EFFECT OF HYPERPHENYLALANINEMIA CHEMICALLY-INDUCED ON IN-VITRO INCORPORATION OF P-32 INTO CYTOSKELETAL PROTEINS FROM CEREBRAL-CORTEX OF DEVELOPING RATS

We studied the effect of hyperphenylalaninemia on in vitro incorporati on of P-32 into cytoskeletal proteins from cerebral cortex of rats by injecting L-phenylalanine plus alpha-methylphenylalanine subcutaneousl y from the 6th to the 14th day postpartum. Chronic hyperphenylalaninem ia induced an increased in vitro phosphorylation of the 150-kDa neurof ilament subunit and tubulins present in the cytoskeletal fraction at t he end of the treatment and 3 days after treatment discontinuation. In addition, when in vitro phosphorylation of the cytoskeletal proteins from treated animals was performed in the presence of the drugs we obs erved a decreased in vitro incorporation of P-32 into these proteins. Thus, the effect of L-phenylalanine plus alpha-methylphenylalanine on the endogenous protein kinase and phosphatase activities was examined and the results demonstrated that these drugs have an inhibitory effec t on calcium/calmodulin-dependent protein kinase II and protein phosph atase type 1. (C) 1997 Academic Press.