protein spinophilin. In order to examine the effects of PP1/2A blockade on CTA acquisition and extinction, rats received bilateral infusions of okadaic acid (OA) (100nM, 1microl/hemisphere) or vehicle (0.15M NaCl) into the amygdala either 5min prior to, or 5min after, a single pairing of sodium saccharin (0.125%, 10-min access) and LiCl or NaCl (0.15M, 3ml/kg i.p.). Two-bottle, 24-h preference tests were conducted for 13days to measure CTA expression and extinction. Rats conditioned with saccharin and LiCl showed a decreased preference for saccharin, and OA administered before (but not after) the pairing of saccharin and LiCl resulted in a significantly stronger CTA that did not extinguish over 13days. The enhancement of the CTA was not due to aversive effects of OA, because rats given OA and a pairing of saccharin and NaCl did not acquire a CTA. Finally, OA administration increased levels of phosphorylated CREB immunoreactivity following a CTA trial. Together, these results suggest a critical role for PP1/2A during normal CTA learning. Because CTA learning was enhanced only when OA was given prior to conditioning, phosphatase activity may be a constraint on learning during the taste-toxin interval but not during acquisition and consolidation processes that occur after toxin administration.
authors.affiliation: Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306, USA.
authors.forename: Denesa L
authors.initials: DL
authors.lastname: Oberbeck
authors.forename: Stefanie
authors.initials: S
authors.lastname: McCormack
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Houpt
mesh_terms: D000679:Amygdala / Q000187:drug effects*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D050882:CREB-Binding Protein / Q000378:metabolism*; D003214:Conditioning, Classical / Q000187:drug effects; D005518:Food Preferences / Q000187:drug effects; D018021:Lithium Chloride / Q000008:administration & dosage; D008297:Male; D019319:Okadaic Acid / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012439:Saccharin / Q000008:administration & dosage; D018709:Statistics, Nonparametric; D013549:Sweetening Agents / Q000008:administration & dosage; D013649:Taste / Q000187:drug effects*
chemical_list: D013549:Sweetening Agents; D019319:Okadaic Acid; D050882:CREB-Binding Protein; D012439:Saccharin; D018021:Lithium Chloride