Dispersal and immunohistochemical characteristics of neurons in the stem of the porcine vagus nerve

The present study investigated the distribution and chemical properties of nerve cell bodies within the trunk of the vagus nerve in juvenile female pigs (n=4) using double-labelling immunofluorescence. The neurons appeared mostly as single cells or formed streaks of cells or small ganglia. Many of the perikarya were cholinergic (VAChT-positive; VAChT+) or adrenergic (DβH+) in nature and no SP+ or CGRP+ neurons were encountered. There were no distinct left-right differences regarding the number and chemical coding of the neuronal somata, however, these characteristics significantly varied between particular nerve segments investigated. The vagosympathetic trunks, and thoracic and abdominal segments of the vagus nerve contained on average (the numerical values represent the means for both the left and right corresponding nerve segments) 142, 236, and 111 PGP 9.5-positive neurons, respectively. Proportions of cholinergic and adrenergic neurons were as follows: 0% and 100%, 54.2% and 33.2%, and 52.8% and 35.4%, respectively. Relatively many neurons in the thoracic and abdominal segments stained also for NOS (39.2% and 39.9%, respectively). It remains to be determined whether the porcine intravagal neurons represent a developmental relic, or whether they have any specific functional significance.

Immunohistochemical characterization of nerve elements in porcine intrinsic laryngeal ganglia

The present study investigated the chemical coding of neurons and nerve fibres in local laryngeal ganglia in pigs (n=5) using double-labelling immunohistochemistry. Virtually all the neurons were cholinergic in nature (ChAT- or VAChT-positive). Only very solitary, small nerve cells (presumably representing interneurons) stained intensely for adrenergic marker, DβH. Many neurons also contained immunoreactivity for NOS (91%), VIP (62.7%), NPY (24.7%), galanin (10%), SP (1.3%) and CGRP (5.3%). No neurons expressing somatostatin or Leu-enkephalin were observed. Nearly all the neuronal somata were densely supplied with varicose cholinergic nerve terminals, which presumably represented preganglionic axons, and some of them were also closely apposed with CGRP- and/or SP-positive varicose nerve endings, which were putative collaterals of extrinsic primary sensory fibres. In conclusion, this study has revealed that intrinsic neurons in the porcine larynx, like in many other mammalian species studied, should be classified as parasympathetic cholinergic neurons expressing biologically active substances, predominantly NOS and VIP. Furthermore, they are likely to receive inputs from not only preganglionic neurons but also primary sensory nerve cells. Finally, it appears that the information on the occurrence of the local laryngeal ganglia should be regularly included in textbooks dealing with the cranial portion of the parasympathetic nervous system in mammals.

Nerve structures of the heart and their immunohistochemical characterization in 10-week-old porcine foetuses

The aim of the present study was to investigate the distribution of neuronal perikarya and nerve fibres and their chemical coding in the heart of 10-week-old porcine foetuses. The foetuses, obtained from a local slaughterhouse, were fixed by immersion in 4% buffered (pH 7.4) paraformaldehyde. Cryostat sections of the hearts were processed for single- or double-labelling immunofluorescence methods using antibodies against protein gene product (PGP) dopamine beta-hydroxylase (DβH), acetylcholine vesicular transporter (VAChT) and calcitonin gene-related peptide (CGRP). Numerous clusters of the PGP-positive nerve cells were observed throughout the heart wall. The majority of the clusters were found beneath the epicardium around the root of the aorta, pulmonary trunk and main veins. Some single PGP-positive neurons or small clusters of nerve cells were observed in the epicardium of heart atria and ventricles. The richest network of PGP-positive nerve fibres was observed in the base of the heart near the main cardiac blood vessel openings. Many bundles of PGP-positive nerve fibres were observed throughout the four cardiac chambers. Double-immunohistochemical staining revealed that the majority of the neurons contained immunoreactivity to VAChT, some of them stained for CGRP and the single neuronal somata were DβH-positive. The nerve fibres supplying the heart expressed immunoreactivity to DβH, VAChT or CGRP. The distribution and neurochemical coding of the nerve structures in ten-week-old foetuses are different from those observed in the hearts of juvenile pigs.

