Muller Jay F, Mascagni Franco, McDonald Alexander J
Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina 29208, USA.
J Neurosci. 2005 Aug 10;25(32):7366-76. doi: 10.1523/JNEUROSCI.0899-05.2005.
Recent studies indicate that the basolateral amygdala exhibits fast rhythmic oscillations during emotional arousal, but the neuronal mechanisms underlying this activity are not known. Similar oscillations in the cerebral cortex are generated by a network of parvalbumin (PV)-immunoreactive interneurons interconnected by chemical synapses and dendritic gap junctions. The present immunoelectron microscopic study revealed that the basolateral amygdalar nucleus (BLa) contains a network of parvalbumin-immunoreactive (PV+) interneurons interconnected by chemical synapses, dendritic gap junctions, and axonal gap junctions. Twenty percent of synapses onto PV+ neurons were formed by PV+ axon terminals. All of these PV+ synapses were symmetrical. PV+ perikarya exhibited the greatest incidence of PV+ synapses (30%), with lower percentages associated with PV+ dendrites (15%) and spines (25%). These synapses comprised half of all symmetrical synapses formed with PV+ cells. A total of 18 dendrodendritic gap junctions between PV+ neurons were observed, mostly involving secondary and more distal dendrites (0.5-1.0 microm thick). Dendritic gap junctions were often in close proximity to PV+ chemical synapses. Six gap junctions were observed between PV+ axon terminals. In most cases, one or both of these terminals formed synapses with the perikarya of principal neurons. This is the first study to describe dendritic gap junctions interconnecting PV+ interneurons in the basolateral amygdala. It also provides the first documentation of gap junctions between interneuronal axon terminals in the mammalian forebrain. These data provide the anatomical basis for a PV+ network that may play a role in the generation of rhythmic oscillations in the BLa during emotional arousal.
近期研究表明，基底外侧杏仁核在情绪唤醒期间呈现快速节律性振荡，但其背后的神经元机制尚不清楚。大脑皮层中的类似振荡是由一个通过化学突触和树突缝隙连接相互连接的小白蛋白（PV）免疫反应性中间神经元网络产生的。目前的免疫电子显微镜研究显示，基底外侧杏仁核（BLa）包含一个由化学突触、树突缝隙连接和轴突缝隙连接相互连接的小白蛋白免疫反应性（PV+）中间神经元网络。PV+神经元上20%的突触由PV+轴突终末形成。所有这些PV+突触都是对称的。PV+胞体上PV+突触的发生率最高（30%），PV+树突（15%）和棘（25%）上的发生率较低。这些突触占与PV+细胞形成的所有对称突触的一半。共观察到PV+神经元之间有18个树突-树突缝隙连接，主要涉及二级和更远端的树突（0.5-1.0微米厚）。树突缝隙连接通常紧邻PV+化学突触。在PV+轴突终末之间观察到6个缝隙连接。在大多数情况下，这些终末中的一个或两个与主神经元的胞体形成突触。这是第一项描述基底外侧杏仁核中连接PV+中间神经元的树突缝隙连接的研究。它还首次记录了哺乳动物前脑中间神经元轴突终末之间的缝隙连接。这些数据为一个PV+网络提供了解剖学基础，该网络可能在情绪唤醒期间BLa的节律性振荡产生中发挥作用。
