與胰島素抗性相關之代謝性疾病繼發之膀胱失能

Abstract

背景 近數十年來，由於全世界的經濟進展，使得人類營養過剩與肥胖的問題日趨嚴重。胰島素抗性引發之代謝性疾病如代謝症或第二型糖尿病之盛行率在亞洲與婦女人口也大幅提高。這些代謝性疾病在目前已知的研究裡，都能引起膀胱失能。糖尿病膀胱失能是第二型糖尿病患者重要的合併症之ㄧ，在門診或社區型患者中有相當高的盛行率。第二型糖尿病膀胱失能這個問題相對於其他糖尿病病變而言，常常被忽視。主要是由於病徵不明顯且醫師與患者皆缺乏警覺性。同時，學界對於此合併症的致病機轉、疾病進程與治療方針，皆未有效掌握。 而代謝症所繼發之膀胱失能，則是一個新興的題目。在一些流行病學調查中，學者們漸漸發現，代謝症能造成多方之影響。在中等程度的胰島素抗性產生後，第二型糖尿病、多囊性卵巢症候群、心血管疾病、與高血壓等也隨之而來。當胰島素抗性產生而未達糖尿病之時，代謝症似乎已能引起種種病徵，其中也包括了下泌尿道症狀的出現與增加前列腺肥大的風險。學者報告代謝症症患者之夜尿、尿流速減弱與排空不良的風險增加。這些問題的產生則歸咎於代謝症候群的干擾。 在代謝症的研究裡，胰島素抗性的出現被認為是重要的病徵，而第二型糖尿病正是由胰島素抗性所引起，因此代謝症也被認為是一種糖尿病前期的表現。在本論文的研究裡，我們主要針對第二型糖尿病婦女患者進行尿路動力學檢查與膀胱內電流感覺閥值測試，來了解糖尿病膀胱失能的致病機轉。同時，以高果糖飼料餵養大白母鼠建立代謝症動物模式，進而研究代謝症膀胱病變。藉由此兩種研究模式來明瞭代謝性疾病所繼發之膀胱病變。 目標、材料與方法 臨床研究: 女性糖尿病患者之排尿障礙與膀胱內感覺閥值測定的關聯性研究 本計劃的目標為研究無干擾因子下的糖尿病膀胱病變患者，糖尿病膀胱病變的發生與周邊神經病變的相關性。我們測量糖尿病患者膀胱內電流感覺閥值 (Current perception thresholds) 測定膀胱內感覺神經Aδ與C纖維的反應，配合傳統尿路動力學檢查的診斷來了解膀胱內感覺缺失與糖尿病膀胱病變的關聯性。在通過人體試驗委員會審查之後，從2005年7月到2007年4月，我們由門診中召集86名女性糖尿病患者進行膀胱尿路動力學檢查與膀胱內電刺激測試。在收集病例的過程中，若患者具有中風或曾經接受過骨盆腔手術等病史、理學檢查發現膀胱脫垂、尿液檢查顯示正處於尿路感染的病人皆直接排除在外。我們以尿路動力學檢查之診斷分類糖尿病患者之膀胱功能，並比較其膀胱內電流感覺測試的結果。 基礎研究：高果糖飼料長期餵養大白母鼠誘發代謝症膀胱病變之動物模式 以果糖飼養大白鼠，使老鼠產生肥胖、高血壓、及高血脂，是一廣為採用的代謝症動物的模式。我們以高果糖飼料餵養大白鼠分別餵養3、6個月以進行膀胱病變研究。在實驗中，我們以代謝箱、膀胱壓、逼尿肌電場刺激與藥物濃度收縮力實驗，來了解代謝症果糖鼠之膀胱生理功能。同時以顯微鏡、電子顯微鏡研究膀胱形態學。最後以西方墨點法研究膀胱內神經受體P2X1-purinergic receptor、 M2-muscarinic receptor、M3-muscarinic receptor蛋白質濃度的改變。 結果 第一部分:臨床研究 在這86名女性糖尿病患者中。其中有33(38.4%)名患者顯示正常之逼尿肌功能，30(34.9%)名患者出現逼尿肌無力，12(14.0%)名患者出現逼尿肌過動，11(12.8%)名患者出現膀胱出口阻塞。在本實驗中，糖尿病女性之膀胱出口阻塞經診斷後多為骨盆底肌肉無法放鬆，同時此類病人可能對於逼尿肌功能的評估造成干擾的效果，因此排除於膀胱內電流感覺閥值的統計。膀胱內電流感覺閥值的統計顯示，相對於正常之逼尿肌功能與逼尿肌過動的糖尿病患者，逼尿肌無力的患者有較高的膀胱內電流感覺閥值。若將無力組與逼尿肌正常組合併進行多變量分析，我們發現膀胱內感覺閥值的增加與膀胱排空效率下降呈現有意義的關連。 第二部份: 基礎研究 研究顯示，以高果糖飼料餵養大白母鼠達三個月以後皆可以順利誘發代謝症產生，其中有66.7％的果糖鼠會產生不正常的膀胱波形。以逼尿肌進行電場刺激與藥物濃度收縮力實驗後發現，3個月組只有以高濃度的氯化鉀刺激才能顯示果糖鼠逼尿肌收縮力下降的差別。而6個月組的研究顯示，在電場頻率、氯化鉀carbachol刺激下，果糖鼠逼尿肌收縮力明顯下降。而以高濃度的ATP刺激時，果糖鼠逼尿肌收縮力呈現有意義的增加。形態學檢查則顯示有果糖鼠逼尿肌有白血球浸潤的發炎前期現象，電子顯微鏡下則發現果糖鼠逼尿肌的粒線體腫脹與橡樹葉化(Oak leaf like)的特徵。西方墨點法顯示果糖鼠膀胱內神經受體M2-muscarinic receptor、M3-muscarinic receptor蛋白質濃度增加。而P2X1-purinergic receptor蛋白質在3個月組沒有明顯變化，而6個月組的果糖鼠膀胱內的P2X1-purinergic receptor蛋白質有濃染的情形。 結論 胰島素抗性相關的代謝性疾病能以不同的形式引發膀胱失能，在門診病人的研究中，我們發現逼尿肌無力的糖尿病患者具有較高的膀胱內電流感覺閥值，這說明感覺缺失對於逼尿肌無力型糖尿病膀胱病變具有高度的意義。我們的研究對於糖尿病膀胱內感覺缺損直接造成膀胱收縮無力提供一個電生理學的證據。而在高果糖餵養的代謝症動物模式裡，我們的研究顯示有一部分的代謝症果糖鼠會發生膀胱形態學、生理功能的改變。這種改變與發炎前期、逼尿肌病變與膀胱內神經末梢受體變化有關。

Background Insulin resistance related metabolic disease have become an important worldwide public health problem because the prevalence has risen steadily during recent decades, particularly in the Asian and female populations. Rapid economic development and urbanization have increased the prevalence of metabolic syndrome and type 2 diabetes in Asia. Both metabolic syndrome and type 2 diabetes are known to be risk factors for the development of bladder