Expression of neurofilament proteins in the rat cerebellar cortex as a function of age: an immunohistochemical study

The present study was designed to assess changes in the expression of cytoskeletal proteins in the cerebellar cortex of rats of different ages using immunohistochemical techniques associated with image analysis. Male Wistar rats of 3 months (young), 12 months (adult) and 24 months (old) were used. Neuronal cytoskeleton was investigated using monoclonal antibodies to phosphorylated neurofilament (NF) proteins of high (H), medium (M) and low+H+M molecular weight (NF triplet). In young and adult rats in which the expression of phosphorylated NF immunostaining was similar, a dark-brown immunoreactivity was observed primarily in axons of the white matter and of basket neurons which surround Purkinje neurons and enter in the molecular layer. In adult rats a NF-H immunoreactivity was sometimes observed within the dendritic tree of Purkinje neurons. A significant decrease in the density of NF immunoreactivity involving the three different subunits investigated was found in the cerebellar cortex of old rats. This suggests that cytoskeletal abnormalities occur not only in senile dementia, but also in the so called 'physiological aging'. The cerebellar cortex may represent an interesting model for evaluating age-dependent changes of cytoskeleton.