Demonstration of paracervical ganglion origin for the vasoactive intestinal peptide-containing nerves of the rat uterus using retrograde tracing techniques combined with immunocytochemistry and denervation procedures

Uterine Inflammation Changes the Expression of Cholinergic Neurotransmitters and Decreases the Population of AChE-Positive, Uterus-Innervating Neurons in the Paracervical Ganglion of Sexually Mature Gilts

Simple Summary

Endometritis, both with non-infectious and infectious backgrounds, is one of the most prevalent pathological states among domestic animals. In animals, it generates severe economic problems, including lowered reproductive indices and rising medical treatment costs, and in women, it might lead to severe fertility impairment. In order to determine how the autonomic nervous system responds to such a pathological state, an experimental group of pigs were treated with Escherichia coli injection into the uterine horns, and several ganglions responsible for innervation of this organ were examined, including the paracervical ganglion located on both sides of the broad ligament of the uterus. The results clearly showed a strong impact of the inflammation on the chemical coding of neurons, some even synthesizing neurotransmitters de novo such as the GAL-expressing perikarya. Additionally, applied injections decreased the number of parasympathetic, acetylcholinesterase-expressing neurons implying the importance of the cholinergic population to keep the inflammation under control. The obtained data serve as a basis for the future implementation of modern treatment and enhancements in animal breeding.

Abstract

The focus of this study was based on examining the impact of endometritis on the chemical coding of the paracervical ganglion (PCG) perikaryal populations supplying pig uterus. Four weeks after the injection of Fast Blue retrograde tracer into uterine horns, either the Escherichia coli (E. coli) suspension or saline solution was applied to both horns. Laparotomy treatment was performed for the control group. Uterine cervices containing PCG were extracted on the eighth day after previous treatments. Subsequent macroscopic and histopathologic examinations acknowledged the severe form of acute endometritis in the E. coli-treated gilts, whereas double-labeling immunofluorescence procedures allowed changes to be analyzed in the PCG perikaryal populations coded with vesicular acetylcholine transporter (VAChT) and/or somatostatin (SOM), vasoactive intestinal polypeptide (VIP), a neuronal isoform of nitric oxide synthase (nNOS), galanin (GAL). The acetylcholinesterase (AChE) detection method was used to check for the presence and changes in the expression of this enzyme and further confirm the presence of cholinergic perikarya in PCG. Treatment with E. coli resulted in an increase in VAChT+/VIP+, VAChT+/VIP−, VAChT+/SOM+, VAChT+/SOM−, VAChT+/GAL− and VAChT+/nNOS− PCG uterine perikarya. An additional increase was noted in the non-cholinergic VIP-, SOM- and nNOS-immunopositive populations, as well as a decrease in the number of cholinergic nNOS-positive perikarya. Moreover, the population of cholinergic GAL-expressing perikarya that appeared in the E. coli-injected gilts and E. coli injections lowered the number of AChE-positive perikarya. The neurochemical characteristics of the cholinergic uterine perikarya of the PCG were altered and influenced by the pathological state (inflammation of the uterus). These results may indicate the additional influence of such a state on the functioning of this organ.

Endometritis decreases the population of uterine neurons in the paracervical ganglion and changes the expression of sympathetic neurotransmitters in sexually mature gilts

BACKGROUND

The focus of the study was to examine the impact of the inflamed uterus on the population of the paracervical ganglion (PCG) uterus-innervating perikarya and their chemical coding. Fast Blue retrograde tracer was injected into the wall of uterine horns on the 17th day of the first studied estrous cycle. After 28 days, either Escherichia coli suspension or saline was applied to the horns of the uterus, whereas the control group received laparotomy only. Eight days after the above-mentioned procedures, uterine cervices with PCG were collected. Both macroscopic and histopathologic examinations confirmed severe acute endometritis in the Escherichia coli-injected uteri. The double immunofluorescence method was used to analyze changes in the PCG populations coded with dopamine-β-hydroxylase (DβH) and/or neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP) and neuronal isoform of nitric oxide synthase (nNOS).

RESULTS

The use of Escherichia coli lowered the total number of Fast Blue-positive neurons. Moreover, an increase in DβH+/VIP+, DβH+/NPY+, DβH+/SOM + and DβH+/nNOS + expressing perikarya was noted. A rise in non-noradrenergic VIP-, SOM- and nNOS-immunopositive populations was also recorded, as well as a drop in DβH-positive neurotransmitter-negative neurons.

CONCLUSIONS

To sum up, inflammation of the uterus has an impact on the neurochemical properties of the uterine perikarya in PCG, possibly affecting the functions of the organ.

