The influence of afferent inputs from skin and viscera on the activity of the bladder and the skeletal muscle surrounding the urethra in the rat

Sophisticated regulation of micturition: review of basic neurourology

The neurological regulation of the lower urinary tract can be viewed separately from the perspective of sensory neurons and motor neurons. First, in the receptors of the bladder and urethra of sensory nerves, sensations are transmitted through the periaqueductal gray matter of the midbrain to the cerebral cortex, and the cerebrum goes through the process of decision-making. Motor neurons are divided into upper motor neurons (UMNs) and lower motor neurons (LMNs). UMNs coordinate storage and micturition in the brain stem so that synergic voiding can occur. LMNs facilitate muscle contractions in the spinal cord. The muscles involved in urinary storage and micturition are innervated by the somatic branches of sympathetic, parasympathetic, and peripheral nerves. Sympathetic nerves are responsible for contractions of urethral smooth muscles, while parasympathetic nerves originate from S2–S4 and are in charge of contractions of the bladder muscle. Somatic nerves originate from the motor neurons in Onuf’s nucleus, which is a specific part of somatic nerves. In this review, we will investigate the structures of the nervous systems related to the lower urinary tract and the regulatory system of innervation for the urinary storage and micturition and discuss the clinical significance and future prospects of neurourological research.

Effect of low-threshold versus high-threshold genitalia stimuli on the cystometry parameters in male rats

The cross talk between external genitalia and urinary bladder could be used as part of management to certain pathological conditions affecting urinary bladder. Since urinary bladder function is also affected by pathologies of other organs (e.g., colon and esophagus), the effect of genitalia stimuli on parameters of bladder function in normal or under different pathological conditions needs to be characterized. Cystometry recordings in male rats were used to examine the effect of low-threshold (LT) and high-threshold (HT) stimulation of the scrotum and penis on urinary bladder function. These effects were studied in intact, colon irritation (CI), and esophagus irritation (EI) groups. Although HT penile stimulation had a significant inhibitory effect on micturition reflex in all groups, CI hypersensitized the penile-bladder inhibitory reflex. In addition, LT penile stimulation had a significant inhibitory effect on micturition, which was significant in CI group only. On the other hand, HT penile stimulation in CI group significantly increased the timing parameters of cystometry. Whereas LT and HT penile stimuli in EI group had a significantly increasing effect on all pressure parameters of cystometry. The scrotal stimuli had minimal effect on bladder function in all groups except for HT scrotal stimulation in the CI group, where it had a significant inhibitory effect on micturition reflex and significantly increased the maximum pressure and pressure amplitude of micturition cycles. These results show that CI and EI exacerbate the effects of genitalia stimuli, especially penile stimuli, on urinary bladder function.

Age-Related Changes in Neuromodulatory Control of Bladder Micturition Contractions Originating in the Skin

The brainstem is essential for producing micturition contractions of the urinary bladder. Afferent input from perineal skin evoked by gentle mechanical stimulation inhibits micturition contractions by decreasing both ascending and descending transmissions between the brainstem and spinal cord. Dysfunction of this inhibitory mechanism may be one cause of the increase in the prevalence of overactive bladder in old age. The aim of this study was to examine effect of aging on function of skin afferent fibers that inhibit bladder micturition contractions in rats. We used anesthetized male rats in three different age groups: young adult (4–5 months old), middle aged (6–9 months old), and aged (27–30 months old). The bladder was expanded to produce isovolumetric rhythmic micturition contractions. Skin afferent fibers were activated for 1 min either by electrical stimulation (0.5 ms, 0.2–10 V, 0.1–10 Hz) of the cutaneous branch of the pudendal nerve (CBPN) or by gentle mechanical skin stimulation with an elastomer roller. When skin afferent nerves were activated electrically, micturition contractions were inhibited in a similar manner in all age groups, with long latency inhibition induced by excitation of Aβ fibers and short latency inhibition by additional Aδ and C fiber excitation (at 1–10 Hz). On the contrary, when skin afferent nerves were activated mechanically by rolling, latency of inhibition following rolling stimulation was prolonged in aged rats. Single unitary afferent nerve activity of low-threshold mechanoreceptors (LTMs) from the cutaneous nerve was recorded. The discharge rate during rolling was not significantly reduced in Aβ units but was much lower in Aδ and C units in aged rats (0.4 and 0.5 Hz, respectively) than in young adult rats (3 and 7 Hz). These results suggest that the neural mechanism that inhibits bladder micturition contractions by skin afferent input is well maintained in old age, but the early inhibition by gentle skin stimulation is decreased because of reduced responses of Aδ- and C-LTMs.

