Pelvic Neurons Research Articles

In vitro high glucose increases apoptosis, decreases nerve outgrowth, and promotes survival of sympathetic pelvic neurons.

Diabetes mellitus (DM) is a common cause of erectile dysfunction (ED), yet the molecular basis of DM neurogenic ED remains unknown. In this study we examined the impact of high glucose on survival and growth of primary cultured pelvic neurons in a rat model and assessed whether coculturing with healthy Schwann cells (SCs) can rescue pelvic neuron growth in patients with DM. Major pelvic ganglia (MPGs) from adult male Sprague Dawley rats (n = 8) were dissociated and plated on coverslips. Neurons were exposed to high glucose (45mM) for 24 or 48hours and compared to time-matched controls (25mM). Neurons were stained for neuron-specific beta-tubulin, neuronal nitric oxide synthase, vesicular acetylcholine transferase, tyrosine hydroxylase, and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling) assay. Schwann cells were dissociated from MPGs of healthy male Sprague Dawley rats (n = 4) and grown to confluence. Additional Sprague Dawley rats were made diabetic with streptozotocin (50mg/kg, n = 4), and 5weeks later MPGs were collected from these rats, dissociated, and cocultured on healthy SCs. Neurons and SCs were stained with beta-tubulin and S100. Length, branching, and survival of nitrergic, parasympathetic, and sympathetic neurons was assessed in neurons exposed to normal or high glucose concentrations, and neuron length was measured in neuron-SC coculture. The total number of neurons and the length and number of branches were significantly decreased after 24 and 48hours of high glucose (P < .05). The percentage of nitrergic neurons decreased 10% after 24 hours and 50% after 48 hours of high glucose (P < .05). After 24 hours of high glucose, cholinergic-positive neurons were unchanged; however, these neurons decreased 30% after 48 hours (P < .05). The proportion of sympathetic neurons increased 25% after 48 hours of high glucose (P < .05). At both timepoints, there was a 2-fold increase in the total apoptotic neurons with high glucose (P < .05). Neurite outgrowth recovered to control lengths after coculture of diabetic neurons with healthy SCs (P < .05). Glucose can be used as a tool to investigate the direct effects of DM on neuritogenesis. Our data suggest that an effective treatment for DM ED protects and repairs the penile neuronal supply. Exposing MPG neurons to high glucose offers a quick and, inexpensive proxy for DM-related conditions. A limitation of our study is that our model reflects type 1 DM, whereas clinically, most diabetic ED patients have type 2 DM. Culturing pelvic neurons in high glucose can be used as a tool to elucidate how to protect proerectile neurons from cell death and may lead to new therapeutic strategies for diabetic men suffering from ED.

Cocultured Schwann Cells Rescue Irradiated Pelvic Neuron Outgrowth and Increase Survival

