Changes in urinary bladder neurotrophic factor mRNA and NGF protein following urinary bladder dysfunction

DECREASE IN BLADDER OVERACTIVITY WITH REN1820 IN RATS WITH CYCLOPHOSPHAMIDE INDUCED CYSTITIS

PURPOSE

Studies suggest that nerve growth factor (NGF) contributes to bladder overactivity stemming from bladder inflammation. Studies were performed to determine the NGF dependence of cyclophosphamide (CYP) induced changes in bladder function using the recombinant NGF sequestering protein REN1820.

MATERIALS AND METHODS

Urodynamic testing and behavioral observations were made in female rats treated with CYP (4 or 48 hours) and REN1820 or vehicle.

RESULTS

Rats examined 4 or 48 hours after CYP treatment plus REN1820 showed significantly fewer nonvoiding contractions with smaller amplitude (p </=0.01). Rats examined 48 hours after CYP treatment plus REN1820 showed decreased voiding frequency (p </=0.01). No changes in filling, threshold or micturition pressure were observed with REN1820 treatment. Rats treated with CYP plus REN1820 showed greater mobility and normal resting postures compared with rats treated with CYP plus vehicle.

CONCLUSIONS

These studies demonstrate that the use of the NGF sequestering protein REN1820 in rats with CYP induced cystitis decreases bladder overactivity. This is characterized by 1) a decrease in the number and amplitude of nonvoiding contractions and 2) decreased voiding frequency. Rats treated with REN1820 showed greater mobility and normal resting postures, which may reflect improved overall health or well-being. REN1820 may prove to be a novel therapeutic in individuals with the chronic inflammatory bladder syndrome interstitial cystitis.

Capsaicin receptor TRPV1 in urothelium of neurogenic human bladders and effect of intravesical resiniferatoxin

OBJECTIVES

To study TRPV1 immunoreactivity in the urothelium of patients with neurogenic detrusor overactivity (NDO) before and after treatment with resiniferatoxin (RTX) and controls. Functional capsaicin TRPV1 receptors have been demonstrated in urothelial cells of rodent urinary bladder, and TRPV1-knockout mice exhibit diminished nitric oxide and stretch-evoked adenosine triphosphate release from urothelial cells. In patients with NDO, TRPV1 suburothelial nerve density is increased, which is reversed by successful treatment with intravesical RTX. However, the role of urothelial TRPV1 in human bladder disorders is unknown.

METHODS

Flexible cystoscopic bladder biopsies were obtained from 14 patients with NDO before and after treatment with RTX and from 8 control patients. Using a specific antibody for immunostaining, TRPV1 immunoreactivity in the urothelium was quantified by image analysis.

RESULTS

TRPV1 immunoreactivity was observed in basal and apical urothelial cells. Basal cell layer TRPV1 immunoreactivity was significantly increased in NDO compared with control bladders (P = 0.003). In 5 patients who responded clinically to RTX, basal cell layer and total urothelial TRPV1 immunoreactivity decreased significantly after treatment (P = 0.032 and P = 0.016, respectively). The decreases in the basal cell layer TRPV1 immunoreactivity after RTX were comparable to the decreases in suburothelial TRPV1 nerve fibers in the biopsies previously studied from the same patients.

CONCLUSIONS

Increased urothelial TRPV1 in patients with NDO may play a role in the pathophysiology, in concert with increased TRPV1 nerve fibers. Although it is not known whether similar pathogenic mechanisms are involved in the increase of urothelial and neuronal TRPV1, both may be targeted by successful RTX therapy.

Expression and function of bradykinin B1 and B2 receptors in normal and inflamed rat urinary bladder urothelium

The bladder urothelium exhibits dynamic sensory properties that adapt to changes in the local environment. These studies investigated the localization and function of bradykinin receptor subtypes B1 and B2 in the normal and inflamed (cyclophosphamide (CYP)-induced cystitis) bladder urothelium and their contribution to lower urinary tract function in the rat. Our findings indicate that the bradykinin 2 receptor (B2R) but not the bradykinin 1 receptor (B1R) is expressed in control bladder urothelium. B2R immunoreactivity was localized throughout the bladder, including the urothelium and detrusor smooth muscle. Bradykinin-evoked activation of this receptor elevated intracellular calcium (EC(50) = 8.4 nM) in a concentration-related manner and evoked ATP release from control cultured rat urothelial cells. In contrast, B1R mRNA was not detected in control rat urinary bladder; however, following acute (24 h) and chronic (8 day) CYP-induced cystitis in the rat, B1R mRNA was detected throughout the bladder. Functional B1Rs were demonstrated by evoking ATP release and increases in [Ca(2+)](i) in CYP (24 h)-treated cultured rat urothelial cells with a selective B1 receptor agonist (des-Arg(9)-bradykinin). Cystometry performed on control anaesthetized rats revealed that intravesical instillation of bradykinin activated the micturition pathway. Attenuation of this response by the P2 receptor antagonist PPADS suggests that bradykinin-induced micturition facilitation may be due in part to increased purinergic responsiveness. CYP (24 h)-treated rats demonstrated bladder hyperactivity that was significantly reduced by intravesical administration of either B1 (des-Arg(10)-Hoe-140) or B2 (Hoe-140) receptor antagonists. These studies demonstrate that urothelial expression of bradykinin receptors is plastic and is altered by pathology.

CYCLOPHOSPHAMIDE INDUCED CYSTITIS ALTERS NEUROTROPHIN AND RECEPTOR TYROSINE KINASE EXPRESSION IN PELVIC GANGLIA AND BLADDER

PURPOSE

We examined neurotrophin and receptor tyrosine kinase (Trk) expression in the bladder and major pelvic ganglia (MPG) after cyclophosphamide induced cystitis in rats.

MATERIALS AND METHODS

The bladder and MPG were used in immunohistochemical studies, enzyme-linked immunoassays and Western blots for nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), TrkA and TrkB. Bladder postganglionic MPG cells were labeled by tracing techniques.

RESULTS

NGF and BDNF expression was decreased in the bladder of all rats after cystitis (p < or =0.001). NGF and BDNF expression was increased in the MPG in male rats with cystitis (p < or =0.01). Cells expressing TrkA and TrkB immunoreactivity (IR) increased 78% to 81% in the MPG in male rats with cystitis. TrkA-IR or TrkB-IR bladder postganglionic cells increased 50% to 74% with cystitis. Cystitis increased TrkA-IR 5 to 10-fold and TrkB-IR 10 to 12-fold in detrusor muscle. TrkA-IR and TrkB-IR were prominent in control urothelium but decreased with cystitis. After cystitis TrkB-IR nerve fibers and TrkA-IR cellular infiltrates were more apparent compared to controls.

