The role of nitric oxide in bladder urothelial injury after bladder outlet obstruction

Pharmacogenetic inhibition of lumbosacral sensory neurons alleviates visceral hypersensitivity in a mouse model of chronic pelvic pain

The study investigated the cellular and molecular mechanisms in the peripheral nervous system (PNS) underlying the symptoms of urologic chronic pelvic pain syndrome (UCPPS) in mice. This work also aimed to test the feasibility of reversing peripheral sensitization in vivo in alleviating UCPPS symptoms. Intravesical instillation of vascular endothelial growth factor A (VEGFA) was used to induce UCPPS-like symptoms in mice. Spontaneous voiding spot assays and manual Von Frey tests were used to evaluate the severity of lower urinary tract symptoms (LUTS) and visceral hypersensitivity in VEGFA-instilled mice. Bladder smooth muscle strip contractility recordings (BSMSC) were used to identify the potential changes in myogenic and neurogenic detrusor muscle contractility at the tissue-level. Quantitative real-time PCR (qPCR) and fluorescent immunohistochemistry were performed to compare the expression levels of VEGF receptors and nociceptors in lumbosacral dorsal root ganglia (DRG) between VEGFA-instilled mice and saline-instilled controls. To manipulate primary afferent activity, Gi-coupled Designer Receptors Exclusively Activated by Designer Drugs (Gi-DREADD) were expressed in lumbosacral DRG neurons of TRPV1-Cre-ZGreen mice via targeted adeno-associated viral vector (AAVs) injections. A small molecule agonist of Gi-DREADD, clozapine-N-oxide (CNO), was injected into the peritoneum (i. p.) in awake animals to silence TRPV1 expressing sensory neurons in vivo during physiological and behavioral recordings of bladder function. Intravesical instillation of VEGFA in the urinary bladders increased visceral mechanical sensitivity and enhanced RTX-sensitive detrusor contractility. Sex differences were identified in the baseline detrusor contractility responses and VEGF-induced visceral hypersensitivity. VEGFA instillations in the urinary bladder led to significant increases in the mRNA and protein expression of transient receptor potential cation channel subfamily A member 1 (TRPA1) in lumbosacral DRG, whereas the expression levels of transient receptor potential cation channel subfamily V member 1 (TRPV1) and VEGF receptors (VEGFR1 and VEGFR2) remained unchanged when compared to saline-instilled animals. Importantly, the VEGFA-induced visceral hypersensitivity was reversed by Gi-DREADD-mediated neuronal silencing in lumbosacral sensory neurons. Activation of bladder VEGF signaling causes sensory neural plasticity and visceral hypersensitivity in mice, confirming its role of an UCPPS biomarker as identified by the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) research studies. Pharmacogenetic inhibition of lumbosacral sensory neurons in vivo completely reversed VEGFA-induced pelvic hypersensitivity in mice, suggesting the strong therapeutic potential for decreasing primary afferent activity in the treatment of pain severity in UCPPS patients.

Gene expression profiles during tissue remodeling following bladder outlet obstruction

Bladder outlet obstruction (BOO) often results in lower urinary tract symptoms (LUTSs) and negatively affects quality of life. Here, we evaluated gene expression patterns in the urinary bladder during tissue remodeling due to BOO. We divided BOO model rats into two groups according to the degree of hypertrophy of smooth muscle in the bladder. The strong muscular hypertrophy group, which exhibited markedly increased bladder smooth muscle proportion and HIF1α mRNA levels compared with the control group, was considered a model for the termination of hypertrophy, whereas the mild muscular hypertrophy group was considered a model of the initiation of hypertrophy. Some genes related to urinary function showed different expression patterns between the two groups. Furthermore, we found that several genes, including D-box binding PAR bZIP transcription factor (DBP), were upregulated only in the mild muscular hypertrophy group. DBP expression levels were increased in bladder smooth muscle cells in response to hypoxic stress. DBP associated with enhancer and promoter regions of NOS3 gene locus and upregulated NOS3 gene expression under hypoxic conditions. These findings suggested that the regulatory systems of gene expression were altered during tissue remodeling following BOO. Furthermore, circadian clock components might be involved in control of urinary function via transcriptional gene regulation in response to hypoxic stimuli.

