The role of AKT phosphiorylation in acquisition and extinction of conditioned taste aversion: The Israel Society for Neuroscience 19th Annual Meeting Eilat, Dec. 12 - 14, 2010 www.isfn.org.il

Association between a novel taste and a visceral malaise produces conditioned taste aversion (CTA); repeated presentation of the taste without the malaise causes aversion extinction. In the brain, the acquisition and extinction of CTA are suggested to be mediated by the insular cortex (IC)-basolateral amygdala (BLA)-prefrontal cortex (PFC) circuit. AKT is a main kinase of the PI 3-kinase cascade, implicated in long-term memory and synaptic plasticity and we hypothesized that it may be differentially involved in the IC-BLA-PFC neural network in the acquisition and extinction of CTA. To that end, we inhibited AKT phosphorylation by injection of LY294002 (LY; the PI 3-kinase cascade inhibitor) into the IC at different stages of the acquisition or extinction of CTA in rats. Inhibition of AKT phosphorylation in the IC prior or after the first extinction training (T1) facilitated the acquisition and consolidation of extinction on T2. In contrast, microinjection of the LY into the IC before T2 impaired the retrieval of extinction memory. These effects were transient, and extinction behavior returned to baseline levels on T3. Interference with AKT phosphorylation after T2 had no effect on extinction, suggesting that after being well consolidated, extinction is resistant to disruption by the AKT inhibitor.

These results suggest that AKT in the IC is differentially involved in acquisition and extinction of CTA.