Immunohistochemical properties and spinal connections of pelvic autonomic neurons that innervate the rat prostate gland

Autonomic innervation of the prostate gland supplies the acini, and non-vascular and vascular smooth muscle. The activity of each of these tissues is enhanced by sympathetic outflow, whereas the role of the parasympathetic nervous system in this organ is unclear. In the present study, a range of methods was applied in rats to determine the location of autonomic neurons supplying this gland, the immunohistochemical properties of these neurons, the spinal connections made with the postganglionic pathways and the distribution of various axon types within the gland. Injection of the retrograde tracer, FluoroGold, into the ventral gland visualised neurons within the major pelvic ganglion and sympathetic chain. Fluorescence immunohistochemical studies on the labelled pelvic neurons showed that most were noradrenergic (also containing neuropeptide Y, NPY), the others being non-noradrenergic and containing either vasoactive intestinal peptide (VIP) or NPY. Sympathetic dyelabelled neurons were identified by the presence of varicose nerve terminals stained for synaptophysin on their somata following lesion of sacral inputs. Parasympathetic innervation of dye-labelled neurons was identified by continued innervation after hypogastric nerve lesion. Most noradrenergic prostate-projecting neurons were sympathetic, as were many of the non-noradrenergic VIP neurons. Parasympathetic prostate-projecting neurons were largely non-noradrenergic and contained either VIP or NPY. All substances found in retrogradely labelled somata were located in axons within the prostate gland but had slightly different patterns of distribution. The studies have shown that there are a significant number of non-noradrenergic sympathetic prostate-projecting neurons, which contain VIP.     

Distribution,immunohistochemical characteristics and nerve pathways of primary sensory neurons supplying the porcine vas deferens

The present study investigated: (1) the distribution and chemical coding of primary sensory neurons supplying the vas deferens in juvenile pigs by the use of retrograde tracing combined with double-labelling immunofluorescence, (2) nerve pathways from dorsal root ganglia (DRG) to the vas deferens by means of denervation procedures involving transection of the hypogastric or pelvic nerve combined with a retrograde tracing method, and (3) possible interactions of the substance P (SP)/calcitonin gene-related peptide (CGRP)-immunoreactive varicose nerve fibres on vas deferens projecting neurons (VDPN) in the anterior pelvic ganglion (APG). The vast majority of VDPN were found mainly in the lumbar L2, L3 and sacral S2, S3 pairs of DRG and showed a clear ipsilaterally organized projection pattern. Immunohistochemistry revealed that most of these neurons contained SP and/or CGRP, occasionally coexpressed with galanin. Interestingly, pronounced differences in the expression of SP and/or CGRP were observed between the lumbar and sacral VDPN in that most of the lumbar but less than half of the sacral neurons stained for these peptides. Denervation experiments showed that the neurons located within the lumbar DRG project through the ipsilateral hypogastric nerve, whereas those found within the sacral DRG send their processes through the ipsilateral and contralateral pelvic nerve. In the nerve-lesioned animals, especially in those with the hypogastric nerve cut, a dramatic reduction in the number of SP and/or CGRP-containing nerve terminals surrounding the efferent VDPN within the APG was observed. This study has disclosed the distribution and, for the first time, chemical coding and nerve pathways of vas deferens-projecting primary sensory neurons in a mammalian species, the pig. The results obtained also provide some novel information about the possible morphological and functional relationship between vas deferens-projecting primary sensory and pelvic efferent nerve cells.     

