Pudendal Motoneurons Research Articles

A study evaluating and comparing the effectiveness of combination therapy – Duloxetine with darifenacin versus darifenacin as monotherapy on perception of symptoms, quality and standard of life in patients suffering with overactive bladder (OAB)

: Overactive bladder is chronic debilitating condition, with physical, psychological, and economical consequences. Urinary vesicle tissue contains muscarinic receptors, M3 is principal mediator of detrusor contraction. Muscarinic receptor antagonists, comprises traditional pharmacological treatment. But due to non-selective inhibition, these agents, probably been related with safety and tolerability concerns. Drugs particular inhibiting sM3 receptor (Darifenacin) have potential to present effective relief while reducing side effects concerned with blockade of M1, M2 and M5 receptors. Duloxetine is Serotonin and nor-epinephrine reuptake inhibitor, leading increased concentration of 5-HT and NE in synaptic cleft, increases stimulation of pudendal motor neurons, thus increasing resting tone and contraction of urethral sphincter.: In present prospective, randomized, parallel group, comparative open label study with 60 OAB patients the combination therapy of Duloxetine with Darifenacin was equated with monotherapy using Darifenacin. The outcome thus analyzed using three different OAB-questionnaires and was statistically compared. : We demonstrated that addition of Duloxetine has shown better result outcome in symptoms as well as quality of life, though the difference of OAB-V8, OABss mean score was non-significant, but for OAB-qSF the reduction (percentage change) in mean score was more in treatment group II as compare to group I (w6:13.82±3.17% vs 12.13±3.24% & W12 29.99±5.40% Vs 25.56±5.17%) , and was statistically significant.(p<0.05).: Duloxetine has synergistic effect to Darifenacin, its ability to increase bladder capacity may be the reason for the improvement OAB symptoms, promising in controlling and treating symptoms either alone or in combination with anti-cholinergic drugs.

Electrical stimulation of the pudendal nerve promotes neuroregeneration and functional recovery from stress urinary incontinence in a rat model.

The pudendal nerve can be injured during vaginal delivery of children, and slowed pudendal nerve regeneration has been correlated with development of stress urinary incontinence (SUI). Simultaneous injury to the pudendal nerve and its target muscle, the external urethral sphincter (EUS), during delivery likely leads to slowed neuroregeneration. The goal of this study was to determine if repeat electrical stimulation of the pudendal nerve improves SUI recovery and promotes neuroregeneration in a dual muscle and nerve injury rat model of SUI. Rats received electrical stimulation or sham stimulation of the pudendal nerve twice weekly for up to 2 wk after injury. A separate cohort of rats received sham injury and sham stimulation. Expression of brain-derived neurotrophic factor (BDNF) and βII-tubulin expression in Onuf's nucleus were measured 2, 7, and 14 days after injury. Urodynamics, leak point pressure (LPP), and EUS electromyography (EMG) were recorded 14 days after injury. Electrical stimulation significantly increased expression of BDNF at all time points and βII-tubulin 1 and 2 wk after injury. Two weeks after injury, LPP and EUS EMG during voiding and LPP testing were significantly decreased compared with sham-injured animals. Electrical stimulation significantly increased EUS activity during voiding, although LPP did not fully recover. Repeat pudendal nerve stimulation promotes neuromuscular continence mechanism recovery possibly via a neuroregenerative response through BDNF upregulation in the pudendal motoneurons in this model of SUI. Electrical stimulation of the pudendal nerve may therefore improve recovery after childbirth and ameliorate symptoms of SUI by promoting neuroregeneration after injury.

1008 SACRAL NEUROSTIMULATION (SNS) IN A RODENT MODEL: EFFECTS OF NERVE LOCATION AND PULSE PARAMETERS ON SYNAPTIC ELEMENTS OF A SEXUAL RESPONSE SPINAL CIRCUIT

