Phosphorylation of rat brain cytoskeletal proteins is increased after orally administered aluminum

In rats, administration of 0.3% aluminum in the drinking water for 4-5 weeks significantly increased the in vivo incorporation of 32-phosphorous (32Pi) into proteins with apparent molecular weights of 300 and 210 kDa in the brainstem and cerebral cortex. The identities of these two phosphoproteins as microtubule-associated protein-2 (MAP-2) and the 200 kDa neurofilament subunit (NF), respectively, were established using immunoprecipitation techniques with monoclonal antibodies. Aluminum treatment did not significantly change the amount of MAP-2 or 200 kDa NF in the cerebral cortex and brainstem. Phosphorylation of MAP-2 in aluminum-treated rats in the brainstem and cerebral cortex was 163 and 155% of control values, respectively. The phosphorylation of 200 kDa NF in the brainstem and cerebral cortex of aluminum-treated rats was 148 and 209% of control values, respectively. These results demonstrate that chronic oral aluminum administration to rats increases the phosphorylation of certain cytoskeletal proteins. This treatment regimen may provide a model system with which the mechanisms and consequences of altered in vivo phosphorylation of cytoskeletal proteins can be studied.