Commande nerveuse peripherique de l’erection

Local mechanisms causing penile erection and detumescence result from variation in tone of vascular and trabecular smooth muscles and in a lesser part of striated muscles around the crura penis. All these events are neurally mediated. We reviewed human and animal data concerning the functional peripheral neuroanatorny of erection. General organization of peripheral nervous system is recalled. Somatic efferents of the pudendal nerve, originating in the sacral spinal cord, innervate the striated musculature of the perineum. Somatic afferents of the penis are conveyed by the dorsal penile nerve, a branch of the pudendal nerve. Afferent terminations project into the spinal cord, their role is discussed. Parasympathetic pathways are involved in the reflexogenic erections. Sympathetic pathways destinated to the erectile structures are more complex. They are issued from thoracolumbar spinal cord and travel through the hypogastric nerve or the lumbosacral sympathetic chain. Sympathetic fibers originating in the sacral sympathetic chain are present in both pelvic and pudendal nerves. Inhibitory role on the erection of the sympathetic nervous system is well-known, it could be also responsible for psychogenic erections. Parasympathetic and sympathetic fibees are mixed in the pelvic plexus and the cavernous nerves which are described. Relations between the four sets of peripheral nerves (somatic efferents, penile afferents, thoracolumbar sympathetic sacral parasympathetic and sympathetic) are discussed.     

Patterns of co-existence of peptides and differences of nerve fibre types associated with noradrenergic and non-noradrenergic (putative cholinergic) neurons in the major pelvic ganglion of the male rat

Summary The pelvic ganglia supply cholinergic and noradrenergic nerve pathways to many organs. Other possible transmitters are also present in these nerves, including peptides. Multiple labelling immunofluorescence techniques were used in this study of the male rat major pelvic ganglion (MPG) to examine: (1) the peptides present in noradrenergic (tyrosine hydroxylase (TH)-positive) and non-noradrenergic (putative cholinergic) neurons, and (2) the types of peptide-containing nerve fibres closely associated with these two groups of neurons. The distribution of the peptide galanin (GAL) within the MPG was also investigated. All of the TH-neurons contained neuropeptide Y (NPY), but none of the other tested peptides. However, many NPY neurons did not contain TH and may have been cholinergic. TH-negative neurons also displayed vasoactive intestinal peptide (VIP), enkephalin (ENK) or GAL. VIP and NPY formed the most common types of putative cholinergic pelvic neurons, but few cells contained both peptides. Many ENK neurons exhibited VIP, NPY or GAL. Varicose nerve terminals surrounding ganglion cells contained ENK, GAL, somatostatin (SOM) and cholecystokinin (CCK). These peptide-immunoreactive fibres were more often associated with the non-noradrenergic (putative cholinergic) than the noradrenergic neurons; two types (SOM and CCK) were preferentially associated with the non-noradrenergic NPY neurons. GAL was distributed throughout the MPG, in small neurons, scattered small, intensely fluorescent (SIF) cells, and both varicose and non-varicose nerve fibres. The nerve fibres were concentrated near the pelvic and penile nerves; most of the varicose fibres formed baskets surrounding individual GAL-negative somata.     

Identification of neurons that express ghrelin receptors in autonomic pathways originating from the spinal cord

Functional studies have shown that subsets of autonomic preganglionic neurons respond to ghrelin and ghrelin mimetics and in situ hybridisation has revealed receptor gene expression in the cell bodies of some preganglionic neurons. Our present goal has been to determine which preganglionic neurons express ghrelin receptors by using mice expressing enhanced green fluorescent protein (EGFP) under the control of the promoter for the ghrelin receptor (also called growth hormone secretagogue receptor). The retrograde tracer Fast Blue was injected into target organs of reporter mice under anaesthesia to identify specific functional subsets of postganglionic sympathetic neurons. Cryo-sections were immunohistochemically stained by using anti-EGFP and antibodies to neuronal markers. EGFP was detected in nerve terminal varicosities in all sympathetic chain, prevertebral and pelvic ganglia and in the adrenal medulla. Non-varicose fibres associated with the ganglia were also immunoreactive. No postganglionic cell bodies contained EGFP. In sympathetic chain ganglia, most neurons were surrounded by EGFP-positive terminals. In the stellate ganglion, neurons with choline acetyltransferase immunoreactivity, some being sudomotor neurons, lacked surrounding ghrelin-receptor-expressing terminals, although these terminals were found around other neurons. In the superior cervical ganglion, the ghrelin receptor terminals innervated subgroups of neurons including neuropeptide Y (NPY)-immunoreactive neurons that projected to the anterior chamber of the eye. However, large NPY-negative neurons projecting to the acini of the submaxillary gland were not innervated by EGFP-positive varicosities. In the celiaco-superior mesenteric ganglion, almost all neurons were surrounded by positive terminals but the VIP-immunoreactive terminals of intestinofugal neurons were EGFP-negative. The pelvic ganglia contained groups of neurons without ghrelin receptor terminal innervation and other groups with positive terminals around them. Ghrelin receptors are therefore expressed by subgroups of preganglionic neurons, including those of vasoconstrictor pathways and of pathways controlling gut function, but are absent from some other neurons, including those innervating sweat glands and the secretomotor neurons that supply the submaxillary salivary glands.     