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Basic Research II1 Apr 20121008 SACRAL NEUROSTIMULATION (SNS) IN A RODENT MODEL: EFFECTS OF NERVE LOCATION AND PULSE PARAMETERS ON SYNAPTIC ELEMENTS OF A SEXUAL RESPONSE SPINAL CIRCUIT Richard Johnson, Sunny Ferrero, and Victoria Dugan Richard JohnsonRichard Johnson Gainesville, FL More articles by this author , Sunny FerreroSunny Ferrero Gainesville, FL More articles by this author , and Victoria DuganVictoria Dugan Gainesville, FL More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.1110AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Electrical neurostimulation of human sacral spinal nerves (SNS) is used to treat overactive bladder. SNS also activates axons involved in sexual function and recent clinical studies document a potential benefit on sexual outcomes. A rat model was developed to investigate neurostimulation (NS) nerve sites and pulse parameters. We evaluated the NS effects on a spinal reflex circuit involved in sexual response. The pudendal motoneuron reflex discharge (PMRD) has been previously described in males as a sensitive measure of the spinal circuit integrity for ejaculation (e.g. chronic spinal cord injury, premature ejaculation) and in females to assess treatments for bladder control. The PMRD is triggered by the dorsal nerve of the penis (DNP). Elimination of any of the penile sensory, spinal cord, or pudendal motor limbs of this reflex prevents the occurrence of ejaculation and sensations of orgasm. METHODS In anesthetized male rats, the magnitude of the DNP-elicited PMRD test response on the right side of the animal was quantitated by recording reflex-evoked action potentials in pudendal motor axons elicited by penile afferent activation. The central spinal effects of NS applied to multiple nerves on the left side was evaluated by quantifying the contralateral synaptic modulation of the right-sided PMRD in this bilateral circuit. NS periods of 20 sec to 5 min were induced over a wide range of frequencies (1- 50 Hz) and pulse configurations. RESULTS Results were (i) a frequency-dependent (maximum at 20-25 Hz) but mostly transient (initial 20 sec) depression of PMRD magnitude occurred during NS of the DNP, compound pudendal nerve, and L6 spinal nerve but not during NS of the superficial perineal nerve or the S1 spinal nerve, and (ii) the reflex depression was significantly less when only large diameter afferents were stimulated (biphasic NS pulse widths of 0.01-0.02 ms) compared to when large and small diameter afferents are stimulated (pulse widths of 0.5 ms) particularly when the current intensity was set near 1.0 times reflex threshold. CONCLUSIONS We conclude that the NS at certain targets and parameters, can induce transient depression of the PMRD. The PMRD depression is elicited only when nerves containing DNP afferents are stimulated. The depression is frequency dependent and minimized when only large diameter myelinated afferents are stimulated using short duration pulses and low current intensity. The nerve site and parameter differences may explain the high variability in NS-induced sexual response effects in patients. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e410 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Richard Johnson Gainesville, FL More articles by this author Sunny Ferrero Gainesville, FL More articles by this author Victoria Dugan Gainesville, FL More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Bilateral Bulbospinal Projections to Pudendal Motoneuron Circuitry after Chronic Spinal Cord Hemisection Injury as Revealed by Transsynaptic Tracing with Pseudorabies Virus

Complications of spinal cord injury in males include losing brainstem control of pudendal nerve-innervated perineal muscles involved in erection and ejaculation. We previously described, in adult male rats, a bulbospinal pathway originating in a discrete area within the medullary gigantocellularis (GiA/Gi), and lateral paragigantocellularis (LPGi) nuclei, which when electrically microstimulated unilaterally, produces a bilateral inhibition of pudendal motoneuron reflex circuitry after crossing to the contralateral spinal cord below T8. Microstimulation following a long-term lateral hemisection, however, revealed reflex inhibition from both sides of the medulla, suggesting the development or unmasking of an injury-induced bulbospinal pathway crossing the midline cranial to the spinal lesion. In the present study, we investigated this pathway anatomically using the transsynaptic neuronal tracer pseudorabies virus (PRV) injected unilaterally into the bulbospongiosus muscle in uninjured controls, and ipsilateral to a chronic (1-2 months) unilateral lesion of the lateral funiculus. At 4.75 days post-injection, PRV-labeled cells were found bilaterally in the GiA/Gi/LPGi with equal side-to-side labeling in uninjured controls, and with significantly greater labeling contralateral to the lesion/injection in lesioned animals. The finding of PRV-labeled neurons on both sides of the medulla after removing the mid-thoracic spinal pathway on one side provides anatomical evidence for the bilaterality in both the brainstem origin and the lumbosacral pudendal circuit termination of the spared lateral funicular bulbospinal pathway. This also suggests that this bilaterality may contribute to the quick functional recovery of bladder and sexual functions observed in animals and humans with lateral hemisection injury.