Distribution and chemical coding of urinary bladder apex-projecting neurons in aorticorenal and testicular ganglia of the male pig

Combined retrograde tracing and double-labelling immunofluorescence were used to investigate the distribution and chemical coding of neurons in aorticoerenal (ARG) and testicular (TG) ganglia supplying the urinary bladder apex (UBA) in the juvenile male pig (n=4, 12 kg. body weight). Retrograde fluorescent tracer Fast Blue (FB) was injected into the wall of the bladder apex under pentobarbital anesthesia. After three weeks all the pigs were deeply anesthetized and transcardially perfused with 4% buffered paraformaldehyde. TG and ARG were collected and processed for double-labelling immunofluorescence. The presence of tyrosine hydroxylase (TH) or dopamine beta-hydroxylase (DBH), neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL), nitric oxide synthase (NOS) and vesicular acetylcholine transporter (VAChT) were investigated. The cryostat sections were examined with a Zeiss LSM 710 confocal microscope equipped with adequate filter blocks. The TG and ARG were found to contain many FB-positive neurons projecting to the UBA (UBA-PN). The UBA-PN were distributed in both TG and ARG. The majority were found in the left ganglia, mostly in TG. Immunohistochemistry disclosed that the vast majority of UBA-PN were noradrenergic (TH- and/or DBH-positive). Many noradrenergic neurons also contained immunoreactivity to NPY, SOM or GAL. Most of the UBA-PN were supplied with varicose VAChT-, or NOS- IR (immunoreactive) nerve fibres. This study has revealed a relatively large population of differently coded ARG and TG neurons projecting to the porcine urinary bladder. As judged from their neurochemical organization these nerve cells constitute an important element of the complex neuro-endocrine system involved in the regulation of the porcine urogenital organ function.

Enteric nervous system in the European beaver (Castor fiber) pylorus - an immunohistochemical study

European beaver (Castor fiber), the largest rodent species inhabiting a wide area of Eurasia, feeds mainly on dry parts of plants, bark or wood. Such kind of nourishment needs to be properly digested in each part of the gastrointestinal tract. The time of stomach digestion, which directly influences all the following steps of the digestion process, is precisely controlled by the pylorus and its innervation. However, virtually no data is available on the organization of the enteric nervous system in most of the wild animal species, including beavers. On the other hand, a pecu- liar diet consumed by beavers, suggests that the arrangement of their stomach intramural nerve elements can be atypical. Therefore, the present study investigated the distribution and chemical coding of neurons and nerve fibers in the pylorus of the European beaver. The experiment was performed on stomachs obtained from a group of 6 beavers caught in Northeastern region of Poland (due to beaver overpopulation). Pyloric wall tissue cryosections were double immunostained with a mixture of antibodies against pan-neuronal marker PGP 9.5 (to visualize enteric neurons) and ChAT (cholinergic marker), nNOS (nitrergic marker), SP, CGRP, Gal (peptidergic markers). Confocal microscopy analysis revealed that the majority of enteric nerve cells were clustered forming submucosal and myenteric ganglia and all the studied substances were expressed (in various amounts) in these neurons. We conclude, that the anatomical arrangement and chemical coding of intramural nerve elements in the beaver pylorus resemble those found in other mammalian species.

The Influence of Gastric Antral Ulcerations on the Expression of Galanin and GalR1, GalR2, GalR3 Receptors in the Pylorus with Regard to Gastric Intrinsic Innervation of the Pyloric Sphincter

Gastric antrum ulcerations are common disorders occurring in humans and animals. Such localization of ulcers disturbs the gastric emptying process, which is precisely controlled by the pylorus. Galanin (Gal) and its receptors are commonly accepted to participate in the regulation of inflammatory processes and neuronal plasticity. Their role in the regulation of gastrointestinal motility is also widely described. However, there is lack of data considering antral ulcerations in relation to changes in the expression of Gal and GalR1, GalR2, GalR3 receptors in the pyloric wall tissue and galaninergic intramural innervation of the pylorus. Two groups of pigs were used in the study: healthy gilts and gilts with experimentally induced antral ulcers. By double immunocytochemistry percentages of myenteric and submucosal neurons expressing Gal-immunoreactivity were determined in the pyloric wall tissue and in the population of gastric descending neurons supplying the pyloric sphincter (labelled by retrograde Fast Blue neuronal tracer). The percentage of Gal-immunoreactive neurons increased only in the myenteric plexus of the pyloric wall (from 16.14±2.06% in control to 25.5±2.07% in experimental animals), while no significant differences in other neuronal populations were observed between animals of both groups. Real-Time PCR revealed the increased expression of mRNA encoding Gal and GalR1 receptor in the pyloric wall tissue of the experimental animals, while the expression(s) of GalR2 and GalR3 were not significantly changed. The results obtained suggest the involvement of Gal, GalR1 and galaninergic pyloric myenteric neurons in the response of pyloric wall structures to antral ulcerations.