BackgroundProstatic radiation therapy (RT) leads to erectile dysfunction by damaging peri-prostatic pro-erectile nerves of the pelvic ganglion. Schwann cells (SC) facilitate neuronal repair after mechanical injury, however, their role in repair of pelvic neurons post-radiation hasn't been explored. AimTo determine if SCs cocultured with primary pelvic neurons can rescue neuronal survival and growth after ex vivo RT. MethodsMajor pelvic ganglia (MPG) were collected from adult male Sprague-Dawley rats (n = 12) to isolate SCs. SCs received RT (0 or 8 Gy), were plated on coated coverslips and grown to confluence before the addition of neurons. Additional MPGs were irradiated (0 or 8 Gy) and digested to isolate pelvic neurons. Dissociated neurons were plated alone or atop SC-coated coverslips to create 6 experimental groups (n = 3/grp): (i) Control (CON) MPG, (ii) RT MPG, (iii) CON SC + CON MPG, (iv) CONSC + RT MPG, (v) RT SC + CON MPG, and (iv) RT SC + RT MPG. After 72 hours, coverslips were fixed and stained for beta-tubulin (neuron marker), S100 (SC marker), neuronal nitric oxide synthase (nitrergic marker), tyrosine hydroxylase (sympathetic marker), and terminal deoxynucleotidyl transferase dUTP nick-end labeling. OutcomesWe measured neurite length, branching, specific neuron populations and apoptosis. ResultsEx vivo RT decreased MPG neuron length, increased apoptosis and decreased nitrergic neurons in monoculture. Compared to all other groups, CON SC + RT MPG cocultures demonstrated increased neurite outgrowth (P < .001). Neurite branching was decreased in the RT MPG + RT SC coculture, but unchanged in other cocultures. Groups containing RT MPG neurons exhibited increased apoptosis, but coculture with CON SC reduced the degree of RT-induced apoptosis (P < .01). The number of tyrosine hydroxylase positive neurons was unchanged while nitrergic neurons were significantly lower in RT neurons and coculture with CON SCs was unable to prevent nitrergic loss. Clinical TranslationThese findings suggest that SCs may be an important target in prostate cancer patients with radiation-induced pelvic neuropathy to promote MPG neuron survival and neuronal repair after RT. Strengths and LimitationsThis is the first study to characterize the ex vivo ability of SCs to rescue pelvic nerve growth and survival. The study is limited by little supporting mechanistic molecular data and the need to confirm the ability of healthy SCs to promote pelvic neuron survival and repair following prostatic RT in vivo. ConclusionUnirradiated SCs partially mitigated RT-induced MPG apoptosis but did not affect the loss of nitrergic neuron populations suggesting that SCs promote irradiated MPG neuron survival and facilitate intrinsic repair functions.Randolph JT, Pak ES, McMains JC, et al. Cocultured Schwann Cells Rescue Irradiated Pelvic Neuron Outgrowth and Increase Survival. J Sex Med 2022;19:1333–1342.

Cocultured Schwann Cells Rescue Irradiated Pelvic Neuron Outgrowth and Increase Survival

ABSTRACT Introduction Prostatic radiation therapy (RT) leads to erectile dysfunction (ED) by damaging adjacent pro-erectile nerves of pelvic ganglion. Preclinical cell culture studies have shown that RT induces pelvic neuron death and impairs neurite outgrowth. However, ex vivo RT and culture of whole pelvic ganglia leads to enhanced neurite outgrowth. Schwann cells (SC), which are present in intact ganglia, facilitate neuron repair after mechanical injury. The role of SCs in supporting neuron growth and survival in the context of RT has not been investigated. Objective Determine if SCs cocultured with primary pelvic neurons improve neuronal survival and growth after ex vivo RT. Methods Major pelvic ganglia (MPG) were collected from male Sprague-Dawley rats (n=12) and digested in collagenase/dispase to isolate SCs. SCs were plated on poly-L lysine-coated coverslips and grown in SC-selective medium to confluence for 24 hours. Confluent SCs received RT (0 or 8 Gy) before the addition of neurons. Additional MPGs (n=18) were irradiated (0 or 8 Gy) and digested to isolate pelvic neurons. Dissociated neurons were plated separately or atop SC-coated coverslips to create 6 experimental groups (n=3/grp): 1) CON MPG, 2) RT MPG, 3) CON SC+CON MPG, 4) CONSC+RT MPG, 5) RT SC+CON MPG, and 6) RT SC+RT MPG. After 72 hours, coverslips were fixed and stained for beta-tubulin (neuron marker), S100 protein (myelinating SC marker), neuronal nitric oxide synthase (nNOS; nitrergic marker), tyrosine hydroxylase (TH; sympathetic marker), and TUNEL to assess neurite length, branching, specific neuron populations and apoptosis. Results Consistent with previous findings, ex vivo RT decreased MPG neuron length, increased apoptosis and decreased nitrergic neurons in monoculture. In the current study, CON SC+RT MPG cocultures demonstrated increased neurite outgrowth compared to all other groups (p&amp;lt;0.001). Neurite branching was decreased in the RT MPG+RT SC coculture, but unchanged in other cocultures. Groups containing RT MPG neurons exhibited increased proportions of apoptosis, but coculture with CON SC reduced the degree of RT-induced apoptosis (p&amp;lt;0.01). The proportion of adrenergic TH positive neurons was unchanged while nitrergic neurons were significantly lower in RT neurons and coculture with CON SCs was unable to prevent nitrergic loss. Conclusions RT induces MPG neuronal apoptosis, inhibits post-injury neuritogenesis, and diminishes erectogenic nitrergic neuron populations. The presence of CON SCs in coculture augments MPG neuron repair mechanisms such as neurite outgrowth and branching. CON SCs partially mitigated overall RT MPG apoptosis, but did not affect the loss of nitrergic neuron populations after RT. These findings suggest that SCs promote MPG neuron survival and facilitate intrinsic repair functions acutely after RT. Further in vivo studies are needed to confirm the potential for healthy SCs to promote pelvic neuron survival and repair following prostatic RT. Disclosure No

Low-Dose Cyclophosphamide Induces Nerve Injury and Functional Overactivity in the Urinary Bladder of Rats.