Spontaneous ejaculation after spinal cord trauma

Dear Editor, I am Dr Hossam A. Yasien, from the Department of Dermatology, Andrology & STDs, Faculty of Medicine, Menoufiya University, Menoufiya, Egypt. Spinal cord lesions in humans are associated with impaired ejaculation 1, suggesting that the effects of descending pathways on the spinal ejaculatory mechanism are predominantly excitatory. In rodents, however, there may be an additional and important descending inhibitory pathway 2. We report a case of a patient in whom a spinal trauma was unusually associated with spontaneous ejaculation. A 23-year-old male patient presented to our Department of Andrology with spontaneous ejaculation. The patient is single and was previously normal until he experienced an accident by falling from the fifth floor about 8 months ago. The patient was then paraplegic with absent sensation of both lower limbs, urinary and stool incontinence, absent erection including morning erection. Both spinal computerized tomography (CT) and magnetic resonance imaging (MRI) revealed fracture of vertebrae T12, L1 and L2. Neurological examination at that time revealed Grade A impairment according to the American Spinal Injury Association (ASIA impairment scale) with no sacral sparing. Till that time the patient did not report any abnormality in the ejaculation. Neurosurgeons then decided to perform immediate fixation of the fractured vertebrae, which had been already done to the patient. After 1 month, the patient started physiotherapy for 7 months, after which he gained lower limb power, urinary and fecal control and even erection on excitation, but began to experience spontaneous ejaculation without desire, erection and even in unsatisfactory circumstances like praying in the mosque and during manual work. This complaint occurs many times per week and sometimes per day without any sexual desire, sexual excitation or any provocative factors with preserved orgasm at every time ejaculation occurs. However, ejaculation occurs normally during masturbation and night emission as well. By examination, the patient had hyperesthesia of both lower limbs, normal to exaggerated cremasteric and bulbocavernosal reflexes. Anal reflex was normal. The patient's ejaculate was tested for the presence of sperms and was positive. Routine investigations of the patient including fasting and postprandial blood sugar were normal. Drug history revealed a course of broad-spectrum antibiotics, Metronidazole, Vitamin B12, drugs that decrease edema, like alpha-chemotrypsin and non-steroidal anti-inflammatory drugs. No drugs were received for the current complaint. Earlier reports of this association have been anecdotal 3, and cord pathology is generally found to lead to the impairment of ejaculation. It is, however, known that a reflex mechanism exists in the T9-L2 (sympathetically driven emission of semen) and S2-3 cord segments (somatically driven propulsion of semen) from which involuntary ejaculation may be produced 2. Thus in patients with spinal injuries above T9, ejaculation can be induced using electroejaculation, vibrator stimulation or sympathetic stimulation below the level of the lesion 4, 5. In rodents this spinal sexual mechanism receives descending inhibition to pudendal motor neurons and lumbosacral interneurons, and, in male animals with a spinal cord transection ejaculation, can be induced by fluid distension of the urethra or by mechanical stimulation of the glans 6 in a manner reminiscent of our patient's symptomatology. We think that the lesion in this patient was compression more than a cut injury and edema following the fracture or the surgical procedure is global, and affecting not only the site of the injury but extending above and below as well. Denervation supersensitivity of the post-synaptic receptors, which occurs after a long period of compression, may be the cause of this condition. In summary, we conclude that in humans the overriding supraspinal influence on sexual function is usually excitatory, but it is possible that spinal lesions could result in a situation resembling that in rodents by selectively interfering with an additional, smaller descending inhibitory pathway projecting to the spinal ejaculatory mechanism. In addition, we should consider the phenomenon of denervation supersensitivity in these cases.

Properties of Renshaw cells excited by recurrent collaterals of pudendal motoneurons in the cat

Properties of Renshaw cells excited by recurrent collaterals of pudendal motoneurons in the cat

Pudendal motoneurons of the rat located in separated spinal nuclei possess nicotinic acetylcholine receptors having distinct pharmacological profiles

