糖尿病初期對膀胱功能的影響

The early effect of diabetes mellitus on the urinary bladder function

王炯珵(Chiung-Cheng Wang)

指導教授 ： 謝瑞香

中原大學/工學院/醫學工程研究所/博士(2009年)

https://doi.org/10.6840/CYCU.2009.00905

摘要

背景和假說
糖尿病和糖尿病膀胱功能障礙在全世界都是很常見的健康問題，且隨著年紀增加，盛行率和發生率都明顯增加，超過百分之五十的糖尿病病患會表現出各式各樣的膀胱病變，如：大膀胱容量，降低膀胱感覺或逼尿肌過動，收縮力不良和殘尿增加等。糖尿病膀胱功能障礙可能是由糖尿病神經病變或相關利尿所造成的，然而糖尿病和利尿對於膀胱組織和器官特殊功能和力學變化的影響至今尚未明瞭，組織組成(力學特性重要決定者)和相關基因的時間序列變化也尚未完全了解，因此，為了要獲得對於糖尿病膀胱病變更好的病理生理學的了解，去釐清預知糖尿病膀胱病變的生物力學變化是必須的，此外，雖然過去研究顯示糖尿病會增加攝護腺肥大老人下泌尿道症狀，但是這些病患通常年紀都超過50歲，會有許多內科的干擾問題存在，這研究的主要興趣來自於我們臨床的觀察，泌尿科醫師通常處理由其他醫師轉介來末期的糖尿病膀胱病變，因此，為了降低及預防末期的病變，在糖尿病的初期，去偵測下泌尿道功能失調和相關因子是很重要的。
第一，我們假說膀胱壁力學特性的改變是糖尿病誘發功能障礙的一個重要指標；第二，我們假說糖尿病的膀胱生理變化會導致基因和外細胞間質的改變，最後，我們假說糖尿病和代謝症候群，在糖尿病初期和下泌尿道症狀，下泌尿道功能和勃起功能障礙有相關性。

材料與方法
在動物研究上，雌性Sprague-Dawley老鼠腹內注射體重每公斤65毫克的Streptozotocin成為糖尿病鼠，除了正常控制組外，老鼠餵食5%糖水作為利尿控制組，在第2.4.8週結束後，做膀胱容量壓力檢查，同時，膀胱壁在後面取得1公分乘1公分的組織，做為雙軸力學實驗的標本，研究隨著時間變化，組織順應性和力學不等向性的改變。從膀胱的逼尿肌取得的核糖核酸加以反錄，用聚合鏈反應放大互補去氧核醣核酸，包括第一型膠原蛋白、第三型膠原蛋白、多型彈力纖維，轉型生長因子乙型一的基因等，膠原蛋白和彈性蛋白的含量則用商用的試劑定量，新型半自動的影像分析方法去定量平滑肌肌束的走向和組成部分。
在臨床研究，在單一糖尿病門診226位小於45歲第二型糖尿病男性和183健康空腹血糖正常男性的下泌尿道症狀，排尿和勃起功能加以比較，受試者接受使用國際攝護腺症狀分數問卷，5項國際勃起功能指標問卷，尿流速和餘尿等檢查，代謝症候群和下泌尿道和勃起功能障礙的相關性也加以評估。

結果
在我們Streptozotocin誘發糖尿病和糖水餵食的利尿老鼠模型中，利尿作用本身可以解釋許多糖尿病初期的影響，包括膀胱肥厚，順應性增加，和容量增加；使用雙軸力學測試，我們證實糖尿病鼠和利尿鼠膀胱都表現出非線性的應力形變關係和力學不等向性，環軸比縱軸有更好的順應性，這些材料特性的改變可能是膀胱從直立橢圓變成橫橢圓的形態改變以獲得更好的膀胱順應性。
這些生物力學特性的改變進一步由分子生物學、生化測試和定量影像分析來證實。膀胱組織重塑和轉型生長因子乙型一和膠原蛋白訊息核醣核酸的向下調節有關；利尿作用造成膠原蛋白減少和彈性蛋白增加導致於膀胱順應性的增加；半自動影像分析組織切片顯示糖尿病鼠和利尿鼠膀胱的平滑肌部分上昇但膠原蛋白部分下降，此外，糖尿病鼠和利尿鼠膀胱的平滑肌走向主要分布在環軸和縱軸，但正常對照組的膀胱平滑肌走向主要分布在縱軸，這些研究都提供膀胱組織微小結構和時間序列改變的膀胱力學特性相聯性的證據。
在臨床研究方面，平均病患是38.9 ± 6.1歲(範圍20~45)且平均糖尿病發病2.8 ± 3.1年(範圍0.5~20)和對照組相比，男性糖尿病病患有顯著高的國際攝護腺症狀評分分數(6.1 ± 5.8 vs 4.1 ± 4.6，p＜0.001)較多的中度至重度下泌尿症狀(OR=1.78，95% CI 1.12，2.84，p=0.01)較大的排尿體積(376 ± 177ml vs 326 ± 102ml，p=0.04)，較糟的5項國際勃起功能指標的分數(17.3 ± 6.4 vs 20.0± 3.8，p＜0.001)和較多的中度至重度的勃起功能障礙(OR=3.5，95% CI 2.1，5.8，p＜0.001)，但類似的最大尿流速(22.8 ± 7.9ml vs 22.6 ±8.1ml/sec，p=0.84)和排尿後的餘尿(20 ± 20ml vs 23 ± 35ml，P=0.82)。國際勃起功能指標與國際攝護腺肥大指標(p=0.0004，相關=-0.23，95% CI-0.35~-0.11)和糖化血色素(p=0.02，相關=-0.14，95%CI-0.26~-0.01)呈負相關。共有156(69%)符合代謝症候群的標準、平均年齡、病程、糖化血色素、國際攝護腺功能指標、排尿體積，最大尿流速和國際勃起功能指標和在糖尿病患者中，有或無代謝症候群比較起來是相類似的。

