膀胱出口梗阻大鼠逼尿肌中神经生长因子mRNA的变化及其意义

目的探讨膀胱出口梗阻(BOO)大鼠模型膀胱逼尿肌中神经生长因子(NGF)mR- NA的表达变化及意义。方法建立BOO大鼠模型,采用逆转录-聚合酶链反应(RT-PER)检测大鼠膀胱逼尿肌中NGF mRNA的表达。结果:NGF mRNA在模型组和对照组的膀胱逼尿肌细胞中均有表达,模型组大鼠的逼尿肌NGF mRNA水平高于对照组,两组间的mRNA平均水平差异有统计学意义(P<0.01)。结论膀胱出口梗阻后,膀胱逼尿肌细胞中NGF mRNA表达水平增高,这可能与BOO所致膀胱功能受损的发生有关。     

Changes of bladder activity and glycine levels in the lumbosacral cord after partial bladder outlet obstruction in rats

Objectives: We investigated the time course of changes in bladder activity as well as in spinal and serum levels of glutamate and glycine after partial bladder outlet obstruction (BOO) in rats. Methods: A total of 36 female rats were divided into six groups: sham operation (control); 3 days, 14 days, and 28 days after BOO; 3 days and 28 days after relief of BOO. Under urethane anesthesia, isovolumetric cystometry was carried out in each group. Then, spinal and serum levels of glutamate and glycine were measured. Results: The interval between bladder contractions was shorter in all of the groups compared with the control group. The amplitude and duration of bladder contractions was decreased at 3 days, 14 days, and 28 days after BOO, and at 3 days after relief of BOO. Spinal and serum glutamate levels showed no changes. However, the spinal glycine level was decreased at 14 days and 28 days after BOO, and at 28 days after relief of BOO. Serum glycine level was also decreased at 28 days after BOO and 28 days after relief of BOO. Conclusions: Detrusor overactivity during the chronic phase of partial BOO is partly caused by a decrease of glycinergic neuronal activity in the lumbosacral cord. A 3‐day period of BOO produces detrusor overactivity, which might be due to an irreversible decrease of spinal glycinergic neuronal activity.     

Morphometric analysis of the collagen changes induced by subcutaneous injection of interferon-gamma after bladder outlet obstruction in the rat

AIMS: The objective of this study was to examine the effects of interferon-gamma injection on changes in collagen content, after the creation of partial bladder outlet obstruction in the rats. METHODS: A total of 50 Sprague-Dawley female rats were subjected to partial bladder outlet obstruction by using metal rods. The rats were divided into five groups (n = 10 in each group): normal control (N), sham operation (S), bladder outlet obstruction for 4 weeks (BOO), interferon-gamma injection after sham operation (S + IFN), and interferon-gamma injection after bladder outlet obstruction (BOO + IFN). Interferon-gamma was subcutaneously injected (100,000 units per injection, LG chemical Co., Seoul, Korea) daily for 4 weeks in the injection groups, after which all rats were sacrificed. RESULTS: The collagen area percentage (collagen/collagen + muscle) in each bladder, calculated through image analysis, was 40.7 +/- 1.6% in the N, 38.2 +/- 2.0% in the S, 26.6 +/- 3.8% in the S + IFN, 19.9 +/- 2.5% in the BOO, and 12.4 +/- 2.0% in the BOO + IFN group (mean +/- standard error). The difference in the collagen area percentage between the N and S groups (P > 0.05) was not significant, but there were significant differences between the N and S + IFN groups (P < 0.05), between the S and S + IFN groups (P < 0.05), and between the BOO and BOO + IFN groups (P < 0.05). CONCLUSIONS: It appears that interferon-gamma decreases the collagen content in the obstructed rat bladder.     

Change in acetylcholine release from rat bladder with partial outlet obstruction

OBJECTIVE

To investigate changes in acetylcholine release from the bladder of rats with partial bladder outlet obstruction (BOO), as partial BOO leads to hypertrophy and an alteration in the contractions of the detrusor smooth muscle, and acetylcholine plays an important role in urinary bladder contractions but there is little available information on acetylcholine release after BOO.