CONCLUSIONS

Cystitis decreases bladder NGF and BDNF expression, whereas MPG expression is increased. This change may reflect neurotrophin release at the bladder and retrograde transport to the MPG. TrkA-IR and TrkB-IR are increased in bladder postganglionic cells and bladders with cystitis. This increase may reflect a shift in Trk staining from urothelium to detrusor muscle and nerve fibers with cystitis. Neurotrophin/Trk interactions in the bladder and MPG may contribute to bladder overactivity with cystitis.

Increased expression of neuronal nitric oxide synthase in bladder afferent cells in the lumbosacral dorsal root ganglia after chronic bladder outflow obstruction

Nitric oxide (NO), a neurotransmitter in autonomic reflex pathways, plays a role in functional neuroregulation of the lower urinary tract. Upregulation of the levels of neuronal nitric oxide synthase (nNOS), the enzyme system responsible for NO synthesis, has been documented in the peripheral, spinal and supraspinal segments of the micturition reflex in diseases such as cystitis, bladder/sphincter dyssynergia following spinal cord injury and bladder overactivity after cerebral infarction. These observations suggest that NO might play a role in the development of bladder overactivity. In this study, nNOS-immunoreactivity (IR) was evaluated in bladder afferent and spinal neurons following bladder outflow obstruction (BOO) in male and female rats. Chronic BOO was induced by placing lumen reducing ligatures around the proximal urethra. Six weeks following the obstructive or sham surgery, bladder function was evaluated by awake cystometry. Bladder afferent neurons in L1, L2, L6 and S1 dorsal root ganglia (DRG) were identified by retrograde neuronal labeling with injection of Fast Blue into the bladder smooth muscle. A differential distribution of nNOS-IR was subsequently evaluated in bladder afferent neurons in the DRG and in the associated spinal cord segments. The percentage of bladder afferent neurons expressing nNOS-IR was increased in L6 (1.8-fold in males and 1.9-fold in females) and S1 (2.8-fold in males and 5.3-fold in females) DRG. In contrast, no changes in nNOS-IR in neurons or fiber distribution were observed in any spinal cord segments examined.

Artificial autonomic reflexes: using functional electrical stimulation to mimic bladder reflexes after injury or disease

Autonomic reflexes controlling bladder storage (continence) and emptying (micturition) involve spinal and supraspinal nerve pathways, with complex mechanisms coordinating smooth muscle activity of the lower urinary tract with voluntary muscle activity of the external urethral sphincter (EUS). These reflexes can be severely disrupted by various diseases and by neurotrauma, particularly spinal cord injury (SCI). Functional electrical stimulation (FES) refers to a group of techniques that involve application of low levels of electrical current to artificially induce or modify nerve activation or muscle contraction, in order to restore function, improve health or rectify physiological dysfunction. Various types of FES have been developed specifically for improving bladder function and while successful for many urological patients, still require substantial refinement for use after spinal cord injury. Improved knowledge of the neural circuitry and physiology of human bladder reflexes, and the mechanisms by which various types of FES alter spinal outflow, is urgently required. Following spinal cord injury, physical and chemical changes occur within peripheral, spinal and supraspinal components of bladder reflex circuitry. Better understanding of this plasticity may determine the most suitable methods of FES at particular times after injury, or may lead to new FES approaches that exploit this remodeling or perhaps even influence the plasticity. Advances in studies of the neuroanatomy, neurophysiology and plasticity of lumbosacral nerve circuits will provide many further opportunities to improve FES approaches, and will provide "artificial autonomic reflexes" that much more closely resemble the original, healthy neuronal regulatory mechanisms.

Parallel changes in bladder suburothelial vanilloid receptor TRPV1 and pan-neuronal marker PGP9.5 immunoreactivity in patients with neurogenic detrusor overactivity after intravesical resiniferatoxin treatment

OBJECTIVE

To compare PGP9.5 and transient receptor potential vanilloid receptor (TRPV1) suburothelial immunoreactivity between controls and patients with spinal neurogenic detrusor overactivity (NDO) before and after treatment with intravesical resiniferatoxin, as suburothelial PGP9.5-staining nerve fibres decrease in patients with spinal NDO who respond to intravesical capsaicin, and TRPV1 is present on these suburothelial nerve fibres in normal and overactive human urinary bladder.

PATIENTS AND METHODS

Patients with refractory NDO were enrolled in a prospective, randomized, parallel-group, double-blind, placebo-controlled trial using escalating doses of resiniferatoxin to a maximum of 1 micro mol/L. Flexible cystoscopic bladder biopsies obtained at baseline, 4 weeks after each instillation and at the time of maximum clinical response were compared with biopsies taken from control subjects. Frozen sections were incubated with rabbit antibodies to TRPV1 and PGP9.5, and assessed using standard immunohistochemical methods. PGP9.5 nerve density was analysed using a nerve-counting graticule by an observer unaware of sample origin. Another two independent observers unaware of each other's results used a random grading scale to evaluate TRPV1 nerve fibre density and intensity. The immunohistochemistry results were compared with histology findings (haematoxylin-eosin), and the Mann-Whitney test used to assess any differences (P < 0.05 significant) and the Pearson test for correlation.

RESULTS

There were eight controls and 20 patients with spinal NDO, 14 (five clinical responders and nine not) who received the maximum dose of resiniferatoxin. There were more PGP9.5 and TRPV1 nerve fibres in patients with NDO than in controls (P = 0.007 and 0.002, respectively). Immunoreactivity before resiniferatoxin was similar in both groups for both PGP9.5 and TRPV1. In responders there were fewer PGP9.5 and TRPV1-positive fibres after treatment (P = 0.008 for each) but no change in those not responding. Changes after treatment for TRPV1 correlated well with those for PGP9.5 (r = 0.88, P < 0.001).

CONCLUSIONS

The decrease of PGP9.5 and TRPV1 immunoreactive nerve fibres in responders to resiniferatoxin (to levels in control tissues) suggests that the increased numbers of nerve fibres in patients with NDO are mainly of sensory origin and express TRPV1. As baseline nerve fibre values were similar in responders and nonresponders, an additional factor may account for the difference in treatment outcome.

