Aging and the neurocytoskeleton.

It has been often demonstrated that during senescence some neurons undergo atrophic changes while others add new processes and terminals. Because microtubules form a substantial component of the dendritic and axonal cytoskeleton, we have studied the amount of tubulin and acetylated alpha-tubulin in three young (6 months) and three old (24 months) rats (Fischer 344). We have used sodium dodecyl sulfate (SDS) extracts of brain homogenates and Triton solubilized fractionated brain homogenates. With the first method we did not detect any age-related differences in total brain protein, total tubulin, or in relative amounts of acetylated alpha-tubulin. With the second method, we have observed a small systematic increase in relative amount of acetylated alpha-tubulin in the Ca2+/cold insoluble fraction. These results are similar to those reported in the literature, and they indicate a possible alteration in the cytoskeletal dynamics.