MATERIAL AND METHODS

Partial BOO was induced in adult female rats by ligating the proximal urethra over a 1 mm angiocatheter; sham‐operated rats served as controls. The rats were killed 2 weeks, 3 and 6 months after induction of BOO. We investigated the contractions induced by carbachol, KCl (80 mm ), ATP and electrical‐field stimulation (EFS, 2.5–40 Hz), and collected the dialysate obtained from a microdialysis probe inserted into the muscle strips during EFS, and measured the amount of acetylcholine in the dialysate fraction by high‐performance liquid chromatography with electro‐chemical detection. S‐100 immunohistochemical staining of the bladder preparations was used for histological examination in BOO and control rats.

RESULTS

The bladder weight gradually increased after BOO. There were no significant changes in KCl‐induced contractions throughout the experimental period in either group. There were no significant changes in carbachol‐induced contractions until 3 months after BOO but there was a significant reduction at 6 months. ATP‐induced contractions were significantly increased 2 weeks and 3 months after BOO. EFS‐induced contractions were gradually reduced after BOO. Acetylcholine release from the bladder strips was not significantly different between the groups until 2 weeks after BOO. However, acetylcholine release in BOO rats was significantly decreased 3–6 months after BOO, being significantly lower than that of the control rats. In the histological study, the number of nerve fibres in the BOO rats was significantly lower than in the control rats.

CONCLUSIONS

We suggest that the prolonged BOO caused a decrease in EFS‐induced acetylcholine release and the number of nerves in the rat urinary bladder, which might contribute to bladder underactivity in BOO.     

膀胱出口梗阻大鼠膀胱过度活动的研究

目的:建立膀胱出口梗阻大鼠模型,诱发逼尿肌不稳定(DI),研究膀胱出口梗阻伴发膀胱过度活动的病理生理学特征。方法:选择38只成年SD雌性大鼠,随机分为模型组和对照组,结扎膀胱颈部建立膀胱出口梗阻模型。建模后3、6、9、12周采用BL-410生物机能实验系统测定膀胱压,以充盈期出现DI作为膀胱过度活动存在的标准,记录并计算DI阳性率和频率、最大排尿压(MVP)、最大膀胱容量(MCC)、膀胱顺应性(BC)和剩余尿量(PVR)。用光镜观察建模不同时期膀胱组织的病理学改变。结果:模型组大鼠3、6、9、12周DI阳性率分别为37.50%、75.00%、75.00%、62.50%。MVP、MCC、BC、PVR和DI频率较对照组增高(P<0.01),第9周大鼠PVR、MVP、MCC高于第3、6和12周。不同时期病理学改变呈现出膀胱容量增加、肌层逐渐增厚和纤维化的过程。结论:膀胱出口梗阻与逼尿肌不稳定的发生具有潜在的相关性,其病理学改变和尿流动力学参数反映了膀胱的病理生理学特点。     

Protective effect of an oral endothelin converting enzyme inhibitor on rat detrusor function after outlet obstruction

PURPOSE: Endothelin (ET)-1, one of the most potent vasoconstrictors known, is converted from its less potent precursor big ET by the endothelin converting enzyme (ECE). In vitro studies suggest that ET has an important role in smooth muscle growth after bladder outlet obstruction (BOO). We investigated the effect of an orally administered ECE inhibitor by cystometry in conscious rats with and without BOO. MATERIAL AND METHODS: BOO was produced in female rats by a standardized method and the animals were divided into 2 groups. One group received the ECE inhibitor WO-03028719 and the remaining animals received vehicle daily by oral gavage. Five sham operated animals served as controls and were treated with WO-03028719. Two weeks after surgery cystometry was performed. RESULTS: BOO led to a significant increase in bladder weight in vehicle treated animals and a nonsignificant increase in the treatment group. Micturition interval and volume increased in each obstructed group. Micturition pressure was significantly decreased in the vehicle group but unchanged in the BOO treatment group. Residual urine occurred in 4 of 11 BOO vehicle animals but not in the sham operated or BOO treatment group. Spontaneous nonvoiding bladder contractions occurred in 37% of BOO treatment animals but in 82% of the BOO vehicle group. Voiding contractions were markedly prolonged in the BOO vehicle group, while they were normal in the BOO treatment group. CONCLUSIONS: ECE inhibition did not prevent an increase in bladder weight after BOO but it appeared to have a beneficial effect on detrusor function and decrease detrusor overactivity in conscious rats.     

