The effect of monocular enucleation on molecular expression patterns in adult mouse visual cortex

A series of transcriptomic experiments in adult mouse brain conducted in our lab have shown that upon enucleation, the visual cortical target regions, located contralateral to the deprived eye, are capable of restoring normal activity levels as measured via the activity-reporter gene zif268 (Van Brussel, 2009). In the first days and weeks after treatment the contralateral visual cortex displayed drastically decreased zif268 levels, yet within 7 weeks the zif268 levels had returned to normal values illustrating the capacity for lesion-induced neocortical plasticity in the adult mammalian brain. The main goal of this study was to obtain a better understanding of the molecular mechanisms responsible for this restoration of activity. Hence, we opted to study proteome expression changes in the monocular and binocular segment of the contralateral visual cortex 1, 3 and 7 weeks post-lesion by 2-D DIGE and mass spectrometry. Most protein changes in the monocular segment (49 identified proteins) occured 7 weeks post-enucleation, while in the binocular segment comparable changes were detected for every post-lesion time tested (67 identified proteins). Quantitative immunoblot analyses further indicated survival-time-related differences in vesicular glutamate and GABA transporters and synapsinIIa/b expression. Obviously, the lesion-induced cortical reorganization goes hand in hand with region-specific plasticity-related protein expression changes, possibly mirroring distinct structural modifications mediating the necessary adaptations within the monocular and binocular segment to allow functional adaptation to the modified pattern of sensory input.status: publishe