The autonomic innervation of Rana ridibunda intestine

1. The innervation of Rana ridibunda intestine has been studied by the following methods: (a) demonstration of cholinesterase activity; (b) FIF method for catecholamines; (c) immunohistochemistry for VIP, SP and SOM, and (d) conventional electron microscopy. 2. The intrinsic intestinal innervation is represented by cholinergic-, VIPergic-, SP- and SOM-like plexuses. The intestinal adrenergic component is of extrinsic origin. 3. The intestinal peptidergic innervation is the most developed, the large intestine being the portion where the studied peptidergic plexuses are more widely distributed. 4. Against a poorly developed cholinergic/adrenergic innervation, it seems that there is a predominant peptidergic innervation in the amphibians intestine wall. 5. Taking into account that amphibians sacral parasympathetic as well as sympathetic innervation development are limited, it could be considered that in vertebrates the intestinal peptidergic innervation is phylogenetically earlier and hence better developed.     

The projections of chemically identified nerve fibres in canine ileum

Summary The projections of nerve fibres with immunoreactivity for the peptides enkephalin (ENK), gastrin-releasing peptide (GRP), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP) were studied in canine small intestine by analysing the consequences of lesions of intrinsic and extrinsic nerves. Of peptides present in fibres supplying myenteric ganglia, GRP, SOM and VIP were in anally directed nerve pathways, whereas ENK and NPY were in orally directed pathways. Pathways ran for up to about 30 mm. SP fibres ran for short distances in both directions in the myenteric plexus. The circular muscle was supplied with ENK, NPY, SP and VIP fibres arising from the myenteric ganglia, whereas most mucosal SP and VIP fibres were deduced to arise from submucous ganglia. There were projections of fibres reactive for ENK, GRP, SOM, SP and VIP from myenteric ganglia to submucous ganglia. Antibodies to tyrosine hydroxylase were used to locate noradrenaline nerve fibres supplying the intestine; these fibres all disappeared when extrinsic nerves running through the mesentery to the small intestine were cut. It is deduced that there is an ordered pattern of projections of peptide-containing fibres in the canine intestine.     

Calcitonin gene-related peptide neurons innervating the canine digestive system.

The pattern of nerve cells and fibers containing calcitonin gene-related peptide immunoreactivity (CGRP-IR) was investigated in the canine digestive tract by means of immunohistochemistry. CGRP-IR nerve fibers innervate all the layers of the gut, including the vasculature, with different densities depending on the region. CGRP-IR processes are sparse in the esophagus and stomach, where they are mostly confined to the enteric plexuses and vasculature. CGRP-IR fibers are quite abundant in the small and large intestine, where they form dense arborizations in the mucosa, and are numerous in the muscularis mucosae, deep muscular plexus and circular muscle. The myenteric and submucous plexuses of the intestine contain dense networks of CGRP-IR fibers and numerous CGRP-IR ganglion cells. On the other hand, in the enteric ganglia of the esophagus and stomach, in the intrapancreatic ganglia and in the ganglionated plexus of the gallbladder, CGRP-IR is restricted to non-varicose processes. A moderate density of CGRP-IR fibers supplies the endocrine and exocrine pancreas, and the fibromuscular layer and lamina propria of the gallbladder. The density of CGRP innervation in different regions can be summarized as follows: intestine > pancreas and gallbladder > or = antrum > cardia > gastric corpus and distal esophagus. CGRP- and tachykinin (TK)-IRs are colocalized in a substantial population of fibers, particularly those distributed to the mucosa, muscularis mucosae and vasculature, whereas there was no evidence of colocalization in intrinsic ganglion cells. The present results suggest that (1) the CGRP innervation of the dog digestive system includes an intrinsic and an extrinsic component, and (2) CGRP- and TK-IRs are co-expressed in extrinsic nerve fibers. These findings extend previous observations in rats and guinea pigs and provide insights into the sites of action of CGRP in the digestive system of the dog, which has served as a model for CGRP functional studies.     