Autonomic Receptor-mediated Regulation of Production and Release of Nitric Oxide in Normal and Malignant Human Urothelial Cells

In the urinary bladder, the main source of NO seems to be the urothelium and the underlying suburothelium. In this study, we aimed to characterize how receptors in the human urothelium regulate the production and release of NO. For this, we cultured two human urothelial cell lines - the normal immortalized cell line UROtsa and the malignant cell line T24. These were treated with an array of agonists and antagonists with affinity for adrenergic, muscarinic and purinergic receptors. The production of NO and expression of nitric oxide synthase (NOS) was studied by immunocytochemistry and Western blotting. The amount of released NO was measured indirectly by detecting nitrite using amperometry and a Griess reaction kit. The results showed that NO, endothelial NOS and inducible NOS were predominantly produced and expressed in the close vicinity of the nucleus in untreated human urothelial cells. Upon treatment with a beta-adrenoceptor agonist, but not any of the other agonists or antagonists, the pattern of NO production changed, showing a more even production throughout the cytosol. The pattern of expression of endothelial NOS changed in a similar way upon dobutamine treatment. The release of nitrite, as a measurement of NO, increased after treatment with dobutamine from 0.31 ± 0.029 to 1.97 ± 0.18 nmol and 0.80 ± 0.12 to 3.27 ± 0.24 nmol in UROtsa and T24, respectively. In conclusion, our results show that the expression of NOS and production of NO as well as the release of NO from human urothelial cells is regulated by beta-adrenoceptor activation.

Crucial roles of nitric oxide synthases in β-adrenoceptor-mediated bladder relaxation in mice

The specific roles of nitric oxide (NO) synthases (NOSs) in bladder smooth muscle remain to be elucidated. We examined the roles of NOSs in β-adrenoceptor (AR)-mediated bladder relaxation. Male mice (C57BL6) deficient of neuronal NOS [nNOS-knockout (KO)], endothelial NOS (eNOS-KO), neuronal/endothelial NOS (n/eNOS-KO), neuronal/endothelial/inducible NOS (n/e/iNOS-KO), and their controls [wild-type (WT)] were used. Immunohistochemical analysis was performed in the bladder. Then the responses to relaxing agents and the effects of several inhibitors on the relaxing responses were examined in bladder strips precontracted with carbachol. Immunofluorescence staining showed expressions of nNOS and eNOS in the urothelium and smooth muscle of the bladder. Isoproterenol-induced relaxations were significantly reduced in nNOS-KO mice and were further reduced in n/eNOS-KO and n/e/iNOS-KO mice compared with WT mice. The relaxation in n/e/iNOS-KO mice was almost the same as in n/eNOS-KO mice. Inhibition of Ca2+-activated K+ (KCa) channel with charybdotoxin and apamin abolished isoproterenol-induced bladder relaxation in WT mice. Moreover, direct activation of KCa channel with NS1619 caused comparable extent of relaxations among WT, nNOS-KO, and n/eNOS-KO mice. In contrast, NONOate (a NO donor) or hydrogen peroxide (H2O2) (another possible relaxing factor from eNOS) caused minimal relaxations, and catalase (H2O2 scavenger) had no inhibitory effects on isoproterenol-induced relaxations. These results indicate that both nNOS and eNOS are substantially involved in β-AR-mediated bladder relaxations in a NO- or H2O2-independent manner through activation of KCa channels.

Alteration of Urothelial Inflammation, Apoptosis, and Junction Protein in Patients with Various Bladder Conditions and Storage Bladder Symptoms Suggest Common Pathway Involved in Underlying Pathophysiology

OBJECTIVE

Lower urinary tract symptoms (LUTS) are common in various bladder disorders. This study investigated urothelial dysfunction and chronic inflammation in the urothelium in different types of lower urinary tract dysfunction (LUTD), which causes bladder storage symptoms.