dysfunction. Metabolic diseases are likely to result in major economic burdens for countries in Asia, the most populous area in the world. Diabetic bladder dysfunction is one of the most frequent complications of diabetes mellitus. Over 50 % of patients with diabetes exhibit diabetic bladder dysfunction. Although the complications of diabetes mellitus have been well studied, the development and severity of lower urinary tract disorders in patients with diabetes mellitus are still poorly understood. The bladder dysfunction secondary to metabolic syndrome is the other interesting issue. The patients with metabolic syndrome also have a higher risk of lower urinary tract symptoms. To study the bladder dysfunction secondary to metabolic syndrome plays an important role in the prevention and early treatment of diabetic complications. Insulin resistance is the core metabolic perturbation of the metabolic syndrome and can result in type 2 diabetes. Moderate degrees of insulin resistance are closely linked to a range of common disease, such as polycystic ovary syndrome, obesity, hypertension and benign prostatic hyperplasia. Currently, metabolic syndrome is considered as a pre-diabetic status. In this dissertation, we present our observations on the bladder dysfunction secondary to metabolic diseases related to insulin resistance. In human study, the urodynamic studies along with the intravesical CPT test were used to evaluate the lower urinary tract function in type 2 diabetic women. We also established an animal model of fructose-fed rats to study the bladder dysfunction secondary to metabolic syndrome. Aims, materials and methods Clinic study: The relationship between urodynamic findings and intravesical current perception thresholds testing among diabetic bladder women. Eighty-six consecutive type 2 diabetic women followed-up at a diabetes clinic with minimal confounders of voiding dysfunction were prospectively enrolled and subjected to urodynamic studies. The sensory response of Aδ- and C-fibers of the bladder was measured by intravesical current perception threshold (CPT) testing at frequencies of 250 and 5 Hz, respectively. Basic study: Bladder dysfunction in rats with metabolic syndrome induced by long-term fructose feeding. Female Wistar rats were fed with fructose-enriched (60%) or control diet for three and six months. In vitro contractile responses to electric field stimulation, KCl, carbachol, adenosine triphosphate and in vivo cystometry were used to evaluate bladder function. Tissue staining and electron microscopy were also performed to evaluate the structural changes in rats subjected to metabolic syndrome. The western blotting was used to evaluate the protein amount of M2-muscarinic、M3-muscarinic and P2X1-purinergic receptors