Systemic and topical hormone therapies reduce vaginal innervation density in postmenopausal women

OBJECTIVE

Menopause is often accompanied by vaginal discomfort including burning, itching, dryness, and spontaneous or provoked pain. Although the direct effects of estrogen withdrawal on vaginal cells are implicated, surgical menopause in rodents causes autonomic and sensory nerves to proliferate, suggesting that indirect effects mediated by changes in vaginal innervation may contribute. We assessed whether postmenopausal women display hormone-dependent changes in vaginal innervation.

METHODS

Vaginal biopsies from 20 postmenopausal women undergoing surgery for stress urinary incontinence and pelvic organ prolapse were fixed and immunostained for the pan-neuronal marker protein gene product 9.5, sympathetic marker tyrosine hydroxylase, parasympathetic marker vasoactive intestinal polypeptide, and sensory nociceptor marker calcitonin gene-related peptide. Innervation density was measured as an apparent percentage of the section area occupied by immunofluorescent axons. Specimens were grouped according to whether participants received systemic hormone therapy (HT), topical (vaginal) HT, or no HT.

RESULTS

Women not receiving HT showed relatively high levels of total innervation, with most axons expressing tyrosine hydroxylase or vasoactive intestinal polypeptide immunoreactivity. In women receiving systemic HT, overall innervation was reduced, as were presumptive parasympathetic, sympathetic, and sensory axon populations. Topical HT elicited more dramatic reductions in innervation than in systemic HT.

CONCLUSIONS

Hormone therapy reduces autonomic and sensory vaginal innervation density, which may, in part, contribute to relief from vaginal discomfort. Moreover, topical therapy is more effective than systemic therapy, which may help explain the greater improvement reported with topical compared with systemic HT.

Upregulation of LENK and VIP in paracervical ganglion neurons supplying the urinary bladder of tetrodotoxin- and resiniferatoxin-treated female pigs

Both resiniferatoxin (RTX) and tetrodotoxin (TTX) have been reported to be effective in several clinical trials aiming to cure urinary bladder dysfunction. The goal of this experiment was to study the effect of intravesical administration of RTX and TTX on the chemical coding of paracervical ganglion (PCG) neurons that supply the urinary bladder in pigs. The vasoactive intestinal peptide (VIP) and the opioid family member Leu5-enkephalin (LENK) are both known for their regulatory effects in the function of the porcine genitourinary tract. The PCG neurons innervating the urinary bladder were identified by application of the retrograde tracer Fast Blue (FB), injected into the bladder wall prior to intravesical RTX or TTX administration. Immunocytochemical detection of LENK and VIP expression in the FB-labelled perikarya revealed that in the control group 25.15% of the FB-positive PCG neurons contained LENK, and 9.22% of them expressed VIP. Intravesical infusion of RTX resulted in an increase in the number of LENKIR neurons to 48.19% and VIP-IR perikarya to 11.25%. Optional treatment with TTX induced increase of LENK-IR neurons up to 81.67% and VIP-IR population to 16.46% of the FB-positive PCG cells. The present results show that both neurotoxins affect the chemical coding of PCG nervous cells supplying the porcine urinary bladder and that they stimulate both LENK and VIP expression. Furthermore, the results indicate a possible involvement of LENK and VIP neurons in the mechanisms of action of RTX and TTX in the therapy of overactive bladder disorder.

Distribution of substance P (SP) and vasoactive intestinal peptide (VIP) in pseudocapsules of uterine fibroids

The authors examined the presence of Substance P (SP) and Vasoactive Intestinal Polypeptide (VIP) and their related fibers in the pseudocapsule of uterine fibroids (PUF) and in normal myometrium (NM) during myomectomies in 57 non-pregnant women. 4 samples were removed from the normal myometrium (NM) and from PUF. The samples were sent for histological and immune-fluorescent investigations. SP and VIP values were found non-significantly higher in PUF than in NM: SP values were 10.2±0.1 conventional units (C.U.) in PUF at the fundus of the uterus (FU) vs. 8.1±0.6C.U. of NM in the FU (p>0.05), and SP values were 25.1±0.9C.U. in PUF in the uterine body (UB) compared to. 23.2±1.4C.U. of NM in the myometrium of the UB (p>0.05). VIP values were 11.5±0.9C.U. in the PUF in FU compared to 9.8±1.4C.U. of NM in the FU (p>0.05), and VIP values were 33.9±3.9C.U. in the PUF in the UB vs. 32.6±4.8C.U. of the NM in the UB (p>0.05). These findings show that SP and VIP neurofibers are present in the fibroid pseudocapsule, similar to the values in the normal myometrium of a non-pregnant uterus. An intracapsular myoma excision which respects the pseudocapsule permits a physiological healing process of the uterine scar, due to a neurotransmitter sparing at the hysterotomic site. In women planning pregnancy, the myomectomy should be preferably performed respecting the pseudocapsule in order to preserve the neurotransmission.

