老年大鼠膀胱排尿功能及平滑肌细胞表型变化

Changes of bladder function and smooth muscle cell phenotype in aged rats

目的探讨老年大鼠膀胱排尿功能及平滑肌细胞表型变化。方法选取3、24月龄SD大鼠各8只,采用膀胱穿刺测压法行膀胱排尿功能检测,Masson染色法检测膀胱组织胶原纤维占比。采用酶消化法分离培养8周龄SD大鼠膀胱平滑肌细胞(BSMC),构建复制性衰老细胞模型,观察细胞形态及表型变化。结果与3月龄组比较,24月龄组大鼠膀胱内残余尿量(RUV)明显升高,而排尿率(VE)、最大排尿压力(MVP)均明显降低,差异均有统计学意义(均P<0.05)。Masson染色可见3月龄组大鼠逼尿肌排列整齐,胶原纤维较少,而24月龄组大鼠膀胱组织中逼尿肌纤维排列紊乱、松散,胶原纤维较多;24月龄组大鼠膀胱组织胶原纤维占比明显高于3月龄组(P<0.05)。在倒置显微镜下观察,随着细胞代数的增长,细胞从原来的细长梭形变为宽大畸形,α平滑肌肌动蛋白、肌间线蛋白表达均明显减少(均P<0.05),但Ⅰ型胶原、Ⅲ型胶原表达均明显增加(均P<0.05)。结论老年大鼠存在膀胱排尿功能减退及胶原比例失衡等,衰老所致BSMC表型转化可能是其中的病理、生理机制之一。

Objective To investigate the changes of bladder function and smooth muscle cell phenotype in aged rats.Methods Bladder urination function was determined by bladder puncture manometry in 8 SD rats aged 3 and 24 months,and the proportion of collagen fiber in bladder tissue was detected by Masson staining.Bladder smooth muscle cells(BSMC)of 8-week-old SD rats were isolated by enzyme digestion method and cultured in vitro,the cell morphology and phenotype were observed.Results Compared with the 3-month-old rats,the residual urine volume(RUV)in the 24-month-old rats was significantly increased,while the voiding efficiency(VE)and maximum voiding pressure(MVP)were significantly decreased(all P<0.05).Masson staining showed that the detrusor of 3-month-old rats was arranged orderly with less collagen fiber,while the bladder tissue of 24-month-old rats was disorderly and loose,with more collagen fiber.The proportion of collagen fiber in bladder tissue of 24-month-old rats was significantly higher than that of 3-month-old rats(P<0.05).Under the inverted microscope,with the growth of cell generation,the cells were deformed from the original slender spindle to the wide deformity,and the expressions ofα-smooth muscle actin and desmin were significantly decreased(all P<0.05),but the expressions of typeⅠcollagen and typeⅢcollagen increased significantly(all P<0.05).Conclusion The aged rats have decreased bladder and urination function and collagen imbalance,and the aging-related phenotypic transformation of BSMC may be one of the pathological and physiological mechanisms.