The effect of homocysteine thiolactone on acetylcholinesterase activity in rat brain, blood and heart

Abstract

Limited data exist in the literature regarding the effects of homocysteine thiolactone on the activity of the acetylcholinesterase (AChE) in the blood, and practically no data exist regarding the influence of homocysteine thiolactone on the enzyme in the brain and heart. Taking into consideration the importance of hyperhomocysteinemia in clinical practice, it has been thought to be of particular interest to examine the effect of homocysteine thiolactone on the activity of AChE in the rat's blood, brain and heart. In this study, male Wistar rats (weighing 250-300g) were used, and they were divided into two groups; one served as a control group and receieved a placebo (1 ml 0.9 % NaCl, i.p.), while the other group received a homocysteine thiolactone solution (5.5 mmol/kg b.m., i.p.). An hour after the administration, the rats were euthanized by decapitation, heir tissues were harvested, buffered, and homogenized in a phosphate buffer (pH 8). The concentration in the tissue homogenates was 20 mg of tissue per 1 ml of buffer. The buffered and homogenized parts of the tissues were used as substrates for spectrophotometric measurements. The AChE activity was then measured by the Ellman method. Statistical analysis was conducted using a one-way ANOVA test, and the intergroup comparisons were performed using a Bonfferoni test. The results showed a significant reduction in AChE activity in all tissues obtained from the animals treated with homocysteine thiolactone compared to the enzyme activity of the control group. In addition, the results also showed that the blood enzyme activity inhibition was the lowest (12%), while the enzyme activity was slightly higher in the brain (27.8%) and heart specimens (86.3%). It was concluded that homocysteine thiolactone significantly inhibited AChE activity in the heart and brain tissue, but not in the blood of the rat.