Peptide-containing nerves in human urinary bladder

Bisphenol A affects vipergic nervous structures in the porcine urinary bladder trigone

Bisphenol A (BPA) is used in the production of plastics approved for contact with feed and food. Upon entering living organisms, BPA, as a potent endocrine disruptor, negatively affects various internal organs and regulatory systems, especially in young individuals. Although previous studies have described the neurotoxic effects of BPA on various tissues, it should be underlined that the putative influence of this substance on the chemical architecture of the urinary bladder intrinsic innervation has not yet been studied. One of the most important neuronal substances involved in the regulation of urinary bladder functions is vasoactive intestinal polypeptide (VIP), which primarily participates in the regulation of muscular activity and blood flow. Therefore, this study aimed to determine the influence of various doses of BPA on the distribution pattern of VIP-positive neural structures located in the wall of the porcine urinary bladder trigone using the double-immunofluorescence method. The obtained results show that BPA influence leads to an increase in the number of both neurons and nerve fibres containing VIP in the porcine urinary bladder trigone. This may indicate that VIP participates in adaptive processes of the urinary bladder evoked by BPA.

Immunohistochemical characteristics and distribution of neurons in the intramural ganglia supplying the urinary bladder in the male pig

This study investigated the distribution and chemical coding of neurons in intramural ganglia of the urinary bladder trigone (UBT-IG) and cervix (UBC-IG) in the male pig using combined retrograde tracing and double-labelling immunohistochemistry. Additionally, immunoblotting was used to confirm the presence of marker enzymes for main populations of autonomic neurons. Retrograde fluorescent tracer Fast Blue (FB) was injected into the wall of both the left and right side of the bladder trigone, cervix and apex during laparotomy performed under thiopental anaesthesia. Twelve μm-thick cryostat sections were processed for double-labelling immunofluorescence with antibodies against tyrosine hydroxylase (TH), dopamine β-hydroxylase (DBH), neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL), vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), calcitonin gene-related peptide (CGRP), substance P (SP) and vesicular acetylcholine transporter (VAChT). UBT-IG and UBC-IG neurons in both parts of the organ formed characteristic clusters (from few to tens of neuronal cells) found under visceral peritoneum or in the outer muscular layer. Immunohistochemistry revealed several subpopulations in UBT-IG and UBC-IG neurons, namely noradrenergic (ca. 76% and 76%), cholinergic (ca. 22% and 20%), non-adrenergic/non-cholinergic nerve cells (ca. 1.5% and 3.8%), NPY- (ca. 66% and 58%), SOM- (ca. 39% and 39 %), VIP- (ca. 5% and 0%) and NOS- immunoreactive (IR) (ca. 1.5% and 3.8%), respectively. Immunoblotting using antibodies to TH and VAChT showed the presence of studied proteins as revealed by the presence of protein bands of the correct molecular weight. This study has revealed a relatively large population of differently coded UBT- and UBC- IG neurons, which constitute an important element of the complex neuroendocrine system involved in the regulation of the male urogenital organs function.

Neurogenic inflammation of Guinea-pig bladder

Capsaicin, substance P, and ovalbumin, instilled into the bladders of naive and ovalbumin (OVA) sensitized guineapigs caused inflammation, as indicated by increased vascular permeability. Histological changes after exposure to these compounds progressed with time from intense vasodilatation to marginalization of granulocytes followed by interstitial migration of leukocytes. In vitro incubation of guinea-pig bladder tissue with substance P and ovalbumin stimulated release of prostaglandin D₂ and leukotrienes. In vitro incubation of bladder tissue with capsaicin, OVA, prostaglandin D₂, leukotriene C₄, histamine, or calcium ionophore A-23587 all stimulated substance P release. These data suggest that bladder inflammation initiated by a variety of stimuli could lead to a cyclic pattern of release of inflammatory mediators and neuropeptides, which could result in amplification and persistence of cystitis after the inciting cause has subsided.

Neural control of the lower urinary tract: peripheral and spinal mechanisms

This review deals with individual components regulating the neural control of the urinary bladder. This article will focus on factors and processes involved in the two modes of operation of the bladder: storage and elimination. Topics included in this review include: (1) The urothelium and its roles in sensor and transducer functions including interactions with other cell types within the bladder wall ("sensory web"), (2) The location and properties of bladder afferents including factors involved in regulating afferent sensitization, (3) The neural control of the pelvic floor muscle and pharmacology of urethral and anal sphincters (focusing on monoamine pathways), (4) Efferent pathways to the urinary bladder, and (5) Abnormalities in bladder function including mechanisms underlying comorbid disorders associated with bladder pain syndrome and incontinence.

The role of vasoactive intestinal polypeptide and pituitary adenylate cyclase-activating polypeptide in the neural pathways controlling the lower urinary tract

Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are expressed in the neural pathways regulating the lower urinary tract. VIP-immunoreactivity (IR) is present in afferent and autonomic efferent neurons innervating the bladder and urethra, whereas PACAP-IR is present primarily in afferent neurons. Exogenously applied VIP relaxes bladder and urethral smooth muscle and excites parasympathetic neurons in bladder ganglia. PACAP relaxes bladder and urethral smooth muscle in some species (pig) but excites the smooth muscle in other species (mouse). Intrathecal administration of VIP in cats with an intact spinal cord suppresses reflex bladder activity, but intrathecal administration of VIP or PACAP in rats enhances bladder activity and suppresses urethral sphincter activity. PACAP has presynaptic facilitatory effects and direct excitatory effects on lumbosacral parasympathetic preganglionic neurons. Chronic spinal cord transection produces an expansion of VIP-IR (cats) and PACAP-IR (rats) in primary afferent axons in the lumbosacral spinal cord and unmasks spinal excitatory effects of VIP on bladder reflexes in cats. Intrathecal administration of PACAP6-38, a PAC1 receptor antagonist, reduces bladder hyperactivity in chronic spinal-cord-injured rats. These observations raise the possibility that VIP or PACAP have a role in the control of normal or abnormal voiding.

Effects of ischemia on tachykinin-containing nerves and neurokinin receptors in the rabbit bladder

OBJECTIVES

Our previous studies showed marked changes in efferent nerve structure and reactivity in the ischemic bladder. The goal of this study was to examine the effects of bladder ischemia on tachykinin (TK) containing sensory nerves and neurokinin receptors (NKR) in a rabbit model.

METHODS

We recorded bladder blood flow and spontaneous contractions in treated animals at week 8 after the induction of iliac arteries atherosclerosis and in age-matched controls. Bladder tissues were processed for studies of isometric smooth muscle tension in the organ bath, NK2R gene expression using quantitative real-time polymerase chain reaction (PCR), immunohistochemical staining of TK containing nerves and epithelial TK expression, and transmission electron microscopy.