Nitric oxide nerves in the uterus are parasympathetic,sensory, and contain neuropeptides

Nitric oxide (NO) is synthesized in neurons and is a potent relaxor of vascular and nonvascular smooth muscle. The uterus contains abundant NO-synthesizing nerves which could be autonomic and/or sensory. This study was undertaken to determine: 1) the source(s) of NO-synthesizing nerves in the rat uterus and 2) what other neuropeptides or transmitter markers might coexist with NO in these nerves. Retrograde axonal tracing, utilizing Fluorogold injected into the uterine cervix, was employed for identifying sources of uterine-projecting neurons. NO-synthesizing nerves were visualized by staining for nicotinamide adenine dinucleotide phosphate (reduced)-diaphorase (NADPH-d) and immunostaining with an antibody against neuronal/type I NO synthase (NOS). NADPH-d-positive perikarya and terminal fibers were NOS-immunoreactive (-I). Some NOS-I/NADPH-d-positive nerves in the uterus are parasympathetic and originate from neurons in the pelvic paracervical ganglia (PG) and some are sensory and originate from neurons in thoracic, lumbar, and sacral dorsal root ganglia. No evidence for NOS-I/NADPH-d-positive sympathetic nerves in the uterus was obtained. Furthermore, double immunostaining revealed that in parasympathetic neurons, NO-I/NADPH-d-reactivity coexists with vasoactive intestinal polypeptide, neuropeptide Y, and acetylcholinesterase and in sensory nerves, NOS-I/NADPH-d-reactivity coexists with calcitonin generelated peptide and substance P. In addition, tyrosine hydroxylase(TH)-I neurons of the PG do not contain NOS-I/NADPH-d-reactivity, but some TH-I neurons are apposed by NOS-I varicosities. These results suggest NO-synthesizing nerves in the uterus are autonomic and sensory, and could play significant roles, possibly in conjunction with other putative transmitter agents, in the control of uterine myometrium and vasculature.     

Vagal afferents from the uterus and cervix provide direct connections to the brainstem

Previous anatomical studies demonstrated vagal innervation to the ovary and distal colon and suggested the vagus nerve has uterine inputs. Recent behavioral and physiological evidence indicated that the vagus nerves conduct sensory information from the uterus to the brainstem. The present study was undertaken to identify vagal sensory connections to the uterus. Retrograde tracers, Fluorogold and pseudorabies virus were injected into the uterus and cervix. DiI, an anterograde tracer, was injected into the nodose ganglia. Neurectomies involving the pelvic, hypogastric, ovarian and abdominal vagus nerves were performed, and then uterine whole-mounts examined for sensory nerves containing calcitonin gene-related peptide. Nodose ganglia and caudal brainstem sections were examined for the presence of estrogen receptor-containing neurons in ”vagal locales." Labeling of uterine-related neurons in the nodose ganglia (Fluorogold and pseudorabies virus) and in the brainstem nuclei (pseudorabies virus) was obtained. DiI-labeled nerve fibers occurred near uterine horn and uterine cervical blood vessels, in the myometrium, and in paracervical ganglia. Rats with vagal, pelvic, hypogastric and ovarian neurectomies exhibited a marked decrease in calcitonin gene-related peptide-immunoreactive nerves in the uterus relative to rats with pelvic, hypogastric, and ovarian neurectomies with intact vagus nerves. Neurons in the nodose ganglia and nucleus tractus solitarius were immunoreactive for estrogen receptors. These results demonstrated: (1) the vagus nerves serve as connections between the uterus and CNS, (2) the nodose ganglia contain uterine-related vagal afferent neuron cell bodies, and (3) neurons in vagal locales contain estrogen receptors.     