Acupuncture at homotopic acupoints exerts dual effects on bladder motility in anesthetized rats

BACKGROUND

In Chinese medicine, dual effects on target organs are considered a primary characteristic of acupoint. Acupoints may be classified as heterotopic or homotopic in terms of spinal segmental innervation: homotopic acupoints contain afferent innervation in the same segment from which efferent fibers innervate target visceral organs, and heterotopic acupoints utilize different spinal segments to innervate target visceral organs than the segment receiving the afferent signal. It is well-known that dual effects of acupuncture on the bladder can be generated based on different states of the bladder, however, the dual effects of single acupoint stimulation and acupoint site-specificity (homotopic acupoints and heterotopic acupoints) on the bladder have yet to be investigated.

METHODS

Twenty Sprague-Dawley rats were anesthetized and the intravesical pressure was measured via a manometric balloon inserted into the bladder. The acupuncture needle was separately inserted to a depth of 4 mm at the acupoints RN1 (Huiyin), RN3 (Zhongji), BL28 (Pangguangshu), BL32 (Ciliao), RN2 (Qugu) or BL23 (Shenshu), and manually rotated right then left with a frequency of 2 Hz for 1 min. Following acupuncture stimulation, bladder pressure was recorded and compared against the pre-stimulation measurements.

RESULTS

During the bladder's active state, manual acupuncture (MA) at RN1, RN3, BL28, BL32 or RN2 inhibited bladder motility (P < 0.01). In the static bladder, MA at RN1, RN3, BL28, BL32, RN2 or BL23 increased bladder motility (P < 0.01).

CONCLUSIONS

MA at homotopic acupoints may produce dual effects on bladder motility: inhibiting bladder motility when in an active state and enhancing bladder motility when in a static state.

Gentle Mechanical Skin Stimulation Inhibits Micturition Contractions via the Spinal Opioidergic System and by Decreasing Both Ascending and Descending Transmissions of the Micturition Reflex in the Spinal Cord

Recently, we found that gentle mechanical skin stimulation inhibits the micturition reflex in anesthetized rats. However, the central mechanisms underlying this inhibition have not been determined. This study aimed to clarify the central neural mechanisms underlying this inhibitory effect. In urethane-anesthetized rats, cutaneous stimuli were applied for 1 min to the skin of the perineum using an elastic polymer roller with a smooth, soft surface. Inhibition of rhythmic micturition contractions by perineal stimulation was abolished by naloxone, an antagonist of opioidergic receptors, administered into the intrathecal space of the lumbosacral spinal cord at doses of 2–20 μg but was not affected by the same doses of naloxone administered into the subarachnoid space of the cisterna magna. Next, we examined whether perineal rolling stimulation inhibited the descending and ascending limbs of the micturition reflex. Perineal rolling stimulation inhibited bladder contractions induced by electrical stimulation of the pontine micturition center (PMC) or the descending tract of the micturition reflex pathway. It also inhibited the bladder distension-induced increase in the blood flow of the dorsal cord at L5–S1, reflecting the neural activity of this area, as well as pelvic afferent-evoked field potentials in the dorsal commissure at the lumbosacral level; these areas contain long ascending neurons to the PMC. Neuronal activities in this center were also inhibited by the rolling stimulation. These results suggest that the perineal rolling stimulation activates the spinal opioidergic system and inhibits both ascending and descending transmissions of the micturition reflex pathway in the spinal cord. These inhibitions would lead to the shutting down of positive feedback between the bladder and the PMC, resulting in inhibition of the micturition reflex. Based on the central neural mechanisms we show here, gentle perineal stimulation may be applicable to several different types of overactive bladder.

