TWO PKA ACTIVATION PHASES DURING LONG-TERM MEMORY FORMATION INVOLVE CHANGES IN KINASE ISOFORMS LEVELS IN THE CRAB CHASMAGNATHUS

LOCATELLI F; MALDONADO H; ROMANO A

Washington DC , EEUU.

Congreso; XXXIV Annual Meeting of American Society for Neurosciences (SFN); 2002

American Society for Neuroscience

Abstract View PKA ACTIVATION DURING LONG-TERM MEMORY FORMATION INVOLVES CHANGES IN KINASE ISOFORMS LEVELS IN THE CRAB CHASMAGNATHUS F.F. Locatelli*; H. Maldonado; A.G. Romano Neurobiology of Memory Laboratory, FCEyN, University of Buenos Aires, Buenos Aires, Argentina The role of cyclic AMP (cAMP) signaling pathway in long-term memory (LTM) formation has been demonstrated in a wide range of animal models. Protein kinase A (PKA) is activated by cAMP, but recent studies demonstrated that LTM formation involves PKA activation that persists even when cAMP level decays. In the context-signal learning model of the crab Chasmagnathus, we found pharmacological evidence of two critical periods in which PKA activity is necessary for memory consolidation. Inhibition of PKA during training or between 4 and 8 h after training induces amnesia. We have previously characterized PKA isoforms I and II from crab neural tissues. At present work we measured PKA activity and the levels of each PKA isoform during the critical periods in brains from animals under three different conditions: nave (NV), trained (TR) and untrained animals exposed to the context (CT). Immediately after training, CT and TR showed higher PKA activity compared to NV. CT showed lower level of PKA type II compared to NV. During the second critical period TR showed higher PKA activity and also higher level of PKA I compared to NV and CT. Since crab PKA I shows ten fold higher sensitivity to cAMP than PKA II, increases observed in PKA activation can be explained in terms of changes in PKA isoforms proportion. Higher PKA I levels can reduce cAMP thresholds for PKA activation and set neurons to higher kinase activity even at basal cAMP levels. Thus, changes in the PKAI/PKAII ratio are proposed as a novel mechanism for regulation of PKA activity during memory consolidation.Supported by: FoNCyT Grants, Argentina Citation:F.F. Locatelli, H. Maldonado, A.G. Romano. PKA ACTIVATION DURING LONG-TERM MEMORY FORMATION INVOLVES CHANGES IN KINASE ISOFORMS LEVELS IN THE CRAB CHASMAGNATHUS Program No. 186.7. 2002 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2002. Online.