NEUROCHEMICAL CLASSIFICATION OF MYENTERIC NEURONS IN THE GUINEA-PIG ILEUM

A strategy has been developed to identify and quantify the different n eurochemical populations of myenteric neurons in the guinea-pig ileum using double-labelling fluorescence immunohistochemistry of whole-moun t preparations. First, six histochemical markers were used to identify exclusive, nonoverlapping populations of nerve cell bodies. They incl uded immunoreactivity for the calcium binding proteins calbindin and c alretinin, the neuropeptides vasoactive intestinal polypeptide, substa nce P and somatostatin, and the amine, 5-hydroxytryptamine. The sizes of these populations of neurons were established directly or indirectl y in double-labelling experiments using a marker for all nerve cell bo dies. Each of these exclusive populations was further subdivided into classes by other markers, including immunoreactivity for enkephalins a nd neurofilament protein triplet. The size of each class was then esta blished directly or by calculation. These distinct, neurochemically-id entified classes were related to other published work on the histochem istry, electrophysiology and retrograde labelling of enteric neurons a nd to the simple Dogiel morphological classification. A classification scheme, consistent with previous studies, is proposed. It includes 14 distinct classes of myenteric neurons and accounts for nearly all neu rons in the myenteric plexus of the guinea-pig ileum. Copyright (C) 19 96 IBRO.