Pudendal motoneurons are located in the ventral horn of the caudal lumbar spinal cord and innervate striated pelvic muscles implicated in sexual and eliminative functions. In rats they are distributed in the dorsomedial (DM) and dorsolateral (DL) nucleus. In male rats, dorsomedial motoneurons innervate the bulbocavernosus, the levator ani and the external anal sphincter, whereas dorsolateral motoneurons control the ischiocavernosus and external urethral sphincter. Using spinal cord slices of young male rats and whole-cell patch-clamp recordings, we investigated the sensitivity of pudendal motoneurons to nicotinic cholinergic agonists. Motoneurons were identified following 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine, 4-chlorobenzenesulphonate retrograde labelling. In the presence of atropine, both dorsomedial and dorsolateral motoneurons responded to acetylcholine (ACh) by generating a rapidly activating inward current. By using selective nicotinic antagonists and a nicotinic positive allosteric modulator, we found that nicotinic ACh receptors present in dorsomedial and dorsolateral motoneurons display distinct pharmacological profiles. Whereas the former are of the heteromeric type, the latter are predominantly of the alpha7-containing type. These data were confirmed by light microscopic autoradiography. In young rats, a ligand for heteromeric nicotinic receptors labelled all laminae of the central grey matter, whereas in the ventral part of the central grey, a ligand selective for alpha7-containing nicotinic receptors labelled the DL but not the DM. Dorsolateral and dorsomedial motoneurons innervate two distinct groups of pelvic muscles. A difference in their nicotinic pharmacology may be clinically relevant, as it might allow a selective pharmacological intervention in view of influencing the activity of one or the other set of muscles.

Effect of Acute Dapoxetine Administration on the Pudendal Motoneuron Reflex in Anesthetized Rats: Comparison With Paroxetine

Pudendal motoneuron reflex discharges elicited by bilateral electrical stimulation of the dorsal nerves of the penis were used as an experimental model of the expulsion reflex of ejaculation to investigate the effect of acute intravenous delivery of dapoxetine, a short acting selective serotonin reuptake inhibitor, in anesthetized rats. Dapoxetine was compared with paroxetine, the selective serotonin reuptake inhibitor of reference. Stimulating electrodes were placed bilaterally on the dorsal nerves of the penis and a recording electrode was placed on the motor branch of the pudendal nerve to monitor pudendal motoneuron reflex discharges in urethane anesthetized rats. Pudendal motoneuron reflex discharges induced by penile dorsal nerve stimulation were measured before and 60 minutes after a single intravenous injection of dapoxetine or paroxetine, each tested at 3 doses (1, 3 and 10 mg/kg) or after a single injection of vehicle. At all doses tested dapoxetine significantly lengthened the latency of pudendal motoneuron reflex discharges following bilateral stimulation of the dorsal nerves of the penis in comparison with vehicle, whereas only the 1 mg/kg dose of paroxetine was effective. The amplitudes of pudendal motoneuron reflex discharges were significantly decreased only in rats treated with 3 mg/kg dapoxetine compared to vehicle. Acute systemic delivery of selective serotonin reuptake inhibitors is capable of modulating the expulsion reflex of ejaculation in anesthetized rats with dapoxetine appearing to be more effective than paroxetine. These findings support the beneficial effect of on-demand administration of dapoxetine for premature ejaculation.

Identified Motoneurons Involved in Sexual and Eliminative Functions in the Rat Are Powerfully Excited by Vasopressin and Tachykinins

The pudendal motor system is constituted by striated muscles of the pelvic floor and the spinal motoneurons that innervate them. It plays a role in eliminative functions of the bladder and intestine and in sexual function. Pudendal motoneurons are located in the ventral horn of the caudal lumbar spinal cord and send their axon into the pudendal nerve. In the rat, binding sites for vasopressin and tachykinin are present in the dorsomedial and dorsolateral pudendal nuclei, suggesting that these neuropeptides may affect pudendal motoneurons. The aim of the present study was to investigate possible effects of vasopressin and tachykinins on these motoneurons. Recordings were performed in spinal cord slices of young male rats using the whole-cell patch-clamp technique. Before recording, motoneurons were identified by 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine, 4-chlorobenzenesulfonate retrograde labeling. The identification was confirmed, a posteriori, by choline acetyltransferase immunocytochemistry. Vasopressin and tachykinins caused a powerful excitation of pudendal motoneurons. The peptide-evoked depolarization, or the peptide-evoked inward current, persisted in the presence of tetrodotoxin, indicating that these effects were mainly postsynaptic. By using selective receptor agonists and antagonist, we determined that vasopressin acted via vasopressin 1a (V1a), but not V1b, V2, or oxytocin receptors, whereas tachykinins acted via neurokinin 1 (NK1), but not NK2 or NK3, receptors. Vasopressin acted by enhancing a nonselective cationic conductance; in some motoneurons, it also probably suppressed a resting K+ conductance. Our data show that vasopressin and tachykinins can excite pudendal motoneurons and thus influence the force of striated perineal muscles involved in eliminative and sexual functions.