Substance P (SP) and vasoactive intestinal polypeptide (VIP) in the lower uterine segment in first and repeated cesarean sections

The authors studied the presence of substance P (SP) and vasoactive intestinal polypeptide (VIP) and their related fibers in the lower uterine segment (LUS) in 133 women undergoing cesarean sections (CS) during active labor. These were divided into 2 groups: women undergoing repeat or first CSs. Specimens were collected from the LUS and were evaluated by light microscopy and by immunohistochemistry, for the morphometrical quantification of the SP and VIP fibers in the LUS. The SP amount was higher in the post-CS scar, while the VIP amount decreased: nerve fibers contained an SP amount of up to 13 ± 2.6C.U., while nerve fibers contained a VIP amount of up to 7 ± 1.9 C.U. The SP amount counts 10 ± 1.5% of the total Bodian fibers, and the ratio of the VIP is 10 ± 1.8% of their total amount. In normal conditions only 6.61 C.U. of the Bodian surface is occupied by SP related nerve fibers in contrast to 6.63 C.U. of the total surface by VIP; the amount of SP increased up to 13 ± 2.6C.U., while it decreased in the LUS previous scars. The SP levels are higher in repeat CS, while the VIP levels are reduced in the LUS. The increase of SP is probably linked to the attempt to achieve cervical ripening in a post-CS LUS, with the possible consequences of dystocia during vaginal birth after CS. Nevertheless, the decrease of VIP probably affects the relaxation of the internal uterine orifice, compromising the LUS formation and cervical ripening.

Plasticity of pelvic autonomic ganglia and urogenital innervation

Pelvic ganglia contain a mixture of sympathetic and parasympathetic neurons and provide most of the motor innervation of the urogenital organs. They show a remarkable sensitivity to androgens and estrogens, which impacts on their development into sexually dimorphic structures and provide an array of mechanisms by which plasticity of these neurons can occur during puberty and adulthood. The structure of pelvic ganglia varies widely among species, ranging from rodents, which have a pair of large ganglia, to humans, in whom pelvic ganglion neurons are distributed in a large, complex plexus. This plexus is frequently injured during pelvic surgical procedures, yet strategies for its repair have yet to be developed. Advances in this area will come from a better understanding of the effects of injury on the cellular signaling process in pelvic neurons and also the role of neurotrophic factors during development, maintenance, and repair of these axons.

Target specific organization and neuron types of the dog pelvic ganglia: a retrograde-tracing and immunohistochemical study

The major pelvic ganglion in both the rat and guinea pig has been extensively studied because of its anatomical simplicity. To clarify the target specific neural pathway in the diffusely distributed pelvic ganglia of larger animals, the pelvic plexus of the female dog was investigated by retrograde tracing and immunohistochemistry. The whole mount staining of the pelvic plexus with acetylcholinesterase histochemistry revealed 70-100 ganglia of varying sizes. Neurons retrogradely labeled from the rectum were mainly found in ganglia located in the dorso-caudal part of the plexus. The majority of these were non-catecholaminergic, immunoreactive for either calbindin (Calb) or neuropeptide Y (NPY), and characteristically associated with baskets of enkephalin (ENK)-immunoreactive varicose fibers. Neurons projecting to the utero-vaginal walls were distributed in ganglia located in the ventro-caudal part of the plexus. These mainly consisted of two major neuron groups: catecholaminergic Calb-immunoreactive neurons, and non-catecholaminergic neurons containing nitric oxide synthase (NOS) and/or vasoactive intestinal peptide (VIP), which were preferentially associated with a network of ENK-immunoreactive varicose fibers. Neurons retrogradely labeled from the urinary bladder mainly occurred in ganglia located around the junction between the ureter and the bladder. These consisted of catecholaminergic Calb neurons and noncatecholaminergic neurons containing Calb or NOS. Only a few ENK-immunoreactive fibers were found within the clusters of catecholaminergic neurons. These results indicate that organ specific neurons are located in separate ganglia and have both a distinctive composition of neuron types as well as different innervation by preganglionic fibers.

Expression of vasoactive intestinal peptide (VIP) receptors in human uterus

We show the existence of functional vasoactive intestinal peptide (VIP) receptors in normal human female genital tract (endometrium, myometrium, ovary and Fallopian tube) as well as in leiomyoma (a frequent uterine pathology). The correlation between VIP binding and stimulation of adenylyl cyclase activity for all studied tissues was linear (r = 0.86) suggesting the expression of VIP receptors throughout the human female genital tract. Immunodetection of VIP receptor subtypes gave different molecular weights for VPAC(1) (47 kDa primarily) and VPAC(2) (65 kDa), which may be due to different glycosylation extents. In conclusion, this study demonstrates the expression of both subtypes of VIP receptors and their functionality in human female genital tract, suggesting that this neuropeptide could play an important physiological and pathophysiological role at this level.

