Localized NMDA receptor ablation as a tool for memory dissection in Chasmagnathus granulatus

Y HEPP; R FREUDENTHAL; PEDREIRA M. E.

Huerta Grande Córdoba

Congreso; Primera Reunión Conjunta de Neurociencias (IRCN); 2009

The main objective of this project is to identify the central nervous system (CNS) areas associated with the mnemonic processes in an invertebrate model, the crab Chasmagnathus granulatus. A well-known technique employed to determine these areas implies the administration of neurotoxic drugs by localized microinjection. To reach this proposal we divided the technique into three parts: First, we created a stereotaxic map of the crab nervous system. The results show that it would be possible to generate a coordinates system of reference for the eyestalks and the supraesophageal ganglion (SEG), considering external anatomical features. Second, we choose a neurotoxic agent: the ibotenic acid, a glutamatergic agonist, which acts on the NMDA type receptors. However, to determine the target areas it is necessary to know the distribution of these receptors through the nervous system. Thus, immunohistochemistry techniques were applied using anti-NMDAR1antibody to characterize their distribution. An NMDA like receptor (NR1L) signal was observed with a broad distribution all over the structures. With Western Blot techniques we evaluated the antibody specificity and the molecular weight of this receptor subunit in Chasmagnathus. The next step was the localized administration of ibotenic acid by microinjections in the (SEG) and the evaluation of its effect by immunohistochemistry. The brains treated with the drug show a deceased signal for NR1L when compared with vehicle injected brains. This decrement was evaluated at a sub-cellular level. Finally, we will perform localized-lesions and we will evaluate the correlation between the zones injured and the behavioral changes observed.