The origin and possible significance of substance P immunoreactive networks in the prevertebral ganglia and related structures in the guinea-pig

The distribution and origin of substance P immunoreactive nerve elements have been studied in the guinea-pig prevertebral ganglia by the indirect immunohistochemical technique, using a monoclonal antibody to substance P. Non-varicose substance P immunoreactive nerve fibres enter or leave the ganglia in all nerves associated with them, traversing the ganglia in larger or smaller bundles. Networks, mainly single-stranded, of varicose substance P immunoreactive nerve fibres also permeate the ganglia, forming a loose meshwork among the neurons. Similar networks are present in the lumbar paravertebral ganglia. In all these ganglia, neuronal somata do not in general show substance P immunoreactivity. The various nerves connected with the inferior mesenteric ganglion have been cut, in single categories and in various combinations, and the ganglion examined, after intervals of up to six days. Cutting the colonic or hypogastric nerves, which connect the ganglion with the hindgut and pelvic organs, leads to accumulation of substance P immunoreactive material in their ganglionic stumps, extending retrogradely to intraganglionic non-varicose fibres traceable through into the intermesenteric and lumbar splanchnic nerves. There is some local depletion of intraganglionic varicose networks. Cutting the intermesenteric nerve, which connects the coeliac-superior mesenteric ganglion complex with the ganglion, leads to accumulation of substance P immunoreactive material in its cranial stump and depletion of its distal stump; a minimal depletion is detectable in the inferior mesenteric ganglion itself. Cutting the lumbar splanchnic nerves, which connect the ganglion with the upper lumbar spinal cord and dorsal root ganglia, leads to accumulation of substance P immunoreactive material in their proximal stumps and total depletion of their distal, ganglionic stumps; in the ganglion there is subtotal loss of non-varicose substance P immunoreactive fibres and of varicose nerve networks, and the few surviving non-varicose fibres are traceable across the ganglion from the intermesenteric nerve to the colonic and hypogastric nerves. Cutting the intermesenteric and lumbar splanchnic nerves virtually abolishes substance P immunoreactive elements from the ganglion within three days postoperatively. It is concluded that these arise centrally to the ganglion.(ABSTRACT TRUNCATED AT 400 WORDS)     

Nitric oxide synthase-containing neurons in rat parasympathetic, sympathetic and sensory ganglia: a comparative study

Summary In rats, the distribution of nerve structures staining for NADPH-diaphorase, and showing immunoreactivities for nitric oxide synthase (NOS), tyrosine hydroxylase and various neuropeptides was studied in sensory ganglia (dorsal root, nodose and trigeminal ganglia), in sympathetic ganglia (superior cervical, stellate, coeliac-superior and inferior mesenteric ganglia), parasympathetic ganglia (sphenopalatine, submandibular, sublingual and otic ganglia), and in the mixed parasympathetic/ sympathetic ganglia (major pelvic ganglia). The coincidence of neuronal cell bodies with strong NOS-immunoreactivity and strong NADPH diaphorase reactivity was almost total. The relative proportions of NOS-immunoreactive nerve cell bodies were largest in parasympathetic ganglia and major pelvic ganglia followed by sensory ganglia. In sympathetic ganglia no NOS-immunoreactive neuronal cell bodies could be detected. In parasympathetic and major pelvic ganglia, there was a very significant neuronal co-localization of immunoreactivities for NOS and vasoactive intestinal polypeptide (VIP). This was almost total in major pelvic ganglia, in which NOS-/VIP-immunoreactive nerve cell bodies were separate from sympathetic (tyrosine hydroxylase-/neuropeptide Y-immunoreactive), suggesting that NOS-/VIP-immuno-reactive neurons might also be parasympathetic.     