The autonomic innervation of the liver and gallbladder of Rana ridibunda

1--The innervation of the liver and gallbladder of Rana ridibunda has been studied by the following methods: (a) demonstration of cholinesterase activity; (b) FIF method for catecholamines; (c) immunohistochemistry for VIP and (d) electron microscopy. 2--The hepatocytes are arranged in regular rows of hepatic cords, very little connective tissue is distributed in the parenchyma, the innervation being restricted to the big branches of blood vessels. 3--Well defined cholinergic and adrenergic plexuses surround the hepatic arteries, portal veins and biliary ducts. The VIPergic innervation is scarce in the liver but a richly branched plexus spreads in the wall of the gallbladder. 4--Cholinesterase-positive cells are widely distributed accompanying the nerve trunks of the gallbladder. The innervation distribution is prominent in the portion of the gallbladder next to the hepatic hilus. 5--A population of melanin-storing cells besides free melanin granules are present in the liver parenchyma and are prominent in the gallbladder where the melanocytes are disposed in close contact with blood vessels and nerve structures. We have observed that the number of these visceral melanocytes considerably increases in winter, particularly in the liver.     

Distribution of Peptide-Containing Neurons in the Developing Rat Right Atrium,Studied Using Immunofluorescence and Confocal Laser Scanning

The developmental pattern and distribution of peptide-containing neurons in the rat heart right atrium has been studied by indirect immunofluorescence. Antibodies against neuropeptide Y (NPY), substance P (SP), and vasoactive intestinal polypeptide (VIP) were applied to whole-mount stretch preparations of the right atria from hearts of newborn to 40-day-old animals. NPY-like immunoreactivity (LI) was compared with the synaptic vesicle marker SV2 in double immunoincubation studies. The distribution of immunofluorescence was studied by confocal laser scanning microscopy. NPY-LI and SP-LI were present throughout the atria already at birth, in contrast to VIP-LI that was observed at day 10. The postnatal changes of innervation were basically quantitative, with an increase in density of nerve fibres and number of varicosities, while the basic pattern of innervation was essentially established during the first 1–10 days. NPY- and SP-positive bundles of fibres appeared to enter the right atrium along the superior caval vein, having extrinsic origins. Nerve fibres with NPY-LI colocalized in most nerve terminals with SV2-LI, and showed a developmental pattern similar to that observed for adrenergic neurons earlier. These NPY/SV2 positive fibres probably represent the extrinsic NPY innervation. In addition, NPY-LI was identified in large intrinsic nerve cells bodies located near the atrioventricular (AV) region. Most of the VIP-LI was observed in short nerve fibres originating in intrinsic VIP-positive cell bodies, but a few apparently extrinsic VIP-positive fibres were found, probably representing preganglionic parasympathetic neurons. SP in the atria was probably of extrinsic (sensory) origin and no nerve cell bodies with SP-LI were detected. The results show that the peptidergic innervation in the developing rat right atrium involves both extrinsic and intrinsic peptidergic neurons which may participate in the regulation of neurotransmission in local neuronal circuits.     

Peptide-containing neurons intrinsic to the gut wall

Summary Nerve fibers containing substance P, VIP, enkephalin or somatostatin are numerous in the porcine gut wall. They are particularly numerous in the submucosal and myenteric plexuses where peptide-containing cell bodies are also observed. Peptide-containing nerve fibers occur also in the vagus nerves, suggesting that the gut receives an extrinsic supply of peptidergic nerves. The extrinsic contribution to the peptide-containing nerve supply of the gut wall has not yet been quantitatively assessed. In an attempt to clarify this question pigs were subjected to bilateral subdiaphragmatic vagotomy. Another group of animals was subjected to complete extrinsic denervation by autotransplantation of a jejunal segment. The pigs were killed at various time intervals after the operations; the longest time interval studied was four months. Following vagotomy the innervation pattern of the jejunum appeared completely unaffected. Following complete extrinsic denervation the adrenergic nerve fibers disappeared, while peptide-containing and acetylcholinesterase-positive nerve fibers remained apparently unaltered. This was confirmed chemically in the case of substance P.The motor activity of smooth muscle from the jejunum was studied in vitro. At low stimulation frequencies the smooth muscle from control jejunum responded by relaxation; upon cessation of stimulation a contraction occurred. With increasing stimulation frequencies the duration of the relaxation decreased; at high frequency stimulation only a contraction was recorded. In the autotransplant low frequency stimulation induced no or only a weak relaxation; high frequency stimulation induced contraction. After cholinergic and adrenergic blockade, the muscle responded with relaxation at all frequencies; the response was similar in innervated and denervated specimens. On the whole, the effects of extrinsic denervation on the motor activity of smooth muscle from porcine jejunum were minor, possibly reflecting the high degree of autonomy of the gut.     

