大鼠杏仁体基底外侧核中DA能与GABA能神经元之间突触关系的免疫电镜研究

AN IMMUNOELECTRON MICROSCOPIC STUDY ON THE SYNAPTIC RELATIONSHIP BETWEEN DOPAMINERGIC AND GABAergic NEURONS IN THE BASOLATERALNUCLEUS OF THE RAT AMYGDALA

目的 了解杏仁体中多巴胺 (DA)能神经末梢和γ 氨基丁酸 (GABA)能神经元之间的相互关系、探索两者在精神分裂症中作用的神经解剖学机制。 方法 用免疫电镜双标技术 ,分别以抗DA和抗谷氨酸脱羧酶(GAD、GABA的合成酶 )标记大鼠杏仁体基底外侧核中DA能神经末梢和GABA能神经元 ,在电镜下观察DA能神经末梢和GABA能神经元之间的突触联系。 结果 由DA免疫阳性神经末梢形成的突触中 ,有 4 3%直接或间接形成于DA免疫阳性神经末梢与GAD免疫反应阳性树突结构之间 ,其中单一性突触为 38%、汇聚性突触为 30 %、连续性突触为 2 0 %、末梢间突触样联系为 12 %。另外的 5 7%由DA免疫阳性神经末梢与未标记的神经结构形成 ,其中在未标记的神经元胞体形成 10 %、树突上 82 %、轴突末梢上 8%。由DA免疫反应阳性末梢形成的所有突触均为对称性即抑制性突触。 结论 在大鼠杏仁体基底外侧核中 ,DA能神经末梢系统以对称性突触支配着GABA能中间神经元 ,同时 ,又与核内的谷氨酸能投射神经元形成突触联系 ,并影响其活动。

Objective To explore the relationship between dopaminergic axon terminal and GABAergic neurons and explore the neuroanatomic mechanism of their effects in schizophrenia. Methods The co-location and the association of dopaminergic axon terminal and GABAergic neurons in the basolateral nucleus (BL) of rat amygdala were examined by using double labeling immunoelectron microscopic techniques. Dopaminergic axon terminal and GABAergic neurons were labeled with the antidopamine (anti-DA) and the anti-glutamic acid decarboxylase (anti-GAD) antibodies respectively. Results 43% of the DA-input synapses was observed to relate directly or indirectly to GAD-immunoreactive(IR) dendritic structures(DA/GAD), which includes single (38%), convergent (30%), serial (20%), and axoaxonic (12%) contact types.And 57% of the DA-input synapses was found to associate with unlabeled elements (DA/UE), which includes unlabeled perikarya (10%), dendrites (82%) and axons (8%). All of the synapses that show DA-IR terminals profiles were found to be symmetric (inhibitory) synapses.Conclusion These results suggest that the dopaminergic system in the BL of rat amygdala controls the mediations of the GABAergic interneurons via symmetric synapses. In addition, the dopaminergic axon terminal associates with the glutamatergic projection neurons and exerts influence on its activity.