Mechanisms involved in new therapies for overactive bladder

During the last few years, vanilloid substances and botulinum-A toxin were extensively investigated as new therapies for overactive bladder. Intravesical administration of capsaicin or resiniferatoxin--2 members of the vanilloid family--has been shown to increase bladder capacity and decrease urge incontinence in patients with neurogenic, as well as nonneurogenic, forms of detrusor overactivity. In addition, vanilloids have been shown also to reduce bladder pain in patients with hypersensitive disorders. Vanilloids are exogenous ligands of vanilloid receptor type 1 (VR1), an ion channel present in the membrane of type C primary afferent nerve fibers. This receptor, which plays a key role in pain perception and control of the micturition reflex, may be upregulated by nerve growth factor (NGF), a neurotrophic molecule detected in high concentrations in overactive detrusor tissue. Vanilloids, by reducing uptake of NGF through sensory neurons, may counteract VR1 upregulation. Intravesical injections of botulinum-A toxin, a neurotoxin produced by Clostridium botulinum, were shown to increase bladder capacity and to decrease urge incontinence episodes in patients with neurogenic detrusor overactivity. Botulinum-A toxin impedes the release of acetylcholine from cholinergic nerve endings at the neuromuscular junction, leading to paralysis of the detrusor smooth muscle.

Urodynamic effects of estradiol (E2) in ovariectomized (ovx) rats

Whether estrogens have a beneficial effect in the urinary bladder to prevent or to delay occurrence of urinary bladder incontinence is an open question. Good animal models are missing. Therefore, in ovariectomized (ovx) rats we studied the effects of estradiol (E2) administered with food for 3 mo on urodynamic properties of the urinary bladder and the urethra. A biluminal catheter with one outlet in the bladder and another in the urethra in juxtaposition to the external sphincter was inserted in isoflurane anaesthetized animals. Within 2 x 30 s (1 min apart) 0.5 mL Ringer's solution was infused into the bladder and the inner vesicular and urethral pressure were recorded. In comparison to ovx estradiol-treated rats, ovx animals had significantly (p < 0.05) lower vesicular and urethral pressure. In the sham-treated ovx animals vesicular and urethral pressures were unstable and appeared uncoordinated, whereas estrogens increased vesicular and urethral pressure in a coordinated way, such that in these animals leaked volume was significantly lower than in the sham-treated ovx animals. By means of quantitative RT-PCR we demonstrate that the upper and lower part of the bladder and the urethra express estrogen receptor of the alpha- and beta-subtype (ER alpha and beta) and nerve growth factor, which is associated with painful sensations in inflamed urinary bladders. E2 downregulated both ERs in the bladder but not in the urethra, while NGF gene expression was downregulated in the urethra but unaffected by E2 in the bladder. It is concluded that estrogen deprivation causes uncoordinated function of the detrusor and sphincter muscles and that this effect can be prevented by estradiol.

Suppression of detrusor-sphincter dyssynergia by immunoneutralization of nerve growth factor in lumbosacral spinal cord in spinal cord injured rats

PURPOSE

We investigated the effects of intrathecal application of nerve growth factor (NGF) antibodies (NGF-Abs) and desensitization of C-fiber afferent pathways by capsaicin treatment on detrusor-sphincter dyssynergia (DSD) after spinal cord injury (SCI).

MATERIALS AND METHODS

In adult female rats SCI was induced by complete transection of the spinal cord at Th8 to 9. Ten days after spinalization vehicle or NGF-Ab (10 microg daily) was continuously administered at the level of the L6-S1 spinal cord through an implanted intrathecal catheter connected to an osmotic pump for 2 weeks. Another group of spinalized rats was treated with capsaicin (125 mg/kg subcutaneously) 3 weeks after spinalization and 5 days before experiments. Simultaneous recordings of intravesical pressure and urethral perfusion pressure were then performed. NGF levels in the L6 spinal cord were measured in vehicle or NGF-Ab treated spinalized rats using enzyme-linked immunosorbent assay.

RESULTS

DSD was observed in all vehicle treated spinalized rats. The average urethral pressure increase at the peak bladder contraction was significantly lower by 84% and 78% in NGF-Ab and capsaicin treated spinalized rats, respectively, than in vehicle treated rats. After NGF-Ab treatment NGF levels were significantly decreased by 38% in the L6 spinal cord compared with vehicle treated spinalized rats, in which NGF levels in the L6 spinal cord were 7 times higher than in spinal intact rats.

CONCLUSIONS

Increased levels of NGF in the spinal cord could contribute to the emergence of DSD that is at least in part mediated by C-fiber bladder afferents after SCI. Thus suppression of NGF levels in afferent pathways could be useful for treating DSD following SCI.

Changes in galanin immunoreactivity in rat lumbosacral spinal cord and dorsal root ganglia after spinal cord injury

Alterations in the expression of the neuropeptide galanin were examined in micturition reflex pathways 6 weeks after complete spinal cord transection (T8). In control animals, galanin expression was present in specific regions of the gray matter in the rostral lumbar and caudal lumbosacral spinal cord, including: (1) the dorsal commissure; (2) the superficial dorsal horn; (3) the regions of the intermediolateral cell column (L1-L2) and the sacral parasympathetic nucleus (L6-S1); and (4) the lateral collateral pathway in lumbosacral spinal segments. Densitometry analysis demonstrated significant increases (P < or = 0.001) in galanin immunoreactivity (IR) in these regions of the S1 spinal cord after spinal cord injury (SCI). Changes in galanin-IR were not observed at the L4-L6 segments except for an increase in galanin-IR in the dorsal commissure in the L4 segment. In contrast, decreases in galanin-IR were observed in the L1 segment. The number of galanin-IR cells increased (P < or = 0.001) in the L1 and S1 dorsal root ganglia (DRG) after SCI. In all DRG examined (L1, L2, L6, and S1), the percentage of bladder afferent cells expressing galanin-IR significantly increased (4-19-fold) after chronic SCI. In contrast, galanin expression in nerve fibers in the urinary bladder detrusor and urothelium was decreased or eliminated after SCI. Expression of the neurotrophic factors nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) was altered in the spinal cord after SCI. A significant increase in BDNF expression was present in spinal cord segments after SCI. In contrast, NGF expression was only increased in the spinal segments adjacent and rostral to the transection site (T7-T8), whereas spinal segments (T13-L1; L6-S1), distal to the transection site exhibited decreased NGF expression. Changes in galanin expression in micturition pathways after SCI may be mediated by changing neurotrophic factor expression, particularly BDNF. These changes may contribute to urinary bladder dysfunction after SCI.

Nerve-mediated bladder contraction is impaired by cytokines: involvement of inducible nitric oxide synthase

We investigated the possible involvement of inducible nitric oxide synthase (iNOS) in the effect of cytokines on neuromuscular function in isolated rat bladder strips. Bladder strips were incubated in cell culture medium for 24 h with or without tumour necrosis factor-alpha (TNF-alpha)+interleukin-1beta. Mechanical activity in response to electrical field stimulation and carbachol was recorded in organ baths. Both the electrical field stimulation- and carbachol-induced contractions were reduced by the incubation. The electrical field stimulation-induced contraction was significantly further impaired after prolonged exposure to TNF-alpha+interleukin-1beta. This impairment was restored by dexamethasone, the iNOS inhibitor aminoguanidine and partially by brain-derived neurotrophic factor (BDNF). In contrast, carbachol-induced contractions were not affected by cytokines. iNOS protein expression was detected in cytokine-incubated bladder strips by immunohistochemistry and Western blot analysis. The results demonstrated that TNF-alpha+interleukin-1beta impaired nerve-mediated bladder contractions. Aminoguanidine, and to some extent BDNF, exerted neuroprotective effects.