Intrinsic Innervation of the Chicken Lower Digestive Tract

We have studied the different components of the enteric nervous system in the rectum and cloaca of the chicken by means of hystochemical and immunohistochemical techniques. We found cholinergic neuronal bodies as well as nervous fibers, which constitute part of the Meissner and Auerbach plexuses. We also observed plentiful catecholaminergic fibers in both plexuses, though there were no catecholaminergic neuronal bodies. With respect to the Vasoactive Intestinal Peptide (VIP) and substance P (SP) positive peptidergic innervation, only positive fibers were found, which were less abundant than in the other zones of the gastrointestinal tract. The optic microscopy results were confirmed by electron microscopy.     

Intrinsic Innervation of a Reptilian Esophagus (Podarcis hispanica)

We study the esophagus of Podarcis hispanica through different methods to clarify the structure and affinities of its wall innervation. The acetylcholinesterase method reveals cholinesterase activity in two submucosal nervous plexuses, with an increasing degree of structural complexity in the reptilian esophagus, compared with amphibians. Noradrenergic innervation, detected through fluorescence induced by formol, widely spreads its network in both the myenteric and submucosal plexuses (around the blood vessels in the external submucosal plexus, and to the glandular lamina propria in the inner submucosal plexus). Immunohistochemistry for vasoactive intestinal peptide shows a widespread innervation, with neurons clustered in ganglia and also scattered through the VIPergic network, only at the myenteric plexus. Immunohistochemistry for substance P shows a rich innervation along the entire wall of the esophagus, more concentrated in its caudal region, around the blood vessels. Electron microscopy shows the enteric neuronal ultrastructure and its relationship with the esophagus wall.     

Somatostatin selectively inhibits excitatory contractile pathways of the feline lower esophageal sphincter.

Intrinsic reflexes of the feline lower esophageal sphincter (LES) have been shown to be mediated by specific arrangements of excitatory peptidergic interneurons. Inhibition of intrinsic reflexes may also be mediated by neuropeptides. The specific aims of this study were: (1) to examine the effect of somatostatin (SOM) and vasoactive intestinal peptide (VIP) on basal LES tone, and (2) to determine if these transmitters exert selective inhibitory effects on excitatory contractile pathways. Intraluminal pressures were recorded from the LES, esophagus and fundus by a fixed perfused catheter assembly in anesthetized cats. Peptides were administered via the left gastric artery. SOM had no effect on basal LES pressure with doses ranging from 10(-9) to 10(-5) g/kg. VIP induced a dose-dependent inhibition of basal LES pressure. The maximal effective dose of VIP, 10(-6) g/kg, completely inhibited basal LES pressure (34.7 +/- 6.8 to 1.0 +/- 0.6 mmHg, P less than 0.001). We have previously shown that bombesin (BN) but not substance P (SP) or bethanechol contracts the LES via tetrodotoxin-sensitive pathways. BN at the D50 (5.10(-8) g/kg) increased LES pressure by 32.1 +/- 3.6 mmHg. SOM (10(-5) g/kg) decreased this BN response to 19.2 +/- 5.0 mmHg, P less than 0.05. In contrast, while the D50 of SP (5.10(-8) g/kg) gave a similar increase in LES pressure, 28.8 +/- 5.1 mmHg, this effect was not altered by SOM (23.8 +/- 6.7 mmHg, P greater than 0.10). SOM also had no effect on bethanechol-induced LES contractions (P greater than 0.10). VIP (10(-6) g/kg) totally inhibited the LES response to the D50 of BN, SP, and bethanechol. A submaximal dose of VIP (10(-7) g/kg) partially inhibited the contractile response of all three. Conclusions: (1) VIP, but not SOM, inhibits basal LES tone. (2) SOM selectively inhibits BN but not SP- or bethanechol-induced LES contraction. (3) VIP inhibits BN, SP and bethanechol-induced LES contractions. These studies suggest that somatostatin can selectively inhibit excitatory interneurons at the LES.     