Supraspinal Site of Action for the Inhibition of Ejaculatory Reflex by Dapoxetine

ObjectivesThe aim of the study was to determine whether dapoxetine, a short-acting selective serotonin reuptake inhibitor, acts at the spinal or supraspinal level to inhibit the ejaculatory reflex. MethodsThe pudendal motoneuron reflex discharges (PMRDs) model was used as an experimental paradigm of the ejaculatory expulsion reflex in anaesthetised male rats. A spinal site of action was evaluated by testing the effect of intrathecal delivery of dapoxetine on PMRDs elicited by electric stimulation of the dorsal nerves of the penis (DNP). A supraspinal site of action was evaluated by testing the effect of intravenous administration of dapoxetine on DNP-induced PMRDs in rats with chemical bilateral lesion of the lateral paragigantocellular nucleus (LPGi). ResultsCompared with control (NaCl 0.9%, intrathecally), intrathecal injection of dapoxetine (1 and 80μg) significantly increased amplitude of DNP-elicited PMRDs in a similar fashion than serotonin (5-HT; 10 and 100μg, intrathecally). In rats having received bilaterally NaCl 0.9% into LPGi, intravenous treatment with dapoxetine (3mg/kg) induced significant delay in PMRD latency and decrease in PMRD amplitude compared with pretreatment values. These effects were abolished in rats having received bilaterally kainic acid into LPGi 1 d before testing. ConclusionsThe present study showed that dapoxetine inhibits ejaculatory expulsion reflex by acting at a supraspinal level with LPGi as a necessary brain structure for this effect.

What do we know about duloxetine's mode of action? Evidence from animals to humans

The serotonin (5-hydroxytryptamine [5-HT]) and noradrenalin (NA) reuptake inhibitor duloxetine is currently the only widely approved pharmacological treatment option for women with stress urinary incontinence (SUI). The rationale for employing duloxetine in SUI is based on the role of 5-HT and NA in the neurological control of the lower urinary tract. Animal studies have shown that duloxetine increases the concentration of 5-HT and NA in the sacral spinal cord, thereby facilitating an increased activity of the external urethral sphincter (rhabdosphincter) and preventing urine leakage during the storage phase of the micturition cycle. Importantly, 5-HT and NA exert only a modulatory effect as they are not able to directly excite motor neurons. Glutamate is the key descending neurotransmitter and can be considered as the "on/off" switch for micturition. In the absence of glutamate, no rhabdosphincter activity is observed, irrespective of the presence of 5-HT and NA. Hence, duloxetine enhances sphincter activity during urine storage when glutamate is released but allows complete relaxation of the rhabdosphincter once glutamate release is inhibited during the voiding phase. The efficacy of duloxetine for treating women with SUI, as shown in several double-blind, placebo-controlled randomised clinical trials, has suggested a similar mode of action, although no direct evidence for this pathway in humans was available until recently. Two recent studies provide support for duloxetine's mechanism of action in humans. Duloxetine was shown to have a significant effect on the excitability of pudendal motor neurons and on sphincter contractility in healthy women. In contrast, no relevant effect was observed on urethral resting tone. Another study reported important increases in Valsalva leak point pressure and in the rhabdosphincter electrical activity at rest and with coughing in women with SUI who responded to duloxetine. These studies support the hypothesis that duloxetine in women with SUI enhances urethral closure through neuromodulation of the rhabdosphincter.

Facilitatory Neuromodulative Effect of Duloxetine on Pudendal Motor Neurons Controlling the Urethral Pressure: A Functional Urodynamic Study in Healthy Women

ObjectiveThe aim of this functional urodynamic experiment in healthy women was to study the effect of duloxetine, which is a combined serotonin and norepinephrine (5-HT/NE) reuptake inhibitor, on urethral resting pressure, excitability of pudendal motor neurons, and urethral sphincter contractility. MethodsIn 11 healthy female subjects three baseline urethral pressure profiles (UPPs) were obtained to study resting pressure. Afterward the individual motor threshold (MT) for external urethral sphincter (EUS) contraction in response to transcranial magnetic stimulation (TMS) was determined to study the excitability of pudendal motor neurons. Another three UPPs were recorded while sacral root magnetic stimulation (SMS) was performed to evoke reproducible urethral contractions to study urethral sphincter contractility. Then the women received 40mg duloxetine and the protocol was repeated 4h after drug administration. The resting pressure values, MT values following TMS, and the EUS pressure amplitudes in response to SMS obtained at baseline were statistically compared to the corresponding values at follow-up after duloxetine. ResultsOral administration of duloxetine significantly lowered MT for EUS contraction in response to TMS (p=0.013). In addition, duloxetine significantly increased EUS pressure amplitudes in response to SMS (p=0.0007, 5 of 11 subjects evaluated) but did not change urethral resting pressures. ConclusionsThis is the first functional, urodynamic controlled study to show that the combined 5-HT/NE reuptake inhibitor duloxetine has a significant effect on the excitability of pudendal motor neurons and on urethral sphincter contractility in healthy women in vivo but no significant effect on urethral resting tone. Our data confirm a facilitatory neuromodulative effect of duloxetine on sphincter motor neurons in humans.

