French Sarah Jane, Totterdell Susan
Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
Brain Res. 2004 May 8;1007(1-2):167-77. doi: 10.1016/j.brainres.2004.02.018.
The nucleus accumbens (Acb) receives convergent glutamatergic inputs from the prefrontal cortex (PFC), central thalamus, basolateral amygdala and the ventral subiculum of the hippocampus. The principal neurons of the nucleus accumbens are modulated by specific sets of convergent afferent inputs, the local circuit neurons also receive a substantial number of glutamatergic inputs, but the full complement of these has yet to be established. The aim of these studies was to define characteristics of the different glutamatergic afferent inputs to the nucleus accumbens that would aid their identification. To enable the characterisation of the glutamatergic inputs to nucleus accumbens neurons we first labelled the four main glutamatergic sources of afferent input to the accumbens with the anterograde tracer biotinylated dextran amine (BDA). Using an unbiased systematic sampling method, the morphological characteristics of their synaptic boutons were measured and assessed at the electron microscopic level. From the criteria assessed, a comparison of the four afferent sources was made, characteristics such as bouton size and vesicle density had significantly different population means, however, the only characteristic that allowed discrimination between the four major glutamatergic afferent to the nucleus accumbens was that of vesicle size. The vesicles in boutons from amygdala were larger than the subiculum which, in turn, were larger than the prefrontal cortex, the thalamus were the smallest in size. The methods used also allow a comparison of the relative frequency of different sized postsynaptic structures targeted, the prefrontal cortex almost exclusively targeted spines whereas the thalamus and the subiculum, in addition to spines, targeted proximal and distal dendrites.
伏隔核（Acb）接收来自前额叶皮质（PFC）、丘脑中央核、基底外侧杏仁核和海马腹侧下托的汇聚性谷氨酸能输入。伏隔核的主要神经元受到特定汇聚性传入输入组的调节，局部回路神经元也接收大量谷氨酸能输入，但其完整组成尚未确定。这些研究的目的是确定伏隔核不同谷氨酸能传入输入的特征，以有助于对它们进行识别。为了能够表征伏隔核神经元的谷氨酸能输入，我们首先用顺行示踪剂生物素化葡聚糖胺（BDA）标记伏隔核传入输入的四个主要谷氨酸能来源。使用无偏系统抽样方法，在电子显微镜水平测量并评估了它们突触小体的形态特征。根据评估标准，对这四个传入来源进行了比较，突触小体大小和囊泡密度等特征的总体均值有显著差异，然而，能够区分伏隔核四个主要谷氨酸能传入的唯一特征是囊泡大小。杏仁核突触小体中的囊泡大于下托，下托又大于前额叶皮质囊泡，丘脑囊泡大小最小。所使用的方法还允许比较不同大小的突触后结构被靶向的相对频率，前额叶皮质几乎只靶向棘突，而丘脑和下托除了靶向棘突外，还靶向近端和远端树突。