Aim: This research aimed to investigate the neurotoxicity of low-dose cyclophosphamide (CYP) on the urinary bladder of rats by in vivo and in vitro studies.Methods: To establish CYP-induced cystitis rat model, rats were treated with three intraperitoneal injections of CYP (25 mg/kg) in a week. During treatment, the up-down method was used to assess the mechanical withdrawal threshold. On day 8, urodynamic test and bladder smooth muscle contractility study, including the contraction of bladder strips to electrical field stimulation (EFS, 2–64 Hz), carbachol (CCh, 10–8–10–5 M) and KCl (120 mM), were performed to evaluate the function of bladder function. Body weight and bladder weight were also recorded. Morphometric analysis using an optical microscope and transmission electron microscope was performed to observe the changes of microstructure and submicrostructure of the bladder. The major pelvic neurons were isolated and treated with acrolein (the main CYP metabolite) to assess apoptosis in vitro. RT-PCR assays were used to quantify the mRNA expression levels of Nlrp6, Asc, Casp11 and Casp1 in bladder tissues and primary neurons.Results: After CYP injections, the body weights decreased, but the bladder weights increased in the model group. The mechanical withdrawal threshold of the cystitis model remained at a low level. The morphometric analysis suggested bladder inflammation and neuroinflammation in the bladder of the cystitis rat model. Urodynamic test revealed that, the amplitude, the pressure baseline, the peak pressure and pressure threshold of model rats significantly increased after CYP treatment. The muscle strips of model rats exhibited significantly higher contractility caused by EFS and CCh than the controls. Apoptotic cells appeared at the highest concentration group (100 μM acrolein) after 6 h of acrolein incubation in apoptosis assay of primary neurons. The mRNA expression levels of Nlrp6 and Casp11 were significantly increased in the cystitis rat model and in the acrolein-treated neurons.Conclusions: Low-dose CYP treatment was confirmed to induce nerve injury, which leading to bladder pain and overactive bladder in female rats, and the up-regulation of Nlrp6 and Casp11 may contribute to these pathological changes.

The Effect of Castration on Peripheral Autonomic Neurons Supplying Mammalian Male Genitourinary System.

This review paper deals with the influence of androgens (testosterone) on pelvic autonomic pathways in male mammals. The vast majority of the relevant information has been gained in experiments involving castration (testosterone deprivation) performed in male rats, and recently, in male pigs. In both species, testosterone significantly affects the biology of the pathway components, including the pelvic neurons. However, there are great differences between rats and pigs in this respect. The most significant alteration is that testosterone deprivation accomplished a few days after birth results some months later in the excessive loss (approximately 90%) of pelvic and urinary bladder trigone intramural neurons in the male pig, while no changes in the number of pelvic neurons are observed in male rats (rats do not have the intramural ganglia). In the castrated pigs, much greater numbers of pelvic neurons than in the non-castrated animals express CGRP, GAL, VIP (peptides known to have neuroprotective properties), and caspase 3, suggesting that neurons die due to apoptosis triggered by androgen deprivation. In contrast, only some morpho-electrophysiological changes affecting neurons following castration are found in male rats. Certain clinicopathological consequences of testosterone deprivation for the functioning of urogenital organs are also discussed.