Adrenergic and cholinergic innervation of the prostate in laboratory animals

The prostate innervation has been studied in 50 white rats, 12 rabbits, 12 guinea pigs, 6 cats and 6 dogs. Together with the impregnation techniques, Karnovsky-Roots method has been applied, for revealing cholinergic components, and the incubation method in 2% solution of glyoxylic acid, for revealing adrenergic nervous structures. Density of adrenergic and cholinergic nervous plexuses has been estimated by means of the planimetric point method. The prostate of the laboratory animals possesses well manifested adrenergic and cholinergic nervous plexuses. The organ's alveolus and ducts are covered with adrenergic and cholinergic fibers, however, the relative density of the cholinergic plexuses is less than that of the adrenergic ones. The guinea pig prostate is the most richly supplied with the adrenergic nervous plexuses, and the rabbit prostate--with the cholinergic nervous plexuses.     

Comparative study of the autonomic innervation of the mammalian ovary,with particular regard to the follicular system

Summary The autonomic innervation of the ovary was studied in 12 mammalian species utilizing the cholinesterase method in combination with pseudocholinesterase inhibition for the cholinergic component, and glyoxylic acid histochemistry together with fluorometric determination of noradrenaline for the adrenergic component. Ovaries from cow, sheep, cat, and guinea pig were very richly supplied with adrenergic nerves in the cortical stroma, particularly enclosing follicles in various stages of development. In the follicular wall the nerve terminals were located in the theca externa, where they ran parallel to the follicular surface. Numerous adrenergic terminals also surrounded ovarian blood vessels. The adrenergic innervation was of intermediary density in the human ovary and in the pig, dog, cat, and opossum. Ovaries from rabbit, mouse and hamster had a sparse adrenergic nerve supply. The amount of intraovarian adrenergic nerves agreed well with the tissue concentration of noradrenaline in the various species. The cholinergic innervation was generally less well developed, but had the same distribution as the adrenergic system around blood vessels and in the ovarian stroma, including follicular walls.     

Neural apparatus of the wall of the ductus deferens in the dog

While studying the innervation sources of the deferent duct in 10 dogs, 2-3 nerves have been revealed that take their origin at the pelvic neural plexus and approach the duct together with the blood vessels at the pelvic neural plexus and approach the duct together with the blood vessels at the place where it crosses the ureter ("the vascular-neural hilus"). In the experiment performed in 65 dogs the nature of these sources has been revealed. The motor innervation is presented by the nodes of the celiac plexus, of the lumbar and sacral parts of the sympathetic trunk, of the subceliac, gonadal and splanchic pelvic nerves, and the sensitive innervation is multisegmental and is performed by the intravertebral nodes L2-S3. Quantitative investigation of the degenerated neural fibers in the dog deferent duct wall demonstrates that the innervation sources mentioned above participate te a various degree along the course of the organ. In the "hilus" the nerves of the dog deferent duct are divided into the proximal nad distal groups. The proximal group runs towards the prostate and forms a plexus with large loops connected with the neural plexuses of the urinary bladder, the ureter and the prostate. It has small neural nodes. The distally directed nerves run, together with the blood vessels, in the deferent duct towards the epididymis. In the deferent duct wall, adventitila, muscular and mucous neural plexus are found, the cholinergic component prevailing the adrenergic one. The plexuses are somewhat better developed at the beginning of the deferent duct and they are especially pronounced in the ampule. The receptors of the organ's wall are simple, poorly branching.     

