Melatonin restores impaired contractility in aged guinea pig urinary bladder
Melatonin restores impaired contractility in aged guinea pig urinary bladder
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DOI：
10.1111/j.1600-079x.2007.00544.x
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发表时间：
2008-05-01
影响因子：
10.3
通讯作者：
Pozo, Maria J.
中科院分区：
文献类型：
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作者：
Gomez-Pinilla, Pedro J.;Gomez, Maria F.;Pozo, Maria J.
膀胱功能紊乱在老年人群中很常见，但其发病机制尚不清楚。本研究评估了年龄对逼尿肌肌源性收缩反应的影响以及褪黑激素治疗的影响。用等长收缩记录法测定了成年、老年和褪黑激素处理的豚鼠膀胱肌条的收缩力。通过荧光显微镜观察负载Fura-2的逼尿肌平滑肌细胞的胞浆钙浓度（[Ca 2 +]（i）），并通过Western印迹定量蛋白表达和磷酸化水平。衰老损害逼尿肌条对胆碱能和嘌呤能激动剂以及膜去极化的收缩反应。收缩力受损与刺激引起的[Ca 2 +]（i）增加相关，表明Ca（2+）敏感性降低。事实上，激动剂诱导的收缩在成人条是敏感的封锁与Y27362，抑制剂的Rho激酶（ROCK）和GF 109203 X，抑制剂的蛋白激酶C（PKC），但这些抑制剂有可忽略不计的影响，在老化条。老年组织中Ca 2+敏感性的降低与RhoA、ROCK、PKC和两种效应物CPI-17和MYPT 1的水平较低相关，并且与响应激动剂的CPI-17和MYPT 1磷酸化的缺乏相关。有趣的是，褪黑激素治疗恢复受损的收缩通过正常化的Ca 2+处理和Ca 2+敏化途径。此外，吲哚胺恢复了氧化应激和线粒体极性的年龄诱导的变化。这些结果表明，褪黑激素可能是一种新的治疗工具，以减轻年龄相关的膀胱收缩功能障碍。
Urinary bladder disturbances are frequent in the elderly population but the responsible mechanisms are poorly understood. This study evaluates the effects of aging on detrusor myogenic contractile responses and the impact of melatonin treatment. The contractility of bladder strips from adult, aged and melatonin-treated guinea pigs was evaluated by isometric tension recordings. Cytoplasmatic calcium concentration ([Ca2+](i)) was estimated by epifluorescence microscopy of fura-2-loaded isolated detrusor smooth muscle cells, and the levels of protein expression and phosphorylation were quantitated by Western blotting. Aging impairs the contractile response of detrusor strips to cholinergic and purinergic agonists and to membrane depolarization. The impaired contractility correlates with increased [Ca2+](i) in response to the stimuli, suggesting a reduced Ca(2+)sensitivity. Indeed, the agonist-induced contractions in adult strips were sensitive to blockade with Y27362, an inhibitor of Rho kinase (ROCK) and GF109203X, an inhibitor of protein kinase C (PKC), but these inhibitors had negligible effects in aged strips. The reduced Ca2+ sensitivity in aged tissues correlated with lower levels of RhoA, ROCK, PKC and the two effectors CPI-17 and MYPT1, and with the absence of CPI-17 and MYPT1 phosphorylation in response to agonists. Interestingly, melatonin treatment restored impaired contractility via normalization of Ca2+ handling and Ca2+ sensitizations pathways. Moreover, the indoleamine restored age-induced changes in oxidative stress and mitochondrial polarity. These results suggest that melatonin might be a novel therapeutic tool to palliate aging-related urinary bladder contractile impairment.