Change in muscarinic modulation of transmitter release in the rat urinary bladder after spinal cord injury

Muscarinic facilitation of 14C-ACh release from post-ganglionic parasympathetic nerve terminals was studied in bladder strips prepared from spinal intact (SI) and spinal cord transected (SCT) rats. The spinal cord was transected at the lower thoracic spinal segments 3 weeks prior to the experiments. Using non-facilitatory stimulation (2 Hz) the release of ACh in spinal intact rats did not change in the presence of a non-specific muscarinic antagonist, atropine (100 nM), an M(1) specific antagonist (pirenzepine, 50 nM) or an M(1)-M(3) specific antagonist (4-DAMP, 5 nM). However, during a facilitatory stimulation paradigm (10 Hz or 40 Hz, 100 shocks) atropine and pirenzepine, but not 4-DAMP inhibited the release of ACh in bladders from spinal intact rats, indicating an M(1) receptor-mediated facilitation. In spinal cord transected rats, 2 Hz stimulation-induced release was significantly inhibited by atropine or 4-DAMP but not by pirenzepine indicating that a pre-junctional facilitatory mechanism mediated via M(3) muscarinic receptors could be induced by a non-facilitatory stimulation paradigm after spinal injury. In bladders of spinal cord transected rats, 10 Hz stimulation-evoked release of ACh was also inhibited by atropine and 4-DAMP (5 nM) but not by pirenzepine (50 nM). These results indicate that pre-junctional muscarinic receptors at cholinergic nerve endings in the bladder change after chronic spinal cord injury. It appears that low affinity M(1) muscarinic receptors are replaced by high affinity M(3) receptors. This change in modulation of ACh release may partly explain the bladder hyperactivity after chronic spinal cord injury.

Tetrodotoxin-resistant sodium channels Na(v)1.8/SNS and Na(v)1.9/NaN in afferent neurons innervating urinary bladder in control and spinal cord injured rats

Tetrodotoxin-resistant (TTX-R) sodium channels Na(v)1.8/SNS and Na(v)1.9/NaN are preferentially expressed in small diameter dorsal root ganglia (DRG) neurons. The urinary bladder is innervated by small afferent neurons from L6/S1 DRG, of which approximately 75% exhibit high-threshold action potentials that are mediated by TTX-R sodium channels. Following transection of the spinal cord at T8, the bladder becomes areflexic and then gradually hyper-reflexic, and there is an attenuation of the TTX-R sodium currents in bladder afferent neurons. In the present study, we demonstrate that Na(v)1.8 is expressed in both bladder and non-bladder afferent neurons, while Na(v)1.9 is expressed in non-bladder afferent neurons but is rarely observed in bladder afferent neurons. In spinal cord transected rats 28-32 days following transection, there is a decreased expression of Na(v)1.8 sodium channels in bladder afferents, but no change in the expression of Na(v)1.8 in non-bladder afferent neurons. Both bladder and non-bladder afferent neurons exhibit limited increases in Na(v)1.9 expression following spinal cord transection. These results demonstrate that the expression of TTX-R channels in bladder afferent neurons changes after spinal cord transection, and these changes may contribute to the increased excitability of these neurons following spinal cord injury.

COX-2 and prostanoid expression in micturition pathways after cyclophosphamide-induced cystitis in the rat

The purpose of this study was to determine the role of cyclooxygenase-2 (COX-2) and its metabolites in lower urinary tract function after induction of acute (4 h), intermediate (48 h), or chronic (10 day) cyclophosphamide (CYP)-induced cystitis. Bladders were harvested from euthanized female rats for analyses. Conscious cystometry was used to assess the effects of a COX-2-specific inhibitor, 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl2(5H)-furanone (DFU, 5 mg/kg sc), a disubstituted furanone, in CYP-induced cystitis. COX-2 mRNA was increased in inflamed bladders after acute (12-fold) and chronic (9-fold) treatment. COX-2 protein expression in inflamed bladders paralleled COX-2 mRNA expression. Prostaglandin D2-methoxime expression in the bladder was significantly (P < or = 0.01) increased in acute (3-fold) and chronic (5.5-fold) cystitis. Prostaglandin E2 was significantly (P < or = 0.01) increased (2-fold) in the bladder with intermediate (1.7-fold) and chronic (2.6-fold) cystitis. COX-2-immunoreactive cell profiles were distributed throughout the inflamed bladder and coexpressed histamine immunoreactivity. Conscious cystometry in rats treated with CYP + DFU showed increased micturition intervals 4 and 48 h after CYP treatment and decreased intravesical pressures during filling and micturition compared with rats treated with CYP + vehicle. These studies suggest an involvement of urinary bladder COX-2 and its metabolites in altered micturition reflexes with CYP-induced cystitis.

Up-regulation of phosphorylated CREB but not c-Jun in bladder afferent neurons in dorsal root ganglia after cystitis

We examined the changes of two transcription factors, CREB and c-Jun, in dorsal root ganglia (DRG) after acute (8 or 48 hours) or chronic (10 days) cyclophosphamide (CYP)-induced cystitis. Results showed an increase in the number of p-CREB-immunoreactive (-IR) cells in the L1 and L2 DRG (5-7-fold; P < or = 0.05) as well as L6 and S1 DRG (2-4-fold; P < or = 0.05) after acute and chronic cystitis. The number of p-CREB-IR cells in the L4-L5 DRG was not altered with cystitis. The number of c-Jun-IR cells increased in the L1-L2 DRG (L1: 10-fold; L2: 8-fold; P < or = 0.05) only with chronic cystitis, although it increased in the L6-S1 DRG with CYP-induced cystitis of acute (2-3-fold; P < or = 0.05) and chronic (6-10-fold; P < or = 0.05) duration. After CYP treatment, the percentage of bladder afferent cells expressing p-CREB immunoreactivity (3-7-fold; P < or = 0.05) increased in L1, L2, L6, and S1 DRG. The increase occurred 8 hours post-CYP injection and was maintained with chronic cystitis. There were few c-Jun-IR cells in the bladder afferent population. These results demonstrate that CYP induces p-CREB and c-Jun expression in DRG in a time-dependent manner. However, c-Jun expression is not associated with bladder afferent neurons. Resiniferatoxin reduced CYP-induced up-regulation of p-CREB in DRG, suggesting that cystitis can reveal an altered CREB phosphorylation that may be mediated by capsaicin-sensitive bladder afferents. Colocalization of p-CREB and Trk receptor(s) showed that a subpopulation of p-CREB-IR cells expressed p-Trk with cystitis. These results suggest that up-regulation of p-CREB may be mediated by a neurotrophin/Trk signaling pathway.

