The distribution of nitric oxide synthase-immunoreactive (NOS-IR) axons and their relationship to structures immunoreactive to vasoactive intestinal polypeptide (VIP), substance P (SP) and tyrosine hydroxylase (TH) were studied by means of the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) technique or double-labelling immunofluorescence in the genital organs of cow and pig. Relevant neurons were also investigated in the pig. NOS-containing neural structures were TH-immunonegative in bovine or porcine genital organs, or in the studied ganglia. In the bovine ovary, NOS-IR nerves were neither VIP-IR nor SP-IR, whereas in the pig, most NOS-containing axons were also VIP-IR. The oviduct was supplied by single NOS/VIP- or NOS/SP-containing nerves, whereas in the uterus, NOS-IR axons were moderate in number, often being immunoreactive for VIP or SP. Numerous NOS/VIP-IR and NOS/SP-IR nerves were found in the vagina of both species. In all tissues studied, NOS-IR axons were mainly related to vascular smooth muscle. Most of the neurons of the paracervical ganglia and some neurons in dorsal root ganglia exhibited strong NOS activity. Only single neurons in sympathetic ganglia were NADPH-d-positive. Most nitrergic neurons in the autonomic ganglia were VIP-IR but SP-immunonegative. The sensory neurons were mostly NOS/SP-IR, whereas only single neurons co-expressed NOS and VIP immunoreactivity.

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The present study was designed to investigate the expression of biologically active substances by intramural neurons supplying the stomach in normal (control) pigs and in pigs suffering from dysentery. Eight juvenile female pigs were used. Both dysenteric (n = 4; inoculated with Brachyspira hyodysenteriae) and control (n = 4) animals were deeply anaesthetized, transcardially perfused with buffered paraformalehyde, and tissue samples comprising all layers of the wall of the ventricular fundus were collected. The cryostat sections were processed for double-labelling immunofluorescence to study the distribution of the intramural nerve structures (visualized with antibodies against protein gene-product 9.5) and their chemical coding using antibodies against vesicular acetylcholine (ACh) transporter (VAChT), nitric oxide synthase (NOS), galanin (GAL), vasoactive intestinal polypeptide (VIP), somatostatin (SOM), Leu(5)-enkephalin (LENK), substance P (SP) and calcitonin gene-related peptide (CGRP). In both inner and outer submucosal plexuses of the control pigs, the majority of neurons were SP (55% and 58%, respectively)- or VAChT (54%)-positive. Many neurons stained also for CGRP (43 and 45%) or GAL (20% and 18%) and solitary perikarya were NOS-, SOM- or VIP-positive. The myenteric plexus neurons stained for NOS (20%), VAChT (15%), GAL (10%), VIP (7%), SP (6%) or CGRP (solitary neurons), but they were SOM-negative. No intramural neurons immunoreactive to LENK were found. The most remarkable difference in the chemical coding of enteric neurons between the control and dysenteric pigs was a very increased number of GAL- and VAChT-positive nerve cells (up to 61% and 85%, respectively) in submucosal plexuses of the infected animals. The present results suggest that GAL and ACh have a specific role in local neural circuits of the inflamed porcine stomach in the course of swine dysentery.

The distribution and chemical coding of neurons in the porcine left and right inferior mesenteric ganglion projecting to the ascending colon and rectum have been investigated by using combined retrograde tracing and double-labelling immunohistochemistry. The ganglion contained many neurons supplying both gut regions. The colon-projecting neurons (CPN) occurred exclusively in the cranial part of the ganglia where they formed a large cluster distributed along the dorso-lateral ganglionic border and a smaller cluster located close to the caudal colonic nerve output. The rectum-projecting neurons (RPN) formed a long stripe along the entire length of the lateral ganglionic border and, within the right ganglion only, a small cluster located close to the caudal colonic nerve output. Immunohistochemistry revealed that the vast majority of the CPN and RPN were noradrenergic (tyrosine-hydroxylase-positive). Many noradrenergic neurons supplying the colon contained somatostatin or, less frequently, neuropeptide Y. In contrast, a significant subpopulation of the noradrenergic RPN expressed neuropeptide Y, whereas only a small proportion contained somatostatin. A small number of the non-adrenergic RPN were cholinergic (choline-acetyltransferase-positive) and a much larger subpopulation of the nerve cells supplying both the colon and rectum were non-adrenergic and non-cholinergic. Many cholinergic neurons contained neuropeptide Y. The non-adrenergic non-cholinergic neurons expressed mostly somatostatin or neuropeptide Y and some of those projecting to the rectum contained nitric oxide synthase, galanin or vasoactive intestinal polypeptide. Many of both the CPN and RPN were supplied with varicose nerve fibres exhibiting immunoreactivity against Leu5-enkephalin, somatostatin, choline-acetyltransferase, vasoactive intestinal polypeptide or nitric oxide synthase The somatotopic and neurochemical organization of this relatively large population of differently coded inferior mesenteric ganglion neurons projecting to the large bowel indicates that these cells are probably involved in intestino-intestinal reflexes controlling peristaltic and secretory activities.

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