人脐静脉内皮细胞的生物学特性及细胞内信号转导机制

本实验对人脐静脉内皮细胞（ＨＵＶＥＣ）合成与释放篾这活性多肽（ＶＰｓ）及其作用机制进行了研究。结果表明：（１）无神经支配的人脐血管内皮细胞（ＶＥＣ）所含ＶＰｓ较有神经支配的肠系膜血管ＶＥＣ多;（２）这些ＶＰＳ是ＶＥＣ自身合成且能释放到胞外;（３）血管活性肠肽（ＶＩＰ）和Ｐ物质（ＳＰ）使ＨＵＶＥＣ膜上Ｃａ＾２＋通道开放概率明显增加,生长抑制（ＳＯＭ）使其明显降低,但它们均使胞浆内「Ｃａ＾２＋」和ＣＡ     

Adrenergic innervation of the kidneys in man and various laboratory animals

By means of the neurohistochemical method for slice incubation in 2% solution of glyoxylic acid, innervation of the kidneys of a 57-year-old man after a sudden cardiac death has been investigated, as well as innervation of the kidneys in white rat, rabbit, guinea pig and cat. A rich adrenergic innervation in the organ's blood vessels has been revealed. In particular, adrenergic nervous fibers have been found along the course of afferent glomerular arterioles. Together with innervation of the proximal and distal convoluted tubules, a high density of the terminal adrenergic nervous plexus is revealed along the course of the nephron loops. Adrenergic nervous plexuses of high density are found in the area of the initial part of the urinary excretory pathways and their connection with nervous plexuses of the kidney itself.     

Postnatal development of the rat intrinsic cardiac nervous system: a confocal laser scanning microscopy study in whole-mount atria

We used confocal laser scanning microscopy and fluorescent immunohistochemistry to study the developmental pattern and distribution of specific neuronal phenotypes within the intrinsic cardiac nervous system in whole-mount atrial preparations from newborn to 5 week old rats. Individual ganglia and neuronal cell bodies were localized by means of two general neuronal markers: protein gene product 9.5 (PGP) and microtubule-associated protein two (MAP). In rats < or =2 weeks old there were two main subpopulations of intrinsic neurons located in the intraatrial septum and around the origin of the superior vena cava. The more abundant was a population of strongly tyrosine hydroxylase (TH) immunoreactive (IR) neurons (10-40 microm in diameter) most of which were also PGP-IR. The second, less numerous (approximately 60-70% than the TH-IR group) type of neurons exhibited ChAT-IR which colocalized with MAP-IR. Towards the end of the second postnatal week and during the third, the ganglia containing these neurons became more numerous and their localization also included tissues around the origins of the inferior vena cava and the pulmonary veins, as well as both atrial walls close to the AV junction. During the second and third postnatal weeks, when the extrinsic innervation of the adrenergic and cholinergic phenotypes largely increases, the intrinsic innervation also changed greatly, and around the 21st postnatal day it appeared to acquire mature characteristics. The TH-IR neurons changed their characteristics and formed two types of ganglia. The larger ganglia containing large cells (20-40 microm in diameter) expressed TH-IR mostly close to their inner body surface (approximately 80-90% of identified neurons). Most of these neurons also expressed neuropeptide Y (NPY)-IR, specifically around their nuclei. The second type of small strongly TH-IR neurons (approximately 10% of all identified neurons) were contained in smaller groups (20-50 cells) which were usually embedded into much larger ganglia (100-400 cells), containing large (20-50 microm) neurons. Unlike all other intrinsic neurons, these small TH-IR cells did not exhibit any PGP-IR or MAP-IR. The number of ChAT-IR neurons increased at this stage, reaching approximately 90% of the neurons identified by the general neuronal markers. These neurons were surrounded by a rich network of cholinergic varicose nerve fibers, some of which were likely of an extrinsic origin. We have also identified relatively small ganglia expressing immunoreactivity to vasoactive intestinal polypeptide (VIP), and to substance P (SP). The presented data indicate that the phenotypes of intrinsic neurons in the rat heart change greatly during the first month of postnatal development. This may be at least partially related to the development and maturation of functional extrinsic nervous control of the heart.     