Cystitis-induced upregulation of tyrosine kinase (TrkA, TrkB) receptor expression and phosphorylation in rat micturition pathways

This study examined tyrosine kinase receptor (Trk) expression and phosphorylation in lumbosacral dorsal root ganglia (DRG) after acute (8 or 48 hours) or chronic (10 days) cyclophosphamide (CYP)-induced cystitis. Increases in the number of TrkA-immunoreactive (IR) cell profiles were detected in the L1 and L6 DRG (four-fold; P < or = 0.01) and the S1 DRG (1.5-fold; P < or = 0.05) but not in the L2, L4, and L5 DRG with CYP-induced cystitis of acute and chronic duration compared with control rats. The number of TrkB-IR cell profiles increased in the L1 and L2 DRG (L1: 2.6-fold; L2: 1.4-fold; P < or = 0.05) and in the L6 and S1 DRG (L6: 2.2-fold; S1: 1.3-fold; P < or = 0.05) only after acute CYP treatment (8 hours). After CYP treatment, the percentage of bladder afferent cell profiles expressing TrkA-IR (approximately 50%; P < or = 0.05) increased in L1 and L6 DRG. The percentage of bladder afferent cell profiles expressing TrkB-IR (approximately 45%; P < or = 0.05) in L1, L2, L6, and S1 DRG also increased compared with control cell profiles. The increase in TrkA-IR in bladder afferent cells occurred 8 hours after CYP treatment and was maintained in L1 DRG with chronic (10 days) CYP-induced cystitis. However, the increase in bladder afferent cells expressing TrkB-IR only occurred at the most acute time point examined (8 hours). TrkA-IR and TrkB-IR cell profiles also demonstrated phosphorylated Trk-IR with acute and/or chronic CYP-induced cystitis. These results demonstrated that CYP-induced cystitis increases the expression and phosphorylation of Trk receptors in lumbosacral DRG. Expression of neurotrophic factors in the inflamed urinary bladder may contribute to this increased expression, and neurotrophic factor and Trk interactions may play unique roles in decreased urinary tract plasticity with CYP-induced cystitis.

Differential expression of bladder neurotrophic factor mRNA in male and female rats after bladder outflow obstruction

PURPOSE

We validated a male rat model of bladder outflow obstruction and compared the expression of bladder neurotrophic factor mRNA in male and female rats 6 weeks after bladder outlet obstruction.

MATERIALS AND METHODS

We examined the proximal urethra in male Wistar rats. Urethral lumen reducing ligatures were placed in 15 females and 19 males, while 10 male and 10 female controls underwent sham surgery. Awake cystometry was performed 6 weeks after surgery. Ribonuclease protection assay was used to measure changes in bladder neurotrophic factor mRNA expression in the 2 sexes.

RESULTS

Average bladder capacity in rats with bladder outlet obstruction increased 3-fold in males and 4.4-fold in females compared with controls, while bladder weight increased 2.2 and 4.3-fold, respectively. Filling and threshold pressure increased significantly and nonvoiding bladder contractions were recorded in 100% of female and 80% of male rats with bladder outlet obstruction. An 8-fold increase in bladder brain derived neurotrophic factor mRNA was noted in each sex after obstruction. A 2-fold increase in bladder nerve growth factor mRNA after obstruction was only observed in females.

CONCLUSIONS

This male rat model of bladder outlet obstruction was created by placing lumen reducing ligatures at the urethrovesical junction. The dramatic increase in bladder brain derived neurotrophic factor mRNA expression and differential expression of nerve growth factor mRNA in male and female rats with bladder outlet obstruction suggest that additional neurotrophic factors may contribute to the lower urinary tract neuroplasticity associated with bladder outlet obstruction and this contribution may be gender dependent.

Immunoneutralization of nerve growth factor in lumbosacral spinal cord reduces bladder hyperreflexia in spinal cord injured rats

PURPOSE

We investigated the effects of intrathecal application of nerve growth factor (NGF) antibodies (Ab) on bladder hyperreflexia in chronic spinalized rats.

MATERIALS AND METHODS

In adult female rats an intrathecal catheter was implanted at the level of the L6 to S1 spinal cord, followed by complete transection of the Th8 to 9 spinal cord. At 10 days after spinalization the intrathecal catheter was connected to an osmotic pump for continuous delivery of vehicle or NGF Ab (10 microg daily) for 2 weeks. Awake cystometry was then performed. NGF levels in the L5 to S1 dorsal root ganglia, L6 spinal cord and bladder were also measured using enzyme-linked immunosorbent assay.

RESULTS

The number of uninhibited bladder contractions per voiding cycle, maximal pressure of uninhibited bladder contraction and maximal voiding pressure were significantly decreased in NGF Ab treated versus vehicle treated spinalized rats. Intercontraction interval, baseline intravesical pressure, pressure threshold for voiding and voiding efficiency were not significantly changed by NGF Ab treatment. NGF levels in the bladder, L6 spinal cord and L5 to S1 dorsal root ganglia of vehicle treated spinalized rats was 1.6 to 4.8 times higher than in spinal cord intact rats. After intrathecal NGF Ab treatment NGF levels were significantly lower in the L6 to S1 dorsal root ganglia (30% to 35%) and L6 spinal cord (53%) but not in the bladder or L5 dorsal root ganglia compared with levels in vehicle treated spinalized rats.

CONCLUSIONS

Increased levels of NGF in the bladder, spinal cord and dorsal root ganglia were associated with bladder hyperreflexia after spinal cord injury. Immuno-neutralization of NGF in the spinal cord suppressed NGF levels in the L6 to S1 dorsal root ganglia, which contain bladder afferent neurons, and also suppressed bladder hyperreflexia. Thus, suppression of NGF levels in afferent pathways could be useful for treating bladder hyperreflexia associated with spinal cord injury.