Immunohistochemical Characterization of Sympathetic Chain Ganglia (SChG) Neurons Supplying the Porcine mammary Gland

The aim of this study was to investigate the chemical coding of mammary gland-projecting SChG neurons using double-labelling immunohistochemistry. Earlier observation showed that after injection of the retrograde tracer fast blue (FB) into the second, right thoracic mamma, FB+ mammary gland-projecting neurons were found in Th1-3, Th9-14 and L1-4 right SChG. The greatest number of FB+ nerve cell bodies was observed in Th10 (approx. 843) and Th11 (approx. 567). Neurons projecting to the last right abdominal mamma were found in L1-4 SChG. The greatest number of FB+ neurons was observed in L2 (approx. 1200). Immunohistochemistry revealed that the vast majority of FB+ mammary-projecting neurons contained immunoreactivities to TH (96.97%) and/or DßH (95.92%). Many TH/DßH-positive neurons stained for SOM (41.5%) or NPY (33.2%), and less numerous nerve cells expressed VIP (16.9%). This observation strongly corresponds to the results of previous studies concerning the immunohistochemical characterization of nerve fibres supplying the porcine mammary gland.

The influence of ileitis on the neurochemistry of the caudal mesenteric ganglion in the pig

BACKGROUND

Some literature data suggest that there is a regulatory neuronal circuit between the small and the large bowel. To verify this hypothesis the present study investigated: (i) the distribution, chemical coding and routing of caudal mesenteric ganglion (CaMG) neurons participating in an intestinointestinal reflex pathway involving ileal descending neurons and viscerofugal colonic neurons and (ii) possible changes in the neuroarchitecture of this pathway evoked by chemically induced ileitis in juvenile pigs (n=16).

METHODS

Combined retrograde tract tracing and transections of the intermesenteric or caudal colonic nerves were applied. In addition, double immunostainings was used to investigate the chemical coding of retrogradely labeled CaMG neurons and intraganglionic nerve terminals apposed to them, under normal and inflammatory conditions.

KEY RESULTS

The majority of the ileum-projecting neurons were found in the caudal part of CaMG. Disruption of particular nerve pathways resulted in diminished number of retrogradely labeled neurons, ipsilateral to the side of manipulation. In normal pigs, ileum-projecting CaMG neurons stained for tyrosine hydroxylase, dopamine-β-hydroxylase, neuropeptide Y (NPY), somatostatin and galanin (GAL). The number and chemical coding of the neurons in the inflamed animals were similar to those observed in the normal pigs. However, in the inflamed pigs, the number of NPY-, GAL- or substance P-positive nerve terminals supplying retrogradely labeled neurons was increased.

CONCLUSIONS & INFERENCES

The present results suggest that inflammatory processes of the porcine ileum are able to induce changes in the intraganglionic architecture of a sympathetic ganglion located at discrete distance from the affected bowel segment.

Distribution and nerve pathways of neurons supplying the bulbourethral gland in the pig

The present study has disclosed for the first time the distribution and peripheral nerve pathways of autonomic and primary afferent neurons projecting to the bulbourethral gland (BG) in a mammalian species, the pig (n = 5), using combined retrograde tracing and cutting the hypogastric (n = 3) or pelvic (n = 3) nerve. Neurons projecting to the right BG were found in pelvic ganglia (PG), sympathetic chain ganglia (SChG; L2-S3), the caudal mesenteric ganglion (CaMG) and dorsal root ganglia (DRG; L1-L3, S1-S3). In general, the majority (about 75%) of them were located in the ipsilateral ganglia. Results of denervation experiments suggest that the neurons located in CaMG, and lumbar SChG and DRG project through the hypogastric nerve while processes of those found in the sacral SChG and DRG travel through the pelvic nerve or pelvic branch of the pudendal nerve. Moreover, the results obtained also suggest that the 'crossing points' (i.e. the areas where nerve fibres reach the opposite side) for the neurons found in the contralateral CaMG are located partly at the level of this ganglion and, for a smaller number of the nerve cells, at the level of the pelvic plexus. The crossing points for the SChG and DRG neurons are probably situated at the level of sympathetic chains and, for sacral SChG neurons, at the level of the pelvic plexus. The diversity of sources of the nerve supply to the porcine BG corresponds well with the variety (as previously distinguished with immunohistochemistry) of its intrinsic nerve fibre populations.

The distribution and chemical coding of intramural neurons supplying the porcine stomach - the study on normal pigs and on animals suffering from swine dysentery

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.

