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

High maternal BMI and low maternal blood BDNF may determine the limit of detection of amniotic fluid BDNF throughout gestation: Analysis of mother-fetus trios and literature review

Objective

An increasing number of studies show the importance of brain-derived neurotrophic factor (BDNF) acting at the feto-placental interface, however, only a few studies describe BDNF levels in amniotic fluid (AF).

Methods

In this cross-sectional, prospective study, 109 maternal blood-amniotic fluid pairs (including 66 maternal blood-fetal-blood-amniotic fluid trios) were analyzed. BDNF concentrations were measured with a commercially available immunoassay.

Results

In 71 AF from 109 samples, AF-BDNF concentrations were below the lowest limit of Quantitation (LLoQ) of 1.19 pg/ml (group A), leaving 38 samples with measurable BDNF concentrations (group B). Patients in group A showed significantly higher maternal BMI before pregnancy (mean±SD 26.3± 6.7 (kg/m²) vs. 23.8 ±4.5 (kg/m²) p = 0.04) and lower maternal blood BDNF concentrations than the other group (mean±SD 510.6 ± 554.7 pg/ml vs. mean±SD 910.1± 690.1 pg/ml; p<0.0001). Spearman correlation showed a negative correlation between maternal BMI before pregnancy and maternal BDNF concentrations (r = -0.25, p = 0.01).

Conclusion

Our study is the first to correlate AF-BDNF samples with the corresponding maternal and fetal blood-BDNF samples. The significant negative correlation between maternal BMI before pregnancy and maternal BDNF and AF-BDNF concentrations below the limit of detection has to be evaluated in further studies.

An Examination of the Relationship between Urinary Neurotrophin Concentrations and Transcutaneous Electrical Nerve Stimulation (TENS) Used in Pediatric Overactive Bladder Therapy

This article aims to explore changes in urinary concentrations of selected neurotrophins in the course of TENS therapy in children with overactive bladder (OAB). A two-group open-label prospective study was conducted. The intervention group comprised 30 children aged between 5 and 12 years old with OAB refractory to conservative therapy. They received 12 weeks of TENS therapy in a home setting. The urinary neurotrophins, NGF, BDNF, NT3, NT4, were measured by ELISA at baseline and at the end of the TENS therapy. Total urinary neurotrophins levels were standardized to mg of creatinine (Cr). We compared the results with the reference group of 30 participants with no symptoms of bladder overactivity. The results revealed that children with OAB both before and after TENS therapy had higher NGF, BDNF, and NT4 concentrations in total and after normalization to Cr than the reference group in contrast to NT3. The response to the therapy expressed as a decrease of urinary neurotrophins after TENS depended on the age and the presenting symptoms. In conclusion, children older than 8 years of age with complaints of daytime incontinence responded better to TENS.

Partners in Crime: NGF and BDNF in Visceral Dysfunction

Neurotrophins (NTs), particularly Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF), have attracted increasing attention in the context of visceral function for some years. Here, we examined the current literature and presented a thorough review of the subject. After initial studies linking of NGF to cystitis, it is now well-established that this neurotrophin (NT) is a key modulator of bladder pathologies, including Bladder Pain Syndrome/Interstitial Cystitis (BPS/IC) and Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS. NGF is upregulated in bladder tissue and its blockade results in major improvements on urodynamic parameters and pain. Further studies expanded showed that NGF is also an intervenient in other visceral dysfunctions such as endometriosis and Irritable Bowel Syndrome (IBS). More recently, BDNF was also shown to play an important role in the same visceral dysfunctions, suggesting that both NTs are determinant factors in visceral pathophysiological mechanisms. Manipulation of NGF and BDNF improves visceral function and reduce pain, suggesting that clinical modulation of these NTs may be important; however, much is still to be investigated before this step is taken. Another active area of research is centered on urinary NGF and BDNF. Several studies show that both NTs can be found in the urine of patients with visceral dysfunction in much higher concentration than in healthy individuals, suggesting that they could be used as potential biomarkers. However, there are still technical difficulties to be overcome, including the lack of a large multicentre placebo-controlled studies to prove the relevance of urinary NTs as clinical biomarkers.