RESULTS

Atherosclerosis-induced ischemia significantly increased the frequency of spontaneous bladder contractions in vivo. Electrical field stimulation (EFS)-induced smooth muscle contractions were significantly greater in the ischemic tissues. Inhibition of NK1R diminished contractions to low-frequency EFS in control tissues while having no significant effect on the ischemic tissues. In contrast, NK2R inhibition significantly decreased contractions to both low- and high-frequency EFS in the ischemic tissues. Inhibition of NK3R had no significant effect on EFS-induced contractions. Real-time PCR showed a significant increase in NK2R gene expression in the ischemic bladder. The number of TK immunopositive nerves and epithelial TK immunoreactivity were significantly greater in the ischemic bladder. These alterations were associated with marked ultrastructural reactions to bladder ischemia.

CONCLUSIONS

Alterations of NK2R reactivity and gene expression, increased number of TK immunopositive nerves, and greater epithelial TK immunoreactivity may imply activated bladder afferents to signal ischemic insult.

The dual function of capsaicin-sensitive sensory nerves in the bladder and urethra

The sensory innervation of the urinary bladder and urethra plays a key role in a variety of reflexes involved in urine storage and voiding. Dysfunction of these systems is a possible cause of many disturbances related to urine continence but basic knowledge in this field has been hampered by the lack of tools for studying sensory nerves. The use of capsaicin, the pungent ingredient of red peppers, allowed us to investigate the anatomical and functional properties of a specific subset of sensory neurons in the lower urinary tract. These 'capsaicin-sensitive' neurons play a dual sensory and 'efferent' function, determined by transmitter release from their central and peripheral nerve endings. Tachykinins, including substance P, and other neuropeptides such as calcitonin gene-related peptide, mediate the functions of these sensory neurons. The 'sensory' function includes regulation of micturition threshold, activation of cardiovascular reflexes and perception of pain from the urinary bladder. The 'efferent' function includes local regulation of muscle cell activity, nerve excitability, blood flow and plasma protein extravasation. Recent data suggest that capsaicin-sensitive sensory nerves could be present in the human bladder.

Innervation of bladder and bowel

The autonomic neuromuscular junction is described and neurotransmission, co-transmission and neuromodulation are defined, as well as the 'chemical coding' of sympathetic, parasympathetic, sensory-motor and intrinsic neurons in the wall of the bladder and bowel. A detailed description of the patterns of innervation of smooth muscle of the bowel, bladder and urethra and of the urethral and anal sphincters by intramural and extrinsic autonomic nerves is presented, and the functional and pharmacological features of this innervation are summarized. Finally, changes in the pattern of innervation and expression of co-transmitters and receptors in the bladder and bowel that occur during development and old age and following trauma, surgery and disease are discussed.

Pharmacology of the lower urinary tract: basis for current and future treatments of urinary incontinence

The lower urinary tract constitutes a functional unit controlled by a complex interplay between the central and peripheral nervous systems and local regulatory factors. In the adult, micturition is controlled by a spinobulbospinal reflex, which is under suprapontine control. Several central nervous system transmitters can modulate voiding, as well as, potentially, drugs affecting voiding; for example, noradrenaline, GABA, or dopamine receptors and mechanisms may be therapeutically useful. Peripherally, lower urinary tract function is dependent on the concerted action of the smooth and striated muscles of the urinary bladder, urethra, and periurethral region. Various neurotransmitters, including acetylcholine, noradrenaline, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in this neural regulation. Muscarinic receptors mediate normal bladder contraction as well as at least the main part of contraction in the overactive bladder. Disorders of micturition can roughly be classified as disturbances of storage or disturbances of emptying. Failure to store urine may lead to various forms of incontinence, the main forms of which are urge and stress incontinence. The etiology and pathophysiology of these disorders remain incompletely known, which is reflected in the fact that current drug treatment includes a relatively small number of more or less well-documented alternatives. Antimuscarinics are the main-stay of pharmacological treatment of the overactive bladder syndrome, which is characterized by urgency, frequency, and urge incontinence. Accepted drug treatments of stress incontinence are currently scarce, but new alternatives are emerging. New targets for control of micturition are being defined, but further research is needed to advance the pharmacological treatment of micturition disorders.

Interindividual Variation in Distribution of Extramural Ganglion Cells in the Male Pelvis: A Semi-Quantitative and Immunohistochemical Study Concerning Nerve-Sparing Pelvic Surgery

OBJECTIVE

We examined distribution and numbers of extramural ganglion cells in the male pelvis, classifying them as sympathetic or parasympathetic.

METHODS

Specimens were obtained from 14 formalin-fixed donated male cadavers. Semiserial sections were processed for histologic examination, and for immunohistochemistry using anti-tyrosine hydroxylase (TH) or anti-peptide histidine isoleucine (PHI).

RESULTS

Like those along the sacral sympathetic trunk, most other pelvic ganglion cells were located in and along nerve components. Yet the ganglion cell clusters attached to pelvic viscera accounted for 22% to 38% of ganglion cells. These were seen at the dorsal aspect of the bladder, the bladder/prostate junction, the dorsal aspect of the seminal vesicle, and along the prostate, but not along the extrapelvic pudendal nerve, cavernous tissues including the penile hilum, the rhabdosphincter, retropubic fat or recto-urethral muscle. Two fold interindividual variation was seen for total ganglion cell number (3044 to 6522) in the pelvis. TH-positive and PHI-positive cells intermingled at various ratio in every ganglion cell cluster. Sympathetic TH-positive proportions tended to be site-specific.

CONCLUSIONS

Pelvic autonomic cells exist not only in nerve components but also along viscera. Even nerve-sparing radical prostatectomy can compromise visceral ganglia. Simple classification of pelvic nerve components as sympathetic or parasympathetic would seem misleading given coexistence of both cell types in a ganglion.

Changes in neuropeptide y tissue concentration in the wall of the rat urinary bladder after acute distension

Neuropeptide Y (NPY) is known to be associated with the adrenergic system. The relationship among the late micturition disorders following acute urinary distension, the adrenergic system and NPY was investigated. A total of 90 rats were included in the study of which 30 acted as the control group. Acute urinary distension was created in 60 rats. The NPY concentration within their bladders was assessed by the use of radioimmunoassay (RIA) at 3 h after distension and subsequently on days 2, 7 and 21, then the third and sixth months. The NPY concentrations assessed in the third and sixth months were compared with the control group in the same age group. By means of the RIA method, a substantial decline of NPY concentration was observed at 2 days after distension, while the concentration started to increase after day 7 (P = 0.003). This increase continued until the twenty first day (P = 0.004). However, a significant decline was maintained when compared to the concentration before distension. In the third and sixth months, a significant decline were observed in the NPY concentration in comparison to the control group (P = 0.004 and P = 0.005, respectively). Early and late micturition disorders experienced after acute urinary distension may be the result of adrenergic denervation which may be related to NPY.

Neurogenic inflammation of the bladder

Current evidence suggests multiple and redundant pathways through which the nervous system can initiate, amplify, and perpetuate inflammation. Many of the processes initiated by neurogenic inflammation have the capacity to recruit the participation of additional sensory nerves. These observations indicate that effective strategies for prevention or treatment of neurogenic inflammation of the bladder will entail or require intervention at multiple points. It has been observed that pain management in the future will be based on selective intervention tailored to the specific processes modulating pain perception in individual patients. It is exciting to contemplate the same approach to prevention and treatment of neurogenic bladder inflammation.

