Kristofiková Z, Klaschka J
Prague Psychiatric Center, Czech Republic.
Neurochem Res. 1997 Jan;22(1):67-73. doi: 10.1023/a:1027381421950.
A second messenger role for arachidonic acid (AA) in the regulation of the high-affinity choline uptake (HACU) was suggested. It was reported that micromolar concentrations of AA applied in vitro decreased the HACU values and increased the specific binding of [3H]hemicholinium-3 ([3H]HCh-3). It was published that L-glutamic acid (GA) applied in vivo produced a fall in the HACU values. In addition, GA liberates free AA. In this study, an ability of GA to influence in vitro the activity of presynaptic cholinergic nerve terminals via its effect on the release of AA is investigated in hippocampal synaptosomes of young Wistar rats. Millimolar concentrations of GA decrease both the high- and low-affinity choline uptake, the specific as well as nonspecific binding of [3H]HCh-3 and the activity of Na+, K(+)-ATPase. Kinetic analysis (Lineweaver-Burk and Scatchard plots) reveals a change in Vmax and Bmax, but not in KM and KD. It appears very likely that under normal conditions GA applied in vitro is not able to change markedly the choline transport via its effect on the release of AA. Results confirm the hypothesis about an indirect inhibitory role for glutamatergic receptors on cholinergic cells.
有人提出花生四烯酸（AA）在高亲和力胆碱摄取（HACU）调节中具有第二信使作用。据报道，体外应用微摩尔浓度的AA可降低HACU值并增加[3H]半胱氨酸-3（[3H]HCh-3）的特异性结合。已发表的研究表明，体内应用L-谷氨酸（GA）会使HACU值下降。此外，GA可释放游离AA。在本研究中，在年轻Wistar大鼠的海马突触体中，研究了GA通过影响AA释放来体外影响突触前胆碱能神经末梢活性的能力。毫摩尔浓度的GA可降低高亲和力和低亲和力胆碱摄取、[3H]HCh-3的特异性及非特异性结合以及Na +，K（+）-ATP酶的活性。动力学分析（Lineweaver-Burk和Scatchard图）显示Vmax和Bmax发生变化，但KM和KD未变。在正常条件下，体外应用GA似乎不太可能通过影响AA释放而显著改变胆碱转运。结果证实了关于谷氨酸能受体对胆碱能细胞具有间接抑制作用的假说。
