title: A dense cluster of D1+ cells in the mouse nucleus accumbens.
abstract: The striatum is known to be largely composed of intermingled medium-sized projection neurons expressing either the D1or the D2dopamine 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.
authors: Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, Quebec, Canada.
authors: Sarah
authors: S
authors: Petryszyn
authors: Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, Quebec, Canada.
authors: Maria Gabriela
authors: MG
authors: Sánchez
authors: Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, Quebec, Canada.
authors: Dave
authors: D
authors: Gagnon
authors: Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, Quebec, Canada.
authors: Jean-Martin
authors: JM
authors: Beaulieu
authors: Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, Quebec, Canada.
authors: André
authors: A
authors: Parent
authors: Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, Quebec, Canada.
authors: Martin
authors: M
authors: Parent
mesh_terms: D000818:Animals; D064026:Calbindins / Q000235:genetics / Q000378:metabolism; D059330:GABAergic Neurons / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009714:Nucleus Accumbens / Q000166:cytology* / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000235:genetics / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism
chemical_list: D064026:Calbindins; C000600618:DRD2 protein, mouse; C583261:Drd1 protein, mouse; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2
keywords: basal ganglia; dopamine receptors; mouse; nucleus accumbens; ventral striatum