A dense cluster of D + cells in the mouse nucleus accumbens.

The striatum is known to be largely composed of intermingled medium-sized projection neurons expressing either the D or the D dopamine receptors. In the present study, we took advantage of the double BAC Drd1a-TdTomato/Drd2-GFP (D /D ) transgenic mice to reveal the presence of a peculiar cluster of densely-packed D + 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 + cells, which are all immunoreactive for the neuronal nuclear marker (NeuN).

The number of striatal cholinergic interneurons expressing calretinin is increased in parkinsonian monkeys.

The most abundant interneurons in the primate striatum are those expressing the calcium-binding protein calretinin (CR). The present immunohistochemical study provides detailed assessments of their morphological traits, number, and topographical distribution in normal monkeys (Macaca fascicularis) and in monkeys rendered parkinsonian (PD) by MPTP intoxication. In primates, the CR+ striatal interneurons comprise small (8-12μm), medium (12-20μm) and large-sized (20-45μm) neurons, each with distinctive morphologies.

Distribution and morphological characteristics of striatal interneurons expressing calretinin in mice: a comparison with human and nonhuman primates.

Striatal interneurons display a morphological and chemical heterogeneity that has been particularly well characterized in rats, monkeys and humans. By comparison much less is known of striatal interneurons in mice, although these animals are now widely used as transgenic models of various neurodegenerative diseases. The present immunohistochemical study aimed at characterizing striatal interneurons expressing calretinin (CR) in mice compared to those in squirrel monkeys and humans.