Sympathetic innervation of the reproductive organs of the male opossum, Didelphis albiventris (Lund, 1841)

The dissection of nerves and ganglia anatomically related to the pelvic organs revealed one inferior mesenteric ganglion, two testicular ganglia, two hypogastric nerves, two pelvic ganglia and two pelvic nerves. The histochemical demonstration of catecholamines by a glyoxylic acid fluorescence method revealed a rich sympathetic innervation in the ductus deferens, in the three segments of the prostate and in the convoluted ductuli efferentes. The testis, epididymis and all three pairs of bulbourethral glands presented fluorescent nerve fibers only around blood vessels. Removal of the inferior mesenteric and testicular ganglia, and hypogastric neurectomy with our without ligature and sectioning of testicular arteries, had no effect on the density of the nonvascular fluorescent fibers. Removal of the periprostatic tissue caused complete denervation of the prostate and marked denervation of the ductuli efferentes and ductus deferens. Small ganglia containing fluorescent nerve cell bodies were found close to the capsule of the prostate. The results indicate that short adrenergic neurons are responsible for the sympathetic innervation of the reproductive organs of the male opossum.     

Conducting pathways of the rabbit lumbar sympathetic ganglia

Conducting pathways of ganglia from the lumbar portion (L₃–L₅) of the sympathetic trunk in rabbits were studied by recording action potentials from nerves of the ganglia evoked by stimulation of other nerves of these ganglia, and by intracellular recording from single neurons. Besides the well-known system of descending preganglionic fibers, which enter the trunk through white rami communicantes and, as they pass through the ganglia, form synapses on ganglionic neurons, some preganglionic fibers were shown to enter the sympathetic chain through gray rami communicantes and to run in both ascending and descending directions, forming synaptic connections with neurons of the lumbar ganglia.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 16, No. 2, pp. 247–254, March–April, 1984.     

大鼠直肠肽能神经的支配与起源——HRP与免疫细胞化学法联合研究

用HRP追踪法与免疫细胞化学法观察了大鼠直肠内P物质（SP）、降钙素基因相关肽（CGRP）和血管活性肠肽（VIP）三种肽能神经的支配与来源。结果显示：（1）直肠GCRP和VIP肽能神经起源于盆丛副交感神经节（PSG）。（2）直肠感觉神经纤维来自骶2－4节段双侧背根神经节（S2－4－DRG）SP能或CGRP能神经元。（3）感觉神经元的中枢突进入骶髓2－3节段后角并形成较粗大的外侧束,其中大部分传入纤维经后角外侧缘走行,终止于侧角区中间外侧核交感神经元胞体周围。其余部分传入纤维延伸到骶髓2－3节段灰质第Ⅱ、Ⅲ层和灰质后连合核（中央自主神经核）,进入中间外侧核的传入纤维与后连合核也有联系。上述结果提示,支配直肠的VIP能神经元参与了直肠肌运动的调节;SP和CGRP能神经元可能与直肠的运动、感觉调节有关。     

The origin of VIP-containing nerves in the urinary bladder of rat

The innervation of the urinary bladder is known to include a considerable number of nerves containing vasoactive intestinal polypeptide (VIP). The origin of such nerves in the bladder of rat was investigated in this study using the methods of immunocytochemistry and radioimmunoassay combined with surgical sectioning of the hypogastric and/or pelvic nerves to the bladder. Eight days after pelvic nerve sectioning proximal to the main pelvic ganglion, VIP-immunoreactive nerves and VIP content were markedly increased from the level in the sham-operated rat bladder. Sectioning of hypogastric or both nerve pathways led to a less significant increase. It was therefore postulated that the majority of VIP-immunoreactive nerves originate from ganglia located either close to the bladder or within the bladder wall. It is interesting that in these experiments the VIP content of the bladder nerves is inversely related to the changes in motility that would be expected to result from the nerve sections.     

Distribution of arginine-vasopressin in the trigeminal,dorsal root ganglia and spinal cord of the rat; depletion by capsaicin