Peptidergic innervation of the human clitoris

In the present study, the distributions of neuropeptides in the normal human clitoris and in a clitoris from an adrenogenital syndrome (AGS) was demonstrated by immunohistochemistry (IHC). Immunohistochemical screening detected a complex network of nerve fibers containing vasoactive intestinal polypeptide (VIP), peptide histidine methionine (PHM), neuropeptide tyrosine (neuropeptide Y), C-flanking peptide of neuropeptide Y (CPON), calcitonin gene-related peptide (CGRP) and substance P immunoreactivities. Special attention was given to the VIP-related peptide helospectin, that has been detected in neuronal elements in the clitoris. No visible differences between the localization and distribution of peptidergic nerve fibers of normal and hypertrophic clitoris from AGS have been observed. Co-localization studies showed the co-existence of VIP, PHM and partly helospectin and neuropeptide Y with CPON within nerve fibers in the cavernous tissue and substance P and CGRP co-expression in nerve fibers especially underneath and within the glans clitoris.

Regional difference in the distribution of vasoactive intestinal polypeptide-immunoreactive nerve fibres along the uterus and between myometrial muscle layers in the rat

To investigate a possible regional variation of the vasoactive intestinal polypeptide innervation in the uterus of the cyclic rat, the distribution of vasoactive intestinal polypeptide-containing nerve fibres from the cervix to the oviduct end of the uterine horns was studied using immunohistochemistry. Immunoreactive nerve fibres were most concentrated in the cervix, where they formed a dense plexus in association with the musculature and surrounding blood vessels. In the uterus, a clear regional distribution of the vasoactive intestinal polypeptide innervation was observed. Numerous vascular and non-vascular immunoreactive nerve fibres were present in the lower part of the uterine horns, whereas they were sparse in the median region and absent at the oviduct end. Moreover, non-vascular peptide innervation was mostly concentrated in the circular layer of the myometrium and also occurred in the endometrium. Only a very few immunoreactive nerve fibres were present in the longitudinal muscle layer. No change in the peptide innervation pattern was observed during the different stages of the sexual cycle. The marked regional distribution of the peptide innervation in the rat uterus suggests that the regulatory effects of the peptide occur mainly in the lower part of the organ and principally affect the circular muscle layer in the myometrium.

Pituitary adenylate cyclase activating polypeptide innervation of the rat female reproductive tract and the associated paracervical ganglia: effect of capsaicin

Pituitary adenylate cyclase activating peptide (PACAP) is a novel vasoactive intestinal polypeptide-like peptide which is present in neuronal elements of a number of peripheral organs. PACAP occurs in two forms, PACAP-27 and the C-terminally extended PACAP-38, both derived from the same precursor which in addition gives rise to a structurally-related peptide, PACAP-related peptide. Using specific radioimmunoassays for PACAP-38, PACAP-27 and PACAP-related peptide we found that the three PACAP-precursor-derived peptides were present in tissue extracts from all regions of the rat female genital tract. PACAP-38 was the dominating peptide with the highest concentrations in the Fallopian tube and the ovary. Upon reverse phase high pressure liquid chromatography the immunoreactive material was found to co-elute with synthetic PACAP-38, PACAP-27 and PACAP-related peptide, respectively. By immunohistochemistry, PACAP was shown to be located in varicose nerve fibres associated with blood vessels, smooth muscle and epithelial cells. Within the local paracervical ganglion PACAP-immunoreactive fibres ramified often forming varicose, pericellular plexuses around non-PACAP-positive cell bodies. Also bundles of PACAP-immunoreactive fibres were transversing the ganglion. In the paracervical ganglion of normal rat only a few neuronal cell bodies showed immunostaining for PACAP, but after local colchichine-treatment a moderate number of positive perikarya appeared. The synthesis of PACAP in neurons of the paracervical ganglia was confirmed by in situ hybridization histochemistry with a digoxigenin-labelled cRNA probe. Double immunostaining for PACAP and vasoactive intestinal polypeptide disclosed a partial co-existence of the two peptides in nerve fibres of all tubular organs in the rat female genital tract and in cell bodies and nerve fibres in the paracervical ganglion. After neonatal capsaicin treatment the concentration of immunoreactive PACAP-38 as well as the number and intensity of PACAP-positive nerve fibres were reduced while vasoactive intestinal polypeptide immunoreactivity was unaffected. In conclusion, PACAP-immunoreactive nerve fibres have been demonstrated in all regions of the rat female genital tract associated with blood vessels, smooth musculature and epithelium. In some fibres, which seem to originate in the local paracervical ganglia, PACAP was co-localized with vasoactive intestinal polypeptide. PACAP released from these fibres could alone or in concert with vasoactive intestinal polypeptide play a role in neuroregulation of female reproductive organs acting directly on the musculature and vasculature. Other PACAP-containing fibres are sensory in nature, and some of these might influence ganglionic neurotransmission in the local paracervical ganglia.

