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

Objective: To investigate whether the preincubation of brain homogenates with -phenylalanine (Phe) could reverse the free radical effects on brain acetylcholinesterase (AChE) activity, since it has been reported that Phe binds hydroxyl radicals (•OH). Design and methods: Two well established systems were used for production of free radicals: (a) FeSO4 (84 μM) plus ascorbic acid (400 μM), and (b) FeSO4, ascorbic acid and H2O2 (1 mM) at 37 °C in homogenates of adult rat whole brain. Changes in brain AChE activity were studied in the presence 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 Phe 1.8 mM. Conclusions: In accordance with our previous reports, Phe could protect against the direct action of •OH radicals on brain AChE and in this way it might be useful in the prevention of certain cholinergic neural dysfunctions.