Neurite outgrowth in cultured mouse pelvic ganglia - Effects of neurotrophins and bladder tissue

Neurotrophic factors regulate survival and growth of neurons. The urinary bladder is innervated via both sympathetic and parasympathetic neurons located in the major pelvic ganglion. The aim of the present study was to characterize the effects of the neurotrophins nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and neurotrophin 3 (NT-3) on the sprouting rate of sympathetic and parasympathetic neurites from the female mouse ganglion. The pelvic ganglion was dissected out and attached to a petri dish and cultured in vitro. All three factors (BDNF, NT-3 and NGF) stimulated neurite outgrowth of both sympathetic and parasympathetic neurites although BDNF and NT-3 had a higher stimulatory effect on parasympathetic ganglion cells. The neurotrophin receptors TrkA, TrkB and TrkC were all expressed in neurons of the ganglia. Co-culture of ganglia with urinary bladder tissue, but not diaphragm tissue, increased the sprouting rate of neurites. Active forms of BDNF and NT-3 were detected in urinary bladder tissue using western blotting whereas tissue from the diaphragm expressed NGF. Neurite outgrowth from the pelvic ganglion was inhibited by a TrkB receptor antagonist. We therefore suggest that the urinary bladder releases trophic factors, including BDNF and NT-3, which regulate neurite outgrowth via activation of neuronal Trk-receptors. These findings could influence future strategies for developing pharmaceuticals to improve re-innervation due to bladder pathologies.

Developing a functional urinary bladder: a neuronal context

The development of organs occurs in parallel with the formation of their nerve supply. The innervation of pelvic organs (lower urinary tract, hindgut, and sexual organs) is complex and we know remarkably little about the mechanisms that form these neural pathways. The goal of this short review is to use the urinary bladder as an example to stimulate interest in this question. The bladder requires a healthy mature nervous system to store urine and release it at behaviorally appropriate times. Understanding the mechanisms underlying the construction of these neural circuits is not only relevant to defining the basis of developmental problems but may also suggest strategies to restore connectivity and function following injury or disease in adults. The bladder nerve supply comprises multiple classes of sensory, and parasympathetic or sympathetic autonomic effector (motor) neurons. First, we define the developmental endpoint by describing this circuitry in adult rodents. Next we discuss the innervation of the developing bladder, identifying challenges posed by this area of research. Last we provide examples of genetically modified mice with bladder dysfunction and suggest potential neural contributors to this state.

Neurotrophins in bladder function: what do we know and where do we go from here?

AIMS

Neurotrophins (NTs) have attracted considerable attention in the urologic community. The reason for this resides in the recognition of their ability to induce plastic changes of the neuronal circuits that govern bladder function. In many pathologic states, urinary symptoms, including urgency and urinary frequency, reflect abnormal activity of bladder sensory afferents that results from neuroplastic changes. Accordingly, in pathologies associated with increased sensory input, such as the overactive bladder syndrome (OAB) or bladder pain syndrome/interstitial cystitis (BPS/IC), significant amounts of NTs have been found in the bladder wall.

METHODS

Here, current knowledge about the importance of NTs in bladder function will be reviewed, with a focus on the most well-studied NTs, nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF).

RESULTS

Both NTs are present in the bladder and regulate bladder sensory afferents and urothelial cells. Experimental models of bladder dysfunction show that upregulation of these NTs is strongly linked to bladder hyperactivity and, in some cases, pain. NT manipulation has been tested in animal models of bladder dysfunction, and recently, NGF downregulation, achieved by administration of a monoclonal antibody, has also been tested in patients with BPS/IC and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). NTs have also been found in high quantities in the urine of OAB and BPS/IC patients, raising the possibility of NTs serving as biomarkers.

CONCLUSIONS

Available data show that our knowledge of NTs has greatly increased in recent years and that some results may have future clinical application.