Up-regulation of tyrosine kinase (Trka, Trkb) receptor expression and phosphorylation in lumbosacral dorsal root ganglia after chronic spinal cord (T8-T10) injury

Previous studies have demonstrated changes in urinary bladder neurotrophic factors after bladder dysfunction. We have hypothesized that retrograde transport of neurotrophin(s) from the bladder to lumbosacral dorsal root ganglia (DRG) may play a role in bladder reflex reorganization after spinal cord injury (SCI). In this study, we determined whether the expression of tyrosine kinase receptors (TrkA, TrkB) is altered in lumbosacral DRG after SCI through immunofluorescence techniques. Complete transection of the spinal cord (T8-T10) was performed in female Wistar rats (120-150 g), and animals were studied 5-6 weeks after SCI. One week before killing, Fast Blue (FB) was injected into the bladder to label bladder afferent cells in the L1, L2, L6, and S1 DRG. After SCI, a significant increase in the number of TrkA-immunoreactive (IR) positive cells was detected in the L6-S1 DRG (L6: 1.9-fold, P < or = 0.01; S1: 1.7-fold, P < or = 0.05) and in the L1 DRG (3.0-fold; P < or = 0.01) but not in the L4-L5 DRG compared with spinal-intact (control) rats. After SCI, a significant increase in the number of TrkB-IR cells was also detected in the L6-S1 DRG (L6: 2.2-fold, P < or = 0.01; S1: 1.5-fold, P < or = 0.05) and in the L1-L2 DRG (L1: 1.5-fold, P < or = 0.01; L2: 1.3-fold, P < or = 0.05) but not in the L4-L5 DRG compared with control rats. After SCI, the percentage of FB-labeled cells expressing TrkA immunoreactivity (approximately 68%) or TrkB immunoreactivity (approximately 65%) in L1 and L6 DRG significantly (P < or = 0.01) increased compared with control (20-30%) DRG. After SCI, the percentage of TrkA-IR cells expressing phosphorylated (p)-Trk immunoreactivity significantly increased (1.5- to 2.3-fold increase) in the L1, L6, and S1 DRG. The percentage of TrkB-IR cells expressing p-Trk immunoreactivity after SCI also increased (1.3-fold increase) in the L1 and L6 DRG. These results demonstrate that (1) TrkA and TrkB immunoreactivity is increased in bladder afferent cells after SCI and (2) TrkA and TrkB receptors are phosphorylated in DRG after SCI. Neuroplasticity of lower urinary tract reflexes after SCI may be mediated by both nerve growth factor and brain-derived neurotrophic factor.

Characterization of the neurotrophic response to acute pancreatitis

INTRODUCTION

Interesting preliminary data on changes in the neurotrophin system in various digestive diseases have recently begun to emerge.

AIMS

To measure changes in messenger RNA (mRNA) levels of neurotrophins and to identify cell types expressing neurotrophins in the pancreas of rats with L-arginine-induced pancreatitis.

METHODOLOGY

Rats were killed at time points from 2 hours to 4 weeks after the induction of pancreatitis, and responses were measured by assay.

RESULTS

By RNase protection assay, ciliary neurotrophic factor (CNTF) mRNA expression showed a rapid response (sixfold increase over control) in the inflamed pancreas at 2 hours. The levels of mRNA expression of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) in the inflamed pancreas reached a peak at 1 week (2.5-fold, twofold, fourfold, and fivefold increase, respectively). By immunohistochemistry, immunoreactivity for all neurotrophins examined was observed in the islets of Langerhans in the control pancreas at all time points, but it was markedly reduced in the islets in the inflamed pancreas at 2 and 6 hours. Acinar and ductal cells, inflammatory cells, and neural elements were immunoreactive for those neurotrophins in the inflamed pancreas from 2 hours to 2 weeks.

CONCLUSION

The temporal and spatial expression of neurotrophins in the course of experimental pancreatitis suggests that their upregulation is a critical component of the response of the pancreas to injury in this model.

Gene expression profiling of mouse bladder inflammatory responses to LPS, substance P, and antigen-stimulation

Inflammatory bladder disorders such as interstitial cystitis (IC) deserve attention since a major problem of the disease is diagnosis. IC affects millions of women and is characterized by severe pain, increased frequency of micturition, and chronic inflammation. Characterizing the molecular fingerprint (gene profile) of IC will help elucidate the mechanisms involved and suggest further approaches for therapeutic intervention. Therefore, in the present study we used established animal models of cystitis to determine the time course of bladder inflammatory responses to antigen, Escherichia coli lipopolysaccharide (LPS), and substance P (SP) by morphological analysis and cDNA microarrays. The specific aim of the present study was to compare bladder inflammatory responses to antigen, LPS, and SP by morphological analysis and cDNA microarray profiling to determine whether bladder responses to inflammation elicit a specific universal gene expression response regardless of the stimulating agent. During acute bladder inflammation, there was a predominant infiltrate of polymorphonuclear neutrophils into the bladder. Time-course studies identified early, intermediate, and late genes that were commonly up-regulated by all three stimuli. These genes included: phosphodiesterase 1C, cAMP-dependent protein kinase, iNOS, beta-NGF, proenkephalin B and orphanin, corticotrophin-releasing factor (CRF) R, estrogen R, PAI2, and protease inhibitor 17, NFkB p105, c-fos, fos-B, basic transcription factors, and cytoskeleton and motility proteins. Another cluster indicated genes that were commonly down-regulated by all three stimuli and included HSF2, NF-kappa B p65, ICE, IGF-II and FGF-7, MMP2, MMP14, and presenilin 2. Furthermore, we determined gene profiles that identify the transition between acute and chronic inflammation. During chronic inflammation, the urinary bladder presented a predominance of monocyte/macrophage infiltrate and a concomitant increase in the expression of the following genes: 5-HT 1c, 5-HTR7, beta 2 adrenergic receptor, c-Fgr, collagen 10 alpha 1, mast cell factor, melanocyte-specific gene 2, neural cell adhesion molecule 2, potassium inwardly-rectifying channel, prostaglandin F receptor, and RXR-beta cis-11-retinoic acid receptor. We conclude that microarray analysis of genes expressed in the bladder during experimental inflammation may be predictive of outcome. Further characterization of the inflammation-induced gene expression profiles obtained here may identify novel biomarkers and shed light into the etiology of cystitis.

Changes in urinary bladder cytokine mRNA and protein after cyclophosphamide-induced cystitis

Cyclophosphamide (CYP)-induced cystitis alters micturition function and produces reorganization of the micturition reflex. This reorganization may involve cytokine expression in the urinary bladder. These studies have determined candidate cytokines in the bladder that may contribute to the reorganization process. An RNase protection assay was used to measure changes in rat bladder cytokine mRNA [interferon-gamma (IFN)-gamma, interleukin-1alpha/beta (IL-1alpha/beta), IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, and tumor necrosis factor-alpha/beta (TNF-alpha/beta)] after acute (4 h), intermediate (48 h), or chronic (10 day) cystitis. The correlation between bladder cytokine mRNA and protein expression was also determined by immunoassay. Although at each time point after cystitis significant changes in bladder cytokine mRNA were observed, the magnitude differed (acute > intermediate > chronic). Acute cystitis demonstrated the most robust changes (P </= 0.005; IL-1beta, 330-fold increase; IL-2, 20-fold increase; IL-4, 8-fold increase; IL-6, 80-fold increase) in cytokine mRNA expression and TNF-alpha or TNF-beta mRNA were only increased (2-10-fold) after acute cystitis. More modest increases in cytokine mRNA expression were observed after 48-h or 10-day cystitis. Cytokine protein expression generally paralleled that of mRNA. Increased cytokine expression after CYP-induced cystitis, alone or in combination with other inflammatory mediators or growth factors, may contribute to altered lower urinary tract function after cystitis.

