Glutamate receptor properties of human mesencephalic neural progenitor cells: NMDA enhances dopaminergic neurogenesis in vitro

Abstract

Human midbrain‐derived neural progenitor cells (NPCs) may serve as a continuous source of dopaminergic neurons for the development of novel regenerative therapies in Parkinson’s disease. However, the molecular and functional characteristics of glutamate receptors in human NPCs are largely unknown. Here, we show that differentiated human mesencepahlic NPCs display a distinct pattern of glutamate receptors. In whole‐cell patch‐clamp recordings, l‐glutamate and NMDA elicited currents in 93% of NPCs after 3 weeks of differentiation in vitro. The concentration‐response plots of differentiated NPCs yielded an EC50 of 2.2 μM for glutamate and an EC50 of 36 μM for NMDA. Glutamate‐induced currents were markedly inhibited by memantine in contrast to 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) suggesting a higher density of functional NMDA than alpha‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA)/kainate receptors. NMDA‐evoked currents and calcium signals were blocked by the NR2B‐subunit specific antagonist ifenprodil indicating functional expression of NMDA receptors containing subunits NR1 and NR2B. In calcium imaging experiments, the blockade of voltage‐gated calcium channels by verapamil abolished AMPA‐induced calcium responses but only partially reduced NMDA‐evoked transients suggesting the expression of calcium‐impermeable, GluR2‐containing AMPA receptors. Quantitative real‐time PCR showed a predominant expression of subunits NR2A and NR2B (NMDA), GluR2 (AMPA), GluR7 (kainate), and mGluR3 (metabotropic glutamate receptor). Treatment of NPCs with 100 μM NMDA in vitro during proliferation (2 weeks) and differentiation (1 week) increased the amount of tyrosine hydroxylase‐immunopositive cells significantly, which was reversed by addition of memantine. These data suggest that NMDA receptors in differentiating human mesencephalic NPCs are important regulators of dopaminergic neurogenesis in vitro.

Neuregulin1/ErbB4-induced migration in ST14A striatal progenitors: calcium-dependent mechanisms and modulation by NMDA receptor activation

“…Data from several groups have suggested that neural stem cells and neural progenitors may express low levels of the NMDA receptor [25,26]. We tested the expression of all known NMDAR subunits in wt ST14A cells by RT-PCR.…”

Functional differentiation of midbrain neurons from human cord blood-derived induced pluripotent stem cells

“…We found that Ca 2+ transients in differentiated hCBiPSCs rose in a less pronounced fashion and in a fewer percentage of cells (22%) when glutamate receptors were stimulated, compared to studies with differentiated human fetal NPCs (>95%) [80]. On the other hand, during application of GABA more cells (62%) responded with higher Ca 2+ amplitudes in comparison with differentiated fetal NPCs (48%) [81].…”

Continued growth and circuit building in the anamniote visual system

“…Neurotransmitter-driven proliferation has been observed in the embryonic and adult brains of vertebrates (Schlett, 2006;Borta and Hoglinger, 2007;O'Keeffe et al, 2009;Wegner et al, 2009;Jhaveri et al, 2010;Rodrigo et al, 2010), and multiple reports hint that these small peptides also influence proliferation within the postembryonic retina of chickens, frogs, fish, and salamanders [reviewed in (Martins and Pearson, 2008)]. For example, glucagon, derived from amacrine cells, suppresses CMZ cell proliferation (Fischer et al, 2005) while serotonin, secreted by photoreceptors and found in the aqueous humor, promotes CMZ cell proliferation (De Lucchini et al, 2003;Reisoli et al, 2008).…”