Subcellular distribution of α1G subunit of T‐type calcium channel in the mouse dorsal lateral geniculate nucleus

Abstract

T-type calcium channels play a pivotal role in regulating neural membrane excitability in the nervous system. However, the precise subcellular distributions of T-type channel subunits and their implication for membrane excitability are not well understood. Here we investigated the subcellular distribution of the α1G subunit of the calcium channel which is expressed highly in the mouse dorsal lateral geniculate nucleus (dLGN). Light microscopic analysis demonstrated that dLGN exhibits intense immunoperoxidase reactivity for the α1G subunit. Electron microscopic observation showed that the labeling was present in both the relay cells and interneurons and was found in the somatodendritic, but not axonal, domains of these cells. Most of the immunogold particles for the α1G subunit were either associated with the plasma membrane or the intracellular membranes. Reconstruction analysis of serial electron microscopic images revealed that the intensity of the intracellular labeling exhibited a gradient such that the labeling density was higher in the proximal dendrite and progressively decreased towards the distal dendrite. In contrast, the plasma membrane-associated particles were distributed with a uniform density over the somatodendritic surface of dLGN cells. The labeling density in the relay cell plasma membrane was about 3-fold higher than that of the interneurons. These results provide ultrastructural evidence for cell-type-specific expression levels and for uniform expression density of the α1G subunit over the plasma membrane of dLGN cells.

Anatomical localization of Cav3.1 calcium channels and electrophysiological effects of T-type calcium channel blockade in the motor thalamus of MPTP-treated monkeys

“…In line with previous rodent studies (Craig et al 1999;McKay et al 2006;Parajuli et al 2010;Perez-Reyes 2003;Talley et al 1999), our findings demonstrate that Ca v 3.1 immunoreactivity is strongly expressed throughout the monkey thalamus, with the exception of the reticular nucleus, which is known to be enriched in Ca v 3.3 (Liu et al 2011;Talley et al 1999). At the subcellular level, Ca v 3.1 immunostaining was found throughout the entire dendritic tree of thalamic projection neurons in normal and Parkinsonian monkeys.…”

Quantitative Regional and Ultrastructural Localization of the Cav2.3 Subunit of R-type Calcium Channel in Mouse Brain

“…Approximately 95% of the immunogold particles were found to be located within 42 nm (mean ϩ 2 ϫ SD) of the cytoplasmic face of the membrane, and this distance was taken as the threshold for considering immunogold particles as being attached to the plasma membrane. This threshold distance is consistent with reports from earlier studies (Lörincz et al, 2002;Báldi et al, 2010;Parajuli et al, 2010).…”

“…Animal anesthetization, fixation, and tissue processing for light microscopy (LM) and preembedding immunoelectron microscopy (EM) were performed as described previously (Kulik et al, 2004;Parajuli et al, 2010). Deeply anesthetized animals were transcardially perfused through the ascending aorta with 25 mM PBS, pH 7.4, for 1 min.…”

T-type calcium channels in synaptic plasticity

“…Although few data are already available concerning their precise localization in the various neuronal compartments, 48,49 calcium imaging technique, immunocytochemistry and electrophysiological recordings revealed that T-(R) calcium channels are not evenly distributed along dendrites. [50][51][52][53] For example, in CA1 pyramidal neurons where Ni 2C dependent synaptic plasticity mechanisms have been described at the Schaffer collateral synapses, 19,39 Ni 2C sensitive channels are more abundant in the distal area of the apical dendrites.…”