Presence of NMDA receptor subunits in the male lower urogenital tract.
Presence of NMDA receptor subunits in the male lower urogenital tract.
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DOI：
10.1002/j.1939-4640.2000.tb02122.x
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发表时间：
2000-07
影响因子：
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通讯作者：
N. Gonzalez-Cadavid;Igor Ryndin;D. Vernet;T. Magee;Jacob Rajfer
中科院分区：
文献类型：
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作者：
N. Gonzalez-Cadavid;Igor Ryndin;D. Vernet;T. Magee;Jacob Rajfer
雄性大鼠的一些性反应，特别是阴茎勃起，是由大脑和脊柱中的神经回路控制的，这些神经回路由兴奋性氨基酸（EAA）与突触后N-甲基-D-天冬氨酸受体（NMDAR）的结合刺激。在下丘脑中，EAA/NMDAR相互作用触发神经元型一氧化氮合酶（nNOS）的激活以产生一氧化氮（NO）。这种神经递质在阴茎神经末梢的局部合成导致阴茎海绵体松弛和勃起。在性活动期间，NO被认为参与前列腺中的精液排出和射精，并抑制膀胱中的排尿反射。本研究旨在体外确定NMDAR是否存在于这些器官中，以及它是否通过NO依赖性机制影响组织条的色调。我们从成年雄性大鼠获得阴茎、膀胱和腹侧前列腺组织，从人类男性患者获得同源手术组织。用Western blot法检测NMDA受体蛋白的表达，并测定NMDA受体拮抗剂3 H-CGP的结合率。采用逆转录聚合酶链反应（RT-PCR）检测NMDAR信使核糖核酸（mRNA），并通过克隆和测序进行鉴定。在用氨甲酰胆碱或电场刺激（在大鼠和人膀胱中）、苯肾上腺素（在人海绵体中）或去甲肾上腺素（在人前列腺中）预收缩的组织条中测量对NMDAR拮抗剂的体外反应。在所有研究组织中均检测到NMDAR 2B蛋白、配体结合活性和NMDAR 1、2A和2B mRNA。我们在大鼠前列腺和阴茎以及人类前列腺中发现了一种NMDAR 1变体，其比小脑对应物大，但它编码一种767个氨基酸的截短蛋白（NMDAR 1-T）。NMDAR拮抗剂对以下部位抑制组织条的体外收缩：多胺（与艾芬地尔）;离子通道高亲和力（与地佐环平）;离子通道低亲和力（与美曼替丁、阿托美啡和氯胺酮）;以及，在NO非依赖性、非肾上腺素能-非胆碱能途径中，仅部分受EAA影响。我们的结论是，在体外，所有必需的NMDAR亚基都存在于下泌尿生殖道，亚基1的一种新的变体表达，组织结合NMDAR配体，和NMDAR拮抗剂诱导组织条松弛。进一步的工作是必要的，以确定是否NMDAR亚基形成一个完全活跃的受体，并参与控制器官的紧张度，是有关男性性活动。
Some sexual responses in the male rat, specifically penile erection, are controlled by neural circuits in the brain and spine that are stimulated by the binding of excitatory amino acids (EAAs) to the postsynaptic N-methyl-D-aspartate receptor (NMDAR). In the hypothalamus, EAA/NMDAR interaction triggers the activation of neuronal nitric oxide synthase (nNOS) to produce nitric oxide (NO). The local synthesis of this neurotransmitter in the penile nerve terminals causes corpora cavernosal relaxation and erection. During sexual activity, NO is assumed to participate in seminal emission and ejaculation in the prostate and to inhibit voiding reflexes in the bladder. This study aimed to determine in vitro whether NMDAR is present in these organs and whether it affects the tone of tissue strips through an NO-dependent mechanism. We obtained penile, urinary bladder, and ventral prostate tissues from adult male rats and homologous surgical tissues from human male patients. We detected the NMDAR protein by Western blot and determined the binding of the NMDA antagonist, 3H-CGP. The NMDAR messenger ribonucleic acid (mRNA) was detected by reverse transcription/polymerase chain reaction and identified by cloning and sequencing. The in vitro response to NMDAR antagonists was measured in tissue strips that were precontracted with bethanechol or electrical field stimulation (in rat and human bladder), phenylephrine (in human corpora cavernosa), or norepinephrine (in human prostate). The NMDAR2B protein; ligand-binding activity; and NMDAR1, 2A, and 2B mRNAs were detected in all tissues studied. We found an NMDAR1 variant in rat prostate and penis and in human prostate that is larger than its cerebellar counterpart, but it encodes a 767-amino acid truncated protein (NMDAR1-T). The in vitro contraction of tissue strips was inhibited by NMDAR antagonists against the following sites: polyamine (with ifenprodil); ion channnel high affinity (with dizocilpine); ion channel low affinity (with memantidine, dextrometorphan, and ketamine); and, in an NO-independent, nonadrenergic-noncholinergic pathway that was only partially affected by EAAs. We conclude that, in vitro, all the essential NMDAR subunits are present in the lower urogenital tract, a novel variant of subunit 1 is expressed, the tissues bind an NMDAR ligand, and the NMDAR antagonists induce relaxation of tissue strips. Further work is necessary to determine whether the NMDAR subunits form a fully active receptor and participate in the control of organ tone that is relevant to male sexual activity.