Author:

Abstract:

Although the mammalian brain remains capable of adapting to changes in the sensory input throughout the entire animal's life, there is a marked difference in this capability between young and adult animals. Young cats within a critical period respond to these input changes by modifying their cortical connections, while in adult animals this cortical plasticity is greatly reduced. The molecular basis of this age-dependent difference in modifiability of the visual cortex between kittens and adult cats is, until now, not known in great detail. In an attempt to unravel the proteins involved in this age-dependent cortical plasticity, we compared the protein expression levels of visual area 17 of 30-day old kittens and adult cats, using two-dimensional difference gel electrophoresis (2D-DIGE), combining a recently developed fluorescent pre-labeling technique for the quantitative analysis of proteins on two-dimensional electrophoresis gels, with mass spectrometry for protein identification. This let us to identify 32 proteins showing differential expression levels, of which 18 were more abundantly expressed in kitten striate cortex and 14 were more abundant in adult cats. Next to a number of metabolic enzymes, we isolated several proteins related to axon growth and growth cone guidance (collapsin response mediator proteins) and to the formation of new cytoskeletal filaments (cofilin, T-complex proteins 1 alpha and zeta) in kittens, probably making the rapid outgrowth of new connections possible after sensory changes. In adult cats, the expression level of glial fibrillary acidic protein (GFAP) was raised in comparison to kittens, an observation which has already been implicated in the termination of the critical period in kittens in earlier studies (Müller C. M., 1990, Glia 3, 487-494).