METHODS

Bladder tissues were obtained from patients with LUTD including 17 with interstitial cystitis/bladder pain syndrome (IC/BPS), 15 with bladder outlet obstruction (BOO), 12 with spinal cord injury (SCI), 12 with recurrent urinary tract infection (UTI), 13 with ketamine related cystitis (KC) and 10 controls. The bladder specimens were investigated using immunofluorescence (IF) staining of the urothelial junction protein E-cadherin and the TUNEL assay for urothelial apoptosis. Mast cell activation was also measured by IF using tryptase for mucosal inflammation. Statistical analysis was performed using the Kruskal-Wallis and Wilcoxon rank-sum test and P-values less than 0.05 were considered significant.

RESULTS

Highly significant increases of mast cell infiltration were observed in patients with KC (7.8 ± 3.7), IC/BPS (4.6 ± 3.0), recurrent UTI (2.4 ± 1.2), SCI (3.7 ± 2.7), and BOO (5.1 ± 2.0) compared with controls (1.3 ± 1.2) (all p < 0.05). Statistically significant increases of apoptotic cells were observed in patients with KC (4.2 ± 1.5), IC/BPS (2.4 ± 1.7), SCI (2.4 ± 1.4), recurrent UTI (1.9 ± 2.4), and BOO (1.2 ± 1.1) compared with controls (0.08 ± 0.3) (all p < 0.05). Significantly decreased expression of E-cadherin in patients with IC/BPS (25.1 ± 16.3), KC (11.0 ± 11.3), and recurrent UTI (26.2 ± 5.0) was found compared to controls (42.4 ± 16.7) and patients with SCI (44.4 ± 18.8) or BOO (42.8 ± 14.3) (all P < 0.05).

CONCLUSION

Increased urothelial inflammation and urothelial cell apoptosis seem to share common pathophysiologies of various LUTDs that cause similar bladder symptoms.

Nitric Oxide Synthase is Necessary for Normal Urogenital Development

Introduction

Neuronal nitric oxide synthase (NOS-I) is significantly decreased with Cavernous Nerve (CN) injury in Erectile Dysfunction (ED) models. Increased apoptosis and collagen deposition accompany decreased NOS/CN injury, however these changes are typically attributed to the altered signaling of other factors, and a contribution of NOS in maintenance of urogenital structures has not previously been examined. Morphological changes in the corpora cavernosa occur at the same time as decreased NOS, suggesting a potential connection between decreased/inhibited NOS and morphological changes associated with ED. In this study we propose that NOS impacts urogenital morphology during development and will examine this hypothesis by NOS inhibition with L-NAME.

Methods

Primary outcomes were H&E, western and TUNEL to determine if penis, prostate and bladder morphology were altered with L-NAME treatment of Postnatal day 4 (P4) Sprague Dawley rats for 8 days. Tissue weight and immunohistochemical analysis for NOS were performed. Secondary evaluation of NOS-I regulation by Sonic Hedgehog (SHH) was examined by SHH inhibition in the pelvic ganglia (PG) and NOS-I protein was quantified by western in the PG/CN and penis. Nos abundance was quantified by RT-PCR during urogenital development and after CN injury.

Results

Apoptosis increased and penis, prostate and bladder morphology were altered with L-NAME. NOS inhibition decreased bladder weight 25%. SHH inhibition decreased NOS-I 35% in the PG/CN and 47% in the penis. Nos-III expression spiked within the first two weeks after birth in the penis but remained abundant in the adult. In the prostate, Nos-III was abundant immediately after birth and declined steadily with age. Nos-I expression in the PG/CN decreased sharply with CN injury and returned to baseline by 7 days.

Conclusions

NOS is required for normal urogenital development. Since NOS is decreased with ED, it may contribute to the abnormal morphology observed in ED patients and animal models.