膀胱出口梗阻所致逼尿肌过度活动的神经电生理研究

目的 从膀胱传入神经以及盆底相关神经肌肉角度探讨神经因素及肌源性因素在膀胱出口梗阻所致的逼尿肌过度活动发生中的作用.方法 采用耻骨上膀胱颈梗阻的方法建立逼尿肌过度活动大鼠模型,测定不稳定收缩时盆神经传入电位信号,并同步测定阴部神经运动支电位、尿道外括约肌肌电及腹肌肌电的反射反应.并观察T8段脊髓截断、双侧盆神经截断、腹交感干截断以及双侧阴部神经截断后大鼠膀胱充盈测压不稳定收缩的变化.结果 成功制作了膀胱出口梗阻逼尿肌过度活动大鼠模型,成功率62.5%.充盈性膀胱测压神经肌电生理同步记录结果显示,允盈期逼尿肌过度活动可分为两种类型,一种为收缩幅度高于10 cmH2O(1 cmH2O=0.098 kPa)的逼尿肌过度活动(B-DO),伴有同步盆神经传入的信号明显增强,且能引发阴部神经、尿道外括约和腹肌肌电图出现显著变化;一种为收缩幅度低于10 cmH2O的逼尿肌过度活动(S-DO),没有上述盆神经传入及相关神经肌电变化.T8脊髓截断后,膀胱充盈-排尿收缩周期消失,膀胱基础压显著升高,B-DO消失,S-DO仍然存在,且收缩幅度较截断前略有上升,但差异无统计学意义.依次截断控制膀胱的盆神经、交感神经和阴部神经后,膀胱失去充盈-排尿收缩周期,基础压显著升高,不稳定收缩中B-DO消失,S-DO仍然存在.结论 膀胱出口梗阻所致的逼尿肌过度活动存在不依赖于中枢和周围神经的膀胱源性因素.     

Function and nerve growth factor of the rat urinary bladder during urethral obstruction and its relief]

It has been considered that the urethral obstruction influence the function and the nerve innervation of the bladder. In this study, the changes in the bladder function and the nerve growth factor (NGF) synthesized in the bladder were systematically analyzed both during partial urethral obstruction and after its relief in the rat. The maximum contraction pressure was temporally decreased and then increased 1.5 times of the normal level 6 week after the obstruction. NGF in the bladder, measured by ELISA method, was rapidly increased 5 times of the normal level 1 day after the obstruction. It gradually decreased 2 weeks after the obstruction but did not recover to the normal level. The maximum contraction pressure and the bladder NGF recovered to the normal level after the removal of 1 to 6 weeks obstruction. These results suggest that partial urethral obstruction reversibly increases the contractility and the NGF synthesis of the bladder.     