Postnatal expression of corticotropin releasing factor (CRF) in rat urinary bladder

Corticotropin releasing factor (CRF) is a neuropeptide expressed in micturition reflex circuitry and different roles in these reflexes have been suggested. These studies examined the expression of CRF/CRF receptors in the urinary bladder during postnatal development in the rat. Urinary bladder was harvested from rats (postnatal (P) day 0-adult) euthanized by isoflurane (4%) and thoracotomy. CRF protein expression significantly (p<or=0.01) decreased in the urothelium with increasing postnatal age. In contrast, CRF-immunoreactivity (IR) was increased in nerve fibers in the suburothelial plexus during the second-third postnatal week. Total CRF protein from urinary bladder significantly increased during the second-third postnatal weeks as determined with ELISAs. CRF receptor 2 (CRFR(2)) transcript was expressed in urinary bladder of all postnatal ages examined whereas no CRFR(1) transcript was expressed at any postnatal age examined. We also demonstrated changes in urinary bladder mRNA expression for the neuropeptides, galanin, substance P, vasoactive intestinal polypeptide and pituitary adenylate cyclase activating polypeptide during postnatal development. These studies demonstrate changes in the CRF expression in urinary bladder, specifically in the urothelium and nerve fibers of the suburothelial plexus during postnatal development. Changes in CRF expression and neuropeptide expression in general in the urinary bladder may contribute to the emergence of mature voiding reflexes.

Neurturin regulates postnatal differentiation of parasympathetic pelvic ganglion neurons, initial axonal projections, and maintenance of terminal fields in male urogenital organs

We have investigated the development of autonomic nerves in the urogenital tract of male mice and the effect of neurturin gene deletion on this process. At birth, autonomic innervation of the reproductive organs was sparse, but urinary bladder smooth muscle was well innervated. Further innervation of reproductive tissues occurred until P21, but noradrenergic axons established their complete terminal field later than nitrergic cholinergic axons: in adults the former are more prevalent, yet this became apparent only at P7 (vas deferens, seminal vesicles), P14 (prostate) or after P14 (penis). Neurturin was essential for initial projection of axons (mucosa of vas deferens), maintenance of terminal fields (prostate and seminal vesicles), or both functions (cavernosum of penis). In contrast, some targets (e.g., bladder muscle and suburothelium, vas deferens smooth muscle) were unaffected by neurturin gene deletion. Pelvic ganglion neurons more than doubled between birth and adulthood, probably as aresult of continued maturation of p75-positive undifferentiated neuronal precursors rather than cell division. The adult number of neurons was achieved by P7 (sympathetic) or P21 (parasympathetic). In adult neurturin knockout mice, there were approximately 25% fewer parasympathetic neurons compared with wild types, because of failure of differentiation after P14. This study revealed the complexity of postnatal maturation of urogenital innervation, with each organ showing a distinct chronology of innervation and different requirement for neurturin. Our results also indicate that in adults there will be distinct differences in neurturin dependence between organs, such that proregenerative therapies may have to be tailored specifically for the nerve pathway of interest.

Mechanisms of Disease: the role of nerve growth factor in the pathophysiology of bladder disorders

The case is compelling for the involvement of nerve growth factor (NGF) in the pathogenesis of lower urinary tract disease, especially in conditions with altered neural function. Remodeling of the micturition pathways occurs following experimental bladder-outlet obstruction, denervation, spinal cord injury, cystitis, and diabetes mellitus. Clinically, NGF levels are elevated in the bladders of men with benign prostatic hyperplasia, women with interstitial cystitis and in patients with idiopathic overactive bladder. Blockade of NGF, using either an endogenous antibody or an antibody against the NGF receptor, prevents neural plasticity and bladder overactivity in experimental models of these conditions. The ability of NGF to trigger bladder overactivity might rely on altering the properties of sodium or potassium channels (or their expression) in bladder afferent fibers. Therapies based on altered NGF levels, or changes in channel properties in afferent nerves, represent an intriguing avenue of investigation for the management of detrusor overactivity or diabetic cystopathy.

P2X2 and P2X3 receptor expression in postnatal and adult rat urinary bladder and lumbosacral spinal cord

P2X receptors mediate the effects of ATP in micturition and nociception. During postnatal maturation, a spinobulbospinal reflex and voluntary voiding replace primitive voiding reflexes. This may involve changes in neuroactive compounds and receptors in bladder reflex pathways. We examined P2X2 and P2X3 receptors in bladder and spinal cord from postnatal (P0-P36, indicating number of days) and adult Wistar rats. Western blot of whole bladders for P2X2 and P2X3 expression was performed. Immunostaining for P2X2 and P2X3 receptors in urothelium and detrusor smooth muscle whole mounts and spinal cord sections was examined. Western blot demonstrated an age-dependent decrease (R(2) = 0.96, P Collapse