The tachykinin NK-2 receptor antagonist SR48968 does not block noncholinergic contractions in unstable human bladder

Concentration-response curves to acetylcholine, and responses to electrical field stimulation (EFS) were compared in detrusor muscle strips, from control patients and those with idiopathic detrusor instability (IDI). Responses were similar in both groups. However, atropine abolished responses to EFS in 80% of control but only 33% of IDI patients (P>0.05), with the residual atropine-resistant response in most IDI patients abolished by tetrodotoxin. The post-atropine residual response was unaffected by the tachykinin NK-2 receptor antagonist SR48968. Despite the known existence of NK-2 receptors in the human detrusor, there was no evidence for tachykinin contribution to EFS-induced contractions.

Enhancement of neurokinin A-induced smooth muscle contraction in human urinary bladder by mucosal removal and phosphoramidon: relationship to peptidase inhibition

Neurokinin A (NKA) is potent in contracting the human detrusor muscle. Here, we have investigated whether these contractile responses are influenced by the presence of the mucosa, by the peptidase inhibitor phosphoramidon or by possible modulators, prostaglandins and nitric oxide. Contractile responses to neurokinin A were unaffected by indomethacin or N-omega-nitro-L-arginine, but were significantly reduced in strips containing mucosa. Phosphoramidon, an inhibitor of neutral endopeptidase 24.11 (neprilysin, CD10), was ineffective at 10 microM, but at 100 microM, significant increase in the maximum response was achieved by neurokinin A in detrusor strips with and without mucosa. In immunohistochemical studies, neutral endopeptidase immunoreactivity occurred in peripheral nerve trunks in the detrusor and in a fibrous meshwork in the subepithelial lamina propria. Our data indicate that neutral endopeptidase is present in bladder mucosa and detrusor, and support the concept that this metalloprotease and/or related enzymes are important in regulating the actions of tachykinins.

Neuromuscular transmission and innervation in the urinary bladder of the insectivore Suncus murinus

In isolated preparations of the urinary bladder detrusor of the house musk shrew Suncus murinus (order: insectivora; family: Soricidae), electrical field stimulation (0.5-32 pulses/s) evoked neurogenic contractile responses that were markedly attenuated by atropine (1 microM). The non-cholinergic component was reduced but not abolished by the P2-purinoceptor antagonist, suramin (300 microM). Thus, neuromuscular transmission in the suncus urinary bladder is effected by cholinergic and purinergic nerves together with an as-yet unidentified component. Using immunohistochemical methods, the suncus urinary bladder was seen to be supplied by nerves containing neuropeptide Y, tyrosine hydroxylase, vasoactive intestinal polypeptide, galanin, substance P, calcitonin gene-related peptide and type I nitric oxide synthase. The pattern of responses to electrical field stimulation was more similar to that of humans and Old World primates, than to that of rodents or lagomorphs. The pattern of innervation of the bladder wall, in terms of the distribution of populations containing a given neuropeptide, was very similar to that in humans. Hence, Suncus murinus may provide a novel species for modelling the neuropharmacology of the human bladder, and also for studying the evolution of autonomic innervation.

Presence of putative neurotransmitters in the myenteric plexus of the gastrointestinal tract and in the musculature of the urinary bladder of the ferret

The innervation of the musculature in the ferret stomach, ileum, colon and urinary bladder was investigated using immunohistochemistry in noncolchicin-treated tissues. In the gastrointestinal tract two main subpopulations of myenteric neurones were found: cholinergic neurones expressing choline acetyltransferase (ChAT), which made up 68, 67 and 67% of the neurones in the stomach, ileum and colon, respectively, and nitrergic neurones containing nitric oxide synthase and NADPH-diaphorase (stomach: 23%, ileum: 21%, colon: 26%). In the stomach, cholinergic neurones expressed substance P (SP, 2% of all neurones), dopamine-beta-hydroxylase (DBH, 19%) but not tyrosine hydroxylase (TH) or vasoactive intestinal polypeptide (VIP), while nitrergic neurones contained VIP and neuropeptide Y (NPY). TH- but not DBH-immunoreactivity was observed in 4% of gastric neurones. Intense immunoreactivity in the musculature suggests that part of ChAT/SP- and NOS/NPY/VIP-positive neurones function as motorneurones. In the ileum, a high number (32%) of DBH-positive neurones was demonstrated. About half of the SP-positive neurones in the ileum also contained calcitonin gene-related peptide (CGRP). In the urinary bladder, only few intramural ganglia were observed. The smooth muscle was densely innervated by ChAT, NPY and DBH immunoreactive fibres. The data showed that the innervation of the ferret viscera exhibited similarities but also differences as compared with other mammalian species. Some of the chemical coding of myenteric neurones is remarkably similar to that observed in other mammals.

Effect of octreotide, a somatostatin analogue, on release of inflammatory mediators from isolated guinea pig bladder

OBJECTIVE

Somatostatin has been demonstrated to inhibit inflammation under certain circumstances. We hypothesized that in vivo treatment with octreotide, a long-acting analogue of somatostatin analogue, would diminish the capacity of inflammatory peptides to stimulate in vitro release of inflammatory mediators by the bladder.

METHODS

Female guinea pigs were injected with octreotide (20 mg./kg. i.m.) prior to euthanasia. Control guinea pigs received no treatment prior to euthanasia. Urinary bladders were removed and incubated with substance P (SP, 10 microM), neurokinin A (NKA, 10 microM), or bradykinin (BK, 10 microM) in the presence or absence of indomethacin (50 microM), and release of histamine, prostaglandins (PGE2 and PGF2 alpha), and leukotriene (LTB4) was determined.

RESULTS

Sensory peptides and BK induced time-dependent release of histamine and eicosanoids from isolated urinary bladder. Blockade of cyclooxygenase with indomethacin (50 microM) abolished peptide-induced prostaglandin release but enhanced LTB4 release. In vivo octreotide pretreatment decreased peptide-induced histamine release, had no effect on PGE2 or PGF2 alpha release, and LTB4 release. However, octreotide prevented the increase in LTB4 release in tissues incubated with indomethacin.

CONCLUSIONS

These results indicate that somatostatin has the capacity to suppress the release of histamine and prevents potentiation of LTB4 release by indomethacin by the guinea pig bladder in response to pro-inflammatory peptides, indicating that somatostatin may be useful in preventing or treating some forms of cystitis.

