Biophysical Properties and Ionic Signature of Neuronal Progenitors of the Postnatal Subventricular Zone In Situ

Abstract

Previous studies have reported the presence of neuronal progenitors in the subventricular zone (SVZ) and rostral migratory stream (RMS) of the postnatal mammalian brain. Although many studies have examined the survival and migration of progenitors after transplantation and the factors influencing their proliferation or differentiation, no information is available on the electrophysiological properties of these progenitors in a near-intact environment. Thus we performed whole cell and cell-attached patch-clamp recordings of progenitors in brain slices containing either the SVZ or the RMS from postnatal day 15 to day 25 mice. Both regions displayed strong immunoreactivity for nestin and neuron-specific class III beta-tubulin, and recorded cells displayed a morphology typical of the neuronal progenitors known to migrate throughout the SVZ and RMS to the olfactory bulb. Recorded progenitors had depolarized zero-current resting potentials (mean more depolarized than -28 mV), very high input resistances (about 4 GOmega), and lacked action potentials. Using the reversal potential of K+ currents through a cell-attached patch a mean resting potential of -59 mV was estimated. Recorded progenitors displayed Ca2+-dependent K+ currents and TEA-sensitive-delayed rectifying K+ (KDR) currents, but lacked inward K+ currents and transient outward K+ currents. KDR currents displayed classical kinetics and were also sensitive to 4-aminopyridine and alpha-dendrotoxin, a blocker of Kv1 channels. Na+ currents were found in about 60% of the SVZ neuronal progenitors. No developmental changes were observed in the passive membrane properties and current profile of neuronal progenitors. Together these data suggest that SVZ neuronal progenitors display passive membrane properties and an ionic signature distinct from that of cultured SVZ neuronal progenitors and mature neurons.

Connexin 43 Delimits Functional Domains of Neurogenic Precursors in the Spinal Cord

“…Proliferating cells concentrated on the lateral CG belonged to clusters electrically and metabolically coupled via Cx43. The bipolar morphology and expression of BLBP indicated that these cells represent a subtype of RGs (Pinto and Götz, 2007) with electrophysiological properties similar to precursors found in neurogenic zones of the forebrain (Noctor et al, 2002;Filippov et al, 2003;Wang et al, 2003;Liu et al, 2006). The expression of Pax6 supports the persistence of postnatal neurogenic domains, a property that may be related with the remarkable ability of low vertebrates to recover after spinal cord injury.…”

How, When, and Where New Inhibitory Neurons Release Neurotransmitters in the Adult Olfactory Bulb

“…13a,b, available at www.jneurosci.org as supplemental material). New GCs acquired the ability to fire action potentials when the right balance between sodium and potassium currents was reached (Ͻ1 wpi) (see also Carleton et al, 2003;Wang et al, 2003). Soon after (ϳ2 wpi), we found that newborn neurons form the first functional GABAergic synapses with mitral cells.…”

AQP4 knockout impairs proliferation, migration and neuronal differentiation of adult neural stem cells

“…In mature neurons, this channel opens primarily in response to the depolarization provided by excitatory synaptic inputs (Weisskopf et al, 1999). Measurements of resting potential indicate that neural stem cells maintain resting potentials in the -55 mV range (Wang et al, 2003). Since neural stem cells tend to be more depolarized than mature quiescent neurons, Cav1.2 channels might partially open without depolarization stimulus (Wang et al, 2003;Westerlund et al, 2003 Luo et al, 2005;Wang et al, 2005).…”