Pressure activates epidermal growth factor receptor leading to the induction of iNOS via NFkappaB and STAT3 in human proximal tubule cells

Ureteral obstruction leads to increased pressure and inducible nitric oxide synthase (iNOS) expression. This study examined the involvement of epidermal growth factor (EGF) receptor (EGFR), nuclear factor-kappaB (NFkappaB), and signal transducers and activators of transcription 3 (STAT3) in iNOS induction in human proximal tubule (HKC-8) cells in response to pressure or EGF. HKC-8 cells were subjected to 60 mmHg pressure or treated with EGF for 0-36 h. iNOS was more rapidly induced in response to EGF than pressure. The addition of EGFR, NFkappaB, and STAT3 inhibitors significantly suppressed pressure- or EGF-stimulated iNOS mRNA and protein expression. Analysis of the activated states of EGFR, NFkappaB p65, and STAT3 after exposure to both stimuli demonstrated phosphorylation within 2.5 min. Anti-EGF antibody inhibited iNOS induction in pressurized HKC-8 cells, providing evidence that endogenous EGF mediates the response to pressure. In ureteral obstruction, when pressure is elevated, phosphorylated EGFR was detected in the apical surface of the renal tubules, validating the in vitro findings. These data indicate that EGFR, NFkappaB, and STAT3 are required for human iNOS gene induction in response to pressure or EGF, indicating a similar mechanism of activation.

The role of alpha1-adrenoceptor and arachidonate pathways in increased tone of demucosalized bladder tissue

PURPOSE

We investigated the role of the alpha1-adrenoceptor system, and cyclooxygenase and lipoxygenase pathways in increased contractile reactivity of demucosalized bladder tissues.

MATERIALS AND METHODS

A total of 20 male Sprague-Dawley rats were used. From each bladder 2 tissue strips were prepared. One strip was demucosalized, while the other was kept intact. Isometric tension studies were done at baseline tone with contractile responses assessed to 120 mM potassium, electrical field stimulation (1 to 40 Hz) and carbachol (10(-9) to 10(-4) M). Relaxation responses to electrical field stimulation, isoproterenol (10(-9) to 10(-4) M), papaverine (10(-4) M) and sodium nitroprusside (10(-4) M) were recorded in carbachol precontracted strips. The effects of doxazosin, the cyclooxygenase inhibitor indomethacin and the lipoxygenase inhibitor REV5901 (each 3 x 10(-5) M) on these responses were investigated.

RESULTS

Carbachol and electrical field stimulation induced significantly greater contractions in demucosalized strips. All contractile responses were significantly decreased in the presence of doxazosin, indomethacin and REV5901 in intact and demucosalized tissues. Indomethacin augmented the effect of doxazosin on demucosalized tissue contractions compared to results obtained with doxazosin alone. In carbachol precontracted tissues relaxation responses to isoproterenol and electrical field stimulation were significantly lower in demucosalized tissues. These responses were significantly decreased with doxazosin or indomethacin independent of mucosa.

CONCLUSIONS

Bladder mucosa is a determinant of rat bladder tissue contractility. Doxazosin, and cyclooxygenase and lipoxygenase pathways significantly affect rat bladder tissue contractility independent of mucosa. However, the effect of doxazosin is significantly amplified by cyclooxygenase inhibition in the absence of bladder mucosa. These findings may have important clinical implications regarding the single and combined use of doxazosin with cyclooxygenase inhibitors.

Involvement of hypoxia-triggered endoplasmic reticulum stress in outlet obstruction-induced apoptosis in the urinary bladder

