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A dense cluster of D 1 + cells in the mouse nucleus accumbens
Author(s) -
Petryszyn Sarah,
Sánchez Maria Gabriela,
Gag Dave,
Beaulieu JeanMartin,
Parent André,
Parent Martin
Publication year - 2017
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.21946
Subject(s) - nucleus accumbens , medium spiny neuron , striatum , calbindin , nucleus , neuroscience , chemistry , gabaergic , biology , microbiology and biotechnology , dopamine , biophysics , inhibitory postsynaptic potential , immunohistochemistry , immunology
The striatum is known to be largely composed of intermingled medium‐sized projection neurons expressing either the D 1 or the D 2 dopamine receptors. In the present study, we took advantage of the double BAC Drd1a‐TdTomato/Drd2‐GFP (D 1 /D 2 ) transgenic mice to reveal the presence of a peculiar cluster of densely‐packed D 1 + cells located in the shell compartment of the nucleus accumbens. This spherical cluster has a diameter of 110 µm and is exclusively composed by D 1 + cells, which are all immunoreactive for the neuronal nuclear marker (NeuN). However, in contrast to other D 1 + or D 2 + 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 D 1 + 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 D 1 + cells. Based on their location, morphological characteristics and neurochemical phenotype, we conclude that the D 1 + accumbens cluster form a highly compact group of small neurons distinct from the larger and more diffusely distributed D 1 + or D 2 + striatal projection neurons that surround it. This remarkable nucleus might play a crucial role in the limbic function of the murine striatum.