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Carbamazepine modulates the spatiotemporal activity in the dentate gyrus of rats and pharmacoresistant humans in vitro.

Cappaert NL, Werkman TR, Benito N, Witter MP, Baayen JC, Wadman WJ - Brain Behav (2016)

Bottom Line: Bath applied CBZ (100 μmol/L) reduced the amplitude of the evoked responses in the human DG, albeit that no clear use-dependent effects were found at frequencies of 8 or 16 Hz.This study demonstrates that CBZ still reduced the activity in the DG, although the patients were clinically diagnosed as pharmacoresistant for CBZ.We also concluded that the effect of CBZ was found in the activated region of the DG, quite comparable to the observations in the nonepileptic rat.

View Article: PubMed Central - PubMed

Affiliation: Swammerdam Institute for Life Sciences - Center for NeuroScience University of Amsterdam Amsterdam The Netherlands.

ABSTRACT

Introduction: Human hippocampal tissue resected from pharmacoresistant epilepsy patients was investigated to study the effect of the antiepileptic drug CBZ (carbamazepine) and was compared to similar experiments in the hippocampus of control rats.

Methods: The molecular layer of the DG (dentate gyrus) of human epileptic tissue and rat nonepileptic tissue was electrically stimulated and the evoked responses were recorded with voltage-sensitive dye imaging to characterize the spatiotemporal properties.

Results: Bath applied CBZ (100 μmol/L) reduced the amplitude of the evoked responses in the human DG, albeit that no clear use-dependent effects were found at frequencies of 8 or 16 Hz. In nonepileptic control DG from rats, CBZ also reduced the amplitude of the evoked response in the molecular layer of the DG as well as the spatial extent of the response.

Conclusions: This study demonstrates that CBZ still reduced the activity in the DG, although the patients were clinically diagnosed as pharmacoresistant for CBZ. This suggests that in the human epileptic brain, the targets of CBZ, the voltage-gated Na(+) channels, are still sensitive to CBZ, although we used a relative high concentration and it is not possibility to assess the actual CBZ concentration that reached the target in the patient. We also concluded that the effect of CBZ was found in the activated region of the DG, quite comparable to the observations in the nonepileptic rat.

No MeSH data available.


Related in: MedlinePlus

Input–output response of human dentate gyrus. (A) Image of the DG (dentate gyrus) area of a recorded human hippocampal slice (slice 1 of case 1, Table 1). The black solid line indicates the outline of the ML (molecular layer) and the dotted lines mark the boundaries of the GC (granule cell) layer. The polymorphic layer or hilus is indicated with PML. The red hexagonal overlay represents the outline of the photodiode array. The magenta circle and blue diamond indicate the VSDi recording sites shown in (B). The position of the bipolar stimulation electrode is indicated by the black arrow. The scale bar represents 1 mm. (B) Optical responses recorded in the DG of the human hippocampal slice shown in A to a double pulse stimulus (timing indicated by gray vertical lines) of 100–500 μA, with an interpulse interval (IPI) of 20 msec. The traces are recorded in the ML layer of the DG and are an average of three photodiodes located in the stimulated blade (B1 indicated with a magenta circle in A) and in the nonstimulated blade of DG (B2 indicated with a blue diamond in A). (C) The responses presented in B are integrated from 0 to 15 msec (indicated by the black horizontal lines in B) after the first stimulus pulse for every VSDi recording site. These integrated values are represented in color code at the corresponding location of these recording sites in the photodiode array and are depicted for 100, 300, and 500 μA stimulation. The black and red shapes are the outlines of the anatomical regions and photodiode array, respectively, as in A. The position of the bipolar stimulation electrode is indicated by black arrows.
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brb3463-fig-0001: Input–output response of human dentate gyrus. (A) Image of the DG (dentate gyrus) area of a recorded human hippocampal slice (slice 1 of case 1, Table 1). The black solid line indicates the outline of the ML (molecular layer) and the dotted lines mark the boundaries of the GC (granule cell) layer. The polymorphic layer or hilus is indicated with PML. The red hexagonal overlay represents the outline of the photodiode array. The magenta circle and blue diamond indicate the VSDi recording sites shown in (B). The position of the bipolar stimulation electrode is indicated by the black arrow. The scale bar represents 1 mm. (B) Optical responses recorded in the DG of the human hippocampal slice shown in A to a double pulse stimulus (timing indicated by gray vertical lines) of 100–500 μA, with an interpulse interval (IPI) of 20 msec. The traces are recorded in the ML layer of the DG and are an average of three photodiodes located in the stimulated blade (B1 indicated with a magenta circle in A) and in the nonstimulated blade of DG (B2 indicated with a blue diamond in A). (C) The responses presented in B are integrated from 0 to 15 msec (indicated by the black horizontal lines in B) after the first stimulus pulse for every VSDi recording site. These integrated values are represented in color code at the corresponding location of these recording sites in the photodiode array and are depicted for 100, 300, and 500 μA stimulation. The black and red shapes are the outlines of the anatomical regions and photodiode array, respectively, as in A. The position of the bipolar stimulation electrode is indicated by black arrows.