Vasoactive intestinal polypeptide and other preprovasoactive intestinal polypeptide-derived peptides in the female and male genital tract: localization, biosynthesis, and functional and clinical significance

Vasoactive intestinal polypeptide, a neuropeptide with wide distribution in the central and peripheral nervous system, has a broad spectrum of biologic actions. The demonstration of vasoactive intestinal polypeptide containing nerve fibers within the female and male genital tract 17 years ago indicated a putative role for this peptide in the local nervous control of reproductive functions. The genes encoding the preprovasoactive intestinal polypeptide precursor molecule and the vasoactive intestinal polypeptide receptor have been identified. The gene expression has been studied by the use of specific antibodies against the functional domains of the vasoactive intestinal polypeptide precursor and the biologic action elucidated by both in vivo and in vitro methods. Evidence has been provided to support vasoactive intestinal polypeptide as a neurotransmitter in several physiologic events in the genital tracts (i.e., blood flow and nonvascular smooth muscle relaxation). In the ovary vasoactive intestinal polypeptide seems to play an important role as regulator and/or modulator of folliculogenesis and steroidogenesis. In the male genital tract vasoactive intestinal polypeptide seems to participate in the control of erection. Vasoactive intestinal polypeptide has been suggested as a causative factor in some diseases of the genital organs (e.g., it may play a pathophysiologic role in male impotence and the peptide is currently used in the treatment of this condition). Vasoactive intestinal polypeptide may be important for control of the low resistance in the fetomaternal vascular bed and is therefore a putative factor involved in the development of preeclampsia. The therapeutic potential of vasoactive intestinal polypeptide and future agonists and antagonists will be revealed by ongoing and forthcoming studies.

Parasympathetic preganglionic neurons in the spinal cord involved in uterine innervation are cholinergic and nitric oxide-containing

BACKGROUND

The purpose of this study was to elucidate parasympathetic preganglionic neurons in the spinal cord that project axons in pathways to the uterus and to reveal their neurotransmitter phenotype.

METHODS

"Uterine-related" neurons were identified by using a combination of retrograde axonal tracers: (1) Fluorogold injected into the ganglia of termination of preganglionic fibers, and (2) a transganglionic axonal tracer (pseudorabies virus) injected into the uterus. Immunohistochemistry was used to reveal virus-labeled neurons and their neurotransmitter marker.

RESULTS

Double-labeled (Fluorogold+pseudorabies virus) "uterine" preganglionic neurons were identified in the sacral parasympathetic nucleus of the rat lumbosacral spinal cord. Subpopulations of neurons in the sacral parasympathetic nucleus were shown to be immunoreactive for choline acetyltransferase or nitric oxide synthase. Double-staining immunohistochemistry (for pseudorabies virus+neurotransmitter enzyme) revealed that some of the uterine-related preganglionic neurons were cholinergic and some nitric oxide synthase-containing.

CONCLUSIONS

These results demonstrate a subpopulation of preganglionic parasympathetic neurons in the sacral parasympathetic nucleus that are involved in uterine innervation. In addition, both acetylcholine and nitric oxide could be used to modify activity in the postganglionic neurons, which directly innervate the uterus.

Ontogeny of neurotransmitter systems in the paracervical ganglion and uterine cervix of the rat

BACKGROUND

The paracervical ganglia (PG) are components of the pelvic plexus that provides sensory and motor innervation to the reproductive system of the female rat. Several neurotransmitters including norepinephrine (NE), acetylcholine (ACh), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) are present in neurons of the adult PG and in axons innervating the adult uterus and uterine cervix. The current study was undertaken to describe the onset of immunoreactivity of these neurotransmitters and neuropeptides during development.

METHODS

Female rats, ages E18 to P36, were prepared for immunohistochemistry for TH (tyrosine hydroxylase, a marker of noradrenergic neurons), NPY, or VIP as well as the histochemical demonstration of acetylcholinesterase (AChE).

RESULTS

All four markers were detected in neurons of the PG at E18. Changes in the appearance of these markers from E18 to P36 reflected previously described growth changes in the PG. Axons containing AChE, TH, NPY, or VIP were first detected within the cervix at E20. Immunopositive axons first appeared as thick, unbranched structures at the outermost portion of the cervical myometrium. Over time, these axon bundles ramified to form discrete varicose axons. The ingrowth was similar for axons containing each of the four markers.

CONCLUSIONS

The relative density of each neuronal type in the PG was reflected in the density of axons containing the same marker in the cervix. Changes in neurotransmitter/neuropeptide staining of PG neurons or axons in the cervix were not observed as the animals approached puberty.