A double-label immunohistochemical study of intramural ganglia from the human male urinary bladder neck

Double-label immunocytochemistry was used to investigate the colocalisation of various neuropeptides and the enzymes nitric oxide synthase (NOS) and tyrosine hydroxylase (TH) in intramural ganglia of the human male urinary bladder neck and trigone. Postmortem specimens were obtained from 7 male infants and children ranging in age from 2 mo to 3 y who had died as a result of cot death or accidental trauma. On average 60% of the intramural neurons were non-TH-immunoreactive (-IR) (i.e. presumptive cholinergic) and 40% were TH- and D beta H-IR (i.e. noradrenergic). Within the non-TH-IR population, calcitonin gene-related peptide (CGRP) was found in 65% of cells, neuropeptide Y (NPY) in 90%, nitric oxide synthase (NOS) in 45%, somatostatin (SOM) in 90%, and vasoactive intestinal polypeptide (VIP) in 40%. The corresponding values for the TH-IR neurons were CGRP (54%), NPY (70%), NOS (58%), SOM (73%) and VIP (40%). All the observed bombesin (BOM)-immunoreactivity was colocalised with TH while 90% of VIP and almost all the CGRP was colocalised with NPY. Less than 5% of neurons were immunoreactive for substance P (SP) or met-enkephalin (m-ENK) and some of these also contained TH. Varicose nerve fibres were seen in close proximity to some of the intramural neurons, the majority of such varicosities showing immunoreactivity to CGRP, VIP or TH. Less common were pericellular varicosities immunoreactive to NPY, SOM or SP. These results demonstrate the neurochemical heterogeneity of intramural neurons in the human bladder neck and provide indirect evidence for the complexity of the peripheral innervation of the human urinary bladder.

Colocalisation of NADPH-diaphorase with neuropeptides in the ureterovesical ganglia of humans

Neurones in the ureterovesical ganglion complex provide autonomic innervation to the pelvic ureter, the ureterovesical junction and the bladder trigone. We examined the distribution and peptide co-expression pattern of nitric oxide synthase (NOS) in the human ureterovesical ganglia by combining NADPH-diaphorase histochemistry with immunoreactivity for vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP). Less than 20% of nerve cells in the large ganglia of the ureterovesical complex were stained for NOS activity. In elderly individuals, ganglion cells regularly exhibited conspicuous morphological alterations suggestive of degenerative changes. Most of the NOS-positive cell bodies costained for VIP-immunoreactivity. A minority of NOS-expressing cells also reacted for NPY-immunoreactivity. CGRP-immunoreactivity was present in varicose terminal-like nerve fibres which were found to encircle NOS-containing perikarya. Occasionally, NOS-positive somata were surrounded by plexiform axon terminals which immunostained for VIP or NPY. We conclude that the passage of urine across the ureterovesical junction is under relaxatory control of a local nitric oxide/VIP(NPY) pathway which may be modulated by preganglionic efferent and/or primary afferent input.

Co-localisation of tyrosine hydroxylase, nitric oxide synthase and neuropeptides in neurons of the human postnatal male pelvic ganglia

Double-label immunocytochemistry was used to investigate the co-localisation of neuropeptides and the enzyme nitric oxide synthase (NOS) with tyrosine hydroxylase (TH) in autonomic ganglia of the human postnatal male pelvic plexus. Postmortem specimens were obtained from six male infants and children ranging in age from 2 to 12 months who had died as a result of cot death or accidental trauma. On average, ganglia lying adjacent to the neck of the urinary bladder contained 45% of neurons which were TH-immunoreactive (-IR) while ganglia situated adjacent to the posterior and lateral aspects of the prostate gland contained 67% of neurons which were TH-IR. All the TH-IR neurons also contained dopamine beta-hydroxylase and were considered to be noradrenergic in type. On average, 61% of TH-IR neurons in bladder ganglia contained NOS, compared with 77% of non-TH-IR neurons (based on counts of over 1,000 cells in each case), while the percentages of TH- and non-TH-IR neurons containing neuropeptides were: calcitonin gene-related peptide (CGRP) (30%; 11%), neuropeptide Y (NPY) (66%; 92%), somatostatin (SOM) (70%; 29%), substance P (SP) (64%; 46%), vasoactive intestinal polypeptide (VIP) (64%; 83%). The equivalent values for TH- and non-TH-IR neurons in prostatic ganglia were NOS (38%; 59%), CGRP (55%; 18%), NPY (62%, 65%), SOM (14%, 20%), SP (13%, 8%) and VIP (42%; 82%). Varicose nerve fibers within the ganglia were seen forming pericellular arborizations around many of the ganglion cells, the most numerous containing TH-, CGRP-, NPY-, SOM- or VIP-immunoreactivity. Less common were pericellular varicosities containing SP-immunoreactivity while terminals containing NOS were not observed. No correlation could be detected between the peptide contents of the ganglion cells and of the associated pericellular terminals. However, the peptide content of the ganglion cells found in association with the urinary bladder and prostate gland correlates well with the previously documented coexistence of enzymes and neuropeptides in the intrinsic nerve fibers supplying these two regions of the human postnatal male genitourinary system.

Alterations in urinary bladder synaptosomal neurotransmitter concentrations in two-week streptozotocin-induced diabetic rats

Three-month-old male Wistar rats were rendered diabetic with a single intravenous injection of streptozotocin (60 mg/kg body weight). Two weeks after induction of diabetes, synaptosome-rich fractions were prepared from urinary bladder tissue homogenate of the diabetic rats and control rats by differential centrifugation (1000 x g, 17,000 x g and 100,000 x g) with discontinuous sucrose gradient. Synaptosomal acetylcholine, norepinephrine, epinephrine and dopamine were measured by the method of high-performance liquid chromatography. The respective neurotransmitter concentrations for the diabetic rats were 1537.8 +/- 65.3, 4757.7 +/- 361.9, 3720.7 +/- 276.1, and 2447.8 +/- 196.8 pmol/mg synaptosomal protein, respectively; those for the control rats were 338.1 +/- 25.0, 1009.0 +/- 54.6, 645.3 +/- 52.2, and 1426.1 +/- 123.9 pmol/mg protein, respectively. Thus, the synaptosomal concentrations for all the measured neurotransmitters were significantly higher in the diabetic rats (P < 0.05 for each comparison). In conclusion, it has been demonstrated that the vesicle-bound acetylcholine and catecholamines in the synaptosome-rich fraction of the urinary bladder were significantly increased in 2-week diabetic rats. This finding would suggest impaired neurotransmitter release from both the bladder sympathetic and parasympathetic efferent nerve endings in early streptozotocin-induced diabetes.

Neuropeptides and neurotransmitter-synthesizing enzymes in intrinsic neurons of the human urinary bladder

The expression of neuropeptides, and the enzymes nitric oxide synthase and tyrosine hydroxylase were examined in intramural ganglia of human urinary bladder using single label immunocytochemistry. Scattered ganglia composed of between 1-36 neurons (median 4) were observed in all layers of the lateral wall of the bladder. These contained immunoreactivity to vasoactive intestinal peptide, nitric oxide synthase, neuropeptide Y, and galanin. Neurons within the bladder were heterogeneous with regard to their content of these antigens, with the proportion of immunopositive cells ranging from 58-84%. Occasional neurons with immunoreactivity to the catecholamine-synthesizing enzyme, tyrosine hydroxylase, were also observed. No cell somata, however, were immunoreactive for enkephalin, substance P, calcitonin gene-related peptide or somatostatin. Varicose terminals entering the ganglia were seen to form pericellular baskets surrounding some of the principal ganglion cells. The most prominent pericellular varicosities were those containing calcitonin gene-related peptide- or vasoactive intestinal peptide-immunoreactivity, followed by those with immunoreactivity for enkephalin, neuropeptide Y, or galanin. Less common were pericellular varicosities with substance P-immunoreactivity, which may represent collateral processes of unmyelinated primary sensory fibres, and presumptive noradrenergic processes containing tyrosine hydroxylase. Some calcitonin gene-related peptide-immunoreactive varicosities constituted a distinct type, terminating as large pericellular boutons 2-4 microns in diameter. Fibres containing nitric oxide synthase- or somatostatin-immunoreactivity were not associated with the intramural neurons. The results demonstrate that intrinsic neurons within the human urinary bladder express a number of neuroactive chemicals, and could in principle form circuits with the potential to support integrative activity.