[Noxious stimuli and neurogenic overactive bladder]

OBJECTIVES

Describe the relationships between neurogenic overactive bladder and noxious stimuli.

METHODS

Relevant data from the literature were identified primarily through a Medline search of articles published through July 2014. The search terms included overactive bladder, central nervous system, noxious visceral and cutaneous stimuli.

RESULTS

Overactive bladder often due to overactive detrusor is the most common symptom observed in central neurogenic bladder (70 to 80% in case of spinal cord injury). Pathophysiological mechanisms are various and numerous. Noxious cutaneous stimuli may determine, or maintain, these symptoms by increased afferent inputs in segmental levels, particularly S2S3 levels, determining exaggerated visceral, muscle and bladder responses depending on this considered medullary level. These modifications are only observed in case of central neurogenic lesions secondary to spinal cord involvement. Animal researches have precised the role of lack of the supra-segmental inhibition.

CONCLUSIONS

In presence of neurogenic overactive bladder, it is always necessary to track down noxious stimuli particularly in case of modifications of clinical or urodynamic status or when the usual treatments, generally anticholinergic drugs, have a reduced efficacy. Treatment is first focused on the suppression of these noxious cutaneous stimuli.

Electrical stimulation for the treatment of lower urinary tract dysfunction after spinal cord injury

Electrical stimulation for bladder control is an alternative to traditional methods of treating neurogenic lower urinary tract dysfunction (NLUTD) resulting from spinal cord injury (SCI). In this review, we systematically discuss the neurophysiology of bladder dysfunction following SCI and the applications of electrical stimulation for bladder control following SCI, spanning from historic clinical approaches to recent pre-clinical studies that offer promising new strategies that may improve the feasibility and success of electrical stimulation therapy in patients with SCI. Electrical stimulation provides a unique opportunity to control bladder function by exploiting neural control mechanisms. Our understanding of the applications and limitations of electrical stimulation for bladder control has improved due to many pre-clinical studies performed in animals and translational clinical studies. Techniques that have emerged as possible opportunities to control bladder function include pudendal nerve stimulation and novel methods of stimulation, such as high frequency nerve block. Further development of novel applications of electrical stimulation will drive progress towards effective therapy for SCI. The optimal solution for restoration of bladder control may encompass a combination of efficient, targeted electrical stimulation, possibly at multiple locations, and pharmacological treatment to enhance symptom control.

Visceral nociceptive afferent facilitates reaction of subnucleus reticularis dorsalis to acupoint stimulation in rats

Objective. To explore the area and sensitization variance of acupoint when internal organs are under pathological condition. To observe quantity-effect variance of subnucleus reticularis dorsalis (SRD) to electroacupuncture under both physiological and pathological conditions. To explain medulla oblongata mechanism of acupoint sensitization. Method. Mustard oil was imported into colon and rectum of 20 male SD rats in order to observe its influence on acupoint sensitization. SRD neuron activity was recorded. Visceral nociceptive stimulus was generated by colorectal distension (CRD). Quantity-effect variance of neuron activity to electroacupuncture to “Zusanli-Shangjuxu” area both before and after CRD was observed. Paired t-test is used for cross-group comparison; P < 0.05 is deemed as of statistical differences. Result. Visceral inflammation could facilitate SRD neuron activity to acupoint stimulation. Visceral nociceptive afference could enhance neuron activity to acupoint acupuncture. Wide dynamic range (WDR) neuron activity caused by electroacupuncture increased when visceral nociception increased. Conclusion. The size and function of the acupoints comply with the functionality of the internal organs. The sensitive degree of acupoints changed according to malfunction of internal organs.

