Regional differences in the effect of guanine nucleotides on agonist and antagonist binding to adenosine A1-receptors in rat brain, as revealed by autoradiography
Regional differences in the effect of guanine nucleotides on agonist and antagonist binding to adenosine A1-receptors in rat brain, as revealed by autoradiography
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放射自显影显示鸟嘌呤核苷酸对大鼠脑中腺苷 A1 受体激动剂和拮抗剂结合作用的区域差异
DOI：
10.1016/0306-4522(90)90180-c
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发表时间：
1990
期刊：
影响因子：
3.3
通讯作者：
B. Fredholm
中科院分区：
文献类型：
--
作者：
J. Fastbom;B. Fredholm
用放射自显影法研究了不同剂量GTP对大鼠脑内不同区域腺苷A1受体激动剂和拮抗剂结合的影响。高浓度的GTP（100μM）几乎消除了激动剂[3 H]n6-环己基腺苷在所有区域的结合。然而，低浓度GTP（0.1-10 μM）的影响存在区域差异。在某些区域，例如海马，所有浓度的GTP通过降低Bmax降低[3 H]n6-环己基腺苷结合。在其他结构，如上级丘，有一个双相反应的GTP。0.1-3 μ M的浓度增加激动剂结合，显然是由于KD降低，而更高的浓度也降低了这些区域的结合。稳定的GTP类似物鸟苷-5 '-O-（3-硫代三磷酸）可模拟GTP的作用。GTP（0.5-100μM）可增加所有区域中拮抗剂[3 H]8-环戊基-1，3-二丙基黄嘌呤的结合，但在GTP对激动剂结合具有双相效应的区域中最为显著。通过增加腺苷脱氨酶浓度和加入5 '-核苷酸酶抑制剂α-β-亚甲基腺苷-5'-二磷酸来降低内源性腺苷水平，可增加[3 H]8-环戊基-1，3-二丙基黄嘌呤结合，并降低对GTP的反应。在用腺苷脱氨酶和α-β-亚甲基腺苷-5 '-二磷酸处理的切片中，GTP稳定地降低了所有区域中的[3 H]n6-环己基腺苷结合。因此，GTP诱导的激动剂和拮抗剂结合的增加可能是由于内源性adenosine的置换。在1 mM EDTA的存在下，GTP对[3 H]n6-cyclohexyl-ladenosine在所有区域的结合具有双相效应。在2 mM MgCl 2a的存在下，在所有区域中均观察到对GTP的双相反应。在EDTA洗涤的切片中，MgCl 2对[3 H]n6-环己基腺苷结合的影响在上级丘中更为明显，在那里我们观察到对GTP的双相反应。结果表明，GTP对大鼠脑中腺苷A1受体结合的影响存在区域差异，这反映了内源性腺苷的镁依赖性结合的区域差异，其通过紧密结合与受体结合，非常难以去除，并且在体外实验中容易干扰放射性配体结合。A1受体-G蛋白复合物对镁的敏感性可能存在区域差异，这反映了A1受体偶联的G蛋白的异质性。
The effect of increasing doses of GTP on agonist and antagonist binding to adenosine A1-receptors in different regions of rat brain was studied by autoradiography. A high concentration ofGTP (100μM) practically eliminated the binding of the agonist [3H]n6-cyclohexyladenosine in all regions. However, there were regional differences in the effects of low concentrations of GTP (0.1–10 μM). In some regions, for example the hippocampus, all concentrations of GTP decreased [3H]n6-cyclohexyladenosine binding, by decreasing theBmax. In other structures, e.g. the superior colliculus, there was a biphasic response to GTP. Concentrations of 0.1–3 μ M increased agonist binding, apparently due to a decrease inKD, whereas higher concentrations also decreased binding in these regions. The effects of GTP were mimicked by the stable GTP analogue guanosine-5'-O-(3-thiotriphosphate).GTP (0.5–100μM) increased the binding of the antagonist [3H]8-cyclopentyl-1,3-dipropylxanthine in all regions, but most markedly in those where GTP had a biphasic effect on agonist binding. Decreasing the levels of endogenous adenosine by increasing the concentration of adenosine deaminase and adding the 5'-nucleotidase inhibitor α-β-methylene adenosine-5'-diphosphate gave an increase in [3H]8-cyclopentyl-1,3-dipropylxanthine binding and diminished the response to GTP. In sections treated with adenosine deaminase and α-β-methylene adenosine-5'-diphosphate, GTP steadily decreased [3H]n6-cyclo-hexyladenosine binding in all regions. Thus, the GTP-induced increase in both agonist and antagonist binding may be due to a displacement of endogenous adenosine.In the presence of 1 mM EDTA, GTP had a monophasic effect on the binding of [3H]n6-cyclohexy-ladenosine in all regions. In the presence of 2 mM MgCl2a biphasic response to GTP was seen in all regions. In EDTA washed sections, the effect of MgCl2on [3H]n6-cyclohexyladenosine binding was more pronounced in the superior colliculus, where we had observed a biphasic response to GTP.The results suggest that there are regional differences in the effects of GTP on adenosine A1-receptor binding in rat brain, that reflect regional differences in the magnesium-dependent binding of endogenous adenosine, which is bound to the receptor by tight binding, is very difficult to remove, and easily interferes with radioligand binding inin vitroexperiments. There may be regional differences in the sensitivity of A1-receptor-G-protein complexes to magnesium, that reflect a heterogeneity of the G-proteins to which the A1-receptors are coupled.
鸟嘌呤核苷酸和阳离子对[3H]环己基腺苷和[3H]二乙基苯基黄嘌呤与脑膜中腺苷A1受体结合的调节。
影响因子：
3.6
作者：
Goodman,RR;Cooper,MJ;Gavish,M;Snyder,SH
通讯作者：
Snyder,SH
腺苷受体：放射自显影证据表明它们位于兴奋性神经元的轴突末端。
DOI：
10.1126/science.6302841
发表时间：
1983
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Goodman,RR;Kuhar,MJ;Hester,L;Snyder,SH
通讯作者：
Snyder,SH
镁离子在抑制性腺苷受体的调节中发挥核心作用。
DOI：
10.1042/bj2290091
发表时间：
1985
期刊：
The Biochemical journal
影响因子：
--
作者：
Yeung,SM;Fossom,LH;Gill,DL;Cooper,DM
通讯作者：
Cooper,DM