Nitric oxide synthase in dog urethra: a histochemical and pharmacological analysis

1. To examine the presence of nitric oxide synthase (NOS) activity in female dog urethra, pharmacological experiments were performed using electrical field stimulation (EFS), guanethidine, atropine, NG-nitro-L-arginine methyl ester and L-arginine, NOS immunohistochemistry using specific anti-NOS antibody, and reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase staining were also performed. 2. EFS caused frequency-dependent contractions in all urethral preparations, but in the presence of guanethidine and atropine, EFS caused significant relaxation in the proximal urethra and was without effect on the distal urethra. 3. In the presence of guanethidine, atropine, and NG-nitro-L-arginine methyl ester, small contractions to EFS were re-established in the proximal urethra, but not in the distal urethra. NG-nitro-D-arginine methyl ester had no such effect. 4. In the presence of guanethidine, atropine, and NG-nitro-L-arginine methyl ester, the addition of L-arginine, restored the EFS-elicited relaxant responses previously seen with guanethidine and atropine alone in the proximal urethra (at 30 Hz; 12.89 +/- 5.27% to -2.44 +/- 4.43%, mean +/- s.e., P < 0.05). D-Arginine had no such effect. 5. In the distal urethra, the addition of NG-nitro-L-arginine methyl ester and then L-arginine had no effect on responses to EFS in preparations treated with guanethidine and atropine. 6. Sodium nitroprusside caused relaxation in both the proximal and distal urethra. The relaxant responses per cm2 cross sectional area in the proximal and distal urethra were 1.23 +/- 0.29, and 2.02 +/- 0.54 g cm-2 cross sectional area (mean +/- s.e.), respectively: there was no significant difference between them. 7. Both NOS and NADPH diaphorase-positive neurones were present in dog urethra, the densities of both being higher in the proximal urethra than in the distal urethra. 8. These results show that female dog urethra possesses NOS nerves and that endogenous NO may play a role in relaxation in the proximal but not the distal urethra.

Expression and characterization of preproVIP derived peptides in the human male urogenital tract

Expression of the gene sequence encoding vasoactive intestinal polypeptide (VIP) leads to the synthesis of a 170 amino acid precursor molecule which can be processed to five fragments: preproVIP 22-79, peptide histidine methionine (PHM), or peptide histidine valine (PHV), preproVIP 111-122, VIP and preproVIP 156-170. Using region specific radioimmunoassays and antisera against the functional domains of the VIP precursor in combination with immunocytochemistry and chromatography, the localization, distribution and identity of the preproVIP derived peptides within the human male urogenital tract were investigated. Postmortem as well as fresh tissue specimens were used. All the preproVIP derived peptides were expressed and could be demonstrated in nerve fibres throughout the urogenital tract in close relation to the epithelial lining and in vascular as well as non-vascular smooth muscle. The VIP-related peptide containing fibres were most abundant in the prostate parenchyma and the seminal vesicle. Using double immunostaining, co-localization of the various preproVIP derived peptides could be evidenced. The fact that all preproVIP derived peptides are present in the urogenital tract, should be taken into consideration when the regulatory aspects of neuropeptides in physiological and pathophysiological functions are discussed.

Immunohistochemical localization of neuromarkers and neuropeptides in human fetal and neonatal urinary bladder

OBJECTIVE

To use immunohistochemical techniques to determine the spatial and temporal distribution of a variety of neuropeptides in the human fetal and neonatal urinary bladder.

MATERIALS AND METHODS

Thirteen pre-natal specimens ranging in gestational age from 17 to 35 weeks were acquired following abortion or miscarriage. In addition two post-natal specimens aged 8 and 12 weeks were obtained at post-mortem and were included in this study. The overall innervation of each specimen was visualized using the general nerve marker protein gene product 9.5 (PGP). Localization of dopamine-beta-hydroxylase (DBH) and tyrosine hydroxylase (TH) revealed putative noradrenergic nerves. The neuropeptides studied included neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), substance P (SP), and calcitonin gene-related peptide (CGRP).

RESULTS

At 17 weeks a rich plexus of PGP and NPY-containing nerves was present throughout the detrusor muscle coat. As gestational age increased, VIP, SP and CGRP-containing nerves were observed with increasing frequency although SP and CGRP were mainly confined to perivascular nerve plexuses. TH- and DBH-containing nerves were first observed in the intramural ureters at 30 weeks and the detrusor muscle at 35 weeks and were relatively numerous in the intramural ureters and muscle of the superficial trigone in the two post-natal specimens. PGP-containing nerves were first observed beneath the bladder epithelium at 23 weeks and gradually became more numerous with increasing age. Occasional NPY, VIP, SP and CGRP-containing nerves were observed in the submucosa but TH- and DBH-immunostained nerves were especially numerous in the mucosa of the trigone in the two post-natal specimens, many such nerves being unrelated to the vascular supply.

CONCLUSIONS

The bladder detrusor possesses a rich autonomic innervation by 17 weeks of gestation and this presumptive cholinergic innervation is associated with NPY immunoreactivity. Presumptive noradrenergic nerves appear relatively late in pre-natal development and mainly supply the intramural ureters and superficial trigone. A submucosal plexus of nerves has been demonstrated, the functional significance of which remains uncertain.

Neuropeptide Y in rat detrusor and its effect on nerve-mediated and acetylcholine-evoked contractions

1. Immunohistochemical and isolated organ bath techniques were used to detect the presence of neuropeptide Y (NPY) in the rat urinary bladder and to determine its effect on tone, spontaneous activity and contractile responses of the detrusor muscle to electrical field stimulation, acetylcholine and alpha,beta-methylene ATP (alpha,beta-MeATP). 2. A very rich presence of NPY-immunoreactive nerve fibres was found mainly within the bundles of detrusor muscle cells. Chronic treatment with 6-hydroxydopamine did not affect the density of NPY-positive nerve fibres. 3. NPY (> 1 nM) enhanced the force and frequency of spontaneous contractions and generated a rise in the resting tone of the detrusor. These effects of NPY on the tone and the spontaneous activity remained unaffected by atropine (3 microM), indomethacin (10 microM) and aspirin (100 microM) but were abolished by Ca(2+)-withdrawal from the bathing medium. 4. The enhancing effects of NPY on the spontaneous contractions and the resting tone were not prevented by the induction of purinoceptor desensitization. 5. NPY (1-250 nM) potentiated electrical field stimulation (EFS, 1-64 Hz, 0.1 ms pulses duration, 10s train duration)-evoked, tetrodotoxin (0.5 microM)-sensitive contractions. The atropine (3 microM)-resistant component of EFS-evoked contractions was also potentiated by NPY. By contrast, the nifedipine (1 microM)-resistant but atropine-sensitive component of EFS-evoked contraction was inhibited by NPY. 6. NPY (250 nM) did not affect acetylcholine-evoked contractions, but potentiated alpha,beta-MeATP-evoked contractions. 7. It is concluded that NPY-innervation of rat urinary bladder is largely confined to the detrusor muscle and is abundant and mainly non-adrenergic. It is further concluded that the enhancing effect of NPY on detrusor spontaneous activity and tone is caused by Ca2+ influx through nifedipine-sensitive Ca2+ channels and is not mediated through acetylcholine or cyclo-oxygenase-sensitive eicosanoids or ATP.8. The results are consistent with the hypothesis that intrinsic NPY in the rat detrusor innervation contributes to the motor transmission in two ways: by promoting non-cholinergic motor transmission and by inhibiting prejunctionally the cholinergic transmission.