Immunohistochemical evidence for the interaction between levator ani and pudendal motor neurons in the coordination of pelvic floor and visceral activity in the squirrel monkey

The purpose of this study was to characterize the spinal distribution of afferent and efferent pathways that innervate the levator ani (LA) muscle in the female squirrel monkey. Cholera toxin B (CTB) was injected unilaterally into the LA muscle of 5 monkeys to identify primary sensory neurons in the dorsal root ganglia (DRG) and motor neurons in the spinal cord that contribute fibers to the LA nerve. Fluoro-Gold (FG) was injected into the external anal sphincter of 2 of these animals to label pudendal motor neurons (1 of these animals underwent unilateral LA neurectomy before CTB injection). Spinal cord and DRG were processed for immunofluorescence 3 to 7 days after injections. Retrograde transport of CTB from the LA muscle labeled primary afferent neurons in the ipsilateral DRG, their central projections, and motor neurons in the medial portion of the ipsilateral ventral horn of the spinal cord (L7-S2 segments). Injection of FG into the external anal sphincter labeled cells in Onuf's nucleus, primarily in L7. Importantly, CTB-labeled LA motor neurons were virtually absent in Onuf's nucleus, where all pudendal motor neurons are located. CTB-labeled processes were observed within Onuf's nucleus, adjacent to FG-labeled pudendal motor neurons, and appeared to derive from dendrites of LA motor neurons that project into Onuf's nucleus. The LA muscle has a distinct innervation with very little or no contribution from the pudendal nerve. The intriguing labeling of LA neural elements within a nucleus that innervates the external urethral and anal sphincters (involved in pelvic visceral control) may represent a neuroanatomic substrate for physiologic integration of spinal and supraspinal inputs for the coordination of pelvic floor and visceral activity.

MORPHOLOGICAL STUDY OF THE SPINAL MOTONEURONS CONTROLLING THE URETHRAL SPHINCTER OF FEMALE RATS: ROLE OF ANDROGENS IN A MENOPAUSAL MODEL

In this study in a menopausal rat model we describe the effect of androgen withdrawal on motoneurons innervating 2 muscles involved in female urinary continence, namely the intrinsic urethral sphincter and the pubococcygeus muscle. The 5 groups studied were 2 ovariectomized groups and their sham operated controls plus 1 ovariectomized group with dihydrotestosterone supplementation. Blood testosterone assays were performed. Androgen receptor immunohistochemistry was performed on spinal cord sections, in which specific motoneuron subpopulations were identified. Maximal somal cross-sectional area was compared among the groups. Differences in somal cross-sectional area of motoneurons innervating the pubococcygeus muscle were observed after ovariectomy. Androgen receptor immunopositive nuclei staining disappeared, in line with undetectable blood testosterone levels. The modifications of androgen receptor expression and somal morphological appearance in the pudendal motoneurons controlling the external urethral sphincter of ovariectomized female rats suggests that testosterone probably influences neurotransmission and coordination of urinary continence at the spinal level.

Serotonergic fiber sprouting to external anal sphincter motoneurons after spinal cord contusion