Immunohistochemical characteristics of neurons supplying the porcine bulbourethral gland

In the male pig, the bulbourethral gland (BG) is a particulary well developed accessory genital gland (AGG) which produces complex secretion contributing to the fluid component of semen. The secretory and motor function of AGGs is thought to be under the autonomic nervous system control. Although relatively much is known about the innervation of the prostate gland and, to a lesser degree, of the seminal vesicle, the paucity of data dealing with the innervation of BG is striking. Therefore, combined retrograde tracing and double-labelling immunofluorescence have been used to investigate the distribution and immunohistochemical properties of autonomic and primary afferent neurons projecting to this gland in the pig. BG-projecting neurons were found in some ipsilateral (I) and contralateral (C) sympathetic chain ganglia (SChG), the caudal mesenteric ganglion (CaMG), pelvic ganglia (PG) and some dorsal root ganglia (DRG). Immunohistochemistry revealed that the vast majority of CaMG and SChG BG-projecting neurons contained tyrosine hydroxylase (TH) and dopaminebeta-hydroxylase (DbetaH), and some neuropeptides including neuropeptide Y (NPY), somatostatin (SOM) and galanin (GAL). Three subpopulations of PG neurons supplying BG could be distinguished: 1) cholinergic neurons [vesicular acetylcholine transporter (VAChT)-positive] which also contained vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), SOM and NPY, 2) adrenergic neurons (TH-positive) which also stained for NPY, GAL or leu5-enkephalin (LEU), and 3) non-adrenergic, non-cholinergic neurons (NANC). DRG BG-projecting neurons contained mostly substance P (SP) and/or calcitonin gene-related peptide (CGRP) which sometimes colocalized with GAL. The possible functional significance of the substances found within the neurons is discussed.

Immunohistochemical characterisation of cholinergic neurons in the anterior pelvic ganglion of the male pig

This study investigated immunohistochemical properties of cholinergic neurons in the anterior pelvic ganglion (APG) of juvenile male pigs (n=7). Cholinergic neurons were identified using antibodies against choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT). Immunoblotting was applied to verify the specificity of ChAT-immunostaining. Western blotting performed on APG tissue homogenates detected single immunoreactive protein with a molecular weight matching that of ChAT (71.6 kDa). It was found that many APG neurons expressed immunoreactivity to ChAT or VAChT (40% and 39% of the neurons, respectively). The analysis of adjacent sections from the ganglion revealed complete colocalization of ChAT and VAChT in these nerve cells. Furthermore, virtually all the ChAT-positive neurons were tyrosine hydroxylase (TH)-negative (non-adrenergic) but many of them displayed immunoreactivity to nitric oxide synthase (NOS), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) or somatostatin (SOM). There were also single nerve cell bodies that stained for neither ChAT nor TH. The comparison of the adjacent sections revealed that NOS, VIP, NPY and SOM were simultaneously co-expressed in the majority of the cholinergic somata. ChAT- or VAChT-positive varicose nerve terminals supplied nearly all neuronal profiles within the ganglion often forming loose basket-like formations surrounding the particular nerve cell bodies. The present study for the first time has revealed that nearly all non-adrenergic neurons in the porcine APG are cholinergic in nature, i.e. express immunoreactivity for ChAT and VAChT. Considering a high coincidence between the chemical coding of non-adrenergic (cholinergic) nerve fibres supplying some porcine male reproductive organs described in earlier papers and that of cholinergic pelvic neurons found in this study it is further concluded that pelvic ganglia are probably the major source of cholinergic innervation for the porcine urogenital system.

Differences in the chemical coding of nerve fibres supplying major populations of neurons between the caudal mesenteric ganglion and anterior pelvic ganglion in the male pig

The present study was designed to investigate and to compare the chemical coding of nerve fibres supplying major populations of neurons in the caudal mesenteric (CaMG) and anterior pelvic (APG) ganglion in juvenile male pigs (n=5) using double-labelling immunofluorescence. The co-existence patterns of some biologically active substances including tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT) as well as vasoactive intestinal polypeptide (VIP), substance P (SP), calcitonin gene-related peptide (CGRP), Leu5-enkephalin (LENK) and serotonin (5-HT) were analysed under a confocal laser scanning microscope. Profound differences in the neurochemical features of the nerve terminals between the ganglia were observed. Moreover, there were also distinct differences in the chemical coding of nerve fibres associated with the particular populations and subpopulations of neurons within the ganglia. In both ganglia, nearly all adrenergic and cholinergic neurons were supplied with VAChT-positive nerve fibres (putative preganglionic fibres). However, in the CaMG, they were more numerous and, in contrast to the APG, many of them also stained for VIP. In the APG, a great number of nerve terminals expressed immunoreactivity to SP and CGRP (putative collaterals of sensory neurons). Interestingly, they densely supplied almost exclusively adrenergic neurons. SP-positive nerve fibres were moderate in number in the CaMG, but, in addition to VAChT-IR nerve terminals, the most numerous populations of nerve fibres in this ganglion were those expressing highly colocalized immunoreactivities to CGRP and LENK, and those which stained for 5-HT (putative processes of enteric neurons). However, these fibres supplied almost exclusively larger, intensely stained for TH and clustered adrenergic neurons. This diversity of the nerve terminals reflects the complexity of nerve circuits involved in the innervation of structures supplied by neurons in the porcine CaMG and APG. It also demonstrates the importance of nerve inputs for the proper function of autonomic neurons and thus their target tissues.

