Ontogenetic analysis of the NR2B-receptor dynamics during acquisition of contextual fear learning in preweanling and weanling rats

PISANO MARÍA VICTORIA; FERNÁNDEZ GUILLERMO; FERRERAS SOLEDAD; ARIAS CARLOS; ABATE PAULA; PAGLINI GABRIELA

Córdoba

Congreso; XXVIII CONGRESO ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACION EN NEUROCIENCIAS; 2013

SOCIEDAD ARGENTINA DE INVESTIGACION EN NEUROCIENCIAS

The capability to acquire contextual fear learning emerges around weanling in rats, and is NMDA-type glutamate receptors (NMDAr) dependent. Contextual learning deficits in preweanling rats have been associated with functional immaturity of the hippocampus (HPC). A recent study of our lab using the Context Preexposure Facilitation Effect procedure (CPFE), a HPC-dependent task, demonstrated evidences of contextual fear conditioning in preweanling rats. Moreover, we found that contextual fear memory is NMDAr-dependent at both ages, evidenced by the inhibition of these receptors during the pre-exposure phase of the CPFE. NR2B is an NMDAr subunit that is involved in the transport of NMDAr to synapses improving learning and memory function. The aim of the present study was to evaluate the dynamics of NR2B receptor during the acquisition of contextual fear learning in preweanling and weanling rats. We tested the temporal expression of NR2BY1472 (a phosphorylated state of NR2B subunit that promotes surface expression of NMDAr) after 10 min. of pre-exposure treatment, in the dorsal HPC of animals from both ages. Our results showed the same pattern of temporal expression of NR2BY1472 in weanling and preweanling rats. These results suggest that preweanling rats are capable of acquiring contextual learning through a comparable mechanism than weanling rats. These findings may have important implications for the ontogenetic analysis of the neurobiology of contextual fear conditioning.