膀胱出口部分梗阻中转化生长因子β1/Smads信号通路的激活及低剂量紫杉醇的干预作用

目的探讨膀胱出口部分梗阻(BOO)后转化生长因子β1(TGF-β1)相关的Smads信号通路的激活及低剂量紫杉醇的干预作用。方法雌性Sprague-Dawley大鼠30只,随机分为空白对照组、BOO组和紫杉醇组。BOO组和紫杉醇组行尿道近端梗阻方式制备膀胱出口部分梗阻模型,空白对照组采用假手术方式处理。术后紫杉醇组给予低剂量紫杉醇腹腔注射(0.3mg/kg),每周2次。空白对照组与BOO组以等体积生理盐水同时间腹腔注射。4周后测量膀胱重量,行HE和Masson染色,并计算胶原纤维的含量;透射电镜观察逼尿肌超微结构改变;采用逆转录多聚酶链反应(RT-PCR)检测TGF-β1、Smad 7和α-SMA mRNA的表达;免疫组织化学法检测TGF-β1、磷酸化Smad 2(p-Smad 2)和α-SMA蛋白的表达和分布。结果相比空白对照组,BOO组膀胱重量明显增加,胶原纤维增多,膀胱组织中TGF-β1和α-SMA mRNA表达水平增高(P0.05),TGF-β1、p-Smad 2和α-SMA蛋白表达增高(P0.05)。相比BOO组,紫杉醇组膀胱重量显著降低,胶原纤维面积比值下降(P0.05)。TGF-β1、pSmad 2和α-SMA的表达减少(P0.05),Smad 7表达上升(P0.05)。结论 TGF-β1相关的Smads信号通路的激活可能是BOO后膀胱纤维化的机制之一,低剂量紫衫醇可能通过阻断这一信号通路,在一定程度上有延缓BOO膀胱纤维化进程的作用。     

Effects of a vitamin D(3) analogue in a rat model of bladder outlet obstruction

OBJECTIVES: To explore the effect of the vitamin D3 analogue, BXL-628, on some of the consequences of bladder outlet obstruction (BOO), e.g. hypertrophy and loss of contractile function, as vitamin D3 and BXL-628 inhibit prostate and bladder cell growth in vitro, and there are receptors for vitamin D in rat and human bladder. MATERIAL AND METHODS: In female rats, BOO was produced by a standardized method; one group received daily BXL-628 (150 microg/kg per day) and the remaining rats received vehicle. Sham-operated rats received BXL-628 or vehicle. After 2 weeks, the conscious rats were assessed by cystometry. Plasma calcium levels were determined and in vitro contractility assessed at the end of the experiments. RESULTS: There was a significant increase in bladder weight, micturition interval and volume, and in bladder capacity in both the obstructed groups compared to sham controls, but no difference between the obstructed groups. On plotting the micturition pressure against bladder weight within the obstructed groups, there was a clear correlation in the vehicle-treated group, indicating a decrease in contractile function with increasing bladder weight. There was no such correlation in the treatment group. In vitro, there was a strong correlation of increasing bladder weights vs decrease in response to KCl and electrical-field stimulation in strips from obstructed vehicle-treated rats, but no correlation in those from drug-treated rats. Treatment increased the plasma calcium level by 12%. CONCLUSIONS: The vitamin D(3) analogue used did not prevent bladder hypertrophy, but appeared to reduce some of the negative functional changes of the bladder smooth muscle, which occurs with BOO-induced increases in bladder weight.     

逼尿肌自身肌源性变化与逼尿肌不稳定的关系

目的:探讨逼尿肌不稳定(Detrusor instability,DI)的发病机制。方法:建立Wistar大鼠膀胱流出道梗阻(Bladder outlet obstruction,BOO)动物模型,6周后行充盈性膀胱测压分出梗阻后稳定组和不稳定组,进行离体膀胱充盈性测压、逼尿肌条机械牵拉及胆碱类药物刺激试验。结果:不稳定组膀胱充盈至出现收缩时的压力明显低于稳定组及正常对照组,收缩发生时的容积明显低于稳定组;不稳定组逼尿肌条机械牵拉至其出现收缩时的最小张力明显低于稳定组及正常对照组;不同浓度氯化氨基甲酰胆碱刺激诱发的收缩频率各组间差异无统计学意义(P<0.05)。结论:逼尿肌不稳定的发生与逼尿肌自身的兴奋性增强密切相关。     

Suppression of detrusor overactivity in rats with bladder outlet obstruction by a type 4 phosphodiesterase inhibitor