In bladder outlet obstruction (BOO), mechanical stress and ischemia/hypoxia are implicated in structural and functional alterations of the urinary bladder. Because mechanical stress and hypoxia may trigger endoplasmic reticulum (ER) stress, we examined involvement of ER stress in the damage of the bladder caused by BOO. An experimental model of BOO was established in rats by complete ligature of the urethra for 24 h, and bladders were subjected to northern blot analysis and assessment of apoptosis. Isolated urinary bladders and bladder-derived smooth muscle cells (BSMCs) were also exposed to mechanical strain and hypoxia and used for analyses. To examine involvement of ER stress in the damage of the bladder, the effects of a chemical chaperone 4-phenylbutyrate (4-PBA) were evaluated in vitro and in vivo. Outlet obstruction for 24 h induced expression of ER stress markers, GRP78 and CCAAT/enhancer-binding protein-homologous protein (CHOP), in the bladder. It was associated with induction of markers for mechanical stress (cyclooxygenases 2) and hypoxia (vascular endothelial growth factor and glyceraldehyde-3-phosphate dehydrogenase). When isolated bladders and BSMCs were subjected to mechanical strain, induction of GRP78 and CHOP was not observed. In contrast, when BSMCs were exposed to hypoxic stress caused by CoCl2 or thenoyltrifluoroacetone (TTFA), substantial upregulation of GRP78 and CHOP was observed, suggesting involvement of hypoxia in the induction of ER stress. In the bladder subjected to BOO, the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells increased in the epithelial cells and BSMCs. Similarly, treatment with TTFA or CoCl2 induced apoptosis of BSMCs, and 4-PBA significantly attenuated ER stress and apoptosis triggered by these agents. Furthermore, in vivo administration with 4-PBA significantly reduced apoptosis in the bladder subjected to BOO. These results suggested that outlet obstruction caused ER stress via hypoxic stress in the bladder and that hypoxia-triggered ER stress may be involved in the induction of apoptosis in BOO.

Testosterone decreased urinary-frequency in nNOS-deficient mice

To observe the effect of testosterone on the frequency of urination in mice lacking neuronal nitric oxide synthase (nNOS(-/-)), we compared the urination patterns between unanaesthetized male wild-type (n = 27) and nNOS(-/-) mice (n = 50) with or without testosterone treatment. Compared with wild-type mice, nNOS(-/-) mice showed a greater frequency of urination during a 24-h observation period (3.0 vs. 5.4 times/day, p < 0.0001) without any significant difference in the total voided volume or the functional voiding capacity. While testosterone treatment did not affect the urination patterns in wild-type, it decreased the daytime frequency of urination (5.4 vs. 3.7 times, p = 0.0198) and the nighttime urination (4.4 vs. 2.9 times, p = 0.039) in nNOS(-/-) mice. The nNOS(-/-) mice can be a useful animal model for urinary frequency. Testosterone improved the functional abnormalities in the voiding of nNOS(-/-) mice.

Activity and Expression of Nitric Oxide Synthase in Rat Bladder after Sacral Neuromodulation

The aim of our study is to investigate the effects of chronic sacral neuromodulation on Nitric Oxide (NO) metabolism in the rat bladder. 26 female Sprangue-Dawley rats were considered: group I, normal control rats; group II, a sham treatment, in whom catheters for electrical stimulation were placed in the S1 foramen bilaterally and left in place for 21 days, without performing neuromodulation; group III in whom electrical sacral neuromodulation was performed for 21 days. Finally a cystectomy was performed and the bladder biopsy specimens were sent for immunostaining with n-NOS and i-NOS. Morphological and immunohistochemical analysis was carried out, and evaluated in urothelial cells, endothelial cells and muscle fibers of the muscularis propria. Differences between the 3 groups were analyzed by Student Newman-Keuls test. We could observe that urothelial and endothelial i-NOS (37.00±4.69 and 59.00±7.42 respectively) and urothelial n-NOS (36.80±7.85) expression are significantly increased in neuromodulated rats, compared to groups 1 and 2 (p < 0.005). In conclusion, the increase of i-NOS expression on endothelial cells after sacral neuromodulation could be in some way related to angiogenetic responses in the microvascular structures; the increase of n-NOS and i-NOS expression on urothelial cells can suggest that NO is able to influence the plasticity of bladder response, inducing the release of messengers within the urothelium. This study can therefore improve our understanding of the mechanisms of sacral neuromodulation on chronic bladder dysfunction; further studies will need to better demonstrate the role of angiogenesis in the bladder after sacral neuromodulation and to investigate the effects of neuromodulation in rats with chronically induced bladder dysfunction.