The present study analyzed the anatomical plasticity of serotonergic immunoreactive projections to external anal sphincter (EAS) motoneurons, and the behavioral plasticity of EAS reflexes, penile erection, and locomotion in rats with spinal contusion injury (SCI) or complete spinal cord transection (TX). Electromyographic activity of the EAS, penile erection latency, and BBB locomotor score exhibited parallel recovery over the 6-week recovery period after contusion SCI. This pattern of recovery was not observed in TX animals. While locomotor scores demonstrated a small increase after TX, erectile and anorectal function remained at abnormal levels established immediately after injury. Serotonergic immunofluorescent (5-HT-IF) staining at the lesion site identified a small number of fibers spared after SCI that may provide a substrate for functional recovery. Pixel density measurements of 5-HT-IF in the vicinity of retrogradely labeled EAS and unlabeled pudendal motoneurons necessary for penile erection provide indirect evidence of serotonergic sprouting that parallels the observed functional recovery in animals with SCI. No 5-HT-IF was detected caudal to the injury site in TX animals. These studies indicate: (1) lumbosacral eliminative and reproductive reflexes provide a valid means of studying the mechanisms of post-SCI plasticity; (2) the similar recovery curves suggest similar return of descending control, perhaps through sprouting of descending serotonergic fibers; (3) the observed deficits after TX likely represent the permanent removal of descending inhibition and reflect reorganization of segmental circuitry.

Neural control of erection

Penile erection is a vascular event controlled by the autonomic nervous system. The spinal cord contains the autonomic preganglionic neurons that innervate the penile erectile tissue and the pudendal motoneurons that innervate the perineal striated muscles. Sympathetic pathways are anti-erectile, sacral parasympathetic pathways are pro-erectile, and contraction of the perineal striated muscles upon activity of the pudendal nerves improves penile rigidity. Spinal neurons controlling erection are activated by information from peripheral and supraspinal origin. Both peripheral and supraspinal information is capable of either eliciting erection or modulating or inhibiting an erection already present. Sensory information from the genitals is a potent activator of pro-erectile spinal neurons and elicits reflexive erections. Some pre-motor neurons of the medulla, pons and diencephalon project directly onto spinal sympathetic, parasympathetic and pudendal motoneurons. They receive in turn sensory information from the genitals. These spinal projecting pathways release a variety of neurotransmitters, including biogenic amines (serotonin, dopamine, noradrenaline, and adrenaline) and peptides that, through interactions with many receptor subtypes, exert complex effects on the spinal network that controls penile erection. Some supraspinal structures (e.g. the paraventricular nucleus and the medial preoptic area of the hypothalamus, the medial amygdala), whose roles in erection have been demonstrated in animal models, may not project directly onto spinal pro-erectile neurons. They are nevertheless prone to regulate penile erection in more integrated and coordinated responses of the body, as those occurring during sexual behavior. The application of basic and clinical research data to treatment options for erectile dysfunction has recently proved successful. Pro-erectile effects of phosphodiesterase type 5 inhibitors, acting in the penis, and of melanocortin agonists, acting in the brain, illustrate these recent developments.

Neural control of erection

Penile erection is a vascular event controlled by the autonomic nervous system. The spinal cord contains the autonomic preganglionic neurons that innervate the penile erectile tissue and the pudendal motoneurons that innervate the perineal striated muscles. Sympathetic pathways are anti-erectile, sacral parasympathetic pathways are pro-erectile, and contraction of the perineal striated muscles upon activity of the pudendal nerves improves penile rigidity. Spinal neurons controlling erection are activated by information from peripheral and supraspinal origin. Both peripheral and supraspinal information is capable of either eliciting erection or modulating or inhibiting an erection already present. Sensory information from the genitals is a potent activator of pro-erectile spinal neurons and elicits reflexive erections. Some pre-motor neurons of the medulla, pons and diencephalon project directly onto spinal sympathetic, parasympathetic and pudendal motoneurons. They receive in turn sensory information from the genitals. These spinal projecting pathways release a variety of neurotransmitters, including biogenic amines (serotonin, dopamine, noradrenaline, and adrenaline) and peptides that, through interactions with many receptor subtypes, exert complex effects on the spinal network that controls penile erection. Some supraspinal structures (e.g. the paraventricular nucleus and the medial preoptic area of the hypothalamus, the medial amygdala), whose roles in erection have been demonstrated in animal models, may not project directly onto spinal pro-erectile neurons. They are nevertheless prone to regulate penile erection in more integrated and coordinated responses of the body, as those occurring during sexual behavior. The application of basic and clinical research data to treatment options for erectile dysfunction has recently proved successful. Pro-erectile effects of phosphodiesterase type 5 inhibitors, acting in the penis, and of melanocortin agonists, acting in the brain, illustrate these recent developments.

