Histochemical evidence and consequences of the occurrence of isoenzymes of acetylcholinesterase.

Abstract

Frozen sections of unfixed cat stellate (StG) and ciliary (CG) ganglia and intercostal muscle (ICM) and mouse ICM were exposed to saline (0.9% NaCl) solution and to 0.3% Triton X-100 in saline solution, and then stained for acetylcholinesterase (AChE) by a modification of the standard copper-thiocholine method. In the StG and CG, treatment with saline solution resulted in marked diffusion of AChE, and Triton X-100 caused its marked loss from the CG and nearly complete loss from the StG. In ICM, in contrast, both treatments caused increased intensity of staining of AChE at the motor end plates (MEP's). All of the foregoing effects were reversed progressively, with concomitant reduction in AChE activity, by prior fixation in cold formaldehyde (4%)-sucrose (7.5%)-maleate buffer (pH 7.3) solution for 2-24 hr. Results are interpreted on the basis that the AChE of the ganglia and MEP's exists predominantly in different isoenzymatic forms, the possible natures of which are discussed.