Nerves containing substance P,vasoactive intestinal polypeptide,enkephalin or somatostatin in the guinea-pig taenia coli

Summary The guinea-pig taenia coli is rich in peptide-containing nerves. Nerve fibres containing substance P (SP), vasoactive intestinal peptide (VIP), or enkephalin, were numerous in the smooth muscle while somatostatin fibres were very few. Nerve fibres displaying SP or VIP immunoreactivity were numerous in the myenteric plexus. Enkephalin nerve fibres were fairly numerous in the plexus while somatostatin nerve fibres were sparse. Nerve cell bodies containing immunoreactive SP or VIP were regularly seen in the plexus. Delicate varicose elements of the different types of nerve fibres were found to ramify around nerve cell bodies in a manner suggestive of innervation.In the electron microscope the various peptide-storing nerve fibres (i.e., elements containing SP, VIP or enkephalin) were found to contain a varying number of fairly large, electron-opaque vesicles in the varicose swellings. These vesicles represent the storage site of the neuropeptides.The isolated taenia coli responded to electrical nerve stimulation with a contraction. After cholinergic and adrenergic blockade the contractile response was replaced by a relaxation followed by a contraction upon cessation of stimulation. SP contracted the taenia while VIP caused a relaxation. The enkephalins raised the resting tension slightly while somatostatin had no effect. These observations are compatible with a role for SP as an excitatory neurotransmitter and for VIP as an inhibitory one, and with the view that both SP neurones and VIP neurones act as motor neurones. In preparations contracted by SP the electrically induced contractions were reduced in amplitude while the electrically induced relaxations seen after adrenergic and cholinergic blockade were enhanced in amplitude. In preparations relaxed by VIP there was an increased contractile response to electrical stimulation, while in the atropine + guanethidine-treated preparation the electrically induce relaxations were reduced in amplitude. The enkephalins reduced the contractile response to electrical stimulation, while somatostatin induced a very small reduction in the amplitude of such responses. These observations suggest that SP neurones and VIP neurones may play additional roles as interneurones. Somatostatin neurones probably act as interneurones. Enkephalin-containing fibres may serve to modify the release of transmitter from other nerves in the smooth muscle, perhaps through axo-axonal arrangements. Alternatively, the enkephalin nerve fibres in the smooth muscle are afferent elements involved in mediating sensory impulses to the myenteric plexus.     

Distribution of peptide-containing neurons and endocrine cells in the rabbit gastrointestinal tract,with particular reference to the mucosa

Summary The distribution patterns of peptide-containing neurons and endocrine cells were mapped in sections of oesophagus, stomach, small intestine and large intestine of the rabbit, by use of standard immunohistochemical techniques. Whole mounts of separated layers of ileum were similarly examined. Antibodies raised against vasoactive intestinal peptide (VIP), substance P (SP), somatostatin (SOM), neuropeptide Y (NPY), enkephalins (ENK) and gastrin-releasing peptide (GRP) were used, and for each of these antisera distinct populations of immunoreactive (IR) nerve fibres were observed. Endocrine cells were labelled by the SP, SOM or NPY antisera in some regions.VIP-IR nerve fibres were common in each layer throughout the gastrointestinal tract. With the exception of the oesophagus, GRP-IR nerve fibres also occurred in each layer of the gastrointestinal tract; they formed a particularly rich network in the mucosa of the stomach and small intestine. Fewer nerve fibres containing NPY-IR or SOM-IR were seen in all areas. SOM-IR nerve fibres were very scarce in the circular and longitudinal muscle layers of each area and were absent from the gastric mucosa. The SP-IR innervation of the external musculature and ganglionated plexuses in most regions was rather extensive, whereas the mucosa was only very sparsely innervated. ENK-IR nerve fibres were extremely rare or absent from the mucosa of all areas, although immunoreactive nerve fibres were found in other layers.These studies illustrate the differences in distribution patterns of peptide-containing nerve fibres and endocrine cells along the gastrointestinal tract of the rabbit and also show that there are some marked differences in these patterns, in comparison with other mammalian species.     

人十二指肠血管活性肠肽能P物质能神经分布的研究

本文采用免疫组织化学ＡＢＣ法研究血管活性肠肽（ＶＩＰ） 能神经和Ｐ物质（ＳＰ） 能神经在人十二指肠壁内的分布。结果显示： ＶＩＰ能和ＳＰ能神经纤维和神经元均呈棕褐色; ＶＩＰ能神经纤维遍布肠壁各层,ＳＰ能神经纤维主要分布于肌层和神经丛; ＶＩＰ能和ＳＰ能神经元见于肌间和粘膜下神经, 尤以后者为多, 但形态特点不同; 在肌间神经丛, ＳＰ能神经元比ＶＩＰ能神经元多。粘膜内可见ＶＩＰ能和ＳＰ能神经元, 多单个分布在粘膜肌层内。结果表明： １ＶＩＰ能和ＳＰ能神经在人十二指肠壁内分布有差异。２粘膜内存在ＶＩＰ能和ＳＰ能神经元     

