Learning-associated regulation of polysialylated neural cell adhesion molecule expression in the rat prefrontal cortex is region-, cell type- and paradigm-specific.
The prefrontal cortex (PFC) is an interconnected set of cortical areas that function in the synthesis of a diverse range of information and production of complex behaviour. It is now clear that these frontal structures, through bidirectional excitatory communication with the hippocampal formation, also play a substantial role in long-term memory consolidation. In the hippocampus, morphological synaptic plasticity, supported by regulation of neural cell adhesion molecule (NCAM) polysialylation status, is crucial to information storage. The recent description of polysialylated neurons in the various fields of the medial PFC suggests these structures to possess a similar capacity for synaptic plasticity. Here, using double-labelling immunohistochemistry with glutamic acid decarboxylase 67, we report that the nature of NCAM polysialic acid-positive neurons in the PFC is region-specific, with a high proportion (30-50%) of a gamma-aminobutyric acid (GABA)ergic phenotype in the more ventral infralimbic, orbitofrontal and insular cortices compared with just 10% in the dorsal structures of the cingulate, prelimbic and frontal cortices. Moreover, spatial learning was accompanied by activations in polysialylation expression in ventral PFC structures, while avoidance conditioning involved downregulation of this plasticity marker that was restricted to the dorsomedial PFC--the cingulate and prelimbic cortices. Thus, in contrast to other structures integrated functionally with the hippocampus, memory-associated plasticity mobilized in the PFC is region-, cell type- and task-specific.
Ter Horst
Judith P F
JP
Applied Neurotherapeutics Research Group, UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
Loscher
Jennifer S
JS
Pickering
Mark
M
Regan
Ciaran M
CM
Murphy
Keith J
KJ
D000818:Animals; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D039842:Neural Cell Adhesion Molecule L1 / Q000737:chemistry / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology; D017397:Prefrontal Cortex / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012794:Sialic Acids / Q000737:chemistry / Q000378:metabolism*
D039842:Neural Cell Adhesion Molecule L1; D012794:Sialic Acids; C021319:polysialic acid; C103469:polysialyl neural cell adhesion molecule