結論
膀胱容量壓力圖和力學測試的結果顯示利尿作用主要貢獻於膀胱壁的〝初期〞變化，而糖尿病造成膀胱力學性質更多的〝末期〞變化，基因，細胞外基質蛋白質和膀胱平滑肌排列排列走向在時間序列上的變化和由於糖尿病膀胱病變導致膀胱組織重塑有相關性；臨床上，小於45歲第二型糖尿病病患有較多的下泌尿道症狀，但相似的膀胱排空功能，年齡和排尿症狀是低尿流速的獨立危險因子，在初期糖尿病時，糖尿病和相關的利尿作用似乎比其他代謝症候群的組成成分對於下泌尿道症狀有更強大的影響，因此，我們的研究建議，在糖尿病初期(例如：小於45歲)就有需要注意膀胱功能！此外在糖尿病初期藉由適當飲食和水分攝取來控制血清中的血糖或許是預防由利尿作用導致漸進性膀胱功能障礙很重要的步驟；控制細胞外間質蛋白質含量以獲得正常膀胱壁的力學特性或許是治療糖尿病膀胱病變以回覆健康膀胱功能重要的一步。

關鍵字

糖尿病 ； 生物力學 ； 膀胱

並列摘要

Background and Hypothesis
Diabetes Mellitus and diabetic bladder dysfunction are very common health problems that markedly increase in prevalence and incidence with advancing age around the world. Over 50% of patients with diabetes exhibiting bladder dysfunction characterized by large bladder capacity, diminished bladder sensation or detrusor overactivity, poor contractility and elevated post-residual urine. Diabetic bladder dysfunction might be induced by the diabetic neuropathy and/or diuresis associated with diabetes. However, the effect of diabetes and diuresis at the tissue and organ levels on specific functional and mechanical changes in the bladder remains uncharacterized. The time-course changes of the tissue compositions, important determinants of mechanical properties, and associated regulated genes of diabetic bladders have not been fully understood. Thus, to achieve a better understanding of the pathophysiology of diabetic cystopathy, it is necessary to elucidate the biomechanical changes that underlie the progression of diabetic cystopathy. In addition, although clinically diabetes was associated with increased severity of lower urinary tract symptoms in elderly men with benign prostate hyperplasia, the mean age of the diabetic patients was over 50 years old and the patients often had multiple medical confounding problems in these studies. The main interest of the present study arises from our clinical observation that urologists often manage patients with advanced stage diabetic cystopathy referred from other physicians. Thus to reduce or prevent the complication of late diabetic cystopathy, it is important to identify lower urinary tract dysfunction and its associated factors in the early stage of diabetes.
First, we hypothesize that the changes in the mechanical properties of the bladder wall are an important indicator of the bladder dysfunction induced by diabetes. Second, we hypothesize that physiologic changes associated with diabetes trigger alternation of select gene and extracellular matrix protein in the urinary bladder. Finally, we hypothesize that diabetes and metabolic syndrome are associated with lower urinary tract symptoms, lower urinary tract function and erectile dysfunction in the early stage of diabetes.