Ex Vivo Radiation Leads to Opposing Neurite Growth in Whole Ganglia vs Dissociated Cultured Pelvic Neurons

BackgroundProstatic radiation therapy (RT) often causes erectile dysfunction (ED) and the mechanisms governing RT-induced ED are unclear with a lack of therapeutic strategies. AimTo determine the effects of ex vivo RT on major pelvic ganglion (MPG) neuron survival, and neurite growth in whole vs dissociated culture. MethodsMPGs were removed and irradiated (0 or 8 Gy) from male Sprague Dawley rats. For dissociated culture, MPG neurons were digested in collagenase/dispase and cultured on coverslips. Immunofluorescent staining for beta-tubulin III (TUBB3; neuron marker), neuronal nitric oxide synthase (nNOS; nitrergic marker), tyrosine hydroxylase (TH; sympathetic marker), and terminal deoxynucleotidyl transferase dUTP nick end labeling assessed neurite length, branching, autonomic neuron density, and apoptosis. For whole organ culture, MPGs were grown in Matrigel. Gene expression of apoptotic markers (caspase 1, 3), TUBB3, nNOS, TH, and Schwann cells (Sox10, Krox20, glial fibrillary acid protein) was measured in whole organ cultured MPGs by quantitative polymerase chain reaction. OutcomesAfter 72 hours, neurite length, branching, autonomic neuron density, and apoptosis were assessed, and gene expression was measured. ResultsRT increased apoptosis in dissociated neurons measured by terminal deoxynucleotidyl transferase dUTP nick end labeling (P < .001) and whole MPG culture via upregulation of caspase 3 gene expression (P < .05). Nitrergic neurons were markedly decreased in irradiated dissociated culture (P < .05), while nNOS gene expression was upregulated in irradiated whole organ culture (P < .05). The proportion of dissociated sympathetic neurons and whole organ TH gene expression remained unchanged after RT. Interestingly, RT dissociated neurites were 22% shorter than controls, while RT whole organ neurites were 15% longer than controls (P < .01). MPG Schwann cells markers (Sox10, Krox20) were elevated after RT in whole organ culture. Clinical TranslationProstatic RT leads to increased neuronal cell death and less erectogenic nitrergic neurons contributing to ED. Strengths & LimitationsThe advantages of dissociated neuron culture include distinct neurites which are easily measured for apoptosis, length/branching, and specific neuron types. In contrast, whole MPG culture is advantageous as it contains all the supporting cells present in vivo. ConclusionThe 2 different culture methods demonstrated opposing neurite growth after RT indicating the importance of supporting cell network to promote pelvic neuron neuritogenesis and survival following RT.Randolph JT, Pak ES, Koontz BF, et al. Ex Vivo Radiation Leads to Opposing Neurite Growth in Whole Ganglia vs Dissociated Cultured Pelvic Neurons. J Sex Med 2020;17:1423–1433.

Effect of castration on pelvic neurons in the male pig.

The present study investigated the influence of castration performed at neonatal age on neuronal elements in the anterior pelvic ganglion of the male pig with immunohistochemistry and quantitative real-time PCR (qPCR). The ganglia were examined 3 and 6months after surgery. In 3-month-old castrated pigs (3MCP) 74% of adrenergic and 31% of cholinergic neurons stained for caspase-3 (CASP-3), and much greater numbers of perikarya than in the control animals expressed CGRP, galanin (GAL) and VIP (peptides known to have neuroprotective properties). In 6-months-old castrated pigs (6MCP), an excessive loss (90%) of neurons and intraganglionic nerve fibres was found. The survived adrenergic and cholinergic neurons also expressed CASP-3, CGRP, GAL or VIP. The qPCR results corresponded with immunofluorescence findings. In 3MCP, genes for CASP-3 and CGRP were up-regulated, while the expression of those for DβH, VAChT, GAL, VIP and SP displayed statistically insignificant variations. In 6MCP, distinctly up-regulated were genes for CGRP, GAL, VIP, SP, DβH and VAChT, while the expression of casp3 gene was down-regulated. The study revealed for the first time the excessive loss of pelvic neurons following castration, and a realistic assumption is proposed, that the neurons died due to apoptosis triggered by androgen deprivation.

