title: Subsets of Spiny Striosomal Striatal Neurons Revealed in the Gad1-GFP BAC Transgenic Mouse.
abstract: OBJECTIVE: To characterize GFP-expressing cells in the striatum of Cb6-Tg(Gad1-EGFP)G42Zjh/J mice, in which the Gad1 (also referred to as GAD67) promoter drives GFP expression (Gad1-GFP mouse).  BACKGROUND: GFP-expressing cells of the GAD1-GFP mouse have been described to be a population of parvalbumin-positive basket interneurons residing in the cerebral cortex and the cerebellum. However, the cells in the dorsal striatum of these mice have not been characterized.  METHODS: Using a combination of immunohistochemistry, electrophysiology, DiI labeling, and retrograde tracing, we investigated the phenotypes of GFP-expressing cells in the GAD1-GFP mice.  RESULTS: A small number of striatal neurons express GFP in these mice. In the mature striatum, these cells are preferentially located in the lateral striatum with a strong expression in the lateral striatal streak. The GAD1-GFP positive neurons are distinct from the standard fast-spiking and low-threshold-spiking GAD-67 expressing striatal interneurons and appear to be a subset of medium spiny neurons. These neurons are generally colocalized with striosomal markers such as dynorphin, mu-opioid receptors, as well as CB1 and calretinin-immunopositive fibers. Striatal Gad1-GFP neurons can be separated into two groups based on the shape of the somata and patterns of action potential firing. Retrograde labeling indicated that a proportion of these cells are projection neurons.  CONCLUSIONS: The examination of GAD1-GFP cells in these mice revealed 2 subpopulations of ventral striosomal striatal medium spiny neurons, based on morphology, patch-matrix segregation and membrane properties.
authors.affiliation: Laboratory for Integrative Neuroscience, National Institute of Alcohol Abuse and Alcoholism, Rockville, MD.
authors.forename: Verginia C
authors.initials: VC
authors.lastname: Cuzon Carlson
authors.forename: Brian N
authors.initials: BN
authors.lastname: Mathur
authors.forename: Margaret I
authors.initials: MI
authors.lastname: Davis
authors.forename: David M
authors.initials: DM
authors.lastname: Lovinger