Key Words

• postnatal development
• micturition reflexes
• sacral parasympathetic nucleus
• dorsal commissure
• dorsal horn

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MESH Headings

• Aging/metabolism
• Animals
• Female
• Lumbosacral Region
• Male
• Rats
• Rats, Wistar
• Receptors, Purinergic P2/metabolism
• Receptors, Purinergic P2X2
• Receptors, Purinergic P2X3
• Spinal Cord/metabolism
• Tissue Distribution
• Urinary Bladder/metabolism

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Grants

• DK-060481 NIDDK NIH HHS
• NS-040796 NINDS NIH HHS
• R01 DK065989 NIDDK NIH HHS
• R56 DK060481 NIDDK NIH HHS
• R29 DK051369 NIDDK NIH HHS
• DK-065989 NIDDK NIH HHS
• R01 DK060481 NIDDK NIH HHS
• R01 NS040796 NINDS NIH HHS
• DK-051369 NIDDK NIH HHS
• R01 DK051369 NIDDK NIH HHS

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Affiliation(s)

Simon Studeny Department of Neurology, Anatomy and
Ali Torabi Department of Neurology, Anatomy and
Margaret A. Vizzard Department of Neurology, Anatomy and Neurobiology, University of Vermont, College of Medicine, Burlington, Vermont, VT 05405

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Distribution and fate of cocaine- and amphetamine-regulated transcript peptide (CARTp)-expressing cells in rat urinary bladder: a developmental study

We examined the distribution and fate of cocaine- and amphetamine-regulated transcript peptide (CARTp)(55-102)-immunoreactive (IR) structures in the neonatal and adult rat urinary bladder. Double-labeling studies examining CARTp with tyrosine hydroxylase (TH), neuronal nitric oxide synthase (nNOS), or choline acetyltransferase (ChAT) were performed in wholemounts of urothelium or detrusor or cryostat sections of the bladder. In younger animals (postnatal day [P]1, P3), CARTp-IR cell bodies in detrusor smooth muscle were observed in large clusters ( approximately 100 cells/cluster) at the ureteral insertion and along thick bundles of nerve fibers at the bladder base. The total number of CARTp-IR cells was significantly reduced (by five-fold) at P14, and this reduced number persisted into adulthood. The decrease in the number of CARTp-expressing cells was complemented with positive staining for cleaved caspase-3, suggesting that apoptosis contributed to this decrease. At birth (P1), all CARTp-IR cells expressed the neuronal marker Hu. After birth, CARTp was expressed by some neurons (CARTp-IR, Hu-IR) that represent intramural ganglion cells and by cells that lacked a neuronal phenotype (CARTp-IR, Hu-) but did express TH. Neither of these cell populations expressed ChAT immunoreactivity in adult bladder. These cells (CARTp-IR, Hu-, TH-IR) may represent paraganglion or small intensely fluorescent (SIF) cells. The percentage of colocalization of CARTp-IR and nNOS or TH was dependent on postnatal age and showed an inverse relationship. At P1, 67.1 % of CARTp-IR cells expressed nNOS immunoreactivity. Decreased colocalization was observed with increasing postnatal age. In contrast, 19.5% of CARTp-IR cells expressed TH at P1, but colocalization increased with postnatal age. The suburothelial plexus lacked CARTp-IR nerve fibers until P14, when nerve fibers with varicosities were observed in the urethra and bladder neck region. In summary, we demonstrate 1) a decrease in the number of CARTp-IR cells in rat detrusor in early postnatal development; 2) apoptotic events in the bladder during early postnatal development; 3) rostral migration of CARTp-IR cells from the ureteral insertion toward the bladder body during postnatal development; 4) the presence of different populations of CARTp-IR cells, some with and others without a neuronal phenotype; and (5) age-dependent changes in chemical coding of CARTp-IR cells with postnatal development. This study demonstrates that CARTp-IR intramural ganglia and CARTp-IR paraganglion or SIF cells exist in the postnatal and adult rat bladder, although the role of these cell types remains to be determined.