309 Radiation-induced Schwann Cell Dedifferentiation Leads to Opposing Growth in Whole Ganglia vs Dissociated Cultured Pelvic Neurons

Prostatic radiation therapy (RT) is a highly effective treatment for localized low-grade prostate cancer. Unfortunately, in 67-85% of patients, RT causes erectile dysfunction (ED). The direct molecular mechanisms underlying RT-induced ED are not understood, and no effective therapies have been identified. The major pelvic ganglia (MPG) in rats is anatomically equivalent to the hypogastric plexus in humans and can be used to assess radiation-induced nerve injury. Both whole and dissociated MPG cultures have examined neurite growth and apoptosis in models of ED; however, the impact of radiation on MPG neuron growth and survival has not been directly compared in these culture conditions. Determine the effects of ex vivo radiation on MPG neuron survival, growth, and gene expression in whole vs dissociated culture. MPGs from male Sprague-Dawley rats (n=14) were removed and irradiated ex vivo (0 or 800 cGy). For dissociated culture, MPGs were digested in collagenase/dispase. Neurons were collected by trituration and cultured on coverslips for 72 hours. Immunofluorescent staining for beta-tubulin III (Tubb3; neuron marker), neuronal nitric oxide synthase (nNOS; nitrergic marker), tyrosine hydroxylase (TH; sympathetic marker), and TUNEL assessed neurite length, branching, autonomic neuron density, and apoptosis. For whole culture, MPGs were grown in Matrigel and neurite growth was measured at 72 hours. Gene expression of apoptotic markers (Caspase 1, 3), myelination (Sox2, Sox10, Krox20), glial dedifferentiation (GFAP), Tubb3, nNOS, and TH was measured in irradiated cultures of dissociated MPG neurons, isolated Schwann cells (SCs), and whole cultured MPGs by qPCR.

The expression of androgen receptor in neurons of the anterior pelvic ganglion and celiac-superior mesenteric ganglion in the male pig.

The present study investigated the expression of androgen receptor (AR) in neurons of the anterior pelvic ganglion (APG) and celiac-superior mesenteric ganglion (CSMG; ganglion not involved in the innervation of reproductive organs) in the male pig with quantitative real-time PCR (qPCR) and immunohistochemistry. qPCR investigations revealed that the level of AR gene expression in the APG tissue was approximately 2.5 times higher in the adult (180-day-old) than in the juvenile (7-day-old) boars. Furthermore, in both the adult and juvenile animals it was sig- nificantly higher in the APG than in CSMG tissue (42 and 85 times higher, respectively). Immu- nofluorescence results fully confirmed those obtained with qPCR. In the adult boars, nearly all adrenergic (DβH-positive) and the majority of non-adrenergic neurons in APG stained for AR. In the juvenile animals, about half of the adrenergic and non-adrenergic neurons were AR-posi- tive. In both the adult and juvenile animals, only solitary CSMG neurons stained for AR. The present results suggest that in the male pig, pelvic neurons should be considered as an element of highly testosterone-dependent autonomic circuits involved in the regulation of urogenital func- tion, and that their sensitization to androgens is a dynamic process, increasing during the prepu- bertal period.

40 Neurite outgrowth of pelvic neurons is stimulated by the neurotrophic peptide galanin

40 Neurite outgrowth of pelvic neurons is stimulated by the neurotrophic peptide galanin

Semaphorin 3A inhibits growth of adult sympathetic and parasympathetic neurones via distinct cyclic nucleotide signalling pathways

Semaphorin 3A (Sema3A) is an important secreted repulsive guidance factor for many developing neurones. Sema3A continues to be expressed in adulthood, and expression of its receptor, neuropilin-1 (Nrp-1), can be altered by nerve injury. Autonomic neurones innervating the pelvic viscera are particularly susceptible to damage during pelvic surgical procedures, and failure to regenerate or aberrant growth of sympathetic and parasympathetic nerves lead to organ dysfunction. However, it is not known if adult pelvic neurones are potential targets for Sema3A. The effects of Sema3A and activation or inhibition of cyclic nucleotide signalling were assessed in adult rat pelvic ganglion neurones in culture using a growth cone collapse assay. Sema3A caused growth cone collapse in both parasympathetic and sympathetic neurones expressing Nrp-1. However, the effect of Sema3A was mediated by distinct cyclic nucleotide signalling pathways in each neurone type. In parasympathetic neurones, cAMP and downstream activation of protein kinase A were required for growth cone collapse. In sympathetic neurones, cGMP was required for Sema3A-induced collapse; cAMP can also cause collapse but was not required. Sema3A-mediated, cGMP-dependent collapse in sympathetic neurones may require activation of cyclic nucleotide-gated ion channels (CNGCs). We propose that Sema3A is an important guidance factor for adult pelvic autonomic neurones, and that manipulation of their distinct signalling mechanisms could potentially promote functional selective regeneration or attenuate aberrant growth. To our knowledge, this is also the first study to implicate CNGCs in regulating growth cone dynamics of adult neurones.

