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Hyperphenylalaninemia reduces creatine kinase activity in the cerebral cortex of rats
Author(s) -
Costabeber Elisa,
Kessler Adriana,
Severo DutraFilho Carlos,
Souza Wyse Angela Terezinha,
Wajner Moacir,
Wannmacher Clóvis Milton Duval
Publication year - 2003
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/s0736-5748(02)00108-9
Subject(s) - hyperphenylalaninemia , phenylalanine , creatine kinase , phenylalanine hydroxylase , creatine , endocrinology , medicine , in vivo , metabolite , chemistry , tetrahydrobiopterin , enzyme , biochemistry , biology , cofactor , amino acid , microbiology and biotechnology
Phenylketonuria (PKU) is a metabolic disorder accumulating phenylalanine (Phe) and its metabolites in plasma and tissues of the patients. Considering that phenylalanine is the main neurotoxic metabolite, and brain energy homeostasis seems to be affected in phenylketonuria, our main objective was to investigate the effect of acute and chronic hyperphenylalaninemia (HPA) on creatine kinase (CK) activity in brain cortex of Wistar rats. Hyperphenylalaninemia was induced by subcutaneous administration of 5.2 μmol phenylalanine + 2.4 μmol α‐methylphenylalanine (phenylalanine hydroxylase (PAH) inhibitor)/g of body weight. We also investigated the in vitro effect of phenylalanine and/or α‐methylphenylalanine on creatine kinase activity in the brain cortex of non‐treated rats. The results showed that phenylalanine significantly inhibited creatine kinase activity in vitro and reduced the enzyme activity in vivo. Considering the importance of creatine kinase for the maintenance of energy homeostasis in brain, if this enzyme inhibition also occurs in phenylketonuric patients, it is possible that creatine kinase inhibition may be one of the mechanisms by which phenylalanine is neurotoxic in phenylketonuria.