Immunohistochemical demonstration of choline acetyltransferase of a peripheral type (pChAT) in the enteric nervous system of rats

Using a recently developed antiserum against a splice variant (pChAT) of ch oline acetyltransferase, the enzyme which synthesizes acetylcholine, we car ried out an immunohistochemical examination in the digestive canal of rats. Positive staining was exclusively localized to neuronal cells and fibers. Positive somata were distributed widely in the intramural ganglia throughou t the digestive tract from the esophagus to the rectum. Double staining ind icated that, in the rat, virtually all pChAT immunoreactive somata exhibite d histochemical activity for acetylcholinesterase but not for NADPH-diaphor ase. In the guinea pig, however, there were a few neurons possessing both p ChAT and NADPH-diaphorase. We also found a few neuronal somata which were p ositive for acetylcholinesterase but not for pChAT. The results suggest tha t pChAT immunohistochemistry is useful for studying the enteric cholinergic system. (C) 2000 Elsevier Science B.V. All rights reserved.