CDKL5 deficiency results in atypical subregion-specific expression of perineuronal nets in the mouse primary visual cortex

Cortical perineuronal nets are specialized extracellular matrix structures that form on parvalbumin+ GABAergic neurons, and mark the closure of visual critical period plasticity. More recently, cortical perineuronal nets (PNNs) are used to characterize deficits in critical period plasticity in mouse models for neurodevelopmental disorders such as Rett syndrome, CDKL5 deficiency disorder and Fragile X syndrome. Within the mouse primary visual cortex, studies typically focus on the expression and function of PNNs within the binocular zone, though PNNs are expressed in other subregions of the primary visual cortex. Here, we performed a systematic characterization of wisteria floribunda agglutinin staining, a well-characterized marker for cortical PNNs, in the entire primary visual cortex of wild-type and CDKL5-null male mice. We report a decrease in overall PNN expression in the monocular zone, an increase in high-intensity PNN expression in the binocular zone, and no differences in PNN expression in rostral V1 of CDKL5-null male visual cortex. Additionally, PNN expression was similar across both hemispheres, showing a lack of hemisphere laterality in the early visual cortex. Together, these results suggest that at the closure of the visual critical period plasticity, subregion-specific variations in PNN expression may lead to functional differences in synaptic plasticity in CDKL5-null cortex and lay the groundwork for further studies to probe the roles for PNNs beyond the binocular zone.