Uptake of 5-hydroxydopamine into non-sympathetic nerves of guinea-pig uterine artery in late pregnancy

Perivascular nerve fibres of the uterine artery of virgin and late pregnant guinea-pigs were examined under the electron microscope following loading with 5-hydroxydopamine, a marker for catecholamine uptake, and immunohistochemistry for dopamine beta hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, substance P and calcitonin gene-related peptide. Varicosities, loaded with 5-hydroxydopamine labelled vesicles, and immunoreactive axons were counted in whole transverse sections of uterine arteries. Localization of the immunoreactivities in 5-hydroxydopamine-labelled vesicles was also studied. Colocalization of substance P and dopamine beta hydroxylase immunoreactivities was investigated at the light microscopic level. Both total and relative number of varicosities with 5-hydroxydopamine-labelled vesicles in a whole section of the artery increased in late pregnancy (61.2 +/- 10.2 versus 24.5 +/- 3.2 in virgin, representing 35% and 27% respectively, of all varicosities). Also the number of neuropeptide Y, vasoactive intestinal polypeptide, substance P and calcitonin gene-related peptide-immunoreactive axons increased, but their relative proportion remained unchanged. In virgin guinea-pigs only calcitonin gene-related peptide and neuropeptide Y immunoreactivities were associated with varicosities loaded with small dense-cored vesicles, while in late pregnancy 5-hydroxydopamine-labelled vesicles were also seen in a number of vasoactive intestinal polypeptide, substance P and calcitonin gene-related peptide-immunoreactive axons. Double immunolabelling for dopamine beta hydroxylase and substance P immunoreactivity showed that substance P immunoreactivity was not present in dopamine beta hydroxylase-immunoreactive axons of the uterine artery, of neither virgin nor late pregnant guinea-pigs. It is concluded that vascular hypertrophy of the uterine artery in late pregnancy is associated with an increase in the number of perivascular nerve fibres, that involves many, if not all of the subpopulations of neurons supplying the uterine artery. Also 5-hydroxydopamine-labelled varicosities were increased, but the results of the present study indicate that some of the nerve fibres that are able to take up 5-hydroxydopamine in late pregnancy are not sympathetic (i.e. are sensory and/or parasympathetic in origin). The relevance of these findings in pregnancy is discussed.

Projections of the guinea-pig paracervical ganglion to pelvic viscera

The uterine cervix, urinary bladder and rectum of guinea pigs were injected with Fast Blue dye for retrograde transport studies. Dye-laden neuronal perikarya were detected for each viscus in the paracervical ganglion. These same perikarya also exhibited immunoreactivities for tyrosine hydroxylase, aromatic amino acid decarboxylase, dopamine beta-hydroxylase, neuropeptide Y, or vasoactive intestinal peptide, though the perikarya projecting to the urinary bladder did not exhibit immunoreactivity for aromatic amino acid decarboxylase. The results of this study indicate that the guinea-pig paracervical ganglion projects to viscera in addition to the uterus, and that the ganglion contains a range of immunoreactivities related to adrenergic and non-adrenergic neurotransmitters.

Immunohistochemical localization of Met5-enkephalin-Arg6-Gly7-Leu8 in the female genital organs and in the paracervical ganglion of the pig

Indirect immunofluorescence method was used to study the localization and distribution of the proenkephalin A-derived octapeptide, Met5-enkephalin-Arg6-Gly7-Leu8 (MEAGL), in the paracervical ganglion and in the female genital organs of the pig. In the paracervical ganglion, a subpopulation of principal neurons and nerve fibers contained MEAGL immunoreactivity. In the vagina, numerous MEAGL-immunoreactive nerve fibers were localized in the muscular membrane, under the serous membrane and in the submucous layer. The uterine cervix contained a great number of immunoreactive nerve fibers in muscular membrane and in submucous and subserous layers. The pattern of distribution of MEAGL-immunoreactive nerve fibers in the uterine horns was similar to that of cervix, but their number in the uterine horns was lower. MEAGL-immunoreactive fibers were also observed through different oviductal layers. In the ovary a low number of immunoreactive fibers were seen in the medullary and cortical parts of the organ. The results of this study indicate that the female genital organs, particularly the uterus and vagina, of the pig receive dense innervation by nerve fibers containing the proenkephalin A-derived octapeptide MEAGL. The presence of MEAGL in principal neurons and fibers of the paracervical ganglion suggests that a large proportion of them originate from neurons of the paracervical ganglion.

Peptides and vasomotor mechanisms

The multiple and diverse roles played by neuropeptide Y, vasoactive intestinal polypeptide, substance P, calcitonin gene-related peptide and other biologically active peptides in the cardiovascular system are considered. A model of the vascular neuroeffector junction is described, which illustrates the interactions of peptidergic and nonpeptidergic transmitters that are possible at pre- and postjunctional sites. The effects of peptides on specific endothelial receptors are also described, which highlights the ability of these agents to act as dual regulators of vascular tone at both adventitial and intimal surfaces, following local release from nerves, or from endothelial cells themselves. Changes in expression of vascular neuropeptides that occur during development and aging in some disease situations and following nerve lesion are discussed.

