Differential inhibition of the brain acetylcholinesterase molecular forms following sarin, soman and VX intoxication in laboratory rats.

The female Wistar rats were intoxicated (i.m.) with sarin, soman and VX in doses equal to 1xLD50 and pontomedullar areas of the brain were prepared, homogenized, centrifuged and in these samples, acetylcholinesterase (AChE, EC 3.1.1.7) activities were determined. In the same samples, AChE was separated using polyacrylamide gel electrophoresis and AChE molecular forms were detected and densitometrically evaluated. In control animals, AChE was separated into four forms differing in their electrophoretic mobility and their quantitative content in the sample. The form with lowest electrophoretic mobility represent the main part of AChE activity constituting the whole enzymatic activity. Following intoxication with the nerve agents mentioned, the whole AChE activity in the pontomedullar area of the brain was decreasing in intervals of ten minutes (soman and sarin) or one hour (VX). The AChE activity at the time of death (or terminal stage) was represented 5-30% of controls. Molecular forms of AChE were inhibited in different extent: the form with lowest electrophoretic mobility was diminished to zero level while the form with the highest mobility was practically unaffected, independently on the type of nerve agent. From quantitative expression of percentage content of the forms vs their activity we can imply that value of the total AChE activity represent the "mean" activity of the forms determined.