Patterns of neuronal colocalisation of tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, calcitonin gene-related peptide and substance P in human ureter

The patterns of colocalisation of neuropeptides, tyrosine hydroxylase (TH), and protein gene product 9.5 (PGP), were studied in nerve fibres supplying the upper and lower human ureter using a double labelling immunofluorescence technique. The majority (85%-95%) of nerve fibres within the ureter contained neuropeptide Y-like immunoreactivity (NPY-LIR), in combination with other peptides. Approximately 52%-63% of the total ureteral innervation was made up of NPY-LIR fibres also expressing TH-LIR, while 21%-42% of fibres contained NPY-LIR in combination with vasoactive intestinal polypeptide (VIP)-LIR. These two immunochemically defined classes did not overlap, since TH- and VIP-LIR were never present within the same nerve fibre. Other minor populations of neurones included those containing calcitonin gene-related peptide (CGRP)-LIR in combination with substance P (SP)-LIR (4%-17%) and those without SP (5%). Rare coexistences were also noted between CGRP- and VIP-LIR (1%-2%), CGRP- and NPY-LIR (< or = 1%), and CGRP- and TH-LIR (< 1%). Regional differences in innervation were found. There were fewer of each class of nerve fibres in the upper ureter compared to the lower ureter. In addition, the proportion of VIP/NPY-LIR fibres of the total innervation was less in the upper ureter, where they were very sparse. Differences in the distribution to various tissue targets were also observed. In the lower ureter, TH/NPY-LIR fibres were localised predominantly to the outer muscle fascicles and adventitia, while VIP/NPY immunoreactive nerves supplied the submucosa and inner smooth muscle fascicles. Both of these populations were also found around blood vessels. A population of presumptive sensory fibres expressing CGRP/SP-LIR were typically present immediately beneath the urinary epithelium and around blood vessels, and only very rarely within muscle fascicles. The finding that TH/NPY- and VIP/NPY-LIR fibres innervate different layers of the ureter raises the possibility that the muscle layers of the ureter may be independently controlled.

An immunohistochemical study of the innervation of the ureterovesical junction in infancy and childhood

OBJECTIVE

To use histological and immunohistochemical methods to study the structure and innervation of the human ureterovesical junction (UVJ).

MATERIALS AND METHODS

A series of 24 post-natal specimens taken from patients ranging in age from 1 month to 6 years were examined. Routine histological slides were stained with Masson's trichrome. In addition, an indirect immunohistochemical method was used to study the occurrence and distribution of nerves immunoreactive for the neuropeptides vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), substance P (SP) and calcitonin gene-related peptide (CGRP). Immunoreactivity to tyrosine hydroxylase (TH), dopamine-B-hydroxylase (DBH) and to protein gene product (PGP) 9.5, a general nerve marker, were also studied.

RESULTS

The UVJ comprised a ureteric muscle component (the intramural ureter) and a detrusor component (the immediately adjacent region of the urinary bladder). In the majority of specimens a third or intermediate layer was also present. This additional component consisted of tightly-packed smooth muscle cells which formed an incomplete layer that partially surrounded the juxta-vesical and intramural parts of the ureter. Numerous PGP-, VIP-, NPY, DBH- and TH- like immunoreactive (-LIR) nerves were associated with the smooth muscle bundles which comprised the intramural ureter. Such nerves ran in the connective tissue separating ureteric smooth muscle bundles and rarely coursed amongst individual smooth muscle cell comprising each bundle. SP- and CGRP- containing nerves were rarely observed in association with the intramural ureter and none were detected in the ureteric submucosa. The intermediate muscle layer was richly innervated by PGP-, TH-, DBH- and NPY- containing nerves which ran amongst the smooth muscle cells comprising this layer. VIP-, SP- and CGRP-LIR nerves were not observed within the intermediate layer. The detrusor component of the UVJ was innervated by PGP-, NPY- and VIP-LIR nerves which frequently extended between the smooth muscle cells forming the detrusor muscle bundles. TH-, DBH-, SP- and CGRP-LIR nerve fibres were rarely encountered.

CONCLUSION

These findings indicate that noradrenergic nerves play a major role in the control of the ureteric component of the UVJ. In addition, the present results form baseline morphological data with which to compare the results of future studies on the structure of the UVJ in cases of vesicoureteric reflux.

Inhibition in the human urinary bladder by gamma-amino-butyric acid

OBJECTIVE

To investigate the effects of gamma-amino-butyric acid (GABA) on detrusor activity in man to determine whether it has any inhibitory effect on detrusor contraction. The inhibitory neurotransmitter GABA has been found in mammalian urinary bladders and the effects of GABA on detrusor activity in the rabbit bladder has previously been described [1].

MATERIALS AND METHODS

Human detrusor muscle strips, obtained at cystectomy, were made to contract by electrical stimulation of their autonomic nerves or by the addition of carbachol in a superfusion apparatus. GABA and its analogues were added to the superfusion chamber and any changes in the responses were measured.

RESULTS

The electrically evoked nerve-mediated contractions in human bladder muscle were exclusively cholinergic. GABA inhibited nerve-mediated contractions in human detrusor muscle-strips by the activation of the GABAB receptor, since baclofen (a GABAB receptor agonist) produced similar inhibition and muscimol (a GABAA receptor agonist) did not. There was no inhibition of carbachol-mediated contractions by GABA.

CONCLUSION

This in vitro study shows that GABA has a peripherally mediated inhibitory effect on excitatory neurotransmission in human detrusor muscle. The site of action is on the post-ganglionic nerves and appears to be mediated via the GABAB receptor.

The pathophysiological changes in the bladder obstructed by benign prostatic hyperplasia

None of the hypotheses to explain the genesis of obstructed detrusor instability covered in this report provide a satisfactory explanation, by themselves, for the condition. While symptoms associated with prostatic obstruction are a common cause of patient referral to a urologist, all therapeutic advances so far have been directed towards the relief of bladder outflow resistance. It is possible that pharmacotherapy, for example, with drugs which stabilize muscle cell membranes and autonomically active drugs such as alpha 1-antagonists, possibly combined with anticholinergics, will have a therapeutic role in the treatment of obstructive detrusor instability. Further studies of obstructed human bladder are necessary to investigate the importance of changes in receptor density, affinity and distribution, agonist release and degradation and subsequently the ultrastructural and physiological alterations following the relief of obstruction.