OBJECTIVE: To investigate the effects of a selective type 4 cyclic nucleotide phosphodiesterase (PDE4) inhibitor, IC486051, on bladder activity in normal rats and those with and bladder outlet obstruction (BOO), as inhibition of PDE4 leads to elevation of intracellular cAMP levels and relaxation of smooth muscle. MATERIALS AND METHODS: BOO was induced in female Sprague-Dawley rats by tying a silk ligature around the urethra. At 4 or 6 weeks after inducing BOO, conscious rats were assessed by cystometry with the urethral ligature intact. In unobstructed rats, blood pressure was also measured. RESULTS: In unobstructed rats, IC486051 (0.1 mg/kg intravenously) produced no significant changes in cystometric variables, while at a dose of 0.5 mg/kg maximum voiding pressure was reduced by 34%. At both doses, there was a small, transient increase in blood pressure. In both 4- and 6-week BOO rats IC486051 dose-dependently decreased the number and amplitude of non-voiding bladder contractions by up to 80%, relative to pre-treatment values. At doses of 0.1 and 0.5 mg/kg IC486051 had no significant effect on voiding variables. In the 4-week BOO rats, a dose of 1.0 mg/kg decreased bladder capacity, voided volume and residual volume by 21%, 32% and 18%, respectively. In 6-week BOO rats, a dose of 1.0 mg/kg decreased maximal voiding pressure by 17% and pressure threshold for voiding by 28%. In both groups of rats with BOO, voiding efficiency was unchanged. CONCLUSIONS: A selective PDE4 inhibitor can effectively suppress detrusor overactivity in rats with BOO, at doses that have no effect on voiding bladder contractions. Thus, selective PDE4 inhibitors should be considered for the treatment of overactive bladder in patients with BOO.     

Involvement of angiotensin II type 1 receptor on pathological remodeling and dysfunction in obstructed bladder

Objectives: To determine whether long‐term administration of an angiotensin II type 1 receptor antagonist improves morphology and function in obstructed bladders. Methods: Male Sprague–Dawley rats underwent surgery to produce bladder outlet obstruction (bladder outlet obstruction group; n = 32) or sham surgery (sham group; n = 16). A total of 2 weeks later, 16 bladder outlet obstruction‐rats were given the AT1 antagonist, candesartan, subcutaneously (candesartan group) using an osmotic pump for 4 weeks; the remaining bladder outlet obstruction‐rats received vehicle (bladder outlet obstruction group). A total of 6 weeks after surgery, we compared continuous cystometry, bladder weight, strip contraction, histology and messenger ribonucleic acid expression of growth factors, nicotinamide adenine dinucleotide phosphate oxidase 1 and renin–angiotensin system components among the three groups. Results: Bladder weights markedly increased with bladder outlet obstruction (578 ± 159 mg), and candesartan (344 ± 111 mg) suppressed this increase. Micturition pressure, which was significantly higher with bladder outlet obstruction, was unaffected by candesartan. The shortened micturition interval and decreased micturition volume with bladder outlet obstruction were significantly prolonged and increased by candesartan. Candesartan also significantly decreased residual urine. Histologically, the collagen fiber‐to‐muscle ratio was significantly increased with bladder outlet obstruction (0.85 ± 0.25) compared with the sham group (0.53 ± 0.18); this increase was suppressed by candesartan (0.49 ± 0.21). The messenger ribonucleic acid expression of heparin‐binding epidermal growth factor‐like growth factor, transforming growth factor‐β1 and nicotinamide adenine dinucleotide phosphate oxidase 1 significantly increased with bladder outlet obstruction, but it was significantly reduced by candesartan. Compared with the bladder outlet obstruction group, candesartan increased the maximal contraction of bladder strips for all stimuli except for angiotensin II. Conclusion: These findings suggest that bladder angiotensin II type 1 receptors contribute to the pathophysiology of remodeling and dysfunction in obstructed bladder.     

Altered distribution of interstitial cells in the guinea pig bladder following bladder outlet obstruction