Immunohistochemical characterization of pelvic neurons which project to the bladder, colon, or penis in rats

Retrograde-tracing and immunohistochemical techniques were used in combination to investigate the types of putative transmitters in pelvic neurons that project to the bladder, colon or penis of rats. In addition, populations of axon varicosities associated with these neurons were characterized. Subpopulations of neurons in colchicine-treated major pelvic ganglia and accessory ganglia of male rats contained immunoreactivity (IR) for tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), or enkephalin (ENK), while types of immunoreactivity found in major groups of varicose axons were ENK, cholecystokinin (CCK), and somatostatin (SOM). Substance P (SP)-IR varicose axons were much less common. Bladder and colon neurons were similar in a number of ways. Many neurons contained NPY-IR (greater than or equal to 50%), fewer contained TH-IR (25-30%), and even fewer contained ENK-IR (5-15%) or VIP-IR (5-10%); many neurons were associated with baskets of ENK-IR varicosities (50-65%) and fewer neurons were surrounded by CCK- or SOM-IR varicosities (30-35%). Colon neurons differed from penis neurons in having a slightly larger proportion that contained ENK-IR (10-15%, compared with 1-3%). Penis neurons were markedly different from the other two groups in additional ways. More than 90% of them contained VIP-IR, whereas only 5-7% contained NPY-IR and none were immunoreactive for TH. Furthermore, although the proportion of penile neurons associated with many ENK-IR varicosities was similar to the bladder and colon neurons (45-50%), they were rarely seen close to CCK- or SOM-IR varicose axons. These studies describe similarities and differences in the histochemical properties of neurons which project to the bladder, colon, or penis and of the varicose axons associated with those neurons. This gives further insights into the possible transmitter mechanisms involved in the regulation of different pelvic functions.

VIP and autonomic neurotransmission

A variety of peptides have been proposed as transmitter candidates in non-cholinergic, non-adrenergic nerves. The nerves containing vasoactive intestinal polypeptide (VIP), which innervate blood vessels, non-vascular smooth muscle, mucosal epithelium and glands comprise a major and wide-spread population of the peptide-containing systems. There is now experimental data supporting the view that VIP is a transmitter in non-adrenergic, non-cholinergic nerves in the digestive tract, respiratory tract and urogenital tract, controlling smooth muscle tone and motility, blood flow and secretion. It is possible that impairment of VIP-containing nerves is involved in a number of autonomic dysfunctions.

Regulatory peptides in the mammalian urogenital system

By immunocytochemistry a number of the gut/brain peptides have been demonstrated in nerve fibers of the mammalian urogenital tract. These peptides are localized to large vesicles in nerve terminals of afferent fibers or efferent nerves innervating blood vessels, non-vascular smooth muscle, lining epithelium and glands. There is evidence that some neuropeptides (VIP, NPY) participate in the local non-cholinergic, non-adrenergic nervous control of smooth muscle activity and blood flow, while other peptides (substance P, CGRP) seem to be sensory transmitters. It is likely that impaired function of the peptidergic nerves is involved in sexual dysfunction such as male impotence.

Combined axonal transport tracing and immunocytochemistry for mapping pathways of peptide-containing nerves in the peripheral nervous system

The various combinations of axonal transport tracing and immunocytochemistry used for mapping pathways of peptide-containing nerves, and in particular those of the peripheral nervous system, are reviewed. The advantages and disadvantages of these methods are discussed. The applications and results presented illustrate the future potential value of this approach.

Paracervical ganglia of the female rat: histochemistry and immunohistochemistry of neurons, SIF cells, and nerve terminals

The paracervical ganglia of the female rat were studied to elucidate the variety of neural elements in the ganglia. Light and electron microscopy, histochemistry, and immunohistochemistry were employed to reveal subtypes of neurons; small, intensely fluorescent (SIF) cells; and nerve terminals and to examine the relationships between these elements. On the basis of their histochemical markers, four subtypes of principal neurons were identified: acetylcholinesterase (ACHE)-positive, noradrenergic, neuropeptide tyrosine-immunoreactive (NPY-I), and vasoactive intestinal polypeptide-immunoreactive (VIP-I). The NPY-I neurons appeared to be the most numerous and the noradrenergic the least common type of neuron. Four subtypes of chemically coded SIF cells were revealed: catecholamine-containing, NPY-I, and those immunoreactive for calcitonin-gene-related peptide (CGRP-I) and cholecystokinin-octapeptide (CCK-8-I). The SIF cells were present as single cells among and adjacent to principal neurons and as large clusters near the edges of the ganglia or in nearby nerve trunks. Synaptic contacts on SIF cells, or between SIF-cell processes and neurons, were not observed. Seven subtypes of nerve terminals were stained: ACHE-positive, CGRP-I, CCK-8-I, VIP-I, substance P-I, enkephalin-I, and atrial natriuretic factor-I. Nerve terminals enwrapped the neurons as perineuronal plexuses in synaptic-like relationships. These results demonstrate that the paracervical ganglia of the female rat are a complex system of neural elements. For example, several classes of chemically coded neurons, SIF cells, and terminals exist in the ganglia. Each of these components contains a number of substances, some of which are putative neurotransmitters, which could influence activity in the ganglia or in the effector organs innervated by the ganglia.

