Neurogenesis in the mammalian neostriatum and nucleus accumbens: Parvalbumin-immunoreactive GABAergic interneurons

Abstract

We study the neurogenesis of a distinct subclass of rat striatum gamma-aminobutyric acid (GABA)ergic interneurons marked by the calcium-binding protein parvalbumin (PV). Timed pregnant rats are given an intraperitoneal injection of bromodeoxyuridine (BrdU), a marker of cell proliferation, on designated days between embryonic day (E) 11 and E22. Birthdate of PV neurons is determined in the adult neostriatum and nucleus accumbens by using a BrdU-PV double-labeling immunohistochemical technique. PV-immunoreactive interneurons of the neostriatum show maximum birthrates (>10% double-labeling) between E14-E17, whereas PV-immunoreactive interneurons of the nucleus accumbens show maximum double-labeling between E16-E19. In the neostriatum, caudal PV-immunoreactive neurons are born before those at rostral levels, and lateral PV-immunoreactive neurons become postmitotic before medial neurons. In the postcommissural striatum, ventral PV-immunoreactive neurons become postmitotic before dorsal neurons. In the precommissural striatum, ventral neurons are born before dorsal neurons laterally, but a dorsoventral gradient is seen medially. At corresponding coronal levels, PV-immunoreactive neurons of the nucleus accumbens are born shortly after PV neurons of the neostriatum. Analysis of BrdU labeling intensity in the nucleus accumbens shows that medium spiny projection neurons of the shell become postmitotic before neurons of the core. Similarly, PV-immunoreactive interneurons of the nucleus accumbens shell are born before PV interneurons of the core. Compared with cholinergic interneurons of the neostriatum, PV-immunoreactive interneurons are born later, but neurogenetic gradients are similar. The period of striatum PV interneuron genesis encompasses the period for somatostatin interneurons, although the latter neurons do not show neurogenetic gradients, possibly due to heterogeneous subtypes. Consideration of basal telencephalon neurogenesis suggests that subpopulations of striatum interneurons may share common neurogenetic features with phenotypically similar populations in the basal forebrain, with final morphology and connectivity depending on local cues provided by the host environment.

Pancreatic Homeodomain Transcription Factor IDX1/IPF1 Expressed in Developing Brain Regulates Somatostatin Gene Transcription in Embryonic Neural Cells

“…Thus, IDX1/IPF1 could act coordinately with some of these transcription factors to generate combinatorial codes for the selective regulation of specific genes. Interestingly, striatal somatostatin-expressing interneurons are generated at this time (56,57).…”

Correlations of Behavioral Deficits with Brain Pathology Assessed through Longitudinal MRI and Histopathology in the HdhQ150/Q150 Mouse Model of Huntington’s Disease

“…For both the striatum and M1 cortex, equally spaced sections (50 μm thickness each, 450 μm gap) were analyzed. As defined by Sadikot and Sasseville [49], sections contained within the striatum were sampled anteriorly from the first appearance of the genu of the corpus callosum (Bregma = +1.1 mm) to posteriorly at the first evidence of a hippocampal formation (Bregma = -0.94 mm). The dorsal and lateral boundaries consisted of the corpus callosum with the medial boundary being the lateral ventricles/internal capsule.…”

Origin and Molecular Specification of Striatal Interneurons

“…From E14.5, NKX2.1 expression is found in scattered cells of the striatum ( Fig. 1 A-C), despite the fact that it is not expressed in the proliferative zones of the LGE at the time when striatal neurons are born (mostly between E11 and E16 in the mouse; see references in Semba et al, 1988;Sadikot and Sasseville, 1997). Thus BrdU injections 30 min before death at different developmental stages (E12.5-E16.5) double-label NKX2.1 ϩ cells in the MGE, but not in the LGE (data not shown).…”

“…It has been proposed that neurons sharing the same chemical phenotype (e.g., cholinergic neurons) from different areas of the telencephalon are neurogenetically homologous and that their final morphology and connectivity depend primarily on extrinsic factors (Gähwiler and Hefti, 1985;Semba et al, 1988;Campbell et al, 1995;Sadikot and Sasseville, 1997). An alternative model is that intrinsic factors distinguish projection and interneurons, even when they share the same neurotransmitter phenotype.…”