AIMS: We investigated the effects of bladder outlet obstruction (BOO) on the distribution of interstitial cells (ICs) in the guinea-pig bladder. METHODS: Bladder overactivity of BOO animals was validated with urodynamic studies. Immunohistochemical analyses for Kit and vimentin as markers for ICs were performed on both BOO and control bladders. Morphological and functional properties of detrusor smooth muscle (DSM) were examined with alpha-smooth muscle actin staining and intracellular recording, respectively. Electron microscopy was also carried out to characterize ultrastructural morphology of ICs. RESULTS: Two weeks after surgery, BOO animals showed an increased voiding frequency and a reduced voiding volume. Filling cystometry demonstrated a frequent incidence of non-voiding contractions, a reduced interval between voiding contractions and an increased voiding pressure in BOO bladders. In BOO bladders, the thickness of suburothelial and subserosal connective tissue layers was increased, whilst that of detrusor smooth muscle (DSM) layer was less affected. Population of Kit or vimentin immunoreactive ICs was increased in subserosal layers, and their distribution was altered in suburotherial layer in BOO bladders. Neither alpha-actin immunoreactivity nor spontaneous electrical activity of DSM was altered in BOO bladders. ICs were characterized by their numerous mitochondria and caveolae, and had a close contact with each other and with neighboring DSM or nerves. CONCLUSIONS: These results demonstrated the increased population of ICs in the BOO guinea-pig model for the first time, and suggest that the altered distribution of ICs may contribute to the pathophysiology of bladder overactivity.     

Effects of doxycycline on voiding behaviour of rats with bladder outlet obstruction

OBJECTIVE

To examine the voiding behaviour changes in rats with bladder outlet obstruction (BOO) while inhibiting matrix metalloproteinase (MMP) activity with doxycycline, as increased MMP activity may be involved in obstruction‐induced bladder hypertrophy.

MATERIALS AND METHODS

Female Sprague‐Dawley were divided into eight groups (three rats in each group): normal control (NC) ± doxycycline, 3 weeks partial BOO (3WPBOO) ± doxycycline, 6 weeks PBOO ± doxycycline, and 3 weeks PBOO followed by 3 weeks de‐obstruction (3WOD) ± doxycycline. All rats received the same food and water and were on the same 12 h dark/light cycle housed in metabolic cages. Treatment groups were given doxycycline 15 mg/kg/day subcutaneously twice daily. The voiding variables measured were average voided volume (AV V) and voiding frequency (VF) in 24 h. After completion of the voiding behaviour studies, the rats were killed and their bladders were excised and weighed.

RESULTS

The AV Vs were significantly increased (P < 0.05) in all study groups compared with the NC group except for the 3WPBOO‐doxycycline and 3WOD‐doxycycline groups. The VF was significantly increased (P < 0.05) only in the 3WOD‐doxycycline group. The bladder weights were significantly increased after PBOO in all the study groups (P < 0.05), except for the 3WOD group.

CONCLUSION

These data show that MMP inhibition may affect voiding behaviour during the response to BOO or its relief. This is the first clinical demonstration that interfering with a principal target of bladder muscle wall remodelling may have a direct effect on bladder function.     

膀胱出口梗阻后逼尿肌肾上腺素β3受体mRNA表达和作用

目的：初步研究前列腺增生患者膀胱出口梗阻后逼尿肌肾上腺素能β3受体亚型mRNA表达和作用.方法：选择前列腺增生膀胱出口无梗阻（对照组）9名和膀胱出口梗阻患者（实验组）21名,根据尿动力学将实验组分为逼尿肌稳定组和不稳定组,半定量RT-PCR方法检测三组逼尿肌β3受体亚型mRNA的表达,离体逼尿肌拉力实验检测β3受体激动剂对三组逼尿肌收缩力的影响.结果：对照组、逼尿肌稳定组和不稳定组β3受体mRNA相对含晕为（18.48±2.84）、（17.28±2.57）和（10.42±1.22）,不稳定组β3受体明显降低（P＜0.05）;β受体激动剂和β3受体激动剂诱导逼尿肌松驰效应呈浓度依赖性,对不稳定组作用小于稳定组和对照组（P＜0.05）,对照组与稳定组没有差别.结论：膀胱出口梗阻逼尿肌不稳定患者β3受体mRNA含量下降,并且对β3激动剂的松驰反应降低,逼尿肌肾上腺素能受体β3亚型可能参与膀胱出口梗阻后逼尿肌收缩力变化.     