Effects of l-arginine and N(G)-nitro-l-arginine methyl ester treatments on expression of neuronal nitric oxide synthase in the guinea-pig bladder after partial bladder outlet obstruction

This study was aimed to examine the effects of pharmacological intervention on partial bladder outlet obstruction (PBOO) on expression of neuronal nitric oxide synthase (nNOS) and nitric oxide (NO) production and NO-related free radical damage using nitrotyrosine as a marker in the guinea-pig bladder. Partial urethral ligation was performed in young male guinea pigs which were then intraperitoneally administered l-arginine, N(G)-nitro-l-arginine methyl ester (l-NAME) or vehicle (saline) for 2 or 4 weeks. At the respective time points, the bladder was removed for nNOS immunohistochemistry, Western blot analysis, nitrotyrosine enzyme-linked immunosorbent assay test and NO colorimetric assay. In l-arginine-treated animals killed at 2 and 4 weeks, the total number of nNOS positive intramural neurons was significantly increased when compared with the corresponding control. Some neurons projected long extending fibers that were closely associated with the blood vessels. Furthermore, at 4 weeks, the nNOS protein content and NO production as reflected by the concentration of nitrite and nitrate were drastically elevated as measured by Western blot analysis and NO colorimetric assay, respectively. In l-NAME-treated group killed at 2 weeks, the number of nNOS positive neurons was markedly reduced when compared with the controls, but the change was not significant at 4 weeks. In the latter, however, the NO production as reflected by the concentration of nitrite and nitrate was markedly reduced; in addition, the nitrotyrosine concentration was significantly lower than the control. The present results support the role of NO in the pathophysiological changes following PBOO. We suggest the potential therapeutic application of l-arginine and l-NAME in PBOO; however, ultimately balancing the bidirectional effects of NO would be essential.

Systemic Nitric Oxide Augmentation Leads to a Rapid Decrease of the Bladder Outlet Resistance in Healthy Men

OBJECTIVE

We examined the immediate effect of a systemic nitric oxide augmentation on the bladder outlet resistance in healthy men.

METHODS

Eleven healthy male volunteers with a mean age of 25.5 yr were included in the study. They were prepared for a standard urodynamic study, and a baseline pressure-flow study was obtained. The subjects were then given 20 mg isosorbide dinitrate sublingually, and after refilling their bladder a second pressure-flow study was done after 20 min. The pressure-flow studies were then compared in regard to the average flow rate, the average detrusor pressure during micturition, and the detrusor pressure at maximum flow rate.

RESULTS

One of the subjects was unable to void and had to be excluded from the study. In the remaining 10 men, the mean average flow rate increased from 16.7 ml/s before to 20.2 ml/s after the intake of the NO donor (P=0.013). Concomitantly, the average detrusor pressure during micturition decreased from a mean of 57 to 52 cm H2O (P=0.004) and the mean detrusor pressure at maximum flow rate decreased from 60 to 52 cm H2O (P=0.013).

CONCLUSIONS

Systemic NO augmentation can lower the functional bladder outlet resistance very rapidly in men. Our results support the concept that the NO-cGMP pathway may be a promising target for medical treatment of lower urinary tract symptoms.

Prostasin attenuates inducible nitric oxide synthase expression in lipopolysaccharide-induced urinary bladder inflammation

Prostasin is a glycosylphosphatidylinositol-anchored serine protease, with epithelial sodium channel activation and tumor invasion suppression activities. We identified the bladder as an expression site of prostasin. In the mouse, prostasin mRNA expression was detected by reverse transcription and real-time polymerase chain reaction in the bladder, and the prostasin protein was localized by immunohistochemistry in the urothelial cells. In mice injected intraperitoneally with bacterial lipopolysaccharide (LPS), bladder prostasin mRNA expression was downregulated, whereas the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interferon-gamma (IFN-gamma), TNF-alpha, IL-1beta, and IL-6 was upregulated. Viral promoter-driven expression of the human prostasin homolog in the bladder of transgenic mice attenuated the LPS induction of iNOS but did not abolish the induction. LPS induction of COX-2, TNF-alpha, IL-1beta, and IL-6 expression, however, was not reduced by prostasin transgene expression. Liposome-mediated delivery of prostasin-expressing plasmid into mouse bladder produced similar attenuation effects on LPS-induced iNOS expression, while not affecting COX-2 or cytokine induction. Mice receiving plasmid expressing a catalytic mutant prostasin did not manifest the iNOS induction attenuation phenotype. We propose a proteolytic mechanism for prostasin to intercept cytokine signaling during LPS-induced bladder inflammation.

