Protective effect of L-phenylalanine on rat brain acetylcholinesterase inhibition induced by free radicals

Objective: To investigate whether the preincubation of brain homogenates wi th L-phenylalanine (Phe) could reverse the free radical effects on brain ac etylcholinesterase (AChE) activity, since it has been reported that Phe bin ds hydroxyl radicals ((OH)-O-.). Design and methods: Two well established systems were used for production o f free radicals: (a) FeSO4 (84 mu M) plus ascorbic acid (400 mu M), and (b) FeSO4, ascorbic acid and H2O2 (1 mM) at 37 degrees C in homogenates of adu lt rat whole brain. Changes in brain AChE activity were studied in the pres ence of each system separately. Results: AChE was inhibited (18-28%) by both systems of free radicals. This inhibition was reversed when the brain homogenate was preincubated with Ph e 1.8 mM. Conclusions: In accordance with our previous reports, Phe could protect aga inst the direct action of (OH)-O-. radicals on brain AChE and in this way i t might be useful in the prevention of certain cholinergic neural dysfuncti ons. Copyright (C) 2000 The Canadian Society of Clinical Chemists.