Corticotropin-releasing factor (CRF) expression in postnatal and adult rat sacral parasympathetic nucleus (SPN)

The neural control of micturition undergoes marked changes during the early postnatal development. During the first few postnatal weeks, the spinal micturition reflex is gradually replaced by a spinobulbospinal reflex pathway that is responsible for micturition in adult animals. Upregulation of brainstem regulation of spinal micturition pathways may contribute to development of mature voiding patterns. We examined the expression of corticotropin-releasing factor (CRF), present in descending projections from Barrington's nucleus to the sacral parasympathetic nucleus (SPN), in postnatal (P0-P36) and adult Wistar rats (P60-90). CRF-immunoreactivity (IR) was present predominantly in the SPN region, although some staining was also observed in the dorsal horn and dorsal commissure in L5-S1 spinal segments. CRF-IR in spinal cord regions was age dependent (R2=0.87-0.98). The majority of the CRF-IR in the lumbosacral spinal cord was eliminated by complete spinalization (2-3 weeks). Double-label immunohistochemistry was combined with quantitative confocal laser scanning microscopy to quantify the number and percentage of colocalization between CRF-immunoreactive varicosities and preganglionic somas or proximal neurites in the SPN in postnatal and adult rats. Results demonstrate an age-dependent upregulation of CRF-IR in the SPN region and specifically in association with preganglionic parasympathetic neurons identified with neuronal nitric oxide synthase (nNOS)-IR. CRF-immunoreactive varicosities on or within a 1 microm perimeter of nNOS-immunoreactive somas or proximal neurites also increased with postnatal age. The upregulation of CRF-IR in bulbospinal projections to the SPN may contribute to mature voiding reflexes.

Neurotrophins in murine viscera: a dynamic pattern from birth to adulthood

There is growing evidence that target-derived neurotrophins regulate the function of visceral neurons after birth. However, the postnatal profile of neurotrophin supply from internal organs is poorly described. In this study, we compared neurotrophin concentrations in lysates of murine peripheral target tissues (lung, heart, liver, colon, spleen, thymus, kidney and urinary bladder) at different time points after birth. In most organs, there was a decrease of neurotrophin concentrations in the first weeks after birth. In contrast, there were characteristic increases of specific neurotrophins during adolescence or adulthood. These increases were found for nerve growth factor (NGF) in the heart, thymus, kidney and liver, for brain-derived neurotrophic factor (BDNF) in the lung, and for neurotrophin-3 (NT-3) in the colon. In conclusion, we show that neurotrophins display a very differential and dynamic profile in internal organs after birth.

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.

Differential protein expression at the stage of neural tube closure in the mouse embryo

Analysis of the protein complement of a biological system through proteomics provides the opportunity to directly monitor the functional readout of gene expression. In this study, proteomics was applied to the mouse embryo to investigate the molecular events underlying the processes occurring at the stage of neural tube closure. Protein profiles of embryos between embryonic days 8.5 and 10.5 exhibited a number of stage-specific changes. Identification of developmentally regulated proteins by mass spectrometry revealed several groups of functionally related proteins including circulatory, cytoskeletal, and stress proteins. Additional proteins of unknown function were identified, such as Copine 1 and PICOT, whose developmental regulation was previously unsuspected.

Expression of neurotrophin messenger RNAs during rat urinary bladder development

The family of neurotrophins, encompassing nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5), is important in the regulation of neuronal development and function. We examined the expression of neurotrophin messenger RNAs (mRNAs) in the rat urinary bladder during pre- and postnatal development using competitive reverse transcription-polymerase chain reaction. The mRNA levels showed a biphasic pattern of expression; one peak was at prenatal ages (embryonic day (E)15-E18) and the other peak was at postnatal ages (postnatal day (P)14-P28). NT-4/5, BDNF and NGF mRNA levels were greatest at E15, E16 and E18, respectively. In contrast, NT-3 mRNA levels were significantly highest at P14. These data suggest that neurotrophins are involved in the mechanisms of bladder nerve growth for the prenatal period and reorganization of bladder reflex pathways during the second to the fourth postnatal week.