前列腺增生症所致膀胱出口梗阻患者逼尿肌中神经生长因子mRNA的变化及意义

目的　探讨前列腺增生症 (BPH)所致膀胱出口梗阻 (BOO)患者膀胱逼尿肌中神经生长因子 (NGF)mRNA的表达变化及意义。方法　对同龄对照组 8例膀胱癌患者、BPH梗阻逼尿肌稳定组 2 4例患者和BPH梗阻逼尿肌不稳定组 16例患者的膀胱壁逼尿肌组织 ,采用逆转录聚合酶链反应(RT PCR)检测膀胱逼尿肌细胞中NGFmRNA的表达。结果　NGFmRNA在同龄对照组、BPH梗阻逼尿肌稳定组和梗阻逼尿肌不稳定组患者的膀胱逼尿肌细胞中均有表达 ,三组患者的平均表达水平两两之间差异均有显著性意义 (P <0 0 1) ,而且NGFmRNA在同龄对照组、BPH梗阻逼尿肌稳定组和梗阻逼尿肌不稳定组的平均表达水平逐渐增加。结论　前列腺增生症引起膀胱出口梗阻后 ,膀胱逼尿肌细胞中NGFmRNA表达水平增高 ,并可能与逼尿肌不稳定 (DI)的发生有关。     

Muscarinic and purinergic receptor expression in the urothelium of rats with detrusor overactivity induced by bladder outlet obstruction

OBJECTIVE

To investigate the expression of muscarinic and purinergic receptors in rat urothelium, and changes in their distribution and expression following detrusor overactivity induced by bladder outlet obstruction (BOO).

MATERIALS AND METHODS

Thirty Sprague‐Dawley rats were divided into control (10) and BOO groups (20). Partial BOO was induced for 3 weeks and the rats assessed by cystometrography. A portion of the bladder was stained using immunofluorescence for M₂ and M₃ muscarinic receptors, and P2X₃ purinergic receptors. The remainder was dissected into bladder urothelium and the smooth muscle layer, and the expression of the receptor proteins analysed by Western blotting.

RESULTS

Cystometrography showed a significant decrease in contraction interval and increase in contraction pressure in the BOO group. On immunofluorescence staining, muscarinic and purinergic receptors were localized in both the urothelium and the muscle layer. Immunoreactivity of M₂ and M₃ muscarinic receptors was greater in the urothelium of the BOO group than in the control group; there was a smaller increase in P2X₃ immunoreactivity. On Western blotting, the expression of M₂, M₃ and P2X₃ receptors was increased in the urothelium of the BOO group, and there was increased M₃ receptor expression in the muscle layer of the BOO group.

CONCLUSIONS

There were detectable changes in muscarinic and purinergic receptors with bladder overactivity induced by BOO. Our results suggest that changes in urothelium receptor expression could have a role in mediating the afferent sensory responses in the urinary bladder.     

Effect of aging on bladder function and the response to outlet obstruction in female rats

Bladder dysfunction in the aging population is a significant problem. However the concomitant presence of other diseases in many patients can make it difficult to distinguish between changes in bladder function and other influences. The present study was designed to study, in aging rats, bladder function and the effect of partial bladder outlet obstruction (BOO) on bladder function. Cystometrics were performed in awake, female Fischer 344 rats of four age groups (6, 12, 18 and 24 months) following subcutaneous implantation of a mediport catheter. Cystometric evaluations were carried out in control rats or those subject to three weeks of BOO. Bladder compliance significantly decreased with aging, which reflected an increase in threshold pressure without changes in bladder capacity. Partial BOO caused development of severe bladder instability. Following BOO, bladder capacity and compliance were significantly increased in all age groups. Threshold pressure was lower in obstructed animals, except for 6-month rats. Younger animals were able to generate a higher contraction pressure to compensate for the BOO, whereas older animals did not. Using an awake model of cystometric measurement, we have demonstrated that aging, by itself can affect bladder function. Furthermore, aged animals respond differently to BOO than younger animals. These results demonstrate that both aging and disease can contribute to bladder dysfunction, and suggest that treatment of bladder dysfunction may require a combination of therapies targeted to multiple etiologies. Received: 18 August 1998 / Accepted: 6 July 1999