Esaian N A, Armenian A R, Demirchian A A, Arakelian L N, Chiflikian M D
Vopr Biokhim Mozga. 1975;10:129-36.
It has been previously reported from this laboratory that CABA affects the retention of norepinephrine (NE) and serotonin (5-HT) in rat brain tissue [2, 3, 4]. The addition of GABA (100 mug/ml) to the incubation medium enhances significantly the loss of NE from slices while the loss of 5-HT is, on the contrary, significantly smaller than that observed from slices incubated parallely for the same period. It has also been shown that this effect is observed only in a balanced ionic medium [1]. With the purpose of finding out the importance of Na+ and Cl- ions in the storage of monoamines and in the effect of GABA on this process in the present report we studied the effect of GABA on the loss of NE and 5-HT from slices of rat mesodiencephalic region incubated in media free of Na+ and Cl- ions. The effect of GABA on Na+, K+-ATP-ase activity, an enzyme involved in the active transport of monoamines, was also studied. The results obtained indicate that loss of both NE and 5-HT from slices was significantly enhanced in a Na+-free medium and that on addition of GABA (100 mug/ml) to such a medium no significant changes GABA were noted. In a Cl--free medium loss of NE from slices was enhanced while that of 5-HT was not affected. When GABA was added to such a medium the usual pattern so far observed in our experiments, i.e. an enhancement in the loss of NE from slices, was found to be reversed. The pronounced decrease of NE observed in a Cl--free medium was found to be partially checked by the addition of GABA, the difference observed being statistically significant. Thus, in a Cl--free medium GABA seems to display an effect on NE storage opposite to that observed in a normal medium. Incubation in a Cl--free medium did not induce any noticeable change in the retention of 5-HT in slices. However, when GABA was added to slices incubated in a Cl--free medium, it no more displayed its usual effect, i.e. it did not inhibit the loss of 5-HT from slices. Under the given experimental conditions, GABA added to a balanced ionic medium did not effect Na+,K+-ATP-ase activity. This is in good agreement with previous results from our laboratory [4] where GABA was shown to have no effect on the uptake of NE and 5-HT by slices of rat brain, an active, carrier-mediated process coupled with Na+,K+-ATP-ase activity.
本实验室之前曾报道，γ-氨基丁酸（GABA）会影响大鼠脑组织中去甲肾上腺素（NE）和5-羟色胺（5-HT）的潴留情况[2,3,4]。在孵育培养基中添加GABA（100微克/毫升）可显著增强脑片NE的丢失，而5-HT的丢失情况则相反，明显小于同期平行孵育脑片所观察到的丢失量。研究还表明，这种效应仅在平衡离子培养基中才能观察到[1]。为了弄清楚Na+和Cl-离子在单胺类物质储存以及GABA对这一过程的影响中的重要性，在本报告中我们研究了GABA对在无Na+和Cl-离子的培养基中孵育的大鼠中脑间脑区域脑片NE和5-HT丢失的影响。我们还研究了GABA对Na+,K+-ATP酶活性的影响，该酶参与单胺类物质的主动转运。所得结果表明，在无Na+培养基中脑片NE和5-HT的丢失均显著增强，并且在这种培养基中添加GABA（100微克/毫升）后未观察到显著变化。在无Cl-培养基中，脑片NE的丢失增强，而5-HT的丢失未受影响。当向这种培养基中添加GABA时，我们实验中迄今观察到的通常模式，即脑片NE丢失增强，被逆转。发现在无Cl-培养基中观察到的NE显著减少可通过添加GABA得到部分抑制，所观察到的差异具有统计学意义。因此，在无Cl-培养基中，GABA对NE储存的影响似乎与在正常培养基中观察到的相反。在无Cl-培养基中孵育未引起脑片中5-HT潴留的任何明显变化。然而，当向在无Cl-培养基中孵育的脑片中添加GABA时，它不再表现出其通常的效应，即它并未抑制脑片5-HT的丢失。在给定的实验条件下，添加到平衡离子培养基中的GABA对Na+,K+-ATP酶活性没有影响。这与我们实验室之前的结果[4]非常一致，在该实验中表明GABA对大鼠脑片摄取NE和5-HT没有影响，摄取是一个与Na+,K+-ATP酶活性相关的主动的、载体介导的过程。