Mentions: In the recording chamber, the electrically evoked optical responses were recorded with a 464‐channel, hexagonally arranged, photodiode array (H‐469II Photodiode Array, WuTech Instruments, Gaithersburg, MD). A 5x objective (0.25 NA Fluar, Zeiss, Oberkochen, Germany) was used to project the image of the slice onto the array. A second optical channel in the microscope (Axioskop 2FS, Zeiss, Germany) allowed taking images of the slice (SPOT, Diagnostic Instruments, Stirling Heights, NJ) for offline superposition of the morphology on the diode recording sites. In Figure 1A, the hexagonal‐shaped area of the diode array is indicated as overlay on a human hippocampal slice. The slice was illuminated with 705 ± 5 nm (Jin et al., 2002). The signal from each diode was high‐pass filtered (>0.2 Hz), amplified, and then digitized at 1 kHz with a 12‐bit data acquisition board (DAP 3200a/415 Microstar Laboratories, Bellevue, WA). The data acquisition was controlled by a custom‐made program (for details, see Wu et al., 1999).


Carbamazepine modulates the spatiotemporal activity in the dentate gyrus of rats and pharmacoresistant humans in vitro.

Cappaert NL, Werkman TR, Benito N, Witter MP, Baayen JC, Wadman WJ - Brain Behav (2016)

Input–output response of human dentate gyrus. (A) Image of the DG (dentate gyrus) area of a recorded human hippocampal slice (slice 1 of case 1, Table 1). The black solid line indicates the outline of the ML (molecular layer) and the dotted lines mark the boundaries of the GC (granule cell) layer. The polymorphic layer or hilus is indicated with PML. The red hexagonal overlay represents the outline of the photodiode array. The magenta circle and blue diamond indicate the VSDi recording sites shown in (B). The position of the bipolar stimulation electrode is indicated by the black arrow. The scale bar represents 1 mm. (B) Optical responses recorded in the DG of the human hippocampal slice shown in A to a double pulse stimulus (timing indicated by gray vertical lines) of 100–500 μA, with an interpulse interval (IPI) of 20 msec. The traces are recorded in the ML layer of the DG and are an average of three photodiodes located in the stimulated blade (B1 indicated with a magenta circle in A) and in the nonstimulated blade of DG (B2 indicated with a blue diamond in A). (C) The responses presented in B are integrated from 0 to 15 msec (indicated by the black horizontal lines in B) after the first stimulus pulse for every VSDi recording site. These integrated values are represented in color code at the corresponding location of these recording sites in the photodiode array and are depicted for 100, 300, and 500 μA stimulation. The black and red shapes are the outlines of the anatomical regions and photodiode array, respectively, as in A. The position of the bipolar stimulation electrode is indicated by black arrows.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834359&req=5