Effects of acute selective pudendal nerve electrical stimulation after simulated childbirth injury

During childbirth, a combinatorial injury occurs and can result in stress urinary incontinence (SUI). Simulated childbirth injury, consisting of vaginal distension (VD) and pudendal nerve crush (PNC), results in slowed recovery of continence, as well as decreased expression of brain-derived neurotrophic factor (BDNF), a regenerative cytokine. Electrical stimulation has been shown to upregulate BDNF in motor neurons and facilitate axon regrowth through the increase of β(II)-tubulin expression after injury. In this study, female rats underwent selective pudendal nerve motor branch (PNMB) stimulation after simulated childbirth injury or sham injury to determine whether such stimulation affects bladder and anal function after injury and whether the stimulation increases BDNF expression in Onuf's nucleus after injury. Rats received 4 h of VD followed by bilateral PNC and 1 h of subthreshold electrical stimulation of the left PNMB and sham stimulation of the right PNMB. Rats underwent filling cystometry and anal pressure recording before, during, and after the stimulation. Bladder and anal contractile function were partially disrupted after injury. PNMB stimulation temporarily inhibited bladder contraction after injury. Two days and 1 wk after injury, BDNF expression in Onuf's nucleus of the stimulated side was significantly increased compared with the sham-stimulated side, whereas β(II)-tubulin expression in Onuf's nucleus of the stimulated side was significantly increased only 1 wk after injury. Acute electrical stimulation of the pudendal nerve proximal to the crush site upregulates BDNF and β(II)-tubulin in Onuf's nucleus after simulated childbirth injury, which could be a potential preventive option for SUI after childbirth injury.

Applied kinesiology: distinctions in its definition and interpretation

Modification of the motor system in assessing and treating as well as understanding one of the causes of musculoskeletal dysfunctions is a topic of growing importance in healthcare. Applied kinesiology (AK) addresses this interest in that it is a system which attempts to evaluate numerous aspects of health (structural, chemical, and mental) by the manual testing of muscles combined with other standard methods of diagnosis. It leads to a variety of conservative, non-invasive treatments which involve joint manipulations or mobilizations, myofascial therapies, cranial techniques, meridian and acupuncture skills, clinical nutrition and dietary management, counseling skills, evaluating environmental irritants, and various reflex techniques. The effectiveness of these ancillary treatments is believed to be consistent with the expanded construct validity of the manual muscle test (MMT), as described, although this assertion has primarily been tested in outcome studies. AK and its adjunctive procedures (challenge and therapy localization) are highlighted in this review providing details of its implementation as prescribed by an International College of Applied Kinesiology's Board of Examiners, cited for its scholarly and scientific activities. Because these procedures are believed to identify specific articular, soft tissue, biochemical, or emotional issues underlying muscle function, the applicability of this diagnostic method for all clinicians treating muscle imbalance disorders is described. As of yet, MMT efficacy in therapy localization and challenge techniques has not been established in published, peer-reviewed research. A variety of challenges likewise remain for professional AK to establish itself as an emerging science, with numerous gaps in the literature and testable hypotheses enumerated. Of particular concern are a multiplicity of derivatives of AK that have been described in the literature, which should be greeted with caution in light of the fact that they lack one or more of the essential attributes of AK as described in this report. The validity of these studies which have been critical of applied kinesiology appears in many instances to be no greater than several of the randomized controlled trials, cohort studies, case control studies, and case studies found in this communication to support various aspects of applied kinesiology.

Developmental delay syndromes: psychometric testing before and after chiropractic treatment of 157 children

OBJECTIVE

This study presents a case series of 157 children with developmental delay syndromes, including the conditions such as dyspraxia, dyslexia, attention-deficit hyperactivity disorder, and learning disabilities who received chiropractic care.

CLINICAL FEATURES

A consecutive sample of 157 children aged 6 to 13 years (86 boys and 71 girls) with difficulties in reading, learning, social interaction, and school performance who met these inclusion criteria were included.