Identification of Androgen Receptors in the Motoneurons of the External Urethral Sphincter in the Spinal Cord of Female Rats

In women, aging is associated with profound hormonal changes. Menopause has been implicated in the etiology of urinary tract complaints including incontinence, urgency and recurrent urinary tract infections. However, the use of hormone replacement therapy for these conditions has given conflicting and disappointing results. The role of androgen changes on urinary continence in perimenopausal women has not been studied. We studied the presence of androgen receptors in pudendal motoneurons controlling the external urethral sphincter of female rats. A combination of retrograde labeling of pudendal motoneurons from the external urethral sphincter and immunohistochemistry for the N-terminal portion of androgen receptors on spinal cord sections was performed in adult female rats. Androgen receptors were identified in the nuclei of the ventral horn of the L5-L6 spinal cord. Pudendal motoneurons, retrogradely labeled from the external urethral sphincter, were identified in the dorsolateral nucleus of the ventral horn at the same levels. Confocal microscopy demonstrated the presence of nuclear and cytoplasmic androgen receptors in the cell bodies of these retrogradely labeled pudendal motoneurons. Our study demonstrated the presence of androgen receptors in the cell bodies of retrogradely labeled pudendal motoneurons controlling the urethral sphincter of female rats suggesting a role of androgens in the neuromodulation of urethral sphincter function at the spinal level.

Duloxetine versus Placebo for the Treatment of North American Women with Stress Urinary Incontinence

Six hundred thirty-three women with stress urinary incontinence (SUI) without predominant urge incontinence symptoms were recruited to participate in a double-blind, placebo-controlled, randomized study to investigate the use of duloxetine in the treatment of SUI. This drug is an inhibitor of serotonin and norepinephrine reuptake, which acts by stimulating pudendal motor neurons and increasing striated urethral sphincter contractility. At the time of enrollment, patients underwent the Patient Global Impression Severity rating to establish baseline SUI symptoms and the Beck Depression Inventory-II (BDI-II) to measure baseline depression symptoms. The study included a 2-week lead-in period during which no drugs were given while patients completed a 7-day real-time voiding diary. During a second 2-week period, all participants were given a placebo and completed another 7-day real-time voiding diary. They were then randomized to receive either duloxetine or placebo twice daily for 12 weeks. During this period, patients were seen every 4 weeks and completed a voiding diary for 1 week before each visit. The frequency of incontinence episodes was determined from the diaries. At each visit, patients were evaluated using the Patient Global Impression of Improvement (PGI-I) to determine improvement in SUI symptoms and the Quality of Life Questionnaire (I-QOL) to measure the impact of SUI on social behaviors and interaction. At the end of the 12 weeks, the BDI-II was given again to measure changes in symptoms of depression. There was no difference in demographic or incontinence data between the 2 groups. After the 12-week period, 87% of the participants in the placebo group compared with 63% of those in the duloxetine group were still participating in the study (P <0.001). At least one postrandomization diary was completed by 95% of the placebo group and 83% of the treatment group. Ninety-eight percent and 97% completed an I-QOL, respectively. An intent-to-treat analysis of all patients with at least one postrandomization diary showed a median decrease of 7 incontinence episodes in the duloxetine group compared with a decrease of 3 per week in the placebo group (P <0.001). Over half of participants taking duloxetine experienced a 50% to 100% decrease in incontinence episodes and 10.5% had no episodes compared with 35% and 5.9%, respectively, of women taking placebo (P <0.001 and P <0.05, respectively). The average voiding interval increased significantly for the duloxetine group compared with the placebo group (20 vs. 2 minutes). The duloxetine group had an I-QOL score of 12.1 at the end of the 12-week period compared with 7.2 for the placebo group (P <0.001). Overall, I-QOL scores were 11.1 and 6.8, respectively (P <0.001). Patients receiving duloxetine treatment reported a 62.0% improvement on the PGI-I compared with 39.6% of the women taking placebo (P <0.001). Mean BDI-II scores were normal at both baseline and study completion. Adverse reactions were significantly more common among women taking duloxetine than those taking placebo (Table 1). By the fourth week, nearly all (91%) of the duloxetine group reported nausea symptoms. Most frequently, nausea developed after 2 days of treatment. Symptoms were mild to moderate in severity in 87% of these patients and decreased over time for all except one woman.

Paper 17: Immunohistochemical Evidence for the Interaction between Levator Ani and Pudendal Motor Neurons in the Coordination of Pelvic Floor and Visceral Activity

Paper 17: Immunohistochemical Evidence for the Interaction between Levator Ani and Pudendal Motor Neurons in the Coordination of Pelvic Floor and Visceral Activity