Abstract

Background: Increased homocysteine (Hcy) blood levels are correlated with vascular and neurological problems.

Aim: The aim of the present study was to investigate erythrocyte membrane acetylcholinesterase (AChE) activity in subjects with the MTHFR C677T genotype in relation to Hcy.

Methods: Blood was obtained from 22 individuals with the MTHFR C677T genotype before and after folic acid supplementation and once from controls (n=30). Plasma folate, vitamin B₁₂ and total antioxidant status (TAS) were measured with commercial kits, Hcy by a HPLC method and membrane enzyme activity spectrophotometrically.

Results: In MTHFR C677T carriers, AChE activity was significantly higher (4.20±0.12

× mg protein) and decreased to normal levels (3.14±0.10 × mg protein; p<0.001) after therapy. TAS differed slightly before and after treatment. Hcy levels were significantly higher before (22.4±2.8 μM) compared to after (12.1±2.0 μM; p<0.001) therapy and compared to controls (10.5±2.5 μmol/L; p<0.001). In an in vitro study, incubation of Hcy-activated membrane AChE from controls with phenylalanine resulted in restoration of activity, but failed to reverse the stimulated enzyme from hyperhomocysteinaemic MTHFR C677T subjects before therapy. Alanine incubation protected the enzyme from Hcy activation in controls.

Conclusions: Increased membrane AChE activity may be due to high Hcy levels. In vitro, phenylalanine reversed the Hcy activation of the membrane enzyme from controls and alanine protected it from Hcy action.