Changes in mRNA and protein levels in rat hippocampus during long-term memory formation of single-trial avoidance learning

LIONEL MÜLLER IGAZ; PEDRO BEKINSCHTEIN; IVAN IZQUIERDO; JORGE H. MEDINA

New York, USA

Congreso; 35th Annual Meeting . American Society for Neurochemistry; 2004

American Society for Neurochemistry

Most studies regarding altered gene expression after learning are performedusing multi-trial tasks, which do not allow a clear discrimination of memoryacquisition, consolidation and retrieval. We screened for memory-modulatedgenes in the hippocampus at 3 and 24 h after one-trial inhibitoryavoidance training, using a cDNA array that revealed 33 candidate genes(27 upregulated and seven downregulated). To confirm and extend thesefindings, we performed RT-PCRs and analyzed differences in protein levelsin rat hippocampus using immunoblot assays. Hippocampal mRNA levelsfor the following genes were found to be altered after training: syntaxin 1A(STX1A), syndecan 3 (sdc3), Akt/PKB, Insulin-like growth factor 2 (IGF2)and the BDNF receptor TrkB. We found several proteins upregulated 24 hafter training: extracellular signal-regulated kinase ERK2, Ca2+/CaMdependentprotein kinase II a (CaMKIIa), Syntaxin 1a, c-fos and Homer1a. The total level of none of these proteins were found to be altered whenmeasured 3 h post-training. Several of the mRNAs corresponding to theupregulated proteins were changed at 3 h but not 24 h. Additionally, anumber of other candidates were identified for the first time as modulated bylearning. The results presented here suggest that single-trial tasks can exposedifferences in dynamic regulation of gene expression after behavioralmanipulations, both at the transcriptional and translational levels, allowingdeeper understanding of the molecular basis of memory formation.