Lantin Le Boulch N, Truong-Ngoc N A, Gauchy C
Laboratoire de Neurochimie Anatomie, CNRS, Université Pierre et Marie Curie, Paris, France.
J Neurochem. 1991 Sep;57(3):1080-3. doi: 10.1111/j.1471-4159.1991.tb08261.x.
The release of gamma-[3H]aminobutyric acid ([3H]GABA) newly synthesized from [3H]glutamine was estimated in the superior colliculus of ketamine-anesthetized rats superfused via a push-pull cannula. A significant amount of [3H]GABA was spontaneously released in the superior colliculus (582 +/- 49 pCi/10 min). A major part of the large K(+)-evoked increase of the [3H]GABA release was Ca2+ dependent. When neuronal activity of the substantia nigra was enhanced by nigral application of K+ (30 mM) or bicuculline (10(-4) M), a persistent increase of the collicular [3H]GABA release was observed (60 and 80%, respectively). Conversely, when nigral activity was reduced by nigral application of GABA (10(-4) M) or superfusion with a Ca(2+)-free medium, a sustained decrease of the collicular [3H]GABA release was observed (-30 and -40%, respectively). Following the nigral application of a selective D2-receptor agonist. RU 24926 (10(-6) M), for 30 min in 6-hydroxydopamine-lesioned rats, a phasic increase (60%) of the collicular [3H]GABA release was detected. This effect could result from an activation of nigrocollicular GABAergic neurons by D2-receptor stimulation, because nigral activity and collicular release of [3H]GABA changed in a parallel direction.
通过推挽式套管灌注，在氯胺酮麻醉大鼠的上丘中估计了由[3H]谷氨酰胺新合成的γ-[3H]氨基丁酸（[3H]GABA）的释放量。上丘中大量[3H]GABA自发释放（582±49 pCi/10分钟）。K⁺诱发的[3H]GABA释放大量增加的主要部分依赖于Ca²⁺。当通过黑质应用K⁺（30 mM）或荷包牡丹碱（10⁻⁴ M）增强黑质的神经元活动时，观察到上丘[3H]GABA释放持续增加（分别为60%和80%）。相反，当通过黑质应用GABA（10⁻⁴ M）或用无Ca²⁺培养基灌注来降低黑质活动时，观察到上丘[3H]GABA释放持续减少（分别为-30%和-40%）。在6-羟基多巴胺损伤的大鼠中，黑质应用选择性D2受体激动剂RU 24926（10⁻⁶ M）30分钟后，检测到上丘[3H]GABA释放出现阶段性增加（60%）。这种效应可能是由于D2受体刺激激活了黑质-上丘GABA能神经元，因为黑质活动和上丘[3H]GABA释放呈平行方向变化。