INTERVENTION AND OUTCOMES

Each patient received a multimodal chiropractic treatment protocol, applied kinesiology chiropractic technique. The outcome measures were a series of 8 standardized psychometric tests given to the children by a certified speech therapist pre- and posttreatment, which evaluate 20 separate areas of cognitive function, including patient- or parent-reported improvements in school performance, social interaction, and sporting activities. Individual and group data showed that at the end of treatment, the 157 children showed improvements in the 8 psychometric tests and 20 areas of cognitive function compared with their values before treatment. Their ability to concentrate, maintain focus and attention, and control impulsivity and their performance at home and school improved.

CONCLUSIONS

This report suggests that a multimodal chiropractic method that assesses and treats motor dysfunction reduced symptoms and enhanced the cognitive performance in this group of children.

Emerging drugs for treatment of overactive bladder and detrusor overactivity

BACKGROUND

Overactive bladder (OAB) signifies the presence of urinary urgency and can have major effects on quality of life and social functioning. Standard antimuscarinic drugs have good initial response rates but substantial adverse effects and long-term compliance problems.

OBJECTIVES

To review the complexities of the mechanisms underlying OAB and the current drugs available for treating its symptoms.

METHODS

The literature was reviewed to define current therapies and drugs in clinical trials. Articles were identified by means of a computerised PubMed and Cochrane Library search (using the following keywords: overactive bladder, detrusor overactivity, urgency and bladder), supported by a search of the PharmaProjects database.

CONCLUSIONS

New drug classes, such as beta-3 adrenergic agonists, may work by reducing contractility or excitability of bladder muscle. Moderation of afferent activity may allow improved OAB symptoms, with lower risk of affecting voiding function. Agents acting on the CNS could influence OAB favourably, but target selection and adverse effects are an issue. The recognition of the functional contribution of the urothelium and the diversity of nerve transmitters has sparked interest in both peripheral and central modulation of OAB pathophysiology.

Characterization and restoration of altered inhibitory and excitatory control of micturition reflex in experimental autoimmune encephalomyelitis in rats

Multiple sclerosis (MS) is characterized by inflammatory lesions throughout the central nervous system. Spinal cord inflammation correlates with many neurological defecits. Most MS patients suffer from micturition dysfunction with urinary incontinence and difficulty in emptying the bladder. In experimental autoimmune encephalomyelitis (EAE) induced in female Lewis rats, a model of MS, we investigated at distinct clinical severity scores the micturition reflex by cystometrograms. All rats presenting symptomatic EAE suffered from micturition reflex alterations with either detrusor areflexia or hyperactivity. During pre-symptomatic EAE, a majority of rats presented with detrusor areflexia, whereas at onset of clinical EAE, detrusor hyperactivity was predominant. During progression of EAE, detrusor areflexia and hyperactivity were equally expressed. Bladder hyperactivity was suppressed by activation of glycine and GABA receptors in the lumbosacral spinal cord with an order of potency: glycine > GABA(B) > GABA(A). Detrusor areflexia was transformed into detrusor hyperactivity by blocking glycine and GABA receptors. Spinalization abolished bladder activity in rats presenting detrusor hyperactivity and failed to induce activity in detrusor areflexia. Altogether, the results reveal an exaggerated descending excitatory control in both detrusor reflex alterations. In detrusor areflexia, a strong segmental inhibition dominates this excitatory control. As in treatment of MS, electrical stimulation of sacral roots reduced detrusor hyperactivity in EAE. Blockade of glycine receptors in the lumbosacral spinal cord suppressed the stimulation-induced inhibitory effect. Our data help to better understand bladder dysfunction and treatment mechanisms to suppress detrusor hyperactivity in MS.

Integrated control of lower urinary tract--clinical perspective

The neural mechanisms that determine social bladder control are reviewed, with a particular emphasis on the role played by sensation in the process. Much has been learnt about the neural control of the bladder from studying patients with neurological disease and those disorders that are known to disrupt bladder storage are described. Possible approaches to treatment of the resulting incontinence are reviewed and it is acknowledged that in the future, the optimal treatment for incontinence may be determined by its precise underlying pathophysiology in each instance, for example, suprapontine causes requiring different medication to spinal causes. Although the main emphasis of urological research and development so far has been the treatment of incontinence, effective therapy for other bladder disorders such an impaired emptying or bladder pain could have an important impact on the bladder symptoms of many patients.

