Article ID Journal Published Year Pages File Type
9410890 Molecular Brain Research 2005 13 Pages PDF
Abstract
Neurons of the basal forebrain (BF) possess unique combinations of voltage-gated membrane currents. Here, we describe subtypes of rat basal forebrain neurons based on patch-clamp analysis of low-voltage activated (LVA) calcium and tetrodotoxin-resistant (TTX-R) sodium currents combined with single-cell RT-PCR analysis. Neurons were identified by mRNA expression of choline acetyltransferase (ChAT+, cholinergic) and glutamate decarboxylase (GAD67, GABAergic). Four cell types were encountered: ChAT+, GAD+, ChAT+/GAD+ and ChAT−/GAD− cells. Both ChAT+ and ChAT+/GAD+ cells (71/75) displayed LVA currents and most (34/39) expressed mRNA for LVA Ca2+ channel subunits. Cav3.2 was detected in 31/34 cholinergic neurons and Cav3.1 was expressed in 6/34 cells. Three cells expressed both subunits. No single neurons showed Cav3.3 mRNA expression, although BF tissue expression was observed. In young rats (2-4 mo), ChAT+/GAD+ cells displayed larger LVA current densities compared to ChAT+ neurons, while these latter neurons displayed an age-related increase in current densities. Most (29/38) noncholinergic neurons (GAD+ and ChAT−/GAD−) possessed fast TTX-R sodium currents resembling those mediated by Na+ channel subunit Nav1.5. This subunit was expressed predominately in noncholinergic neurons. No cholinergic cells (0/75) displayed fast TTX-R currents. The TTX-R currents were faster and larger in GAD+ neurons compared to ChAT−/GAD− neurons. The properties of ChAT+/GAD+ neurons resemble those of ChAT+ neurons, rather than of GAD+ neurons. These results suggest novel features of subtypes of cholinergic and noncholinergic neurons within the BF that may provide new insights for understanding normal BF function.
Related Topics
Life Sciences Neuroscience Cellular and Molecular Neuroscience
Authors
, , ,