Immunohistochemical characterization of pelvic neurons projecting to the bladder in rats with the artificial somatic-autonomic reflex arc

Objective Retrograde-tracing and immunohistochemical techniques were used in combination to investigate the types of putative transmitters in pelvic ganglia neurons projecting to the bladder of rats with the artificial somatic-autonomic reflex arc. Methods The artificial somatic-autonomic reflex arc was established in 8 rats by end-to-end microanastomosis of the proximal stump of the left L4 ventral root to the distal stump of L6 ventral root. The major pelvic ganglia (MPG) neurons innervating the urinary bladder were labeled by retrograde axonal tracing methods with the use of horseradish peroxidase (HRP) injected into the bladder wall and identified with TMB-HRP reaction. Then immunohistochemical (ChAT, TH, VIP, SP) and histochemical methods (NADPH-diaphorase activity and nitric oxide synthase immunoreac-tivity) were used to identify the neurotransmitters of HRP-labeled neurons projecting to the bladder. Results HRP-labeled neurons with spherical or oval shape mainly distributed in the MPG. The HRP-labeled neurons were positive for ChAT (112/279, 40. 1%), TH (50/245,20.4%), VIP(25/233, 10.7%), NOS ( 15/230, 6. 5% ) or SP (8/242, 3. 3% ) respectively. Conclusion These results suggest that ace-tylcholine and adrenaline are the predominant neurotransmitters of postganglionic neurons innervating bladder in rats with the artificial somatic-autonomic reflex arc. VIP, NO and SP may be as the neurotransmitters or neuromodulators to participate the procedure of urinary storage and voiding. Key words: Bladder; Pelvic ganglion; Neurotransmitter; Artificial reflex arc

VIP and PACAP Effects on Mouse Major Pelvic Ganglia Neurons

Major pelvic ganglia (MPG) neurons innervate urogenital organs and components of the lower bowel. Immunoreactivity for vasoactive intestinal polypeptide (VIP) has previously been observed in the MPG, and VIP knockout animals have impaired micturition reflexes suggesting a role for this neuropeptide in urogenital function. Here, we investigate the presence and action of VIP and a related neuropeptide, pituitary adenylate cyclase activating polypeptide (PACAP), in the pelvic ganglia of male mice. An abundance of VIP-immunoreactive (IR) neurons and nerve fibers were observed in the ganglion, whereas PACAP immunoreactivity was not seen. Extracts from acutely isolated MPG contained transcripts for the VPAC1, VPAC2, and PAC1 receptors. Local application of VIP, PACAP, or maxadilan to isolated pelvic ganglion neurons shortened the duration of the afterhyperpolarization (AHP) of action potentials elicited by brief intracellular depolarization. All three peptides also increased neuronal excitability within a subpopulation of the sampled neurons. Bath application of apamin, a peptide antagonist of SK channels, shortened the duration of the AHP indicating that AHP duration in pelvic neurons is determined principally by SK-channel activity. The results suggest that VIP has a role in the neural control of pelvic organ function and activation of VPAC and/or PAC1 receptors can modulate the activity of the autonomic neurons innervating pelvic organs.

P5.6 Neuritin message is increased by testosterone in cultured rat pelvic autonomic neurons but is unchanged in pelvic ganglia in experimental diabetes

P5.6 Neuritin message is increased by testosterone in cultured rat pelvic autonomic neurons but is unchanged in pelvic ganglia in experimental diabetes

