Different behavioral experiences induce distinct patterns of PKA activation in central brain of the crab Chasmagnathus.)

LOCATELLI F; ROMANO A

Los Angeles, EEUU.

Congreso; Neural Control of Behaviour Conference; 2004

UCLA.

Different behavioral experiences induce distinct patterns of PKA activation in central brain of the crab Chasmagnathus Fernando Locatelli and Arturo Romano Neurobiology of Memory Laboratory, School of Exact and Natural Sciences, University of Buenos Aires, Argentina. locatellif@yahoo.com.ar In the context-signal learning model of the crab Chasmagnathus, an instance of associative memory, we found pharmacological evidence that PKA activity is necessary during two critical periods for memory consolidation. In order to determine if context-signal training in fact activates PKA during these critical periods, we studied PKA activity in central brain of trained crabs and compared it with crabs that were only exposed to the training context but not trained and with naive crabs. At first, PKA activation seemed to be a common and non-distinct mechanism triggered by both experiences, since context-signal training as well as context exposure induced PKA activation. However, further analyses focused on temporal course of PKA activation and on PKA isoform, suggest the existence of specific patterns of PKA activation, which allow a distinctive biochemical characterization of both experiences. Context-signal training induced a 40% increase of basal PKA activity immediately after training and showed similar levels 6 h latter, during the second critical period. The increase observed during the second period was also accompanied by a similar rise in total PKA activity. In contrast, animals only exposed to the novel context showed a 50% increase of basal PKA activity only immediately after the experience and normal levels were restored 6 h later. In addition, analyses of PKA isoform composition in extracts from central brain after the different treatments allowed us to determine that PKA activation induced by both experiences are mechanistically different. Results suggest that context induced PKA activation is at least in part due to PKA type II activation and that PKA activation observed 6 h after training is in part due to an increase in total level of PKA type I, which is the isoform more sensitive to cAMP.