MULTIPLE EFFECTS OF SPERMINE ON N-METHYL-D-ASPARTIC ACID RECEPTOR RESPONSES OF RAT CULTURED HIPPOCAMPAL-NEURONS
MULTIPLE EFFECTS OF SPERMINE ON N-METHYL-D-ASPARTIC ACID RECEPTOR RESPONSES OF RAT CULTURED HIPPOCAMPAL-NEURONS
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DOI：
10.1113/jphysiol.1993.sp019627
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发表时间：
1993-05-01
影响因子：
5.5
通讯作者：
MAYER, ML
中科院分区：
文献类型：
--
作者：
BENVENISTE, M;MAYER, ML
1.采用快速灌流系统和全细胞电压钳记录技术研究了多胺对分离培养的大鼠海马神经元对N-甲基-D-天冬氨酸（NMDA）反应的调制作用.浓度跃变反应100妈妈NMDA在10妈妈甘氨酸的存在下，显示增强由3 mM精胺在膜电位为+60 mV，但抑郁症在-120 mV;在+60 mV的增强的程度是可变的，从细胞到细胞，而显着的抑郁症在-120 mV，在所有细胞中观察到。精胺对NMDA反应的抑制是高度电压依赖性的（zdelta = 1.17），在0 mV时阻滞的表观平衡解离常数为27 mm。在10妈妈甘氨酸的存在下，在+60 mV记录的响应的精胺剂量增强曲线的分析揭示了在125妈妈的半最大效应。在相同的条件下，但在-60 mV下，对在+60 mV下具有小于5%的增强的细胞进行精胺诱发的抑制的分析，并且在344 mV下显示半最大抑制。在+60 mV时对NMDA受体的甘氨酸敏感性激活的剂量反应分析显示，在1 mm精胺存在下，甘氨酸的表观亲和力增加3-5倍。甘氨酸亲和力的增加伴随着甘氨酸敏感性脱敏的发展速率降低3.3倍，甘氨酸从NMDA受体解离的速率降低2.4倍，而NMDA解离的速率常数没有降低。在非饱和浓度的甘氨酸存在下，精胺诱导的+ 60 mV电位增强由两个指数分量组成：缓慢的甘氨酸敏感分量，其幅度和时间常数随甘氨酸浓度的增加而减小（30 nm甘氨酸，振幅= 80.2 +/-5.1%，tau = 780 +/-79ms; 3 /μ m甘氨酸，振幅= 22.6 +/- 7- 1%，τ = 45 +/- 13 ms），以及更快的组分（在所有浓度的甘氨酸下tau < 20 ms），其幅度在细胞与细胞之间变化，并且随着甘氨酸浓度的增加而变大。当在10 μ M L-丙氨酸而不是100 nm甘氨酸存在下测量对精胺应用的响应时，不存在增强作用的缓慢组分。胍衍生物arylate，和多胺二亚乙基三胺和1，10-diaminodecane也产生电压依赖性阻断响应NMDA，在0 mV的表观平衡解离常数为0.75，2.93和4.79毫米，分别。这些化合物中没有一种似乎在精胺诱导增强对NMDA的反应的位点上作为有效的拮抗剂，它们也没有阻断精胺对脱敏的甘氨酸敏感组分的发作速率的影响。我们的研究结果表明，精胺作用于NMDA受体的多个位点，产生增强和阻断作用。增强的结果从表观亲和力增加甘氨酸以及增加的最大振幅的响应记录在饱和浓度的甘氨酸的存在下，NMDA的结果，我们建议，每个效果的基础上单独的机制。这些影响在单个神经元中发生的程度的变化表明NMDA受体亚群的发生。阻断是电压依赖性的，并且最有可能是由于多胺与离子通道内的位点结合。
1. The modulation by polyamines of responses to N-methyl-D-aspartic acid (NMDA) was studied using a rapid perfusion system and whole-cell voltage-clamp recording from rat hippocampal neurons in dissociated culture.2. Concentration jump responses to 100 mum NMDA in the presence of 10 mum glycine revealed potentiation by 3 mM spermine at a membrane potential of + 60 mV, but depression at - 120 mV; the degree of potentiation at + 60 mV was variable from cell to cell while marked depression at - 120 mV was observed in all cells. The depression of responses to NMDA by spermine was highly voltage dependent (zdelta = 1.17) with an apparent equilibrium dissociation constant for block at 0 mV of 27 mm.3. Analysis of spermine dose-potentiation curves for responses recorded at + 60 mV in the presence of 10 mum glycine revealed a half-maximal effect at 125 mum. Under the same conditions, but at - 60 mV, analysis of spermine-evoked depression was performed for cells with less than 5 % potentiation at + 60 mV, and revealed half-maximal inhibition at 344 mum.4. Dose-response analysis for the glycine-sensitive activation of NMDA receptors at + 60 mV revealed a 3-5-fold increase in apparent affinity for glycine in the presence of 1 mm spermine. This increase in affinity for glycine was accompanied by a 3.3-fold decrease in the rate of development of glycine-sensitive desensitization, and a 2.4-fold decrease in the rate of dissociation of glycine from NMDA receptors, while the rate constant for dissociation of NMDA was not reduced.5. In the presence of non-saturating concentrations of glycine, spermine-induced potentiation at + 60 mV developed with two exponential components: a slow glycine-sensitive component, the amplitude and time constant of which decreased with increasing glycine concentration (30 nm glycine, amplitude = 80.2 +/- 5.1 %, tau = 780 +/- 79 ms; 3 /mum glycine, amplitude = 22.6 +/- 7-1 %, tau = 45 +/- 13 ms), and a faster component (tau < 20 ms at all concentrations of glycine), the amplitude of which varied from cell to cell, and which became larger with increase in concentration of glycine. When responses to the application of spermine were measured in the presence 10 muM L-alanine instead of 100 nm glycine, the slow component of potentiation was absent.6. The guanidine derivative arcaine, and the polyamines diethylenetriamine and 1,10-diaminodecane also produced voltage-dependent block of responses to NMDA, with apparent equilibrium dissociation constants at 0 mV of 0.75, 2.93 and 4.79 mm, respectively. None of these compounds appeared to act as potent antagonists at the site(s) at which spermine induced potentiation of responses to NMDA, nor did they block the effects of spermine on the rate of onset of the glycine-sensitive component of desensitization.7. Our results suggest that spermine acts at multiple sites on NMDA receptors to produce potentiation and block. Potentiation results from both an increase in apparent affinity for glycine as well as an increase in maximum amplitude of responses to NMDA recorded in the presence of a saturating concentration of glycine; we propose that separate mechanisms underlie each effect. Variation in the degree to which these effects occur in individual neurons suggest the occurrence of subpopulations of NMDA receptors. Block is voltage dependent, and most likely due to binding of polyamines to sites within the ion channel.