Effect of steroid hormones on the peripheral nervous system

The aim of the present review is to describe the localization and expression pattern of oestrogens, androgens and progestagens receptors within the rat peripheral nervous system (PNS), and to emphasize the important role of these steroids in regulation of peripheral neurons function(s). Till now, steroid receptors were found predominantly in a subset of sensory and autonomic PNS cells projecting to reproductive organs and/or urinary system, as well as in Schwann cells of the sciatic nerve. Available literature strongly suggests that oestrogens exert diverse effects on sensory and autonomic neurons, among others infl uencing not only the development, plasticity and repair abilities of dorsal root ganglia neurons, but also controlling the neuritogenesis of sympathetic neurons and Schwann cell proliferation. Furthermore, there is growing body of evidence that these steroids are also able to change the neurochemical architecture of circuits involved in analgesia and nociception, most probably by modulation of the chemical coding of sensory and autonomic neurons. In contrast, there is a paucity of data concerning the function(s) of androgens and progestagens on PNS neurons. As of now, while androgens are thought to exert strong impact on the morphology, chemical phenotypes and function(s) of pelvic autonomic neurons, involved in reproductive behaviours in male, progestagens are implicated to infl uence the somatosensory pathways rather, being able to act on morphology of sciatic nerves (e.g., infl uencing expression of myelin proteins and Schwann cell proliferation). Thus, although there is no doubt that an immediate bilateral relationship between the peripheral nervous and endocrine systems exists, it should be stressed that available data are restricted only to experiments performed on rats, in this way limiting the scope of this short review to this species only.

Structural effects and potential changes in growth factor signalling in penis-projecting autonomic neurons after axotomy

BackgroundThe responses of adult parasympathetic ganglion neurons to injury and the neurotrophic mechanisms underlying their axonal regeneration are poorly understood. This is especially relevant to penis-projecting parasympathetic neurons, which are vulnerable to injury during pelvic surgery such as prostatectomy. We investigated the changes in pelvic ganglia of adult male rats in the first week after unilateral cavernous (penile) nerve axotomy (cut or crush lesions). In some experiments FluoroGold was injected into the penis seven days prior to injury to allow later identification of penis-projecting neurons. Neurturin and glial cell line-derived neurotrophic factor (GDNF) are neurotrophic factors for penile parasympathetic neurons, so we also examined expression of relevant receptors, GFRα1 and GFRα2, in injured pelvic ganglion neurons.ResultsAxotomy caused prolific growth of axon collaterals (sprouting) in pelvic ganglia ipsilateral to the injury. These collaterals were most prevalent in the region near the exit of the penile nerve. This region contained the majority of FluoroGold-labelled neurons. Many sprouting fibres formed close associations with sympathetic and parasympathetic pelvic neurons, including many FluoroGold neurons. However immunoreactivity for synaptic proteins could not be demonstrated in these collaterals. Preganglionic terminals showed a marked loss of synaptic proteins, suggesting a retrograde effect of the injury beyond the injured neurons. GFRα2 immunofluorescence intensity was decreased in the cytoplasm of parasympathetic neurons, but GFRα1 immunofluorescence was unaffected in these neurons.ConclusionThese studies show that there are profound changes within the pelvic ganglion after penile nerve injury. Sprouting of injured postganglionic axons occurs concurrently with structural or chemical changes in preganglionic terminals. New growth of postganglionic axon collaterals within the ganglion raises the possibility of the formation of aberrant synaptic connections between injured and un-injured ganglion neurons. Together these changes demonstrate a broader effect on the pelvic autonomic circuitry than simply loss of neuroeffector connections. These structural changes are accompanied by potential changes in neurotrophic factor signalling due to altered expression of receptors for members of the GDNF family. Together our results advance understanding of the responses of pelvic autonomic nerve circuits to injury and may assist in designing strategies for promoting regeneration.

The relationship between serotonin, dopamine beta hydroxylase and GABA immunoreactive inputs and spinal preganglionic neurones projecting to the major pelvic ganglion of wistar rats

