静息和受刺激状态下海马抑制性突触的超微结构特征。

IF 3.3 3区 医学 Q2 NEUROSCIENCES Molecular Brain Pub Date : 2024-10-22 DOI:10.1186/s13041-024-01151-0
Jung-Hwa Tao-Cheng, Sandra Lara Moreira, Christine A Winters
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引用次数: 0

摘要

本研究利用电子显微镜记录了三个实验系统中海马 GABA 能抑制性突触在静息和刺激条件下的超微结构特征。研究人员从(1)灌注固定的小鼠大脑、(2)浸泡固定的大鼠有机切片培养物和(3)混合细胞类型的大鼠离体海马培养物的CA1区金字塔层和放射层采集了突触轮廓样本。大脑灌注固定延迟 5 分钟以触发类似缺血的兴奋状态,并用 90 mM 高 K+处理两种培养系统 2-3 分钟以去极化神经元,从而刺激大脑突触。在这种刺激条件下,抑制性突触的突触前末端表现出与谷氨酸能兴奋性突触类似的结构变化,突触小泡耗竭,凝集素包裹的小泡增加,突触小刺出现。然而,与兴奋性突触不同,抑制性突触的突触后区在受到刺激时没有发现结构上的差异。突触后膜相关物质的外观、膜的长度和弧度均无变化。此外,突触后膜上的 GABA 能突触标记物 gephyrin 的标记密度也没有变化。此外,几乎所有抑制性突触裂隙都保持着刚性贴合,这与兴奋性突触的情况不同,在兴奋性突触中,约有 20-30% 的裂隙边缘在受到刺激时是开放的,这可能是为了促进神经递质从裂隙中清除。抑制性突触在受到刺激时没有开放的裂隙,这一事实表明抑制性输入在这些条件下可能不需要减弱。另一方面,与兴奋性突触类似,EGTA(一种钙螯合剂)在约 18% 的抑制性突触裂隙边缘诱导出开放裂隙,这可能破坏了这两种突触中类似的钙依赖性跨突触桥。
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Ultrastructural characterization of hippocampal inhibitory synapses under resting and stimulated conditions.

The present study uses electron microscopy to document ultrastructural characteristics of hippocampal GABAergic inhibitory synapses under resting and stimulated conditions in three experimental systems. Synaptic profiles were sampled from stratum pyramidale and radiatum of the CA1 region from (1) perfusion fixed mouse brains, (2) immersion fixed rat organotypic slice cultures, and from (3) rat dissociated hippocampal cultures of mixed cell types. Synapses were stimulated in the brain by a 5 min delay in perfusion fixation to trigger an ischemia-like excitatory condition, and by treating the two culture systems with 90 mM high K+ for 2-3 min to depolarize the neurons. Upon such stimulation conditions, the presynaptic terminals of the inhibitory synapses exhibited similar structural changes to those seen in glutamatergic excitatory synapses, with depletion of synaptic vesicles, increase of clathrin-coated vesicles and appearance of synaptic spinules. However, in contrast to excitatory synapses, no structural differences were detected in the postsynaptic compartment of the inhibitory synapses upon stimulation. There were no changes in the appearance of material associated with the postsynaptic membrane or the length and curvature of the membrane. Also no change was detected in the labeling density of gephyrin, a GABAergic synaptic marker, lining the postsynaptic membrane. Furthermore, virtually all inhibitory synaptic clefts remained rigidly apposed, unlike in the case of excitatory synapses where ~ 20-30% of cleft edges were open upon stimulation, presumably to facilitate the clearance of neurotransmitters from the cleft. The fact that no open clefts were induced in inhibitory synapses upon stimulation suggests that inhibitory input may not need to be toned down under these conditions. On the other hand, similar to excitatory synapse, EGTA (a calcium chelator) induced open clefts in ~ 18% of inhibitory synaptic cleft edges, presumably disrupting similar calcium-dependent trans-synaptic bridges in both types of synapses.

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来源期刊
Molecular Brain
Molecular Brain NEUROSCIENCES-
CiteScore
7.30
自引率
0.00%
发文量
97
审稿时长
>12 weeks
期刊介绍: Molecular Brain is an open access, peer-reviewed journal that considers manuscripts on all aspects of studies on the nervous system at the molecular, cellular, and systems level providing a forum for scientists to communicate their findings. Molecular brain research is a rapidly expanding research field in which integrative approaches at the genetic, molecular, cellular and synaptic levels yield key information about the physiological and pathological brain. These studies involve the use of a wide range of modern techniques in molecular biology, genomics, proteomics, imaging and electrophysiology.
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