Materials and Methods
In animal study, female Sprague-Dawley rats were injected with streptozotocin (65mg/kg intraperitoneally). Rats were fed with 5% sucrose served as diuretic controls, in addition to normal control rats. Cystometry was performed at the end of 2, 4, and 8 weeks. At each point, the biaxial mechanical properties of 10 x 10 mm tissue specimens obtained from the posterior part of bladder wall were quantified. The changes in overall tissue compliance and mechanical anisotropy as a function of time were examined. Total ribonucleic acid (RNA) isolated from the detrusor layer of the bladders was reverse transcribed, and then complementary deoxyribonucleic acid was amplified with polymerase chain reaction primer sets for type I collagen, type III collagen, tropoelastin, and transforming growth factor beta 1 (TGF-beta-1). Collagen and elastin contents of the bladders were quantified with commercial available assays. A novel semi-automated image analysis method was developed to quantify smooth muscle bundle orientation and mass fraction in the bladder wall tissues.
In clinical study, lower urinary tract symptoms, voiding and erectile function in 226 men aged less than 45 years with type 2 diabetes at a single diabetes clinic and 183 healthy men with normal fasting blood glucose were compared. Subjects were evaluated using the International Prostate Symptom Score questionnaire (IPSS), five-item version of the International Index of Erectile Function questionnaire (IIEF-5), flow rate and post-void residual urine measurement. The association of metabolic syndrome with lower urinary tract symptoms and erectile dysfunction was also evaluated.

Results
In our streptozotocin induced diabetic and sucrose fed diuretic rat models, diuresis alone may explain many of early diabetic effects, including bladder hypertrophy, increase bladder compliance and elevated bladder capacity. Using biaxial mechanical test, we demonstrated that both diabetic and diuretic rat bladder exhibited non-linear stress-strain relationship and mechanical anisotropy, with a greater compliance in the circumferential direction than in the longitudinal direction. The alternations in the mechanical behavior may be a manifestation of morphological adaptation of the bladder from prolate to oblate spheroid to achieve greater compliance.
The changes of biomechanical properties were further confirmed by the methods of molecular biology, biochemical assay and quantitative image analysis. The bladder tissue remodeling was associated with downregulation of transformation growth factor beta 1 and collagen mRNA levels. The increase of the bladder compliance observed in diabetic cystopathy resulted from both diuresis-driven reduction of collagen synthesis and increased elastin synthesis. Semi-automatic image analysis of histological section of rat bladder tissue showed there were significant increase in smooth muscle and decrease in collagen area fractions in the diabetic and diuretic groups compared to normal control. In addition, the diuretic and diabetic bladders exhibited smooth muscles oriented in both circumferential and longitudinal directions, but the normal bladder exhibited predominant smooth muscle orientation only in the longitudinal direction. All these studies provided the evidence about the link between the tissue microstructure and time-dependent alternations of mechanical properties of the bladder.
In clinical studies, the mean age was 38.9 ± 6.1 years (range 20-45) and the mean duration of diabetes was 2.8 ± 3.1 years (range 0.5-20). Compared with controls, men with diabetes had a significantly higher IPSS score (6.1± 5.8 vs 4.1 ± 4.6, p<0.001), an increased of odds ratio of having moderate to severe LUTS (OR=1.78, 95% CI 1.12, 2.84, p=0.01), greater voiding volume (376 ± 177 vs 326 ± 102, p=0.04), worse IIEF-5 score (17.3 ± 6.4 vs 20.0 ± 3.8, p<0.001), an increased of odds ratio of having moderate to severe ED (OR=3.5, 95% CI 2.1, 5.8, p<0.001) but similar maximal flow rate (22.8 ± 7.9 vs 22.6 ± 8.1, p =0.84) and post-voiding residual (20 ± 20 vs 23 ± 35, p =0.82). IIEF-5 score was negatively correlated with IPSS score (p=0.0004, coefficient = －0.23, 95%CI－0.35 to －0.11) and HbA1c (p=0.02, coefficient= －0.14, 95% CI －0.26 to －0.01). A total of 156 (69%) patients met the criteria for metabolic syndrome. The mean age, duration of diabetes, HbA1c, IPSS, voided volume, maximal urinary flowrate and IIEF-5 score were similar between diabetic patients with and without metabolic syndrome.

Conclusions
The results of these cystometry and mechanical testing have suggested that diuresis mainly contributes to the “early” changes of the bladder wall, with diabetes induced additional “late” changes in the mechanical properties of the bladder. The time-course changes in genes, extracellular matrix proteins and bladder smooth muscle oreintation that are pertinent to bladder tissue remodeling associated with diabetic cystopathy. Clinically, type 2 diabetic male patients aged less than 45 years old have more lower urinary tract symptoms but similar bladder emptying function. Age and voiding symptoms are independent risk factors of weak urinary flow rate. Diabetes associated with diuresis seemed to have a more predominate effect on lower urinary tract symptoms than other component of metabolic syndrome in the early stage of diabetes. Thus, our study suggest that need for increased attention to bladder function in the early stage of diabetes (e.g. less than 45 years old). In addition, controlling serum glucose levels with adequate diet and fluid intake might be an important step to prevent the progressive bladder dysfunction caused by diuresis in the early stage of diabetes. Controlling the extracellular matrix proteins levels and attaining normal mechanical properties of the bladder wall might be an important step in treatment of diabetic cystopathy to restore healthy bladder function.

並列關鍵字

biomechanical ； urinary bladder ； diabetes

參考文獻

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