Effects of digestive status on the reptilian gut

Reptiles, including the Burmese python, Python molurus bivittatus, that feed at infrequent intervals show a prominent increase in gastrointestinal mass, metabolism and brush border transport rates after feeding. Current knowledge and theories around these phenomena, as well as studies on the innervation of the reptilian gut, are summarised in this review. Little is known about the putative changes in the nervous and humoral control systems of the gut, and it is not known whether feeding affects innervation and motility of the stomach and intestine. Using immunohistochemistry, we have investigated possible up/down regulation of several neurotransmitters in specimens that had been fasted for a minimum of 3 weeks and specimens that had ingested a large meal 2 days before the experiments were conducted. There were no major changes in the innervation by nerves containing calcitonin gene-related peptide (CGRP), galanin, nitric oxide synthase (NOS), pituitary adenylate cyclase-activating polypeptide (PACAP), somatostatin (SOM), substance P/neurokinin A (SP/NKA), or vasoactive intestinal polypeptide (VIP)-like immunoreactivity. Nor did we find any differences in the effect of substance P (stomach and intestine), galanin (intestine), or bradykinin (intestine) on motility in strip preparations from the gut wall. A significant increase in dry weight of the intestine was obtained 48 h after feeding. We conclude that although there are considerable changes in gut thickness and absorptive properties after feeding, the smooth muscle and its control appear little affected.     

The localization of sensory nerve fibers and receptor binding sites for sensory neuropeptides in canine mesenteric lymph nodes

Previous work has established that the central nervous system can modulate the immune response. Direct routes through which this regulation may occur are the sympathetic and sensory innervation of lymphoid organs. We investigated the innervation of canine mesenteric lymph nodes using immunohistochemistry and the expression of binding sites for sensory neuropeptides using quantitative receptor autoradiography. The sympathetic innervation of lymph nodes was examined by immunohistochemical methods using an antiserum directed against tyrosine hydroxylase (TOH), the rate limiting enzyme in catecholamine synthesis. TOH-containing fibers were associated with 90% of the blood vessels (arteries, veins, arterioles and venules) in the hilus, medullary and internodular regions of lymph nodes and in trabeculae with no obvious relationship to blood vessels. The sensory innervation of lymph nodes was investigated using antisera directed against the putative sensory neurotransmitters calcitonin gene-related peptide (CGRP) and substance P (SP). CGRP- and SP-containing fibers were detected in the hilus, the medullary region, and the internodular region of lymph nodes usually in association with arterioles and venules. About 50% of the arterioles and venules exhibited a CGRP innervation and a smaller fraction (5-10%) were innervated by SP-containing fibers. Few if any TOH, CGRP, and SP nerve fibers were detected in the germinal centers of lymph nodes. Using quantitative receptor autoradiography we studied the distribution of receptor binding sites for the sensory neuropeptides CGRP, SP, substance K (SK), vasoactive intestinal peptide (VIP), somatostatin (SOM), and bombesin. Specific CGRP binding sites were expressed throughout lymph nodes by trabeculae, arterioles, venules and 25% of the germinal centers. SP receptor binding sites were localized to arterioles and venules in the T cell regions and 25-30% of the germinal centers. VIP binding sites were localized to the internodular and T cell regions, to medullary cords, and to 10-20% of germinal centers. SK, SOM, and bombesin binding sites were not detected in the lymph nodes, although receptor binding sites for these peptides were detected with high specific/nonspecific binding ratios in other canine peripheral tissues. Taken together with previous results these findings suggest that the sympathetic and sensory innervation of mesenteric lymph nodes appears to be involved with the regulation of their blood and lymph flow. The neuropeptide receptor binding sites in lymph node germinal centers may be expressed by lymphocytes upon activation by antigens.(ABSTRACT TRUNCATED AT 400 WORDS)