| 1. |
- Leao, Richardson N., et al.
(författare)
-
A Voltage-Sensitive Dye-Based Assay for the Identification of Differentiated Neurons Derived from Embryonic Neural Stem Cell Cultures
- 2010
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:11, s. e13833-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Pluripotent and multipotent stem cells hold great therapeutical promise for the replacement of degenerated tissue in neurological diseases. To fulfill that promise we have to understand the mechanisms underlying the differentiation of multipotent cells into specific types of neurons. Embryonic stem cell (ESC) and embryonic neural stem cell (NSC) cultures provide a valuable tool to study the processes of neural differentiation, which can be assessed using immunohistochemistry, gene expression, Ca2+-imaging or electrophysiology. However, indirect methods such as protein and gene analysis cannot provide direct evidence of neuronal functionality. In contrast, direct methods such as electrophysiological techniques are well suited to produce direct evidence of neural functionality but are limited to the study of a few cells on a culture plate. Methodology/Principal Findings: In this study we describe a novel method for the detection of action potential-capable neurons differentiated from embryonic NSC cultures using fast voltage-sensitive dyes (VSD). We found that the use of extracellularly applied VSD resulted in a more detailed labeling of cellular processes compared to calcium indicators. In addition, VSD changes in fluorescence translated precisely to action potential kinetics as assessed by the injection of simulated slow and fast sodium currents using the dynamic clamp technique. We further demonstrate the use of a finite element model of the NSC culture cover slip for optimizing electrical stimulation parameters. Conclusions/Significance: Our method allows for a repeatable fast and accurate stimulation of neurons derived from stem cell cultures to assess their differentiation state, which is capable of monitoring large amounts of cells without harming the overall culture.
|
|
| 2. |
- Leão, Richardson N., et al.
(författare)
-
Medial septal dysfunction by A beta-induced KCNQ channel-block in glutamatergic neurons
- 2012
-
Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 33:9, s. 2046-2061
-
Tidskriftsartikel (refereegranskat)abstract
- Amyloid beta (A beta) peptides play a central role in the pathophysiology of Alzheimer's disease (AD). The cellular mechanisms underlying A beta toxicity, however, are poorly understood. Here we show that A beta 25-35 and A beta 1-40 acutely and differentially affect the characteristics of 3 classes of medial septum (MS) neurons in mice. In glutamatergic neurons A beta increases firing frequency and blocks the A-and the M-current (I-A and I-M, respectively). While the I-A block is similar in other MS neuron classes, the block of I-M is specific to glutamatergic neurons. I-M block and a simulated A beta block mimic the A beta-induced increase in spontaneous firing in glutamatergic neurons. Calcium imaging shows that under control conditions glutamatergic neurons rarely fire while nonglutamatergic neurons fire coherently at theta frequencies. A beta increases the firing rate of glutamatergic neurons while nonglutamatergic neurons lose theta firing coherence. Our results demonstrate that A beta-induced dysfunction of glutamatergic neurons via I-M decrease diminishes MS rhythmicity, which may negatively affect hippocampal rhythmogenesis and underlie the memory loss observed in Alzheimer's disease.
|
|
| 3. |
- Leão, Richardson N, et al.
(författare)
-
Medial septal dysfunction by Aβ-induced KCNQ channel-block in glutamatergic neurons.
- 2012
-
Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 33:9, s. 2046-61
-
Tidskriftsartikel (refereegranskat)abstract
- Amyloid β (Aβ) peptides play a central role in the pathophysiology of Alzheimer's disease (AD). The cellular mechanisms underlying Aβ toxicity, however, are poorly understood. Here we show that Aβ(25-35) and Aβ(1-40) acutely and differentially affect the characteristics of 3 classes of medial septum (MS) neurons in mice. In glutamatergic neurons Aβ increases firing frequency and blocks the A- and the M-current (I(A) and I(M), respectively). While the I(A) block is similar in other MS neuron classes, the block of I(M) is specific to glutamatergic neurons. I(M) block and a simulated Aβ block mimic the Aβ-induced increase in spontaneous firing in glutamatergic neurons. Calcium imaging shows that under control conditions glutamatergic neurons rarely fire while nonglutamatergic neurons fire coherently at theta frequencies. Aβ increases the firing rate of glutamatergic neurons while nonglutamatergic neurons lose theta firing coherence. Our results demonstrate that Aβ-induced dysfunction of glutamatergic neurons via I(M) decrease diminishes MS rhythmicity, which may negatively affect hippocampal rhythmogenesis and underlie the memory loss observed in Alzheimer's disease.
|
|
