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Dendritic morphology, synaptic transmission, and activity of mature granule cells born following pilocarpine-induced status epilepticus in the rat.

Gao F, Song X, Zhu D, Wang X, Hao A, Nadler JV, Zhan RZ - Front Cell Neurosci (2015)

Bottom Line: The complexity, spine density, miniature post-synaptic currents, and activity-regulated cytoskeleton-associated protein (Arc) expression of granule cells born 5 days after SE were studied between 10 and 17 weeks after CAG-GFP retroviral vector-mediated labeling.After maturation, granule cells born after SE did not show denser Arc expression in the resting condition or 2 h after being activated by pentylenetetrazol-induced transient seizure activity than vicinal GFP-unlabeled granule cells.Thus our results suggest that normotopic granule cells born after pilocarpine-induced SE are no more active when mature than age-matched, naturally born granule cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Shandong University School of Medicine Jinan, China.

ABSTRACT
To understand the potential role of enhanced hippocampal neurogenesis after pilocarpine-induced status epilepticus (SE) in the development of epilepsy, we quantitatively analyzed the geometry of apical dendrites, synaptic transmission, and activation levels of normotopically distributed mature newborn granule cells in the rat. SE in male Sprague-Dawley rats (between 6 and 7 weeks old) lasting for more than 2 h was induced by an intraperitoneal injection of pilocarpine. The complexity, spine density, miniature post-synaptic currents, and activity-regulated cytoskeleton-associated protein (Arc) expression of granule cells born 5 days after SE were studied between 10 and 17 weeks after CAG-GFP retroviral vector-mediated labeling. Mature granule cells born after SE had dendritic complexity similar to that of granule cells born naturally, but with denser mushroom-like spines in dendritic segments located in the outer molecular layer. Miniature inhibitory post-synaptic currents (mIPSCs) were similar between the controls and rats subjected to SE; however, smaller miniature excitatory post-synaptic current (mEPSC) amplitude with a trend toward less frequent was found in mature granule cells born after SE. After maturation, granule cells born after SE did not show denser Arc expression in the resting condition or 2 h after being activated by pentylenetetrazol-induced transient seizure activity than vicinal GFP-unlabeled granule cells. Thus our results suggest that normotopic granule cells born after pilocarpine-induced SE are no more active when mature than age-matched, naturally born granule cells.

No MeSH data available.


Related in: MedlinePlus

Bar graphs compare Arc immunoreactivity (IR) in the GFP-labeled newborn granule cells to surrounding GFP-negative granule cells in the resting condition and during the period of a transient seizure. The relative intensity of Arc IR in individual GFP-positive cells was normalized to the averaged Arc IR of 10 surrounding granule cells that represent existing granule cells. Each group contains six datasets in which each dataset was acquired from 10 GFP-labeled cells of each animal. Bars are standard error of the mean (SEM). Note that the Arc ratio is higher and more variable in PTZ-untreated control but very close to 1.0 in the rest of three groups. Statistical significances do not exist among the four groups as revealed by one-way variance analysis.
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Figure 8: Bar graphs compare Arc immunoreactivity (IR) in the GFP-labeled newborn granule cells to surrounding GFP-negative granule cells in the resting condition and during the period of a transient seizure. The relative intensity of Arc IR in individual GFP-positive cells was normalized to the averaged Arc IR of 10 surrounding granule cells that represent existing granule cells. Each group contains six datasets in which each dataset was acquired from 10 GFP-labeled cells of each animal. Bars are standard error of the mean (SEM). Note that the Arc ratio is higher and more variable in PTZ-untreated control but very close to 1.0 in the rest of three groups. Statistical significances do not exist among the four groups as revealed by one-way variance analysis.

Mentions: After PTZ treatments, tonic-clonic seizures were observed within 2 min in most rats and the intervals between two adjacent clonic seizures got longer over time. We terminated motor seizures by intraperitoneal injection of diazepam 15 min after the appearance of the first motor seizure. In PTZ-untreated controls, dentate granule cells constitutively expressed Arc at low level (Figure 7A). Arc immunoreactivity in granule cells of PTZ-untreated SE animals appeared more intense than that of granule cells in PTZ-untreated controls; however, the intensity of Arc immunoreactivity in the GFP-labeled newborn cells did not exceed that of nearby GFP-negative granule cells (Figure 7B). Treatment of controls with PTZ dramatically enhanced Arc immunoreactivity in the soma and apical dendrites of almost every granule cell (Figure 7C), but again, a difference between GFP-labeled granule cells and granule cells surrounding them could not be noticed. Treatment of SE rats with PTZ also increased Arc immunoreactivity in both the soma and apical dendrites of almost all granule cells and it appeared that the intensity of Arc immunoreactivity in GFP-labeled newborn granule cells was similar to that in adjacent GFP-negative granule cells (Figure 7D). Quantitative analyses that compared Arc immunoreactivity in GFP-labeled cells to the averaged Arc immunoreactivity of surrounding granule cells clearly shows that the intensities of Arc immunoreactivity in GFP-positive somata and dendrites were not different from surrounding granule cells in the resting condition (Figures 7A,B, 8) or during a transient seizure episode (Figures 7C,D, 8). Similar results were observed when c-fos was used as a cellular activity marker (Supplemental Figures 4, 5).


