HIPPOCAMPAL MOLECULAR MECHANISMS ASOCIATED WITH SPATIAL FAMILIARITY.

MONCADA D; MULLER IGAZ L; VIOLA H

Pinamar, Argentina.

Congreso; Congreso de la Sociedad Argentina de Neuroquímica; 2005

We recently demonstrated that pCREB levels registered in the hippocampus of rats submitted to an extensive exploratory training in an open field (OF), were below to that observed in control animals. Such decrease does not correlate with memory retrieval or improvement in the formation of long-term memory of habituation. Instead, it is associated with the familiarity to the arena and its recognition. To investigate the molecular pathways associated with this pCREB decrease, we study the hippocampal protein levels of several protein kinases and the enzymatic activity of phosphatases involved in CREB phosphorylation. We also examined the mRNA levels of several genes with CRE-dependent promoters. Results show a consistent decrease in PKMz protein amount (a constitutively active fragment of PKCz) measured in hippocampal homogenates and in the sub-cellular fraction that contains synaptics terminals. No changes in other protein kinase levels or protein phosphatases activities were found. RT-PCR analysis shows a decrease in Zif268 and an increase in Homer 1a, without changes in PKMz mRNA levels. Results suggest that decrease in CREB phosphorylation, associated with spatial familiarity, may be due to a biochemical pathway involving PKMz and could in term modulate the expression of different genes.