卵巢切除和雌激素补充治疗对大鼠膀胱功能及结构的影响

目的通过对不同雌激素水平大鼠进行膀胱功能、组织形态和超微结构的比较,探讨雌激素对膀胱功能的影响及其作用机制。方法30只雌性成年SD大鼠均分为3组:OVX+E组(切除双侧卵巢后补充戊酸雌二醇0·8mg·kg-1·d-1,溶于0·5%羧甲基纤维素钠,每日灌胃1次)、OVX组(切除双侧卵巢)、正常对照组(未切除卵巢),后两组大鼠每日给予0·5%羧甲基纤维素钠灌胃1次。3组大鼠用药12周后行膀胱压力容积测定,并用切除膀胱的石蜡切片分析胶原纤维和平滑肌的面密度及两者比值,透射电镜下观察逼尿肌的超微结构。结果(1)OVX组膀胱最大容量(0·32±0·20)ml、顺应性(0·012±0·006)ml/cmH2O(1cmH2O=0·098kPa)和最大收缩力(1·4±0·4)cmH2O,相对于正常对照组分别为(1·11±0·09)ml、(0·026±0·003)ml/cmH2O和(4·4±0·3)cmH2O]明显减少,差异均有统计学意义(P<0·05)。OVX+E组膀胱最大容量为(0·83±0·10)ml,相对于正常对照组减少(P<0·05),而膀胱顺应性(0·029±0·003)ml/cmH2O、最大收缩力(4·8±1·4)cmH2O与正常对照组比较,差异无统计学意义(P>0·05)。(2)胶原纤维面密度、胶原纤维面密度/平滑肌面密度比值,OVX组分别为0·218±0·041和0·54±0·08,相对于正常对照组(0·160±0·039、0·32±0·09)明显增加,差异有统计学意义(P<0·05);而OVX+E组(0·178±0·027、0·38±0·06)与正常对照组比较,差异无统计学意义(P>0·05)。(3)电镜观察OVX组逼尿肌超微结构出现退行性改变,其他两组无类似变化。结论大鼠切除双侧卵巢后膀胱功能明显降低,补充雌激素有利于改善膀胱功能,这一作用可能是通过抑制胶原增生,保护细胞器来实现的。

Effect of ovariectomy and estrogen replacement on bladder function and structure in rats

OBJECTIVE: To investigate the mechanism of estrogen action on bladder. METHODS: By examining the functional, histological and ultrastructural changes that occurred in the bladder of rats with estrogen depletion and supplementation, we studied the actions of estrogen on bladder. A total of 30 female adult Sprague-Dawley rats were divided into 3 groups, including control group, bilateral ovariectomy (OVX) group and bilateral ovariectomy plus estradiol valerate (OVX + E) group. After medication for 12 weeks, cystometry was performed. Masson stain was used to quantify the area densities of collagen fiber and smooth muscle and their ratios, and electron microscopy was used to evaluate ultrastructure of detrusor muscle. RESULTS: In OVX group, bladder maximal capacity, (0.32 +/- 0.20) ml, compliance, (0.012 +/- 0.006) ml/cm H2O (1 cm H2O = 0.098 kPa), and maximal contraction force, (1.4 +/- 0.4) cm H2O were obviously lower than those in control group, which were (1.11 +/- 0.09) ml, (0.026 +/- 0.003) ml/cm H2O, and (4.4 +/- 0.3) cm H2O, respectively (P < 0.05). In OVX + E group, bladder maximal capacity (0.83 +/- 0.10) ml was lower than that in control group (P < 0.05), but compliance, (0.029 +/- 0.003) ml/cm H2O and maximal contraction force, (4.8 +/- 1.4) cm H2O were similar to those of control group (P > 0.05). Collagen fiber area density and collagen fiber to smooth muscle area density ratio in OVX group (0.218 +/- 0.041 and 0.54 +/- 0.08) were higher than those in control group (0.160 +/- 0.039 and 0.32 +/- 0.09, P < 0.05); however, there were no significant differences between OVX + E group (0.178 +/- 0.027, 038 +/- 0.06) and control group (P > 0.05). In OVX group, ultrastructure of detrusor muscle showed degenerative change, while it was not found in the other groups. CONCLUSIONS: When the rat was ovariectomized, bladder function became poor and supplementary estrogen could improve bladder function. This effect may be due to inhibition of collagen hyperplasia and protection of cell organelles. Estrogen replacement should be beneficial for treating postmenopausal lower urinary tract symptoms.