title: Neurochemical classification of enteric neurons in the guinea-pig distal colon.
abstract: Previous studies have identified the chemistries, shapes, projections and electrophysiological characteristics of several populations of neurons in the distal colon of the guinea-pig but it is unknown how these characteristics correlate to define the classes of neurons present. We have used double-label immunohistochemical techniques to identify neurochemically distinct subgroups of enteric neurons in this region. On the basis of colocalisation of neurochemical markers and knowledge gained from previous studies of neural projections, 17 classes of neurons were identified. The myenteric plexus contained the cell bodies of 13 distinct types of neurons. Four classes of descending interneurons and three classes of ascending interneurons were identified, together with inhibitory and excitatory motor neurons to both the circular and longitudinal muscle layers. Dogiel type II neurons, which are presumed to be intrinsic primary afferent neurons, were located in myenteric and submucosal ganglia; they were all immunoreactive for choline acetyltransferase and often calbindin and tachykinins. Three classes of secretomotor neurons with cell bodies in submucosal ganglia were defined. Two of these classes were immunoreactive for choline acetyltransferase and the other class was immunoreactive for both vasoactive intestinal peptide and nitric oxide synthase. Some of the secretomotor neurons probably also have a vasomotor function. The neural subtypes defined in the present study are similar in many respects to those found in the small intestine, although differences are evident, especially in populations of interneurons. These differences presumably reflect the differing physiological roles of the two intestinal regions.
authors.affiliation: Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: A E
authors.initials: AE
authors.lastname: Lomax
authors.forename: J B
authors.initials: JB
authors.lastname: Furness
mesh_terms: D000818:Animals; D064026:Calbindins; D002795:Choline O-Acetyltransferase / Q000032:analysis; D003106:Colon / Q000294:innervation*; D017615:Enteric Nervous System / Q000166:cytology*; D005260:Female; D005728:Ganglia, Sympathetic / Q000166:cytology; D006168:Guinea Pigs; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000294:innervation; D008297:Male; D009130:Muscle, Smooth / Q000294:innervation; D009197:Myenteric Plexus / Q000166:cytology*; D009419:Nerve Tissue Proteins / Q000032:analysis; D009474:Neurons / Q000145:classification* / Q000166:cytology*; D009475:Neurons, Afferent / Q000166:cytology; D019001:Nitric Oxide Synthase / Q000032:analysis; D064030:S100 Calcium Binding Protein G / Q000032:analysis; D014660:Vasoactive Intestinal Peptide / Q000032:analysis
chemical_list: D064026:Calbindins; D009419:Nerve Tissue Proteins; D064030:S100 Calcium Binding Protein G; D014660:Vasoactive Intestinal Peptide; D019001:Nitric Oxide Synthase; D002795:Choline O-Acetyltransferase