Pantazopoulos Harry, Lange Nicholas, Hassinger Linda, Berretta Sabina
Translational Neuroscience Laboratory, McLean Hospital, Belmont, MA 02478, USA.
J Comp Neurol. 2006 Jun 10;496(5):706-22. doi: 10.1002/cne.20961.
Amygdalar intrinsic inhibitory networks comprise several subpopulations of gamma-aminobutyric acidergic neurons, each characterized by distinct morphological features and clusters of functionally relevant neurochemical markers. In rodents, the calcium-binding proteins parvalbumin (PVB) and calbindin D28k (CB) are coexpressed in large subpopulations of amygdalar interneurons. PVB-immunoreactive (-IR) neurons have also been shown to be ensheathed by perineuronal nets (PNN), extracellular matrix envelopes believed to affect ionic homeostasis and synaptic plasticity. We tested the hypothesis that differential expression of these three markers may define distinct neuronal subpopulations within the human amygdala. Toward this end, triple-fluorescent labeling using antisera raised against PVB and CB as well as biotinylated Wisteria floribunda lectin for detection of PNN was combined with confocal microscopy. Among the 1,779 PVB-IR neurons counted, 18% also expressed CB, 31% were ensheathed in PNN, and 7% expressed both CB and PNN. Forty-four percent of PVB-IR neurons did not colocalize with either CB or PNN. The distribution of each of these neuronal subgroups showed substantial rostrocaudal gradients. Furthermore, distinct morphological features were found to characterize each neuronal subgroup. In particular, significant differences relative to the distribution and morphology were detected between PVB-IR neurons expressing CB and PVB-IR neurons wrapped in PNNs. These results indicate that amygdalar PVB-IR neurons can be subdivided into at least four different subgroups, each characterized by a specific neurochemical profile, morphological characteristics, and three-dimensional distribution. Such properties suggest that each of these neuronal subpopulations may play a specific role within the intrinsic circuitry of the amygdala.
杏仁核内在抑制性网络由几个γ-氨基丁酸能神经元亚群组成，每个亚群都具有独特的形态特征和功能相关神经化学标志物簇。在啮齿动物中，钙结合蛋白小白蛋白（PVB）和钙结合蛋白D28k（CB）在杏仁核中间神经元的大量亚群中共同表达。PVB免疫反应性（-IR）神经元也被证明被神经周网（PNN）包裹，神经周网是一种细胞外基质包膜，据信会影响离子稳态和突触可塑性。我们检验了这样一种假设，即这三种标志物的差异表达可能定义人类杏仁核内不同的神经元亚群。为此，将使用针对PVB和CB的抗血清以及用于检测PNN的生物素化紫藤凝集素进行的三重荧光标记与共聚焦显微镜相结合。在计数的1779个PVB-IR神经元中，18%也表达CB，31%被PNN包裹，7%同时表达CB和PNN。44%的PVB-IR神经元与CB或PNN均无共定位。这些神经元亚组中的每一个的分布都显示出明显的前后梯度。此外，发现每个神经元亚组都有独特的形态特征。特别是，在表达CB的PVB-IR神经元和被PNN包裹的PVB-IR神经元之间，检测到相对于分布和形态的显著差异。这些结果表明，杏仁核PVB-IR神经元可细分为至少四个不同的亚组，每个亚组都具有特定的神经化学特征、形态特征和三维分布。这些特性表明，这些神经元亚群中的每一个可能在杏仁核的内在回路中发挥特定作用。