Dendritic morphology, synaptic transmission, and activity of mature granule cells born following pilocarpine-induced status epilepticus in the rat.

Gao F, Song X, Zhu D, Wang X, Hao A, Nadler JV, Zhan RZ - Front Cell Neurosci (2015)

Bar graphs compare Arc immunoreactivity (IR) in the GFP-labeled newborn granule cells to surrounding GFP-negative granule cells in the resting condition and during the period of a transient seizure. The relative intensity of Arc IR in individual GFP-positive cells was normalized to the averaged Arc IR of 10 surrounding granule cells that represent existing granule cells. Each group contains six datasets in which each dataset was acquired from 10 GFP-labeled cells of each animal. Bars are standard error of the mean (SEM). Note that the Arc ratio is higher and more variable in PTZ-untreated control but very close to 1.0 in the rest of three groups. Statistical significances do not exist among the four groups as revealed by one-way variance analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596052&req=5

Figure 8: Bar graphs compare Arc immunoreactivity (IR) in the GFP-labeled newborn granule cells to surrounding GFP-negative granule cells in the resting condition and during the period of a transient seizure. The relative intensity of Arc IR in individual GFP-positive cells was normalized to the averaged Arc IR of 10 surrounding granule cells that represent existing granule cells. Each group contains six datasets in which each dataset was acquired from 10 GFP-labeled cells of each animal. Bars are standard error of the mean (SEM). Note that the Arc ratio is higher and more variable in PTZ-untreated control but very close to 1.0 in the rest of three groups. Statistical significances do not exist among the four groups as revealed by one-way variance analysis.
Mentions: After PTZ treatments, tonic-clonic seizures were observed within 2 min in most rats and the intervals between two adjacent clonic seizures got longer over time. We terminated motor seizures by intraperitoneal injection of diazepam 15 min after the appearance of the first motor seizure. In PTZ-untreated controls, dentate granule cells constitutively expressed Arc at low level (Figure 7A). Arc immunoreactivity in granule cells of PTZ-untreated SE animals appeared more intense than that of granule cells in PTZ-untreated controls; however, the intensity of Arc immunoreactivity in the GFP-labeled newborn cells did not exceed that of nearby GFP-negative granule cells (Figure 7B). Treatment of controls with PTZ dramatically enhanced Arc immunoreactivity in the soma and apical dendrites of almost every granule cell (Figure 7C), but again, a difference between GFP-labeled granule cells and granule cells surrounding them could not be noticed. Treatment of SE rats with PTZ also increased Arc immunoreactivity in both the soma and apical dendrites of almost all granule cells and it appeared that the intensity of Arc immunoreactivity in GFP-labeled newborn granule cells was similar to that in adjacent GFP-negative granule cells (Figure 7D). Quantitative analyses that compared Arc immunoreactivity in GFP-labeled cells to the averaged Arc immunoreactivity of surrounding granule cells clearly shows that the intensities of Arc immunoreactivity in GFP-positive somata and dendrites were not different from surrounding granule cells in the resting condition (Figures 7A,B, 8) or during a transient seizure episode (Figures 7C,D, 8). Similar results were observed when c-fos was used as a cellular activity marker (Supplemental Figures 4, 5).

Bottom Line: The complexity, spine density, miniature post-synaptic currents, and activity-regulated cytoskeleton-associated protein (Arc) expression of granule cells born 5 days after SE were studied between 10 and 17 weeks after CAG-GFP retroviral vector-mediated labeling.After maturation, granule cells born after SE did not show denser Arc expression in the resting condition or 2 h after being activated by pentylenetetrazol-induced transient seizure activity than vicinal GFP-unlabeled granule cells.Thus our results suggest that normotopic granule cells born after pilocarpine-induced SE are no more active when mature than age-matched, naturally born granule cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Shandong University School of Medicine Jinan, China.

ABSTRACT
To understand the potential role of enhanced hippocampal neurogenesis after pilocarpine-induced status epilepticus (SE) in the development of epilepsy, we quantitatively analyzed the geometry of apical dendrites, synaptic transmission, and activation levels of normotopically distributed mature newborn granule cells in the rat. SE in male Sprague-Dawley rats (between 6 and 7 weeks old) lasting for more than 2 h was induced by an intraperitoneal injection of pilocarpine. The complexity, spine density, miniature post-synaptic currents, and activity-regulated cytoskeleton-associated protein (Arc) expression of granule cells born 5 days after SE were studied between 10 and 17 weeks after CAG-GFP retroviral vector-mediated labeling. Mature granule cells born after SE had dendritic complexity similar to that of granule cells born naturally, but with denser mushroom-like spines in dendritic segments located in the outer molecular layer. Miniature inhibitory post-synaptic currents (mIPSCs) were similar between the controls and rats subjected to SE; however, smaller miniature excitatory post-synaptic current (mEPSC) amplitude with a trend toward less frequent was found in mature granule cells born after SE. After maturation, granule cells born after SE did not show denser Arc expression in the resting condition or 2 h after being activated by pentylenetetrazol-induced transient seizure activity than vicinal GFP-unlabeled granule cells. Thus our results suggest that normotopic granule cells born after pilocarpine-induced SE are no more active when mature than age-matched, naturally born granule cells.

No MeSH data available.


Related in: MedlinePlus