Noradrenergic and peptidergic innervation of the mammary gland in the immature pig

The presence and pattern of coexistence of some biologically active substances in nerve fibres supplying the mammary gland in the immature pig were studied using immunohistochemical methods. The substances studied included: protein gene product 9.5 (PGP), tyrosine hydroxylase (TH), somatostatin (SOM), neuropeptide Y (NPY), galanin (GAL), calcitonin gene-related peptide (CGRP) and substance P (SP). The mammary gland was found to be richly supplied by PGP-immunoreactive (PGP-IR) nerve fibres that surrounded blood vessels, bundles of smooth muscle cells and lactiferous ducts. The vast majority of these nerves also displayed immunoreactivity to TH. Immunoreactivity to SOM was observed in a moderate number of nerve fibres which were associated with smooth muscles of the nipple and blood vessels. Immunoreactivity to NPY occurred in many nerve fibres associated with blood vessels and in single nerves supplying smooth muscle cells. Solitary GAL-IR axons supplied mostly blood vessels. Many CGRP-IR nerve fibres were associated with both blood vessels and smooth muscles. SP-IR nerve fibres richly supplied blood vessels only. The colocalization study revealed that SOM, NPY and GAL partly colocalized with TH in nerve fibres supplying the porcine mammary gland.

Distribution of ganglionic sympathetic neurons supplying the subcutaneous, perirenal and mesentery fat tissue depots in the pig

Previous morphological studies revealed that the adipose tissue is innervated by adrenergic nerve fibers. Furthermore, physiological studies showed that the metabolism of adipose tissue is controlled by the adrenergic component of the nervous system. However, nothing is known on the sources of innervation of different fat tissue depots. Therefore, we decided to study the distribution of ganglionic sympathetic neurons innervating adipose tissue in the pig by means of a retrograde tracing method. We used 9 male and 9 female pigs of approximately 50 kg body weight. The retrograde tracer, Fast Blue (FB), was injected into the subcutaneous, perirenal and mesentery fat tissue depots. Results of the present study showed that numerous centers of the sympathetic nervous system innervate adipose tissue in the pig. FB+ neurons projecting to the subcutaneous fat tissue were placed in the thoraco-lumbar region of the sympathetic chain ganglia (SChG). However, neurons supplying perirenal and mesentery fat tissue depots were found in both the SChG and prevertebral ganglia (PVG). We conclude that different adipose tissue depots (subcutaneous, perirenal and mesentery) have different sources of innervation and that there is no significant difference in the distribution of neurons innervating adipose tissue in male and female pigs.

Distribution and immunohistochemical characterisation of paracervical neurons innervating the oviduct in the pig

The present study was aimed at disclosing the distribution of paracervical neurons projecting to the ampulla and isthmus of the porcine oviduct and the pattern(s) of co-existence of tyrosine hydroxylase (TH), dopamine beta-hydroxylase (D beta H), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP) and nitric oxide synthase (NOS) within these nerve cell bodies. The fluorescent retrograde tracer Fast Blue (FB) was injected into the wall of the ampullar (n = 3) and isthmal (n = 3) part of the organ in six sexually immature female pigs. After a survival period of three weeks paracervical ganglia (PCG) were collected. 10 microns-thick cryostat sections of the ganglia were examined for the presence of FB-positive (FB+) nerve cells under the fluorescent microscope. Tracered neurons were counted in every third section and processed for double-labelling immunofluorescence according to the method of Wessendorf and Elde. 78.6% of FB+ neurons were projecting to the isthmus while 21.4% of the studied population innervated the ampulla of the oviduct. Double-labelling immunofluorescence revealed the existence of the following different chemically coded subpopulations of the studied perikarya: TH+/D beta H+, TH+/NPY+, TH+/NOS+, TH+/NOS-, SP-/NOS+, SP+/CGRP+.