Distribution of nitric oxide synthase-immunoreactive nerves and identification of the cellular targets of nitric oxide in guinea-pig and human urinary bladder by cGMP immunohistochemistry
Distribution of nitric oxide synthase-immunoreactive nerves and identification of the cellular targets of nitric oxide in guinea-pig and human urinary bladder by cGMP immunohistochemistry
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DOI：
10.1016/0306-4522(95)00453-x
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发表时间：
1996-03-01
期刊：
影响因子：
3.3
通讯作者：
DeVente, J
中科院分区：
文献类型：
--
作者：
Smet, PJ;Jonavicius, J;DeVente, J
用一氧化氮合酶的抗体，在人和豚鼠的膀胱和近端尿道内检查了具有合成一氧化氮潜力的神经的分布。进一步的实验确定了暴露于一氧化氮供体硝普钠后诱导cGMP免疫反应的细胞。这些细胞代表了神经元释放的一氧化氮的潜在生理靶点，因为可溶性鸟苷酸环化酶的激活以及随之而来的细胞内cGMP的升高介导了这种递质的许多作用。一氧化氮合酶免疫反应性广泛分布于下尿路。在豚鼠中，50-68%的固有膀胱神经元表达一氧化氮合酶免疫反应性，而在人类中，72-96%的膀胱壁神经元含有一氧化氮合酶。在人类和豚鼠，静脉曲张的一氧化氮合酶免疫反应神经末梢提供了一个温和的神经支配逼尿肌的膀胱体，和一个密集的神经支配尿道肌。免疫反应性神经也投射到垂体下和血管周围，但很少观察到环绕壁内膀胱神经节。硝普钠刺激后，尿道平滑肌细胞表达强cGMP免疫反应性，但逼尿肌细胞保持一致的阴性。虽然逼尿肌纤维不表达cGMP，但硝普钠对整个膀胱体的许多间质细胞表现出强烈的cGMP免疫反应性诱导。这些细胞有长的树突状突起平行于平滑肌纤维延伸，并含有波形蛋白，一种由间充质来源的细胞表达的中间丝。其他细胞类型，其中硝普钠暴露诱导cGMP免疫反应性的尿路上皮细胞，血管平滑肌细胞和周细胞，和少数静脉曲张的神经末梢。在豚鼠中，膀胱壁中的一小部分（小于10%）内在神经元也表达cGMP。在cGMP免疫组织化学处理的人膀胱标本中未观察到内源性神经元。结果提供了解剖学证据，一氧化氮可能作为一种神经递质在下尿路。尽管具有产生一氧化氮能力的神经同时供应逼尿肌和尿道，但一氧化氮对环鸟苷酸诱导的影响存在明显的区域差异。如果一氧化氮介导的cGMP诱导是细胞对一氧化氮的生理反应的可靠指标，则平滑肌细胞似乎是尿道中一氧化氮的主要靶点，而在膀胱体中，间质细胞可能起此作用。这些发现支持了以前的研究，其中涉及一氧化氮作为一种抑制性递质参与膀胱颈的松弛。我们的实验进一步表明，下尿路内的一些细胞类型可能介导内源性释放的一氧化氮的作用。
The distribution of nerves with the potential to synthesize nitric oxide was examined within the urinary bladder and proximal urethra of humans and guinea-pigs, using an antibody to nitric oxide synthase. Further experiments identified cells in which cGMP-immunoreactivity was induced following exposure to the nitric oxide donor, sodium nitroprusside. These cells represent the potential physiological targets of neuronally released nitric oxide, since activation of soluble guanylate cyclase, and a consequent rise in intracellular cGMP, mediate many of the effects of this transmitter. Nitric oxide synthase-immunoreactivity was widely distributed in the lower urinary tract. In guinea-pigs, 50-68% of all intrinsic vesical neurons expressed nitric oxide synthase-immunoreactivity, while in humans 72-96% of neurons in the wall of the bladder contained nitric oxide synthase. In both humans and guinea-pigs, varicose nitric oxide synthase-immunoreactive nerve terminals provided a moderate innervation to the detrusor muscle of the bladder body, and a denser innervation to the urethral muscle. Immunoreactive nerves also projected to the subepithelium and around blood vessels, but were rarely observed encircling intramural vesical ganglia. Following stimulation with sodium nitroprusside, smooth muscle cells of the urethra expressed strong cGMP-immunoreactivity, but detrusor muscle cells remained uniformly negative. Although the detrusor muscle fibres did not express cGMP, numerous interstitial cells throughout the bladder body demonstrated an intense induction of cGMP-immunoreactivity by sodium nitroprusside. These cells had long dendritic processes extending parallel to the smooth muscle fibres, and contained vimentin, an intermediate filament expressed by cells of mesenchymal origin. Other cell types in which sodium nitroprusside exposure induced cGMP-immunoreactivity were the uroepithelial cells, vascular smooth muscle cells and pericytes, and a small number of varicose nerve terminals. In the guinea-pig, a minor proportion (less than 10%) of intrinsic neurons in the wall of the bladder also expressed cGMP. No intrinsic neurons were observed in specimens of human bladder processed for cGMP immunohistochemistry. The results provide anatomical evidence that nitric oxide may function as a neurotransmitter in the lower urinary tract. Although nerves with the capacity to produce nitric oxide supply both the detrusor muscle and the urethra, distinct regional differences exist in the effects of nitric oxide on the induction of cGMP. If the nitric oxide-mediated induction of cGMP is a reliable indicator of the physiological responsiveness of a cell to nitric oxide, then smooth muscle cells appear to be the predominant targets of nitric oxide in the urethra, while in the bladder body, interstitial cells may serve this role. These findings support previous studies which have implicated nitric oxide as an inhibitory transmitter involved in the relaxation of the bladder neck. Our experiments further indicate that a number of cell types within the lower urinary tract could potentially mediate the effects of endogenously released nitric oxide.