Expression of neuronal nitric oxide synthase (nNOS) and nitric-oxide-induced changes in cGMP in the urothelial layer of the guinea pig bladder

The urothelium plays a sensory role responding to deformation of the bladder wall; this involves the release of adenosine trisphosphate (ATP) and nitric oxide (NO), which affect afferent nerve discharge and bladder sensation. The urothelial cells responsible for producing ATP and NO and the cellular targets, other than afferent nerves, for ATP and NO remain largely unexplored. Sub-urothelial interstitial cells (SU-ICs) lie immediately below the urothelium and respond to NO with a rise in cGMP. To determine which cells might target SU-ICs by producing NO, areas of dome, lateral wall and base wall were treated with isobutyl-methyl-xanthine, exposed to the NO donor diethylamino NONOate and then fixed for immunohistochemistry. Surface urothelial cells (SUCs) in the base and dome expressed neuronal nitric oxide synthase (nNOS), whereas those in the lateral wall did not. Distinct populations of SUCs were present in the bladder base. SUCs with significant amounts of nNOS lay adjacent to cells with low levels of nNOS. In specific base regions, the few SUCs present contained nNOS within discrete intracellular particles. In the basal urothelial cell (BUC) layer of the lateral wall, nNOS-positive (NOS(+)) BUCs neither showed an elevation in cGMP in response to NO, nor expressed the beta1 sub-unit of soluble guanylate cyclase, protein kinase I or protein kinase II. Thus, they produced but did not respond to NO. The BUC layer also stained for the stem cell factor c-Kit suggesting its involvement in urothelial cell development. No NOS(+) BUCs were present in the SUC-sparse region in the bladder base. Exogenous NO produced an elevation in cGMP in SUCs and SU-ICs. The distribution and proportion of these target cells varied between the dome, lateral wall and base. cGMP(+) SU-ICs were present as a dense layer in the bladder base but were rarely seen in the lateral wall, which contained nNOS(+) BUCs. No nNOS(+) BUCs and cGMP(+) SU-ICs were apparent in the dome. The degree of complexity in nNOS distribution and NO target cells is therefore greater than has previously been described and may reflect distinct physiological functions that have yet to be identified.

Dietary conjugated linoleic acid affects morphofunctional and chemical aspects of subcutaneous adipose tissue in heavy pigs

We investigated the in vivo effects of dietary conjugated linoleic acid (CLA) on subcutaneous adipose tissue from heavy pigs to clarify the involvement of possibly different causative effects in the established antiadipogenic effect of CLA. Pigs [n = 36; initial body weight, 106 kg live weight (LW)] were assigned to 1 of 2 LW-matched groups supplemented with either 0 or 0.75% of a CLA preparation containing 50% CLA isomers. The pigs were slaughtered at 155 kg LW and adipose tissue analyzed. CLA supplementation affected ash content, and decreased iodine values (P < 0.01) and adipocyte size (P < 0.05). The fat content of adipose tissue was lower (P < 0.05) in females than castrated males, and females had smaller (P < 0.01) adipocytes than castrated males. Neither CLA nor sex influenced adipocyte lipid droplet diameter or the extent of lipid peroxidation as determined by quantitation of Schiff's histochemical reaction. NADPH-diaphorase was not influenced by CLA treatment. Preadipocyte proliferation rates were lower in pigs fed CLA (P < 0.05), whereas the number of adipocyte apoptotic nuclei was greater (P < 0.05). Preadipocyte proliferation was also greater (P < 0.05) in females than castrated males. Neuronal and endothelial nitric oxide synthase activities did not differ between groups in adipose tissue vessels, but inducible nitric oxide synthase expression in adipocytes was lower in pigs fed CLA (P = 0.05). These findings suggest that the antiadipogenic effect of CLA in heavy pigs is not a direct effect but may occur by downregulation of a NO-mediated lipolytic pathway.