New neurons are continually generated from the resident populations of precursor cells in selective niches of the adult mammalian brain such as the hippocampal dentate gyrus and the olfactory bulb. However, whether such cells are present in the adult amygdala, and their neurogenic capacity, is not known. Using the neurosphere assay, we demonstrate that a small number of precursor cells, the majority of which express Achaete-scute complex homolog 1 (Ascl1), are present in the basolateral amygdala (BLA) of the adult mouse. Using neuron-specific Thy1-YFP transgenic mice, we show that YFP+ cells in BLA-derived neurospheres have a neuronal morphology, co-express the neuronal marker βIII-tubulin, and generate action potentials, confirming their neuronal phenotype. In vivo, we demonstrate the presence of newly generated BrdU-labeled cells in the adult BLA, and show that a proportion of these cells co-express the immature neuronal marker doublecortin (DCX). Furthermore, we reveal that a significant proportion of GFP+ neurons (~23%) in the BLA are newly generated (BrdU+) in DCX-GFP mice, and using whole-cell recordings in acute slices we demonstrate that the GFP+ cells display electrophysiological properties that are characteristic of interneurons. Using retrovirus-GFP labeling as well as the Ascl1^CreERT2 mouse line, we further confirm that the precursor cells within the BLA give rise to mature and functional interneurons that persist in the BLA for at least 8 weeks after their birth. Contextual fear conditioning has no effect on the number of neurospheres or BrdU-labeled cells in the BLA, but produces an increase in hippocampal cell proliferation. These results demonstrate that neurogenic precursor cells are present in the adult BLA, and generate functional interneurons, but also show that their activity is not regulated by an amygdala-dependent learning paradigm.

中文翻译：

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成年小鼠基底外侧杏仁核中新产生的中间神经元的证据。

在成年哺乳动物脑的选择性壁ni（例如海马齿状回和嗅球）中，前体细胞的常驻种群不断产生新的神经元。然而，尚不知道成年杏仁核中是否存在此类细胞及其神经发生能力。使用神经球测定，我们证明成年小鼠的基底外侧杏仁核（BLA）中存在少量的前体细胞，其中大多数表达Achaete-scute复杂同源物1（Ascl1）。使用神经元特异性Thy1-YFP转基因小鼠，我们显示BLA衍生的神经球中的YFP +细胞具有神经元形态，共表达神经元标记物βIII-微管蛋白，并产生动作电位，从而确认其神经元表型。体内，我们证明了成人BLA中新产生的BrdU标记的细胞的存在，并表明这些细胞中的一部分共同表达了未成熟的神经元标记物双皮质素（DCX）。此外，我们揭示了DCX-GFP小鼠中BLA中有相当大比例的GFP +神经元（〜23％）是新产生的（BrdU +），并且使用急性切片中的全细胞记录，我们证明了GFP +神经元具有电生理特性，是中间神经元的特征。使用逆转录病毒-GFP标记以及Ascl1 并在急性切片中使用全细胞记录，我们证明了GFP +细胞表现出中间神经元特有的电生理特性。使用逆转录病毒-GFP标记以及Ascl1 并在急性切片中使用全细胞记录，我们证明了GFP +细胞表现出中间神经元特有的电生理特性。使用逆转录病毒-GFP标记以及Ascl1^在CreERT2小鼠品系中，我们进一步证实BLA中的前体细胞会产生成熟且功能正常的中间神经元，这些中间神经元在其出生后至少会持续8周。情境恐惧调节对BLA中的神经球或BrdU标记的细胞数量没有影响，但会导致海马细胞增殖增加。这些结果证明，成年BLA中存在神经源性前体细胞，并产生功能性的中间神经元，但也表明其活性不受杏仁核依赖性学习范式的调节。