Modulation of cofilin 1 phosphorylation induces juvenile-like plasticity in the adult mouse visual cortex

Cofilin 1 is an actin-depolymerizing protein that plays a fundamental role in actin dynamics, particularly within dendritic spines, where it has been implicated in both structural and functional plasticity. We recently demonstrated, using a combination of differential proteomics, western blot and immunohistochemistry, that the expression of cofilin 1 and its inactive phosphorylated form is dynamically regulated in the mouse visual cortex. Expression levels change across critical periods of postnatal development and are modulated by visual experience, suggesting that cofilin 1 plays a dynamic role in synaptic remodeling during windows of heightened cortical plasticity. In this study, we sought to determine whether cofilin 1 influences experience-dependent plasticity in the adult visual cortex, a stage where plasticity is more restricted but still inducible under specific conditions. Specifically, we administered a synthetic peptide inhibitor of cofilin 1 activity in vivo (PCOF). Following monocular deprivation, adult mice received either the PCOF peptide or a control peptide. Structural plasticity was assessed by quantifying dendritic spine density using Golgi-like staining, while visual plasticity was evaluated by measuring visual acuity through the optomotor response test. Our results show that, in adult mice treated with the PCOF peptide - but not in controls - monocular deprivation led to a significant reduction in dendritic spine density in the contralateral visual cortex, as well as a decrease in visual acuity of the previously deprived eye. These findings indicate that cofilin 1 activity is crucial for the regulation of experience-dependent plasticity in the adult mouse visual cortex.