NMDA receptor membrane expression during long-term memory consolidation in the central nervous system of the crab Neohelice granulata

SALLES, ANGELES; PEDREIRA, MARIA EUGENIA; HEPP, YANIL; CARBO-TANO, MARTIN; FREUDENTHAL, RAMIRO

Congreso; International Congress of Neuroethology; 2016

Alterations in the strength of synaptic connections between neurons are key to the formation of amemory trace. These alterations may be driven by the molecular compositionof synaptic membranes. NMDAR-dependent changes in strength of glutamatergic synapses are thoughtto underlie some forms of learning and memory both in vertebrates and invertebrates. In this studywe find changes in surface expression of the NMDAR during the consolidation phase of the contextuallearning of the crab Neohelice granulata. Our results show that the surface expression of the NR1subunit of the receptor changes after training without affecting its general expression. Immediatelyafter training, the surface expression of the NMDAR NR1 subunit is decreased, followed by anupregulation 3 hours post-training, returning to naïve and control levels 24 hours after the end oftraining.The changes in NMDAR surface expression observed in the central brain, are not seen in the thoracicganglion. To evaluate if the surface expression of the NMDAR NR1 subunit is affected by neuronalactivity, we used bicuculline injections, that produced an increment in the central brain of the crab 3hours after administration of the drug. A cocktail of MK-801 and CNQX evaluated at same time pointshowed no change. These results suggest that the changes in NR1 in the brain could be part of anevent of metaplasticity that first, during the downregulation, is helping in the stability of the trace andlater at 3 hours post-training changes the threshold of synapse activation.