Substance P-containing axon terminals in the mucosa of the human urinary bladder: pre-embedding immunohistochemistry using cryostat sections for electron microscopy

The ultrastructure of substance P (SP)-containing axon terminals in the mucosa of the human urinary bladder was studied. Numerous SP-immunoreactive varicose nerve fibers were seen in the lamina propria, and most of them ran freely in the connective tissue. Many SP-immunoreactive nerve fibers were observed beneath the epithelium, and perivascular SP-immunoreactive nerves were also found in the submucosal layer. We observed a total of 305 SP-immunoreactive (IR) axon terminals, of which most (89.6%) were free nerve endings at the ultrastructural level; the rest of the SR-IR axon terminale were seen in the vicinity of the epithelium and blood vessels in the lamina propria. Varicose regions of SP-IR axon terminals contained large granular and small agranular synaptic vesicles, and most of them partially lacked a Schwann cell sheath. In some SP-IR varicosities, synaptic vesicles were concentrated in the region without any Schwann cell sheath. Long storage (for more than 1 month) of fixed-tissue pieces in sucrose before freezing has improved the ultrastructure of cryostat sections in pre-embedding immunohistochemistry. Trypsin digestion for the purpose of exposing antigenic sites was also employed before applying the first antiserum.

Nitric oxide synthase in pig lower urinary tract: immunohistochemistry, NADPH diaphorase histochemistry and functional effects

1. The distribution and colocalization of nitric oxide synthase (NOS)-like immunoreactivity and NADPH diaphorase activity in the pig lower urinary tract were investigated by immunohistochemical and histochemical staining techniques. Functional in vitro studies were performed to correlate the presence of NOS-immunoreactivity/NADPH diaphorase staining with smooth muscle responses involving the L-arginine/nitric oxide (NO) pathway. 2. NOS-immunoreactivity and NADPH diaphorase activity were expressed in nerve trunks and fine nerve fibres in and/or around muscular bundles in the detrusor, trigone and urethra. Thin nerve fibres that dispersed within the muscle bundles were mainly found in the urethral/trigonal area, whereas such fibres were less common in the detrusor. 3. Almost all neuronal structures that were NOS-immunolabeled were also stained for NADPH diaphorase. In contrast, the urothelium, which was intensively stained by the NADPH diaphorase technique, remained unstained by immunohistochemistry. 4. Electrical field stimulation of pig isolated trigonal and urethral preparations induced relaxations, which were inhibited by tetrodotoxin (1 microM) and NG-nitro-L-arginine (L-NOARG, 10 microM). 5. L-Arginine (1 mM), but not D-arginine, inhibited (25-30%) electrically evoked detrusor contractions. This inhibition was reversed by L-NOARG (0.1 mM). L-Arginine did not inhibit detrusor contractions in the presence of scopolamine (1 microM) and had no direct smooth muscle effects per se. 6. Acetylcholine (1 nM-10 microM) caused concentration-dependent relaxations of noradrenaline-induced contractions in pig vesical arteries. Removal of the endothelium practically abolished the acetylcholine-induced relaxation. Pretreatment with L-NOARG (0.1 mM and 0.3 mM) caused a rightward shift of the concentration-response curves to acetylcholine, but the maximal relaxation obtained was significantly reduced (to 65 +/- 12%; n = 6; P < 0.05) only at 0.3 mM L-NOARG. 7. In vessel segments contracted with K+ (60 mM), acetylcholine induced concentration-dependent relaxations. When the vessels were incubated with 0.3 mM L-NOARG and then contracted with K+ (60 mM) all relaxant responses to acetylcholine were abolished. 8. The presence of NO synthesizing enzyme in nerve fibres and the pharmacological evidence for NO-mediated relaxation of the trigone and urethra suggest that NO or a NO-related substance may have a role in inhibitory neurotransmission in these regions. In the detrusor, the presence of NO-synthesizing enzyme in nerves can be demonstrated, but its functional importance is unclear. NO, as well as other endothelium-derived factors seem to be involved in the endothelium-dependent acetylcholine-induced relaxation of pig vesical arteries.

Relief of pain following intravesical capsaicin in patients with hypersensitive disorders of the lower urinary tract

We have extended our earlier observations on pain relief produced by intravesical instillation of capsaicin (10 microM in saline) in patients with hypersensitive disorders of the lower urinary tract. Patients in group A (n = 15) received intravesical capsaicin on days 0, 14 and 28: on each occasion the drug produced a warm or burning sensation, reduction in bladder capacity and a delayed, transient improvement or disappearance of symptoms. Patients in group B (n = 5) received intravesical capsaicin (10 microM at cystometry) 3 times on day 0. The initial sensation of warmth was experienced on each occasion, indicating that no significant desensitisation has been produced by the first instillation. Clinical improvement similar to that found in group A was observed. Three patients (group C) received warm saline (42 degrees C) at cystometry. This produced a pricking sensation, no change at cystometry and no subjective clinical improvement. Apart from the initial sensation of warmth, no patient in group A or B experienced side effects, either local or systemic. These findings confirm that intravesical instillation of capsaicin has a beneficial effect on patients with hypersensitive bladder disorders. Counter-irritation rather than desensitisation of primary afferents could be a possible mechanism of action. Further studies are needed to establish whether the intravesical administration of capsaicin or capsaicin-like agents represents a new form of treatment for relief of bladder pain.

Facilitatory effect of vasoactive intestinal polypeptide on spinal and peripheral micturition reflex pathways in conscious rats with and without detrusor instability

In unanesthetized, normal rats, and rats with bladder hypertrophy following infravesical outflow obstruction, cystometry was performed to investigate the effects of spinal and peripheral administration of vasoactive intestinal polypeptide (VIP) on micturition. In addition, the direct effects of the peptide on isolated smooth muscle preparations of detrusor and urethra were studied. In normal animals, 10 micrograms. of VIP administered intrathecally as well as intra-arterially close to the bladder, but not intravenously, decreased micturition volume and bladder capacity, and facilitated spontaneous bladder contractions. In animals with bladder hypertrophy, the same dose of VIP intrathecally had similar effects on these three parameters, but the effects of VIP given intra-arterially were less pronounced. VIP given intravenously was ineffective. Hexamethonium 5 mg. x kg.-1 given intraarterially did not block the stimulatory effect of VIP 10 micrograms. given intra-arterially to normal animals. VIP had negligible effects on isolated detrusor muscle contracted by carbachol or electrical stimulation, or on urethral preparations contracted by noradrenaline. These results suggest that VIP has a facilitatory action on the micturition reflex at the spinal cord and ganglionic levels.

