Modulation of hippocampal NCAM polysialylation and spatial memory consolidation by fear conditioning
BACKGROUND: Cell adhesion molecule function is involved in hippocampal synaptic plasticity and associated with memory consolidation. At the infragranular zone of the dentate gyrus, neurons expressing the polysialylated form of the neural cell adhesion molecule (NCAM PSA) transiently increase their frequency 12 hours after training in different tasks. METHODS: Using immunohistochemical procedures, we investigated NCAM polysialylation following training in a contextual fear conditioning paradigm that employed increasing shock intensities to separately model stressful and traumatic experiences in adult male Wistar rats. RESULTS: Fear conditioning with a stressful.4-mA stimulus resulted in an increased frequency of dentate polysialylated neurons, the magnitude of which was indistinguishable from that observed following water maze training. By contrast, training with a traumatic 1-mA stimulus resulted in a significant decrease in the frequency of polysialylated neurons at the 12 hours posttraining time. Whereas sequential training in the water maze paradigm followed by fear conditioning resulted in potentiated consolidation of spatial information when conditioning involved a.4-mA stimulus, amnesia for spatial learning occurred when conditioning was performed with a 1-mA stimulus. CONCLUSIONS: These results suggest traumatic fear conditioning suppresses NCAM-PSA-mediated plasticity and the concomitant inability to store the trace of recently acquired information.
Keywords: Animals ; Conditioning ; Classical ; Corticosterone/blood ; Dentate Gyrus/ metabolism ; Electric Stimulation ; Fear ; Immunohistochemistry ; Male ; Maze Learning ; Memory ; Neural Cell Adhesion Molecules/ metabolism ; Neurons/ metabolism ; Rats ; Rats ; Wistar ; Space Perception ; Stress ; Psychological/ metabolism ; Water
Author address: Department of Psychobiology (CS, JJM, MIC, NDK), Universidad Nacional de Educacion a Distancia, Ciudad Universitaria, Madrid, Spain.
Record created on 2007-01-18, modified on 2016-08-08