Nevertheless, these findings provide evidence showing that Acb NMDA receptors play an important role in the expression of ethanol-conditioned behavior. “
“Neurons and glia in the central nervous system originate from neural stem and progenitor cells that reside in the ventricular zones. Here we examine the role of β-catenin in neural stem cell (NSC) regulation in mouse embryos lacking β-catenin specifically in the brain germinal zone. PD0332991 An in vitro clonal neurosphere assay was performed in order to ascertain the status of the NSC population. Intact
neurospheres did not form from β-catenin-null cells due to a loss of cell adhesion and the number of expanded cells was reduced. Rescue of β-catenin expression restored adhesion and revealed that the number of NSCs increased in the knockout population. Using a clonal colony-forming assay, which confines precursor cells within a solid collagen matrix, we show that the number of NSCs in the hippocampus is unchanged although the β-catenin knockout striatum actually contains
a larger proportion of NSCs. However, these colonies were smaller than those of control cells, due to increased apoptosis in the progenitor population. Furthermore, β-catenin knockout NSCs also retained multipotentiality as shown by their ability to clonally differentiate into check details neurons and glia. The effects on neural precursor cells were not due to loss of downstream T-cell factor signaling, as this pathway is not active in vivo in regions of the embryonic brain where NSCs and progenitor cells reside, nor is it active in vitro in NSC colonies. These data reveal that β-catenin is not required for the maintenance or differentiation of NSCs, but is required for the MRIP adhesion and survival of neural progenitor cells. “
“The biophysical properties and distribution of voltage-dependent, Ca2+ -modulated K+ (BKCa) currents among subpopulations of acutely dissociated DiI-labeled cutaneous sensory neurons from the adult
rat were characterized with whole-cell patch-clamp techniques. BKCa currents were isolated from total K+ current with iberiotoxin, charybdotoxin or paxilline. There was considerable variability in biophysical properties of BKCa currents. There was also variability in the distribution of BKCa current among subpopulations of cutaneous dorsal root ganglia (DRG) neurons. While present in each of the subpopulations defined by cell body size, IB4 binding or capsaicin sensitivity, BKCa current was present in the vast majority (> 90%) of small-diameter IB4+ neurons, but was present in only a minority of neurons in subpopulations defined by other criteria (i.e. small-diameter IB4−). Current-clamp analysis indicated that in IB4+ neurons, BKCa currents contribute to the repolarization of the action potential and adaptation in response to sustained membrane depolarization, while playing little role in the determination of action potential threshold.