Modulation of nerve growth factor in peripheral organs by estrogen and progesterone

Nerve growth factor (NGF) synthesized in peripheral organs plays a critical role in the development and maintenance of the nervous system and also participates in processing nociceptive stimuli. Previous studies suggest that reproductive hormones may regulate the expression of NGF. Ovariectomies were performed on female mice, and mice were killed 24 h after hormone replacement to evaluate the effects of estrogen and progesterone on NGF in peripheral organs, specifically the uterus, bladder, heart, and salivary gland. Sham-operated intact mice and untreated ovariectomized mice served as controls. Immunohistochemistry demonstrated the presence of NGF, estrogen receptor-alpha, estrogen receptor-beta, and progesterone receptors in these organs. Ovariectomy caused a significant decrease in NGF protein content in the uterus, and short term treatment of ovariectomized mice with estrogen and/or progesterone increased uterine NGF mRNA and restored NGF protein to concentrations similar to intact control mice. Ovariectomy did not affect NGF protein concentrations in the salivary gland, but treatment of ovariectomized mice with estrogen alone or in conjunction with progesterone stimulated concentrations of NGF protein that exceeded those observed in intact control or ovariectomized, untreated mice. NGF mRNA was increased in salivary glands from ovariectomized mice treated with progesterone alone or in combination with estrogen relative to other groups. NGF protein content of the hearts of ovariectomized mice treated with estrogen alone or in conjunction with progesterone was increased relative to intact controls and ovariectomized, untreated mice, but neither ovariectomy or hormone replacement affected NGF mRNA content in the heart. NGF protein content of the bladder was unaffected by ovariectomy or hormone treatment, and bladder NGF mRNA was unaffected by ovariectomy or hormone treatment. Collectively, these results indicate that reproductive hormones have the capacity to regulate NGF message and protein in a manner that varies among organs. Fluctuations in the expression of NGF, in conjunction with other factors, may help to explain gender differences in pain sensation and inflammatory response.

Intravesical Escherichia coli lipopolysaccharide stimulates an increase in bladder nerve growth factor

OBJECTIVE

To investigate the effects of the intravesical instillation of Escherichia coli lipopolysaccharide (LPS) on nerve growth factor (NGF, which may mediate the pain associated with inflammation) protein and mRNA in the bladders of mice.

MATERIALS AND METHODS

E. coli LPS was instilled into the bladders of female mice; the whole-bladder NGF content was then determined by an enzyme-linked immunosorbent assay and the NGF mRNA content of the bladder determined by semiquantitative reverse transcription-polymerase chain reaction. Bladder NGF was also evaluated by immunohistochemistry in some of the mice.

RESULTS

LPS stimulated a significant increase in bladder NGF 90 min after instillation, but bladder NGF content was significantly less than that in bladders of control mice 3 and 7 h after LPS instillation. Twenty-four hours after the intravesical infusion of saline or LPS, there was no difference in NGF content in bladders from saline or LPS-infused mice. Immunohistochemistry confirmed the presence of increased NGF in the mucosa of detrusor from bladders 90 min after LPS instillation. Bladder NGF mRNA increased more slowly in response to LPS, and 7 and 24 h after LPS instillation the relative abundance of NGF mRNA was 1.5 and 2.0 times greater in LPS-infused bladders, respectively.

CONCLUSIONS

E. coli LPS can stimulate increased NGF message and protein in the bladder. The increase in NGF protein preceded the increase in mRNA, suggesting that this increase was not the result of gene transcription. It is possible that NGF participates in the pathogenesis of pain associated with bacterial cystitis.

Estrogen and neuroinflammation

Women have a higher incidence of inflammatory disorders than men and also appear to perceive painful stimuli differently. It has been suggested that neuroinflammation plays a role in painful bladder disorders of uncertain etiology, such as interstitial cystitis. Nerve growth factor (NGF) is a neurotrophin produced in peripheral tissues that can also mediate pain and inflammation. We found that treatment of mice with the estrogen antagonist ICI 182,780 had no effect on bladder NGF content but decreased bladder NGF messenger RNA. Using immunohistochemistry, we demonstrated that the mucosa is the primary source of NGF in the mouse bladder, and the bladder mucosa also expresses estrogen receptor (ER)-alpha, ER-beta, and the high-affinity NGF receptor tyrosine kinase A. Estrogen may also modulate neurogenic inflammation by interaction with other substances and cells that participate in the pathogenesis of neurogenic inflammation, including substance P, bradykinin, and mast cells. Collectively, these observations indicate that estrogen has the capacity to influence the onset and course of neurogenic inflammation of the bladder.