A dense cluster of D₁+ cells in the mouse nucleus accumbens

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• 作者：Sarah Petryszyn ; Maria Gabriela Sá ; nchez ; Dave Gagnon ; Jean-Martin Beaulieu ; André ; Parent and Martin Parent
• 刊名：Synapse
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：71
• 期：1
• 页码：51-54
• 全文大小：590K
• ISSN：1098-2396

文摘

The striatum is known to be largely composed of intermingled medium-sized projection neurons expressing either the D₁ or the D₂ dopamine receptors. In the present study, we took advantage of the double BAC Drd1a-TdTomato/Drd2-GFP (D₁/D₂) transgenic mice to reveal the presence of a peculiar cluster of densely-packed D₁+ cells located in the shell compartment of the nucleus accumbens. This spherical cluster has a diameter of 110 µm and is exclusively composed by D₁+ cells, which are all immunoreactive for the neuronal nuclear marker (NeuN). However, in contrast to other D₁+ or D₂+ striatal cells, those that form the accumbens cluster are devoid of calbindin (CB) and DARPP-32, two faithful markers for striatal projection neurons. Using GAD-GFP transgenic mice, we confirm the GABAergic nature of the D₁+ clustered neurons. Intracellular injections from fixed brain slices indicate that these neurons are endowed with distinctive morphological features, including a small (5–6 µm), round cell body giving rise to a single primary dendrite that branches into two secondary processes. Single-neuronal injections combined to electron microscopy reveal the existence of GAP junctions linking these D₁+ cells. Based on their location, morphological characteristics and neurochemical phenotype, we conclude that the D₁+ accumbens cluster form a highly compact group of small neurons distinct from the larger and more diffusely distributed D₁+ or D₂+ striatal projection neurons that surround it. This remarkable nucleus might play a crucial role in the limbic function of the murine striatum.