Morphological relationship between serotonergic neurons and nitrergic neurons for electrolytes secretion in the submucous plexus of the guinea pig distal colon

In the submucous plexus, double immunocytochemistry revealed that nitric oxide synthase (NOS)-immunoreactivity was found in both numerous nerve fibers and some nerve cell bodies, while 5-hydroxytryptamine (5-HT)-immunoreactivity was limited to many nerve fibers, but not any nerve cell bodies. About 30% of the total NOS positive neurons (978) had close or some contact with 5-HT positive nerve fiber, suggesting that NO may participate in the 5-HT-evoked chloride secretion. (C) 1999 Elsevier Science B.V. All rights reserved.