Afferent bladder nerve activity in the rat: a mechanism for starting and stopping voiding contractions

The objective of this work was to study the relation between afferent bladder nerve activity and bladder mechanics and the mechanisms that initiate and terminate bladder contractions. Bladder nerve activity, pressure and volume were recorded during the micturition cycle in the rat. The highest correlation was found between afferent nerve activity and stress (pressure x volume). Afferent nerve activity depended linearly on stress within 6%, and both slope and offset were independent of the bladder-filling rate. The levels of afferent bladder nerve activity at the onset and cessation of efferent firing to the bladder were highly reproducible with coefficients of variation of <or=17%. We propose a model in which afferent activity is proportional to bladder wall stress, and bladder contraction is initiated when afferent activity exceeds a threshold due to an increasing pressure and volume. The contraction continues until afferent activity drops below a threshold again as a result of a decreasing volume.

Effects of the atypical neuroleptic clozapine on micturition parameters in anesthetized rats

Clozapine, an atypical antipsychotic, has resulted in a number of reports of urinary disturbances in the clinical literature. We examined the effects of clozapine on urodynamic parameters in the anesthetized rat and compared the effects to those of the typical antipsychotic haloperidol and the selective D2 and D4 antagonists, raclopride and L-745,870, respectively. Clozapine abolished high-frequency oscillations (HFO) during the expulsion phase, and profoundly altered a number of other parameters (e.g., intercontraction interval and resting pressure). Clozapine did not affect the peak contraction pressure during cystometrograms but displayed peripheral inhibition of bladder contractions elicited by electrical stimulation of the pelvic nerve (possibly mediated via clozapine's anti-muscarinic effects). Haloperidol had less potent effects than clozapine since it reduced the amplitude of HFO to 25% of control and also affected several other parameters but without peripheral bladder inhibition. Raclopride only resulted in a modest decrease (approximately 70% of control) in the HFO and no alteration in other parameters. L-745,870 was effective only at highest dose tested suggesting that it might not be acting selectively at D4 receptors. Therefore, we propose that clozapine primarily interferes with the function of the external urethral sphincter. These effects can only be partly explained through antagonism of D2 receptors. Since both clozapine and haloperidol have interactions with other transmitter systems beside dopamine, we suggest that central antagonism of D2 receptors, coupled to central antagonism of another receptor system and peripheral muscarinic receptor blockade, may account for clozapine's potent effects on micturition.

Possible action of the proximal rhabdosphincter muscle in micturition of the adult male rat

Micturition requires high bladder pressure and simultaneous opening of the urethra. In adult male rat, a rhabdosphincter (RB) is known to be electrically active when the bladder pressure is high. This indicates a closure rather than an opening of the urethra, which is inconsistent with the requirements of optimal urodynamics. In order to solve this problem, we simultaneously recorded electromyogram (EMG) of the proximal RB, bladder pressure, and flow rate. Micturition was evoked by an increased volume of saline in the bladder. A computer-based recording device was used with minimal filtering. The EMG was recorded with a monopolar flexible suction electrode. The suction electrode records action potentials resembling those obtained with a microelectrode technique. During the early high-frequency intraluminal pressure oscillation period (IPHFO), the increase of pressure initially associated with a decrease of potential of the RB. When the first flow peak appeared, the relationship of the bladder pressure and RB single EMG activities changed. The increasing pressure coincided with the positive potential wave (depolarisation). It was interrupted by a transient negative polarity period called transient repolarisation (TRP) coinciding with a flow rate peak, thus indicating an opening of the RB lumen. After the TRP, the depolarisation continued. Additional experiments employing different methods are needed for positive identification of the TRP mechanism.