Partial mediation by nitric oxide of the relaxation of human isolated detrusor strips in response to electrical field stimulation

1. A method for reproducing relaxation of human isolated detrusor smooth muscle in vitro in response to electrical field stimulation is described. 2. The parameters of stimulation associated with relaxation were those which would be expected to give a largely nerve-mediated response: the relaxations were not reduced by tetrodotoxin (3 x 10(-7) M) and were therefore not dependent on voltage sensitive sodium channels. 3. The relaxations were decreased (mean 74.1%) by nitro L-arginine (NOARG, 10(-5) M). 4. Methylene blue (10(-5) M), an inhibitor of soluble guanylate cyclase, abolished the relaxations. 5. These results indicate that there may be a relaxation mechanism in the human bladder which is at least partly mediated via the production of nitric oxide.

Loss of sensory neuropeptides in the obstructed human bladder

This is the first investigation of alterations in the innervation of the obstructed human bladder by nerves containing neuropeptides. The patient groups studied were those with stable detrusor function, those with unstable detrusor function, and those presenting with acute retention of urine. Specimens of bladder tissue were taken from the lateral wall of the bladder below the peritoneal reflection. A total of 23 patients was studied (control, n = 4; acute retention, n = 5; stable obstruction, n = 5; unstable obstruction, n = 9). Substance P, calcitonin gene-related peptide and vasoactive intestinal polypeptide levels in the bladder were quantified by immunoassay. The density of innervation of the bladder detrusor by nerves containing these neurotransmitters and by those containing neuropeptide Y and somatostatin was assessed using both semiquantitative and quantitative immunohistochemical techniques. A reduction in the density of innervation by vasoactive intestinal polypeptide, calcitonin gene-related peptide, substance P and somatostatin-immunoreactive but not neuropeptide Y-immunoreactive nerve fibres was shown in the obstructed bladder. These findings, combined with the significant reduction in substance P content of the obstructed bladder and in particular of the acute retention bladder, indicate that there may be an afferent nerve dysfunction resulting from prostatic bladder outflow obstruction.

Presence and regional variation in peptide-containing nerves in the human ureter

The occurrence, distribution and regional variation of neurones immunoreactive for the neuropeptides, vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), enkephalin (ENK), calcitonin gene-related peptide (CGRP), and substance P (SP) were investigated in human ureters by indirect immunohistochemistry. In addition, immunoreactivities to tyrosine hydroxylase (TH), a marker of noradrenergic neurones and to protein gene product (PGP) 9.5, a general marker of neurones, were also studied. Neurones displaying PGP-, NPY-, VIP- and TH-like immunoreactivity (-LIR) provided a rich innervation to the smooth muscle and blood vessels of the ureter, where they formed dense muscular and perivascular nerve plexuses. In contrast, there was only a moderate to sparse innervation by SP and CGRP-LIR neurones, most of which were distributed to blood vessels and to the sub mucosal layer, and only rarely to smooth muscle bundles. No ENK-LIR was detected in this study. Nerve fibre bundle densities were estimated for each of the localized neurochemicals according to a method described. NPY-LIR nerve fibre bundles were found to account for 80% of the total nerve fibre bundles (i.e. PGP-LIR) in the ureter. On the other hand, TH-LIR and VIP-LIR nerve fibre bundles each accounted for 50% of the total ureteral innervation, whereas SP- and CGRP-LIR nerve fibre bundles each comprised 20% of the total innervation. The abundance and pattern of tissues innervated by these immunoreactive neurones is consistent with the view that some of these neuropeptide substances co-exist with other peptide substances and/or with other known neurotransmitters, such as noradrenaline or acetylcholine. A gradient of innervation was found to exist for all the neurochemicals demonstrated in the ureter, whereby the lower ureter receives a greater density of innervation than the upper ureter. This finding suggests the human ureter is primarily innervated by fibres arising from or via the lower pelvis, i.e. the pelvic plexus. It also supports the view that the lower ureter may perform an important physiological role, such as coordinating the tone of this region during bladder filling and emptying.

Bladder Wall Histology and Duration of Obstruction

In BPH patients, obstruction leads to a progressive modification in the structure of the bladder wall, with histo-pathological changes which are often irreversible. In order to detect these changes and their possible correlation with function, muscle biopsies of the bladder were taken from 28 patients during endoscopic resection for benign prostatic hyperplasia. The samples were examined by means of electron microscope to show ultrastructural charges. The magnitude of the lesions can be correlated to function, seriousness and duration of the obstruction. Detecting histo-pathological damage can justify earlier treatment in obstructed BPH patients, in order to avoid those bladder lesions, which are the probable cause of clinical disorders which may persist even after therapy of the adenoma.

Effect of bombesin, bradykinin, substance P and CGRP in prostate, bladder body and neck

Lower urinary tract tissues respond heterogeneously to adrenergic and cholinergic agents. However, the action of bioactive peptides on these tissues has not been extensively studied. The contractile and relaxant effects of nine peptides-bradykinin, cholecystokinin, vasoactive intestinal polypeptide, gastrin, substance P, bombesin, neuropeptide Y, calcitonin gene-related peptide, and motilin-have been compared in the rat bladder body, bladder neck, and left ventral prostate in vitro. All three tissues contracted to bombesin and to bradykinin, although the bladder neck was less sensitive to the contractile effects of bradykinin than the other two tissues. Substance P only contracted the bladder body. Of all the peptides tested, relaxation was only observed to calcitonin gene-related peptide, which relaxed the bladder neck and prostate (phenylephrine-contracted) but not the bladder body (carbamylcholine-contracted). Thus lower urinary tract tissues are responsive to certain bioactive peptides in a nonhomogeneous fashion. These studies raise the possibility that selective modulation of peptide function may be an approach to therapy of urogenital disorders.

Distribution and function of cholinergic receptors in the sheep detrusor muscle

The distribution of cholinergic nerve fibres, as well as the characterization of the muscarinic receptors responsible for the contraction, were determined in the detrusor smooth muscle of the sheep. The results obtained demonstrated a rich presence of acetylcholinesterase (AChE)-positive fibres distributed throughout the bladder body forming dense neuromuscular, subepithelial and perivascular plexuses. Furthermore, intramural ganglia containing AChE-positive cell bodies were identified. However, acetylcholine and carbachol induced a dose-dependent contraction of detrusor smooth muscle. The effect observed with carbachol was competitively antagonized by atropine (pA2: 8.94), pirenzepine (pA2: 7.38), AF-DX 116 (pA2: 7.35), 4-DAMP (pA2: 9.26) and hexahydroxiladifenidol (HHSiD) (pA2: 8.49). The pA2 value for pirenzepine is intermediate between M1- and M2-receptors which suggests that this antagonist does not act on M1- or M2-receptors, but that it does on M3-receptors. The pA2 value for AF-DX 116 is consistent with the presence of M2-receptors in this tissue. Moreover, the pA2 values obtained for both 4-DAMP and HHSiD are in agreement with the presence of M3-receptors, due to the lack of effect of pirenzepine on M1-muscarinic receptors. These results indicate the existence of a rich parasympathetic innervation in the sheep detrusor muscle and suggest that its contraction could be mediated by the stimulation of muscarinic receptors belonging to both M3- and M2-subtypes.