多巴胺 D₂ 和乙酰胆碱 α7 型烟碱受体具有亚细胞分布,有利于介导小鼠腹侧被盖区的会聚信号转导。
Dopamine D₂ and acetylcholine α7 nicotinic receptors have subcellular distributions favoring mediation of convergent signaling in the mouse ventral tegmental area.
机构信息
Brain and Mind Research Institute, Weill Cornell Medical College, 407 East 61st Street, New York, NY 10065, USA; Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina UAM, Madrid 28029, Spain; Instituto de Investigación Hospital Universitario La Paz (IDIPAZ), Paseo de la Castellana 261, Madrid 28046, Spain.
出版信息
Neuroscience. 2013 Nov 12;252:126-43. doi: 10.1016/j.neuroscience.2013.08.008. Epub 2013 Aug 15.
Alpha7 nicotinic acetylcholine receptors (α7nAChRs) mediate nicotine-induced burst-firing of dopamine neurons in the ventral tegmental area (VTA), a limbic brain region critically involved in reward and in dopamine D2 receptor (D2R)-related cortical dysfunctions associated with psychosis. The known presence of α7nAChRs and Gi-coupled D2Rs in dopamine neurons of the VTA suggests that these receptors are targeted to at least some of the same neurons in this brain region. To test this hypothesis, we used electron microscopic immunolabeling of antisera against peptide sequences of α7nACh and D2 receptors in the mouse VTA. Dual D2R and α7nAChR labeling was seen in many of the same somata (co-localization over 97%) and dendrites (co-localization over 49%), where immunoreactivity for each of the receptors was localized to endomembranes as well as to non-synaptic or synaptic plasma membranes often near excitatory-type synapses. In comparison with somata and dendrites, many more small axons and axon terminals were separately labeled for each of the receptors. Thus, single-labeled axon terminals were predominant for both α7nAChR (57.9%) and D2R (89.0%). The majority of the immunolabeled axonal profiles contained D2R-immunoreactivity (81.6%) and formed either symmetric or asymmetric synapses consistent with involvement in the release of both inhibitory and excitatory transmitters. Of 160 D2R-labeled terminals, 81.2% were presynaptic to dendrites that expressed α7nAChR alone or together with the D2R. Numerous glial processes inclusive of those enveloping either excitatory- or inhibitory-type synapses also contained single labeling for D2R (n=152) and α7nAChR (n=561). These results suggest that classic antipsychotic drugs, all of which block the D2R, may facilitate α7nAChR-mediated burst-firing by elimination of D2R-dependent inhibition in neurons expressing both receptors as well as by indirect pre-synaptic and glial mechanisms.
α7 型烟碱型乙酰胆碱受体(α7nAChR)介导尼古丁诱导腹侧被盖区(VTA)多巴胺神经元爆发性放电,VTA 是一个边缘脑区,与奖赏及与精神分裂症相关的皮质功能障碍的多巴胺 D2 受体(D2R)有关。VTA 中的多巴胺神经元中已知存在 α7nAChR 和 Gi 偶联的 D2R,这表明这些受体至少靶向到该脑区中的一些相同神经元。为了检验这一假设,我们使用针对小鼠 VTA 中 α7nACh 和 D2 受体肽序列的抗血清进行电子显微镜免疫标记。在许多相同的神经元胞体(共定位超过 97%)和树突(共定位超过 49%)中观察到双重 D2R 和 α7nAChR 标记,其中每个受体的免疫反应性定位于内膜以及非突触或突触质膜,通常靠近兴奋性型突触。与神经元胞体和树突相比,许多更多的小轴突和轴突末梢分别为每个受体单独标记。因此,对于 α7nAChR(57.9%)和 D2R(89.0%),单标记的轴突末梢占主导地位。大多数免疫标记的轴突突包含 D2R 免疫反应性(81.6%),并形成对称或不对称突触,与抑制和兴奋性递质的释放都有关。在 160 个 D2R 标记的末梢中,81.2%的末梢是表达 α7nAChR 或与 D2R 一起表达的树突的突触前末梢。包括包围兴奋性或抑制性突触的许多神经胶质过程也包含 D2R(n=152)和 α7nAChR(n=561)的单标记。这些结果表明,所有阻断 D2R 的经典抗精神病药物都可能通过消除表达两种受体的神经元中 D2R 依赖性抑制以及通过间接的突触前和神经胶质机制,促进 α7nAChR 介导的爆发性放电。