Rescue of Mesencephalic Dopaminergic Neurons in Culture by Low-Level Stimulation of Voltage-Gated Sodium Channels

Abstract

We used a model system in which dopaminergic (DA) neurons from embryonic rat mesencephalon undergo spontaneous and selective degeneration as they develop in culture. Here, we show that DA cell loss can be prevented efficiently by low concentrations of the Na ϩ channel agonist veratridine. The survival promoting effect of veratridine was reproduced by, but independent of, glial cell line-derived neurotrophic factor. Neuroprotection by veratridine was exquisitely specific to DA neurons, short-lived after withdrawal, and abolished by tetrodotoxin, indicating that activation of voltage-gated Na ϩ channels was crucially involved. Calcium measurements showed that veratridine-induced Na ϩ influx was necessary to maintain intracellular Ca 2ϩ within a neuroprotective range through the stimulation of low-voltage activated T-type calcium channels, a mechanism that was distinct from that elicited by high K ϩ -evoked depolarization. Interestingly, increasing neuronal excitability by treatment with apamin, an inhibitor of Ca 2ϩ -activated K ϩ channels, or with ouabain, a blocker of the Na ϩ /K ϩ -ATPase pump, was also neuroprotective by a mechanism involving T-type calcium channel activation. These results support the idea that mesencephalic DA neurons depend primarily on excitatory input for their survival during development.

The Sleep-Modulating Peptide Orexin-B Protects Midbrain Dopamine Neurons from Degeneration, Alone or in Cooperation with Nicotine

“…When comparing TH 1 cell numbers at 0 DIV (i.e., at the time of plating) and at 10 DIV, we found that more than 70% of these neurons had died in the course of maturation of the cultures ( Fig. 2A), which is in good agreement with previous reports (Salthun-Lassalle et al, 2004;Toulorge et al, 2011). This indicates that the increase in TH 1 cell numbers observed in the presence of OXB is most likely due to a reduction of DA cell demise that is spontaneous in this model system.…”

Engrailed protects mouse midbrain dopaminergic neurons against mitochondrial complex I insults

“…Primary mesencephalic cultures of E14.5 rat and mouse embryos were prepared as reported 43,44 . Mitochondrial activity.…”

Roles of Voltage-Dependent Sodium Channels in Neuronal Development, Pain, and Neurodegeneration

“…Immunohistochemical study with anti-tyrosine hydroxylase antibody by Salthun-Lassalle et al (29) showed that cultured dopaminergic neurons of embryonic rats underwent spontaneous apoptotic cell death, with condensed and fragmented chromatin. When the sodium channel agonist veratridine was applied chronically to the cultures, the apoptosis of tyrosine hydroxylase-positive neurons was prevented by approx.…”

“…In addition, sodium channels contribute to neuronal survival (29), remyelination of demyelinated axons (13, 30 -35), epigenetic selection of particular neurotransmitter phenotype out of the multiple repertories of neurotransmitters (36), and auto-modulation of sodium channel expression per se (37).…”