Sensory experience-dependent formation of perineuronal nets and expression of Cat-315 immunoreactive components in the mouse somatosensory cortex.

Perineuronal nets (PNNs) are structures of extracellular matrix molecules surrounding the cell bodies and proximal dendrites of certain neurons. While PNNs are present throughout the mouse cerebral cortex, recent studies have shown that the components differ among cortical sub-regions and layers, suggesting region-specific functions. Parvalbumin-expressing interneurons (PV neurons) may be important regulators of cortical plasticity during the early "critical period" that is sensitive to sensory input. Here we examined the distribution and developmental functions of PNN components associated with PV neurons in the somatosensory cortex during the critical period. Aggrecan, brevican, neurocan, phosphacan, and tenascin-R were identified as PNN components in the mouse somatosensory cortex. High-magnification analysis revealed that some lectin Wisteria floribunda agglutinin (WFA)-reactive molecules did not co-localize with monoclonal antibody Cat-315 recognition molecules around the cell body. During postnatal development, Cat-315-positive (Cat-315+) PNNs appeared later than PNNs binding to the lectin WFA (WFA+ PNNs). These WFA+ PNNs changed from granular-like to reticular-like structures during normal cortical development, while this transition was delayed by sensory deprivation. This study indicates that the formation of reticular-like WFA+ PNNs is dependent on sensory experience in the mouse somatosensory cortex. We suggest that Cat-315+ molecules and WFA expression in PNNs are involved in the early critical period of input-dependent cortical plasticity.