We have measured arginine vasopressin in the neural lobe, the trigeminal ganglion (TG), dorsal root ganglia (DRG), spinal cord, trigeminal and sciatic nerves of the rat by radioimmunoassay. In control rats, the neural lobe contained 1600 pg/mg, the ganglia 52.5, 21.0, 8.5, 4.28, 3.85 pg/mg in the lumbar, sacral, cervical, thoracic, and trigeminal ganglion, respectively, the spinal cord contained 5.1, 4.3, 4.2 and 2.6 pg/mg in the lumbar, thoracic, sacral and cervical cord, respectively and the trigeminal and sciatic nerves contained 3.8 and 13 pg/mg. Neonatal capsaicin treatment depleted about 38–67% of AVP in the ganglia. Residual AVP amounted to 526.8, 30.55, 20.75, 12.88, 4.95, 2.74, 2.14, 7.94 and 2.53 pg/mg in the neural lobe, lumbar, thoracic, sacral, cervical DRG, lumbar, thoracic spinal cord, the sciatic and trigeminal nerves respectively. Capsaicin destroyed about 40.5% of total cells and 52% of AVP-immunoreactive neurons.     

Calretinin-immunoreactive nerves in the uterus, pelvic autonomic ganglia, lumbosacral dorsal root ganglia and lumbosacral spinal cord

Nerves containing the calcium-binding protein calretinin have been reported in several organs but not in female reproductive organs and associated ganglia. This study was undertaken to determine if nerves associated with the uterus contain calretinin and the source(s) of calretinin-synthesizing nerves in the rat (are they sensory, efferent, or both?). Calretinin-immunoreactive nerves were present in the uterine horns and cervix where they were associated with arteries, uterine smooth muscle, glands, and the epithelium. Calretinin-immunoreactive terminals were apposed to neurons in the paracervical ganglia; in addition, some postganglionic neurons in this ganglion were calretinin positive. Calretinin perikarya were present in the lumbosacral dorsal root ganglia, no-dose ganglia, and lumbosacral spinal cord. Retrograde axonal tracing, utilizing Fluorogold injected into the uterus or paracervical parasympathetic ganglia, revealed calretinin-positive/Fluorogold-labeled neurons in the dorsal root and nodose ganglia. Also, capsaicin treatment substantially reduced the calretinin-positive fibers in the uterus and pelvic ganglia, thus indicating the sensory nature of these fibers. The presence of calretinin immunoreactivity identifies a subset of nerves that are involved in innervation of the pelvic viscera and have origins from lumbosacral dorsal root ganglia and vagal nodose ganglia. Though the exact function of calretinin in these nerves is not currently known, calretinin is likely to play a role in calcium regulation and their function.     

Effects of NGF,NT-3 and GDNF family members on neurite outgrowth and migration from pelvic ganglia from embryonic and newborn mice

Background  

Pelvic ganglia are derived from the sacral neural crest and contain both sympathetic and parasympathetic neurons. Various members of the neurotrophin and GDNF families of neurotrophic factors have been shown to play important roles in the development of a variety of peripheral sympathetic and parasympathetic neurons; however, to date, the role of these factors in the development of pelvic ganglia has been limited to postnatal and older ages. We examined the effects of NGF, NT-3, GDNF, neurturin and artemin on cell migration and neurite outgrowth from explants of the pelvic ganglia from embryonic and newborn mice grown on collagen gels, and correlated the responses with the immunohistochemical localization of the relevant receptors in fixed tissue.     

Coexistence of neurons integrating urinary bladder activity and pelvic nerve activity in the same cardiovascular areas of the pontomedulla in cats

The present study examines the coexistence of neurons in the same cardiovascular point of the pontomedulla that integrates urinary bladder (UB) motility, and pelvic nerve activity (PNA). Microinjection of monosodium L-glutamate (Glu) into the locus coeruleus (LC), the gigantocellular tegmental field (FTG), the rostral ventrolateral medulla (RVLM), and the dorsomedial medulla (DM) produced pressor responses, whereas injection into the lateral tegmental field (FTL), the nucleus of tractus solitarii (NTS), and the caudal ventrolateral medulla (CVLM) produced depressor responses. However, microinjection of Glu into the dorsomotor nucleus of the vagus (DMV) and the ambiguus nucleus (AN), where the vagus nerve originates, produced marked bradycardia. Many of these cardiovascular responses were accompanied by increased, or decreased parasympathetic PNA. In six animals, sympathetic renal nerve activity (RNA) and PNA also increased simultaneously during the pressor response. The present study also examines the connection between the DMV-AN and the sacral intermediolateral column (IML), where parasympathetic preganglionic neurons (PGNs) of the pelvic nerve located. Biotinylated dextran amine (BDA), an anterograde tracer, was iontophoretically injected into the DMV or AN. No labelled terminal or neuron was detected in the sacral IML, but labelled terminals were observed in the bilateral LC, and also in the bilateral sides of the FTG, FTL, RVLM, DM, and CVLM. These results suggest that neurons of the DMV and/or AN may indirectly regulate the sacral parasympathetic PGNs through the LC for supraspinal control of the pelvic nerve. Furthermore, these results also suggest the coexistence of multiple autonomic integrating mechanisms of different kinds within various cardiovascular areas of the pontomedulla.     