Separate urinary bladder and external urethral sphincter neurons in the central nervous system of the rat: simultaneous labeling with two immunohistochemically distinguishable pseudorabies viruses

This work examines the distribution, in the central nervous system, of virus-labeled neurons from the rat urinary bladder and the external urethral sphincter simultaneously within the same tissue sections. Two immunohistochemically distinct pseudorabies virus strains were injected into male Sprague--Dawley rats (approximately 280 g). One virus was injected into the bladder and the other into the external urethral sphincter. After incubation intervals of 2, 2.5 and 3 days, sections from the spinal cord and brain were treated immunohistochemically to detect cells which were labeled separately by each virus or were labeled by both viruses. The major result of these experiments is that each strain of virus labeled a separate population of neurons and that some neurons were labeled by both strains. In the lumbosacral cord, 3 days post-infection, neurons labeled by virus from the external urethral sphincter were found in Onuf's nucleus, the dorsal gray commissure, and the superficial dorsal horn. Neurons labeled by virus from the urinary bladder were found in the L6--S1 and L1--L2 spinal cord segments within the dorsal gray commissure, the intermediolateral area and the superficial dorsal horn. Double-labeled interneurons were mainly located in the dorsal gray commissure although some were also found in the intermediolateral area and the superficial dorsal horn. In the medulla, external urethral sphincter neurons and bladder neurons and double-labeled neurons were found in the reticular region and the raphe. More rostrally, bladder neurons were located in the pontine micturition center and external urethral sphincter neurons were found in the locus coeruleus and subcoeruleus. A very small number of double-labeled neurons were found in the pontine micturition center and the locus coeruleus or subcoeruleus.

Non-bacterial cystitis

The concept of non-bacterial cystitis (NBC) combines sterile urine and cystitic symptoms as well as inflammatory changes, in particular in the mucosa and submucosa of the bladder. It includes a multiplicity of vicious circles along the entire continence reflex. An understanding of NBC presupposes knowledge of the origin of the normal urinary urge and its successful control. Against the background of the steadily increasing incidence of interstitial cystitis (often irreversible end-stage NBC), it is suggested here that in the face of a failure of first-line therapeutics (anticholinergics, cyclic antidepressants or oestrogens), one must consider without delay the possible presence of NBC.

Uterine contractility and blood flow are reflexively regulated by cutaneous afferent stimulation in anesthetized rats

The effects of cutaneous mechanical afferent stimulation of various skin areas on uterine contractility and blood flow were examined in anesthetized non-pregnant rats. The contractility of the uterus was measured by the balloon method in the uterus. The uterine blood flow was measured by laser Doppler flowmetry. Noxious pinching stimulation of the perineum for 1 min induced an abrupt contraction of the uterus during stimulation. Pinching of a hindpaw or perineum and innocuous brushing of the perineum for 1 min increased uterine blood flow. Stimulation of other skin areas produced no changes in uterine contractility or blood flow. Most uterine responses were abolished by severance of the pelvic nerves, which innervated the uterus. The activity of pelvic parasympathetic efferent nerves to the uterus increased following perineal pinching. All these cutaneous stimulation-induced responses of uterine contractility, blood flow and pelvic efferent nerve activity still existed, and were even augmented, after acute spinalization. These results indicate that cutaneous mechanical sensory stimulation can regulate uterine contractility and blood flow by a segmental spinal reflex mechanism via uterine parasympathetic efferent nerves.

Neurophysiological modeling of voiding in rats: urethral nerve response to urethral pressure and flow

In male urethan-anesthetized rats, activity was measured in nerves that run over the proximal urethra. The urethral nerve response to stepwise urethral perfusion could be described by a four-parameter model (fit error < 6%). At the onset of perfusion, the urethra was closed and the pressure increased with the infused volume. The nerve activity (NA) increased linearly with this inserted volume to a maximum (NAmax), which was proportional to the instantaneous pressure. The duration of this first episode (delta t) was inversely proportional to the perfusion rate. After infusion of a fixed volume, the urethra opened and the NA decreased with a time constant phi -1 (approximately 1.8 s) to an elevated level (NAlevel). NAlevel was linearly related to the steady-state pressure. Accordingly, sensors in the urethra are sensitive to pressure rather than to the perfusion rate. The parameters NAmax, NAlevel, and delta t showed very good reproducibility (SD approximately 19% of mean). The measured activity was most likely afferent and conducted to the major pelvic ganglion.