Mast cell regulation of inflammation and gene expression during antigen-induced bladder inflammation in mice

Mast cell numbers are significantly increased in bladder disorders including malignancy and interstitial cystitis, but their precise role has been difficult to determine. We characterized the role of mast cells on gene regulation associated with antigen-induced bladder inflammation in mice. For this purpose, we examined the responses in mast cell-deficient (Kit(W)/Kit(W-v)), congenic normal (+/+), and Kit(W)/Kit(W-v) mice that were reconstituted with bone marrow stem cells (BMR) to restore mast cells. All mice were actively sensitized and challenged intravesically with either saline or specific antigen. Bladder inflammation occurred in +/+ and BMR but not the Kit(W)/Kit(W-v) mice. Gene expression was determined using mouse cDNA expression arrays. Self-organizing maps, performed without preconditions, indicated gene expression changes dependent on the presence of mast cells. These genes were upregulated in bladders isolated from antigen challenge of +/+, not altered in Kit(W)/Kit(W-v), and were upregulated in BMR mice. Taken together these results demonstrate an important role for mast cells in allergic cystitis and indicate that mast cells can alter their environment by regulating tissue gene expression.

Tachykinins as modulators of the micturition reflex in the central and peripheral nervous system

In the normal urinary bladder, tachykinins (TKs) are expressed in a population of bladder nociceptors that is sensitive to the excitatory and desensitizing effects of capsaicin (i.e., capsaicin-sensitive primary afferent neurons (CSPANs)). Several endobiotics or xenobiotics excite CSPANs and release TKs and other mediators at both the peripheral and spinal cord level. The peripheral release of TKs determines a set of responses (known as neurogenic inflammation) that includes vasodilatation, plasma protein extravasation, smooth muscle contraction and stimulation of afferent nerves. Following chronic inflammation, both immune cells and capsaicin-resistant sensory neurons can de novo express TKs: whether these pools of TKs are releasable and contribute to inflammatory processes is presently unsettled. At the spinal cord level, the release of TKs contributes in determining an altered pattern of vesicourethral reflexes in response to nociceptive stimulation of the bladder by conveying: (a) the afferent transmission to supraspinal sites, and (b) descending or sensory inputs to the sacral parasympathetic nucleus (SPN). Recent evidence also attribute a synergetic role of TKs in the supraspinal modulation of the sensory arm of the micturition reflex. The overall available information suggests that TK receptor antagonists may affect bladder motility/reflexes which occur during different pathological states, while having little influence on the normal motor bladder function.

Pharmacology of the lower urinary tract

The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the urinary bladder, urethra, and external urethral sphincter. This activity is in turn controlled by neural circuits in the brain, spinal cord, and peripheral ganglia. Various neurotransmitters, including acetylcholine, norepinephrine, dopamine, serotonin, excitatory and inhibitory amino acids, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in the neural regulation of the lower urinary tract. Injuries or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce voiding dysfunctions such as urinary frequency, urgency, and incontinence or inefficient voiding and urinary retention. This chapter will review recent advances in our understanding of the pathophysiology of voiding disorders and the targets for drug therapy.

Time course of LPS-induced gene expression in a mouse model of genitourinary inflammation

In this study, self-organizing map (SOM) gene cluster techniques are applied to the analysis of cDNA microarray analysis of gene expression changes occurring in the early stages of genitourinary inflammation. We determined the time course of lipopolysaccharide (LPS)-induced gene expression in experimental cystitis. Mice were euthanized 0.5, 1, 4, and 24 h after LPS instillation into the urinary bladder, and gene expression was determined using four replicate Atlas mouse cDNA expression arrays containing 588 known genes at each time point. SOM gene cluster analysis, performed without preconditions, identified functionally significant gene clusters based on the kinetics of change in gene expression. Genes were classified as follows: 1) expressed at time 0; 2) early genes (peak expression between 0.5 and 1 h); and 3) late genes (peak expression between 4 and 24 h). One gene cluster maintained a constant level of expression during the entire time period studied. In contrast, LPS treatment downregulated the expression of some genes expressed at time 0, in a cluster including transcription factors, protooncogenes, apoptosis-related proteins (cysteine protease), intracellular kinases, and growth factors. Gene upregulation in response to LPS was observed as early as 0.5 h in a cluster including the interleukin-6 (IL-6) receptor, alpha- and beta-nerve growth factor (alpha- and beta-NGF), vascular endothelial growth factor receptor-1 (VEGF R1), C-C chemokine receptor, and P-selectin. Another tight cluster of genes with marked expression at 1 h after LPS and insignificant expression at all other time points studied included the protooncogenes c-Fos, Fos-B, Fra-2, Jun-B, Jun-D, and Egr-1. Almost all interleukin genes were upregulated as early as 1 h after stimulation with LPS. Nuclear factor-kappaB (NF-kappaB) pathway genes collected in a single cluster with a peak expression 4 h after LPS stimulation. In contrast, most of the interleukin receptors and chemokine receptors presented a late peak of expression 24 h after LPS coinciding with the peak of neutrophil infiltration into the bladder wall. Selected cDNA microarray observations were confirmed by RNase protection assay. In conclusion, the cDNA array experimental approach provided a global profile of gene expression changes in bladder tissue after stimulation with LPS. SOM techniques identified functionally significant gene clusters, providing a powerful technical basis for future analysis of mechanisms of bladder inflammation.