Inhibition and facilitation in parasympathetic ganglia of the urinary bladder

Neurons in vesical parasympathetic ganglia receive excitatory and inhibitory inputs from both divisions of the autonomic nervous system. Sacral parasympathetic pathways (cholinergic) provide the major excitatory input to these ganglia via activation of nicotinic receptors. Parasympathetic pathways also activate muscarinic inhibitory and excitatory receptors, which may exert a modulatory influence on transmission. Cholinergic transmission is relatively inefficient when preganglionic nerves are stimulated at low frequencies (< 1 Hz). However, excitatory postsynaptic potentials (EPSPs) and postganglionic firing markedly increase during repetitive stimulation at frequencies of 1-10 Hz. It is concluded that enhanced transmitter release accounts for the temporal facilitation and that vesical ganglia function as "high pass filters" that amplify the parasympathetic excitatory input to the detrusor muscle during micturition. Transmission in vesical ganglia is also sensitive to adrenergic inhibitory and facilitatory synaptic mechanisms elicited by efferent pathways in the hypogastric nerves. The effects of exogenous norepinephrine indicate that adrenergic inhibition is mediated by alpha receptors and reflects primarily a presynaptic depression of transmitter release although postsynaptic adrenergic hyperpolarizing and depolarizing effects have also been noted. Adrenergic facilitation is mediated by beta receptors as well as unidentified receptors. Norepinephrine also can inhibit or excite spontaneously active neurons in vesical ganglia. The existence of inhibitory and facilitatory synaptic mechanisms in vesical ganglia provides the basis for a complex ganglionic modulation of the central autonomic outflow to the bladder.     

Distribution of enteric nerve cells projecting to the superior and inferior mesenteric ganglia of the guinea-pig

Retrograde tracing, using Fast Blue dye, was employed to determine the distribution of enteric nerve cells that project to the superior mesenteric and inferior mesenteric ganglia of the guinea-pig. Retrogradely labelled neurons were found in the myenteric but not submucous ganglia. When the superior mesenteric ganglion was injected, labelled neurons were found in low frequencies (less than 5 nerve cell bodies/cm²) in the duodenum, jejunum, ileum, caecum and proximal colon. The distal colon was analysed in five segments of equal length (1–5; oral to anal). Segment 1 had about 4 labelled nerve cells/cm², whereas segments 2 to 5 displayed an average of about 25 nerve cells/cm². The rectum contained about 36 labelled neurons/cm². After injection of the inferior mesenteric ganglia with Fast Blue, no labelled neurons were found in the duodenum, jejunum, ileum or caecum. No labelled cells were observed in the gallbladder. A small number of labelled cells occurred in the proximal colon and in segment 1 of the distal colon. The frequency of labelled cells increased markedly in the more anal regions of the distal colon, and reached a peak in the rectum (138 cells/cm²). Both nerve lesions and immersion of the cut nerve in Fast Blue solution showed that the superior mesenteric nerve carries the axons of neurons located in the middle distal colon to the superior mesenteric ganglion. Almost half of the neurons in the rectum that project to the inferior mesenteric ganglia do so via the hypogastric nerves. Of neurons that projected to the inferior or superior mesenteric ganglia from the colon or rectum, similar proportions (about 75–80%) showed immunoreactivity for calbindin or VIP. For each of the prevertebral ganglia (coeliac, superior mesenteric and inferior mesenteric) the great majority of peripheral inputs arise from the large intestine.