Dopamine Affects Parvalbumin Expression during Cortical DevelopmentIn Vitro

Abstract

This study was undertaken to determine how dopamine influences cortical development. It focused on morphogenesis of GABAergic neurons that contained the calcium-binding protein parvalbumin (PV). Organotypic slices of frontoparietal cortex were taken from neonatal rats, cultured with or without dopamine, harvested daily (4-30 d), and immunostained for parvalbumin. Expression of parvalbumin occurred in the same regional and laminar sequence as in vivo. Expression in cingulate and entorhinal preceded that in lateral frontoparietal cortices. Laminar expression progressed from layer V to VI and finally II-IV. Somal labeling preceded fiber labeling by 2 d. Dopamine accelerated PV expression. In treated slices, a dense band of PV-immunoreactive neurons appeared in layer V at 7 d in vitro (DIV), and in all layers of frontoparietal cortex at 14 DIV, whereas in control slices such labeling did not appear until 14 and 21 DIV, respectively. The laminar distribution and dendritic branching of PV-immunoreactive neurons were quantified. More labeled neurons were in the superficial layers, and their dendritic arborizations were significantly increased by dopamine. Treatment with a D1 receptor agonist had little effect, whereas a D2 agonist mimicked dopamine's effects. Likewise, the D2 but not the D1 antagonist blocked dopamine-induced changes, indicating that they were mediated primarily by D2 receptors. Parvalbumin expression was accelerated by dopaminergic reinnervation of cortical slices that were cocultured with mesencephalic slices. Coapplication of the glutamate NMDA receptor antagonist MK801 or AP5 blocked dopamine-induced increases in dendritic branching, suggesting that changes were mediated partly by interaction with glutamate to alter cortical excitability.

Homeostasis of neuronal avalanches during postnatal cortex development in vitro

“…While the spatial resolution of the LFP recordings is too poor to clearly identify layer-specific activity, our analysis revealed that nLFPs were located towards the upper half of the cortex cultures, which corresponds to the developing superficial cortical layers (Cäser and Schüz, 1992;Götz and Bolz, 1992;Porter, Rizzo et al, 1999). Furthermore, cortical slice cultures have been demonstrated to maintain their cortical layers for many months in culture (Plenz and Kitai, 1996;Plenz and Aertsen, 1996a;Klostermann and Wahle, 1999).…”

Neuronal avalanches organize as nested theta- and beta/gamma-oscillations during development of cortical layer 2/3

“…It is well established that layer 2/3 develops in organotypic cortex cultures prepared from tissue taken at early postnatal age (10,21,22). Therefore, slices of somatosensory cortex and the ventral tegmental area (VTA), which provides dopaminergic input to the cortex that facilitates the maturation of layer 2/3 fast-spiking interneurons (23), were taken at P1-P2 and cocultured on planar 8 ϫ 8 MEAs (Fig. 1B).…”

Elevated dopamine levels during gestation produce region-specific decreases in neurogenesis and subtle deficits in neuronal numbers

“…1). Ascorbic acid was used to retard oxidation of L-DOPA in the water [32,44,50]. The treatments began on the 11 th day of pregnancy and lasted until parturition.…”

“…L-DOPA (2mg/ml) was dissolved in drinking water containing 0.025% ascorbic acid (Sigma). Ascorbic acid prevents oxidation of L-DOPA in the water [32,44,50]. Control groups received drinking water containing 0.025% ascorbic acid alone or drinking water without additives.…”