in the bladder. Biochemical and physiological data were compared between fructose-fed rats and age-matched controls. Results: Part I: Clinic study Of these 86 women, 30 (34.9%) were classified as detrusor underactivity, 12 (14.0%) presented signs of detrusor overactivity, 11 (12.8%) were referred as bladder outlet obstruction, and 33 (38.4%) showed a normal detrusor function in urodynamics. The normal detrusor function group was the reference group. The detrusor underactivity group showed impaired emptying function and decreased sensation both in cystometry and intravesical CPT testing. The detrusor overactivity group showed impaired storage and emptying function, but had no significant changes in intravesical CPT values. When the normal detrusor function group and detrusor underactivity group were pooled to perform multivariate analysis, an increase in CPT values was associated with a decrease in bladder voiding efficiency in both 5 Hz and 250 Hz CPT testing. Part II: Basic study All rats fed with fructose-enriched diet for three months developed insulin resistance, hyperinsulinemia, hypertriglycemia, and hypertension. These fructose-fed rats showed a decreased contractile response to high concentrations of KCl, but not to other parameters tested when compared to controls. Eight of the twelve (66.7%) rats showed abnormal cystometry, mainly by increased phasic contractions. In the six-months fructose-fed rats, contractile responses to electric field stimulation, KCl and carbachol were decreased significantly. However, responsiveness to high concentrations of adenosine triphosphate was significantly increased. Morphologic studies on fructose-fed rats showed swollen mitochondria of bladder smooth muscle, increased leukocyte infiltration between interstitial tissue, and neutrophil adhesion around the endothelium of vessels. An up-regulation of M2-muscarinic and M3-muscarinic receptors was observed in 3-month and 6 month fructose-fed rats. The increase amount of P2X1-purinergic receptors in the bladder was also noted in 6 month fructose-fed rats. Conclusion: Bladder dysfunction secondary to metabolic diseases related to insulin resistance has prominent morbidity and affected deeply. Our data of human study provided the electrophysiological evidence that indicates an association between impaired Aδ- as well as C-fiber bladder afferent pathways and poor emptying function in diabetic women with detrusor underactivity. Our animal model showed that a significant proportion of fructose-fed rats develop time-related alterations in the biochemical, morphological and functional properties of the bladder. The proinflammation and myopathy of the bladder induced by metabolic perturbations play important roles in causing bladder dysfunction.