Central effects of (5RS, 1'SR)-5-benzyl-3-(3'-morpholino-1'-phenylpropyl)-1,3-oxazolidin-2 -one monofumarate on the function of the bladder and periurethral skeletal muscle in anesthetized rats

The effects of a newly developed drug for incontinence, (5RS, 1'SR)-5-benzyl-3-(3'-morpholino-1'-phenylpropyl)-1,3-oxazolidin-2- one monofumarate (NC-1800), on bladder and periurethral skeletal muscle functions were tested in urethane-anesthetized rats. When the bladder pressure was low, i.v. administration of NC-1800 at doses of 4 to 16 mg/kg induced dose-dependent increases of vesical pressure associated with increases in pelvic efferent nerve activity. When the bladder was expanded, the same administration of NC-1800 induced dose-dependent inhibitions of both vesical micturition contractions and rhythmic pelvic burst discharges. Hypogastric efferent nerve activity was not affected. The periurethral electromyogram (EMG) activity was excited when the bladder was contracted, and EMG activity was inhibited when the bladder was relaxed by NC-1800. Pelvic ganglionic transmission, neuromuscular transmission of both bladder and urethra, and muscle contractility itself of bladder and urethra were not affected by NC-1800. These results suggest that NC-1800 modulates the functions of the bladder and urethra by influencing pelvic and pudendal nerve activity via the central nervous system.

Excitatory and inhibitory A- and C-reflexes in pelvic parasympathetic efferent nerves elicited by single shock to A and C afferent fibers of perineal and limb somatic nerves in anesthetized rats

The effects of single electrical shocks to myelinated A and unmyelinated C afferent fibers of perineal and limb somatic nerves on the reflex discharges in pelvic parasympathetic (L6/S1) efferent nerves to the bladder were examined in anesthetized central nervous system (CNS)-intact and acute spinal rats. When the bladder was empty, stimulation of perineal somatic inputs to the L6 and S1 segments from the perineo-femoral branch of a pudendal nerve produced excitatory A- and C-reflex discharge components in postganglionic parasympathetic efferent nerve branches on the bladder surface. When the bladder was expanded and pelvic efferent neurons were rhythmically active, additional inhibitory A- and C-reflex components could be seen. After acute spinal transection, the same stimuli elicited excitatory A- and C-reflex discharges of similar latency as those observed before the spinal transection, but were of larger amplitude and longer duration; resting activity in the pelvic nerve was low, and no evoked inhibitory reflex components could be observed. Electrical stimulation of afferents in the tibial nerve had no effect when the bladder pressure was low, but when the bladder was distended, early and late components of reflex inhibition and excitation of parasympathetic activity were visible in CNS-intact rats; these reflex responses were abolished following spinalization.

The nitric oxide synthase inhibitor L-NAME reduces inhibitory components of somato-vesical parasympathetic reflexes in the rat

Reflex discharges of pelvic postganglionic parasympathetic efferent fibers on the bladder surface induced by afferent volleys in the hindlimb nerve have been recorded in anesthetized rats, and the effects of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME) on the reflex discharges have been investigated. Single electrical stimulation of the tibial nerve at intensities supramaximal for excitation of A- and C-afferents evoked a reflex discharge in the postganglionic parasympathetic efferents with four distinct components, i.e., two inhibitory components with latencies of 49 and 203 ms, respectively, and two excitatory components with latencies of 126 and 308 ms, respectively. These reflexes could be observed when the bladder was expanded, but not markedly when the bladder was empty. Intravenous administration of L-NAME resulted in (a) a reduction in the level of resting discharge, (b) a reduction in the size of the first inhibitory component, (c) the disappearance of the second inhibitory component and (d) the exaggeration of the late excitatory component. Intracisternal injection of L-NAME caused changes similar to those observed following intravenous injection. The results suggest that inhibitory components of the somato-pelvic parasympathetic reflex are mediated by pathways that utilize nitric oxide as a neurotransmitter or neuromodulator at the level of the brainstem.