Ultrastructural localization of acetylcholinesterase activity in endocrine cells of rat's pancreas.

Abstract

The electron microscopic localization of the AChE-enzyme activity in some endocrine cells of the rat pancreas was studied using the method of Lewis and Shute (1966) and the diisopropyl fluorophosphate (DFP) pharmacohistochemical method. The results obtained show that some A-, D-, PP- and B-cells situated at the periphery of the islets of Langerhans contain AChE activity. The electron opaque material was distributed within the cisterns of the rough endoplasmic reticulum and the nuclear envelope. Different parts of the halo of single secretory granules were also filled with reaction precipitate. In the animals treated with DFP no enzyme activity was observed during the first 4hr. Six hr after the injection of DFP the enzyme activity recovered and the deposition of the reaction product was again visible in the usual locations. These results show that some endocrine cells of the rat pancreas synthesize AChE.It is suggested that the AChE of the pancreatic endocrine cells most probably plays a non-cholinergic role. The importance of the enzyme for the processing of some endogenous or exogenous hormones and regulatory peptides is emphasized.