brb3463-fig-0001: Input–output response of human dentate gyrus. (A) Image of the DG (dentate gyrus) area of a recorded human hippocampal slice (slice 1 of case 1, Table 1). The black solid line indicates the outline of the ML (molecular layer) and the dotted lines mark the boundaries of the GC (granule cell) layer. The polymorphic layer or hilus is indicated with PML. The red hexagonal overlay represents the outline of the photodiode array. The magenta circle and blue diamond indicate the VSDi recording sites shown in (B). The position of the bipolar stimulation electrode is indicated by the black arrow. The scale bar represents 1 mm. (B) Optical responses recorded in the DG of the human hippocampal slice shown in A to a double pulse stimulus (timing indicated by gray vertical lines) of 100–500 μA, with an interpulse interval (IPI) of 20 msec. The traces are recorded in the ML layer of the DG and are an average of three photodiodes located in the stimulated blade (B1 indicated with a magenta circle in A) and in the nonstimulated blade of DG (B2 indicated with a blue diamond in A). (C) The responses presented in B are integrated from 0 to 15 msec (indicated by the black horizontal lines in B) after the first stimulus pulse for every VSDi recording site. These integrated values are represented in color code at the corresponding location of these recording sites in the photodiode array and are depicted for 100, 300, and 500 μA stimulation. The black and red shapes are the outlines of the anatomical regions and photodiode array, respectively, as in A. The position of the bipolar stimulation electrode is indicated by black arrows.
Mentions: In the recording chamber, the electrically evoked optical responses were recorded with a 464‐channel, hexagonally arranged, photodiode array (H‐469II Photodiode Array, WuTech Instruments, Gaithersburg, MD). A 5x objective (0.25 NA Fluar, Zeiss, Oberkochen, Germany) was used to project the image of the slice onto the array. A second optical channel in the microscope (Axioskop 2FS, Zeiss, Germany) allowed taking images of the slice (SPOT, Diagnostic Instruments, Stirling Heights, NJ) for offline superposition of the morphology on the diode recording sites. In Figure 1A, the hexagonal‐shaped area of the diode array is indicated as overlay on a human hippocampal slice. The slice was illuminated with 705 ± 5 nm (Jin et al., 2002). The signal from each diode was high‐pass filtered (>0.2 Hz), amplified, and then digitized at 1 kHz with a 12‐bit data acquisition board (DAP 3200a/415 Microstar Laboratories, Bellevue, WA). The data acquisition was controlled by a custom‐made program (for details, see Wu et al., 1999).

Bottom Line: Bath applied CBZ (100 μmol/L) reduced the amplitude of the evoked responses in the human DG, albeit that no clear use-dependent effects were found at frequencies of 8 or 16 Hz.This study demonstrates that CBZ still reduced the activity in the DG, although the patients were clinically diagnosed as pharmacoresistant for CBZ.We also concluded that the effect of CBZ was found in the activated region of the DG, quite comparable to the observations in the nonepileptic rat.

View Article: PubMed Central - PubMed

Affiliation: Swammerdam Institute for Life Sciences - Center for NeuroScience University of Amsterdam Amsterdam The Netherlands.

ABSTRACT

Introduction: Human hippocampal tissue resected from pharmacoresistant epilepsy patients was investigated to study the effect of the antiepileptic drug CBZ (carbamazepine) and was compared to similar experiments in the hippocampus of control rats.

Methods: The molecular layer of the DG (dentate gyrus) of human epileptic tissue and rat nonepileptic tissue was electrically stimulated and the evoked responses were recorded with voltage-sensitive dye imaging to characterize the spatiotemporal properties.

Results: Bath applied CBZ (100 μmol/L) reduced the amplitude of the evoked responses in the human DG, albeit that no clear use-dependent effects were found at frequencies of 8 or 16 Hz. In nonepileptic control DG from rats, CBZ also reduced the amplitude of the evoked response in the molecular layer of the DG as well as the spatial extent of the response.

Conclusions: This study demonstrates that CBZ still reduced the activity in the DG, although the patients were clinically diagnosed as pharmacoresistant for CBZ. This suggests that in the human epileptic brain, the targets of CBZ, the voltage-gated Na(+) channels, are still sensitive to CBZ, although we used a relative high concentration and it is not possibility to assess the actual CBZ concentration that reached the target in the patient. We also concluded that the effect of CBZ was found in the activated region of the DG, quite comparable to the observations in the nonepileptic rat.

No MeSH data available.


Related in: MedlinePlus