Preganglionic neurones in the lumbosacral spinal cord give rise to nerves providing the parasympathetic and sympathetic innervation of pelvic organs. These neurones are modulated by neurotransmitters released both from descending supra-spinal pathways and spinal interneurones. Though serotonin has been identified as exerting a significant influence on these neurones, few studies have investigated the circuitry through which it achieves this particularly in relation to sympathetic preganglionic neurones. Using a combination of neuronal tracing and multiple immunolabeling procedures, the current study has shown that pelvic preganglionic neurones receive a sparse, and probably non-synaptic, axosomatic/proximal dendritic input from serotonin-immunoreactive terminals. This was in marked contrast to dopamine beta hydroxylase-immunoreactive terminals, which made multiple contacts. However, the demonstration of both serotonin, and dopamine beta hydroxylase immunoreactive terminals on both parasympathetic and sympathetic preganglionic neurones provides evidence for direct modulation of these cells by both serotonin and norepinephrine. Serotonin-containing terminals displaying conventional synaptic morphology were often seen to contact unlabeled somata and dendritic processes in regions surrounding the labeled preganglionic cells. It is possible that these unlabeled structures represent interneurones that might allow the serotonin containing axons to exert an indirect influence on pelvic preganglionic neurones. Since many spinal interneurones employ GABA as a primary fast acting neurotransmitter we examined the relationship between terminals that were immunoreactive for serotonin or GABA and labeled pelvic preganglionic neurones. These studies were unable to demonstrate any direct connections between serotonin and GABA terminals within the intermediolateral or sacral parasympathetic nuclei. Colocalization of serotonin and GABA was very rare but terminals immunoreactive for each were occasionally seen to contact the same unlabeled processes in close proximity. These results suggest that in the rat, the serotonin modulation of pelvic preganglionic neurones may primarily involve indirect connections via local interneurones.

Remodelling of connections in pelvic ganglia after hypogastric nerve crush

Pelvic ganglia innervate the urogenital organs and contain both sympathetic and parasympathetic neurons. Previous studies have shown that within days of cutting either the lumbar or sacral preganglionic axons that innervate pelvic ganglia, many axon collaterals grow and appear to form specific connections with denervated pelvic neurons. Here we have examined the longer term consequences of partial deafferentation by studying pelvic ganglia up to 7 weeks after hypogastric nerve (HGN) crush, a lesion which also allows faster regeneration of spinal axons. Noradrenergic neurons were denervated by HGN crush, as demonstrated by loss of varicosities immunostained for the synaptic proteins, synaptophysin and synapsin. A week after HGN crush, axon collaterals grew from parasympathetic pelvic ganglion neurons, shown by the presence of numerous varicose fibers immunostained for vasoactive intestinal peptide (VIP). These VIP fibers were poorly stained or unstained for synaptophysin, even after 7 weeks. At early post-operative times the VIP fibers grew irregularly; however, with longer post-operative times they appeared to target particular VIP-negative, noradrenergic neurons. Our results also indicate that some lumbar preganglionic axons regenerated during the post-operative period, although this only affected a minority of sympathetic neurons. These reinnervated sympathetic neurons were not associated with VIP fibers, suggesting that the new intrinsic connections may have precluded regeneration or targeting of preganglionic axons. Together these results demonstrate that there is considerable remodelling within pelvic ganglia after partial deafferentation. This occurs under conditions where spinal preganglionic axons can regenerate. New intra-ganglionic connectivity may be permanent and may impact on this regeneration.

Divalent metals differentially block cloned T-type calcium channels.

We tested divalent metals including Cu2+, Pb2+, and Zn2+ to determine their pharmacological profiles for blockade of cloned T-type Ca2+ channels (alpha1G, alpha1 H, and alpha1I). Effects of the metals were also evaluated for native low and high voltage-activated Ca2+ channels in rat sympathetic pelvic neurons. Cu2+ and Zn2+ blocked three T-type channel isoforms in a concentration-dependent manner with a higher affinity for alpha1H currents (IC50 = 0.9 microM and 2.3 microM). In pelvic neurons, only Zn2+ showed strong selectivity for T-type Ca2+ currents over high voltage-activated Ca2+ currents. Conversely, Pb2+ block on Ca2+ channels did not show distinctive selectivity. Taken together, these results suggest that besides Ni2+, Cu2+ and Zn2+ can be used as selective blockers of alpha1 H at low concentrations.

Alterations in stem cell factor and c-kit mRNA in distal colon, bladder and pelvic DRG neurons following TNBS colitis in the rat: Implications for IBS and interstitial cystitis Co-morbidity

Alterations in stem cell factor and c-kit mRNA in distal colon, bladder and pelvic DRG neurons following TNBS colitis in the rat: Implications for IBS and interstitial cystitis Co-morbidity