Neuropeptides in sensory perikarya projecting to the rat ovary

Afferent perikarya in dorsal root ganglia (DRG) at the T13 and L1 segmental levels projecting to the rat ovary were identified by utilizing the fluorescent retrograde tracer true blue (TB). Subsequently, TB-labeled ovarian afferent perikarya in DRG were examined for vasoactive intestinal polypeptide (VIP), substance P (SP), cholecystokinin-8 (CCK-8), neuropeptide Y (NPY), and somatostatin (SOM) immunoreactivity and for the presence of fluoride-resistant acid phosphatase (FRAP) enzyme activity. Of the ovarian afferent perikarya at the T13 and L1 segmental levels, 20.5% displayed VIP immunoreactivity, 23.8% displayed SP immunoreactivity, and 43.1% were immunoreactive for CCK-8. No ovarian afferent perikarya contained SOM or NYP immunoreactivity or FRAP activity. It is suggested that different neuropeptides may participate in modulation of specific ovarian functions.

Immunohistochemical and biological evidence for a neuromodulator function of neuropeptide Y in the human oviduct

By means of the peroxidase-antiperoxidase technique the existence of neuropeptide Y-immunoreactivity (NPY-IR) in nerve fibers of the normal human uterine tube was established. NPY-IR fibers are found to supply vascular and non-vascular smooth muscles of the uterine tube. In both systems the density of NPY-IR nerves is markedly high. The NPY-IR nerves exhibit a predominance for the arterial portion of the oviductal vasculature in the serosal, the muscle and the mucosal layer. Furthermore in the mucosal layer, some NPY-IR fibers occur in contact with the surface epithelium. In-vitro experiments with helical strips of the human uterine tube reveal no significant effects of NPY alone of the different parameters (resting tension, frequency and amplitude of spontaneous contractions) of mechanical activity while it seems to act in combination with acetylcholine. Thus, the distinct innervation patterns of the NPY-IR nerve fibers as well as the results obtained by bioassay may suggest a neuromodulator function of this neuropeptide in the human uterine tube. In this respect, NPY may play an important role in the transport of the eggs through the tube.

Peptidergic innervation of the human and guinea pig uterus

The peptidergic innervation of the human and guinea pig uterus was studied using immunohistochemical methods. Antibodies against several peptides were applied for the PAP-technique to stain peptidergic nerves specifically. These are located in the adventitia of large uterine vessels in the myometrium and smaller vessels of the myometrium and endometrium. A differential distribution of the individual peptides was observed for VIP-IR (vasoactive intestinal polypeptide immunoreactivity), NPY-IR (neuropeptide Y), SP-IR (substance P), SOM-IR (somatostatin) and NT-IR (neurotensin) nerve fibers. Specific functional implications for these neuropeptides can be derived from their histochemical location.

Localization of peptides in nerve terminals in the paracervical ganglion of the rat by light and electron microscopic immunohistochemistry: enkephalin and atrial natriuretic factor

Enkephalin- and atrial natriuretic factor-like immunoreactivities were localized in nerve terminals in the female rat paracervical ganglia. Immunoreactive terminals were adjacent to and in synaptic contact with many, but not all, principal neurons. Immunoreactivity was restricted to large dense-core synaptic vesicles. These results suggest that there is a complex synaptic input to the principal neurons of the rat paracervical ganglia and that these substances could act as neurotransmitters or neuromodulators in the ganglion.

Cytochemical relationships in the paracervical ganglion (Frankenhäuser) of rat studied by immunocytochemistry

Vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) and calcitonin gene-related peptide (CGRP) immunoreactivities have been demonstrated in the paracervical ganglion of the rat using immunocytochemistry. Dopamine beta-hydroxylase (D beta H) and neurofilament protein triplet immunoreactivities have also been demonstrated in this region. The VIP, NPY, D beta H and neurofilament immunoreactivities were located in ganglion cells and nerve fibres, while CGRP immunoreactivity was localized only in nerve fibres. Many cells immunoreactive with D beta H antiserum were also immunoreactive with NPY antiserum. A small number of cells immunoreactive with VIP antiserum were also immunoreactive with NPY antiserum. CGRP-immunoreactive nerve fibres were distributed in certain regions of the ganglion only.