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Different disruptive effects on the acquisition and expression of conditioned taste aversion by blockades of amygdalar ionotropic and metabotropic glutamatergic receptor subtypes in rats

Department of Behavioral Physiology, Faculty of Human Sciences, Osaka University, 1-2 Yamadaoka, Suita, 565-0871, Osaka, Japan.
Brain Research (Impact Factor: 2.83). 07/2000; 869(1-2):15-24. DOI: 10.1016/S0006-8993(00)02397-0
Source: PubMed

ABSTRACT Conditioned taste aversion (CTA) is based on the gustatory long-term memory established after association of the taste of food (conditioned stimulus, CS) with visceral signals of poisoning (unconditioned stimulus, US). After the acquisition of CTA, hedonics of the taste CS changes from positive to negative as indicated by reduced ingestive and increased aversive taste reactivities in response to re-exposures to the CS. We examined the effects of reversible and selective blockades of the amygdalar glutamate receptor subtypes, AMPA, NMDA and metabotropic glutamate receptors, on the formation of CTA. Blockades of each of the three receptor subtypes between ingestion of saccharin (CS) and malaise-inducing LiCl (US) disrupted the acquisition of CTA. After the acquisition of CTA, however, blockades of only AMPA receptors, but not NMDA or metabotropic receptors, impaired the expression of CTA. This effect was seen only during the period when the antagonistic action to AMPA receptors lasted. These results indicate that both ionotropic and metabotropic glutamate receptor subtypes in the amygdala are indispensable for the acquisition of CTA, but that the expression of acquired CTA is mediated only by AMPA receptors. The present results also suggest that the amygdalar glutamatergic neural transmission is involved in the formation and storage of long-term gustatory memory associated with the altered hedonics from positive to negative.

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    • "Concerning the neurotransmission associated to memory formation, glutamatergic transmission has been implicated in http://dx.doi.org/10.1016/j.bbr.2015.02.020 0166-4328/© 2015 Elsevier B.V. All rights reserved. different types of learning [1] [5] [21] [24] [28]. Glutamate receptors have been classified as ionotropic or metabotropic (mGluR) receptors . "
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    • "participate in taste memory formation (Tucci et al., 1998; Yamamoto & Fujimoto, 1991); acquisition can be blocked by the administration of an AMPAr antagonist, an NMDAr antagonist or a metabotropic glutamate receptor antagonist into the amygdala between the CS and the US on the first CTA trial (Yasoshima et al., 2000). However, taste aversion retrieval is affected only by the blockade of AMPAr in the amygdala (Rodriguez-Ortiz, Balderas, Garcia-DeLaTorre, & Bermudez-Rattoni, 2012; Yasoshima et al., 2000). A different participation of amygdala nuclei has been proposed in CTA memory. "
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    Neurobiology of Learning and Memory 05/2014; DOI:10.1016/j.nlm.2014.03.003 · 4.04 Impact Factor
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