Alterations in neuropeptide expression in lumbosacral bladder pathways following chronic cystitis

These studies examined changes in the expression of calcitonin gene-related peptide (CGRP) and substance P (SP) in lumbosacral (L6-S1) micturition reflex pathways, following chronic cystitis induced by cyclophosphamide (CYP). In control Wistar rats, CGRP- or SP-immunoreactivity (IR) was expressed in fibers in the superficial dorsal horn in all segmental levels examined (L4-S1). Bladder afferent cells in the dorsal root ganglia (DRG; L6, S1) from control animals also exhibited CGRP- (41-55%) or SP-IR (2-3%). Following chronic, CYP-induced cystitis, CGRP- and SP-IR were dramatically increased in spinal segments and DRG (L6, S1) involved in micturition reflexes. The density of CGRP- and SP-IR was increased in the superficial laminae (I-II) of the L6 and S1 spinal segments. No changes in CGRP- or SP-IR were observed in the L4-L5 segments. Staining was also dramatically increased in a fiber bundle extending ventrally from Lissauer's tract in lamina I along the lateral edge of the DH to the sacral parasympathetic nucleus in the L6-S1 spinal segments. Following chronic cystitis, CGRP- and SP-IR in cells in the L6 and S1 DRG significantly (P< or =0.05) increased and the percentage of bladder afferent cells expressing CGRP- (76%) or SP-IR (11-18%) also significantly (P< or =0.001) increased. No changes were observed in the L4-L5 DRG. These studies suggest that the neuropeptides, CGRP and SP, may play a role in urinary bladder afferent pathways, following chronic urinary bladder inflammation. Changes in CGRP or SP expression following cystitis may contribute to the altered visceral sensation (allodynia) and/or urinary bladder hyperreflexia in the clinical syndrome, interstitial cystitis.

Pharmacologic and potential biologic interventions to restore bladder function after spinal cord injury

Spinal cord injury disrupts voluntary control of voiding and the normal reflex pathways that coordinate bladder and urethral sphincter function. The present review addresses studies in animals and humans that have evaluated various therapeutic approaches for normalizing lower urinary tract function after spinal cord injury.

Increased expression of spinal cord Fos protein induced by bladder stimulation after spinal cord injury

These studies examined Fos protein expression in spinal cord neurons synaptically activated by stimulation of bladder afferent pathways after spinal cord injury (SCI). In urethan-anesthetized Wistar rats after SCI for 6 wk, intravesical saline distension significantly (P </= 0.005) increased the number of Fos-immunoreactive (IR) cells in the rostrolumbar (L1, 38 cells/section; L2, 29 cells/section) and caudal lumbosacral (L6, 140 cells/section; S1, 110 cells/section) spinal cord compared with control animals, but Fos expression in the L5 segment was not altered. The distribution of Fos-IR cells was also altered in the lumbosacral spinal cord. Significantly greater numbers of Fos-IR cells were distributed in the dorsal commissure and medial and lateral dorsal horn after intravesical distension in SCI animals. Large percentages of parasympathetic (75%) and sympathetic (85%) preganglionic neurons also expressed Fos-IR after intravesical distension in SCI animals. These results demonstrate that bladder distension produces increased numbers and an altered distribution pattern of Fos-IR cells after SCI. This pattern resembles that after noxious irritation of the bladder in control animals. Pretreatment with capsaicin significantly reduced the number of Fos-IR cells induced by bladder distension after SCI. These data suggest that SCI can reveal an altered Fos expression pattern in response to a nonnoxious bladder stimulus that is partially mediated by capsaicin-sensitive bladder afferents.

Developmental expression of urinary bladder neurotrophic factor mRNA and protein in the neonatal rat

These studies were performed to determine the developmental expression pattern of neurotrophic factor (NTF: nerve growth factor (betaNGF), brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), ciliary neurotrophic factor (CNTF), neurotrophin-3 (NT-3) and NT-4 mRNA and NGF, NT-3 and NT-4 protein in the urinary bladder of the postnatal Wistar rat. It was hypothesized that NTFs may contribute to the development of the spinobulbospinal micturition reflex that represents the adult micturition pattern. Changes in NTF mRNA or protein expression in the urinary bladder at the time of development of the mature micturition reflex (postnatal days (P) 16-18) may suggest an involvement of target-derived NTFs in this maturation process. Developmental ages, prior to (P5, P10, P15) or following (P20, P30, adult P90) the development of the spinobulbospinal micturition reflex were selected and the urinary bladder was analyzed for levels of neurotrophic factor mRNA or protein. Results from ribonuclease protection assays demonstrated a similar developmental pattern among each neurotrophic factor examined. Neurotrophic factor mRNA levels increased by P10 and reach a maximum by P15. Subsequently, NTF mRNA levels declined to adult levels that were less than the earliest postnatal time examined (P5). NTF mRNA expression was significantly (p</=0.05-0.001) greater at P10, P15, P20 and P40 (NT-4 mRNA) compared to adult levels for each NTF examined except GDNF mRNA. In general, NGF, NT-3 and NT-4 urinary bladder protein levels in early postnatal development, as determined by ELISA, were similar when compared to the corresponding mRNA expression. Differences in the correlation between NT-3 and NT-4 mRNA and protein expression were demonstrated in the adult urinary bladder where significantly (p</=0. 001) greater levels of protein were revealed despite relatively low abundance of NT-3 and NT-4 mRNA. The developmental expression pattern (maximum expression at the second to third postnatal week) of NTFs in the urinary bladder is consistent with a potential role in the development of the spinobulbospinal reflex. Relatively high expression of NT-3 and NT-4 protein in the adult urinary bladder suggests a potential importance of these factors in the adult lower urinary tract.

Increased expression of growth-associated protein (GAP-43) in lower urinary tract pathways following cyclophosphamide (CYP)-induced cystitis

Alterations in the expression of growth-associated protein 43 (GAP-43) were examined in lower urinary tract micturition reflex pathways in a chronic model of cyclophosphamide (CYP)-induced cystitis. In control animals, expression of GAP-43 was present in specific regions of the gray matter in the rostral lumbar and caudal lumbosacral spinal cord, including: (1) the dorsal commissure; (2) the dorsal horn and (3) the regions of the intermediolateral cell column (L1-L2) and the sacral parasympathetic nucleus (L6-S1) and (4) in the lateral collateral pathway of Lissauer in L6-S1 spinal segments. Densitometry analysis has demonstrated significant increases (p</=0.001; 1.5-4.0-fold increase) in GAP-43-immunoreactivity (IR) in these regions of the rostral lumbar (L1-L2) and caudal lumbosacral (L6-S1) spinal cord following CYP-induced urinary bladder inflammation. Changes in GAP-43-IR were restricted to those segmental levels examined (L1-L2 and L6-S1) that are involved in lower urinary tract reflexes. Changes in GAP-43-IR were not observed at the L5 segmental level. In contrast to significant increases in GAP-43-IR in specific regions of the rostral lumbar and caudal lumbosacral spinal cord, no changes in GAP-43-IR were observed in the L1, L2 or L6, S1 dorsal root ganglia (DRG). In control animals, virtually all retrogradely labeled (Fast Blue) bladder afferent cells in the L1, L2 and L6, S1 DRG expressed GAP-43-IR. This percentage (approximately 100%) of bladder afferent cells expressing GAP-43-IR was unchanged following CYP-induced urinary bladder inflammation. Alterations in GAP-43-IR following chronic cystitis may suggest a reorganization of bladder afferent projections and spinal elements involved in bladder reflexes consistent with alterations in bladder function observed in animal models of cystitis.