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What Elements of the Inflammatory System Are Necessary for Epileptogenesis In Vitro?(1,2).

Park KI, Dzhala V, Saponjian Y, Staley KJ - eNeuro (2015)

Bottom Line: Organotypic hippocampal brain slices can be maintained in culture independently of the systemic inflammatory system, and the rapid course of epileptogenesis in these cultures supports the idea that inflammation is not necessary for epilepsy.However, this preparation still retains key cellular inflammatory mediators.These data support the idea that although the inflammatory system, neurons, and glia share key intercellular signaling molecules, neither systemic nor CNS-specific cellular elements of the immune and inflammatory systems are necessary components of epileptogenesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts 02129 ; Seoul Paik Hospital, Inje University , Seoul 100-032, South Korea.

ABSTRACT
Epileptogenesis in vivo can be altered by manipulation of molecules such as cytokines and complement that subserve intercellular signaling in both the inflammatory and central nervous systems. Because of the dual roles of these signaling molecules, it has been difficult to precisely define the role of systemic inflammation in epileptogenesis. Organotypic hippocampal brain slices can be maintained in culture independently of the systemic inflammatory system, and the rapid course of epileptogenesis in these cultures supports the idea that inflammation is not necessary for epilepsy. However, this preparation still retains key cellular inflammatory mediators. Here, we found that rodent hippocampal organotypic slice cultures depleted of T lymphocytes and microglia developed epileptic activity at essentially the same rate and to similar degrees of severity as matched control slice cultures. These data support the idea that although the inflammatory system, neurons, and glia share key intercellular signaling molecules, neither systemic nor CNS-specific cellular elements of the immune and inflammatory systems are necessary components of epileptogenesis.

No MeSH data available.


Related in: MedlinePlus

Effect of microglial depletion on epileptogenesis in cultured rat slices. A, Liposomal (Lipo) clodronate or liposome-control was exposed to slices from DIV0 to 6 and spontaneous seizure-like activities were recorded at DIV6, 12, or 22 according to the indicated protocols. B, The proportions of slices demonstrating seizure-like activity during recording were not different between microglia-negative group and control group (n = 6-8 per group, p = 0.24, 0.52, and 0.60. respectively). C−E, Seizure frequency, total recorded seizure time, and mean seizure duration tend to be higher in slices depleted of microglia, although none of these differences were statistically different (n = 6-8 per group, p = 0.24, 0.30, and 0.28, respectively). N.S, Not significant. All values are expressed as mean ± SEM.
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Figure 3: Effect of microglial depletion on epileptogenesis in cultured rat slices. A, Liposomal (Lipo) clodronate or liposome-control was exposed to slices from DIV0 to 6 and spontaneous seizure-like activities were recorded at DIV6, 12, or 22 according to the indicated protocols. B, The proportions of slices demonstrating seizure-like activity during recording were not different between microglia-negative group and control group (n = 6-8 per group, p = 0.24, 0.52, and 0.60. respectively). C−E, Seizure frequency, total recorded seizure time, and mean seizure duration tend to be higher in slices depleted of microglia, although none of these differences were statistically different (n = 6-8 per group, p = 0.24, 0.30, and 0.28, respectively). N.S, Not significant. All values are expressed as mean ± SEM.

Mentions: The preceding experiments indicate that microglial depletion had no anticonvulsant effect on seizure activity in cultured slices in which epilepsy was established. To evaluate the role of microglia on epileptogenesis, we applied clodronate before the onset of seizures, that is, from the beginning of culture (DIV0) to DIV6. In the organotypic hippocampal slice model, this time period is considered as the “latent” period, i.e. the time between brain injury and the development of spontaneous seizure activity (Berdichevsky et al., 2012). Following microglial depletion, field potentials were recorded at DIV6, 12, and 22 (Fig. 3A). SLAs were observed in 83.3% (vs 50% in control, n = 6 each group, p = 0.24h), 83.3% (vs 66.7% in control, n = 6 each group, p = 0.52i), and 37.5% (vs 25.0% in control, n = 8 each group, p = 0.60j) in microglia-depleted slices on recoding at DIV6, 12, and 22, respectively. Overall, the proportions of epileptic slices, which were defined as having more than one seizure during the observation time, were not statistically different between the microglia-depleted and control groups (Fig. 3B). The values for SLA frequency, duty cycle, and duration are listed in Table 3. On recording at DIV6 and 22, there were no significant differences in these parameters between microglia-depleted and control slices. These three parameters tended to be increased in microglia-depleted slices at DIV12, but the differences did not reach significance between the groups (Fig. 3C−E). Overall, there were no statistical differences between groups or agesk.


What Elements of the Inflammatory System Are Necessary for Epileptogenesis In Vitro?(1,2).

Park KI, Dzhala V, Saponjian Y, Staley KJ - eNeuro (2015)

Effect of microglial depletion on epileptogenesis in cultured rat slices. A, Liposomal (Lipo) clodronate or liposome-control was exposed to slices from DIV0 to 6 and spontaneous seizure-like activities were recorded at DIV6, 12, or 22 according to the indicated protocols. B, The proportions of slices demonstrating seizure-like activity during recording were not different between microglia-negative group and control group (n = 6-8 per group, p = 0.24, 0.52, and 0.60. respectively). C−E, Seizure frequency, total recorded seizure time, and mean seizure duration tend to be higher in slices depleted of microglia, although none of these differences were statistically different (n = 6-8 per group, p = 0.24, 0.30, and 0.28, respectively). N.S, Not significant. All values are expressed as mean ± SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596089&req=5

Figure 3: Effect of microglial depletion on epileptogenesis in cultured rat slices. A, Liposomal (Lipo) clodronate or liposome-control was exposed to slices from DIV0 to 6 and spontaneous seizure-like activities were recorded at DIV6, 12, or 22 according to the indicated protocols. B, The proportions of slices demonstrating seizure-like activity during recording were not different between microglia-negative group and control group (n = 6-8 per group, p = 0.24, 0.52, and 0.60. respectively). C−E, Seizure frequency, total recorded seizure time, and mean seizure duration tend to be higher in slices depleted of microglia, although none of these differences were statistically different (n = 6-8 per group, p = 0.24, 0.30, and 0.28, respectively). N.S, Not significant. All values are expressed as mean ± SEM.
Mentions: The preceding experiments indicate that microglial depletion had no anticonvulsant effect on seizure activity in cultured slices in which epilepsy was established. To evaluate the role of microglia on epileptogenesis, we applied clodronate before the onset of seizures, that is, from the beginning of culture (DIV0) to DIV6. In the organotypic hippocampal slice model, this time period is considered as the “latent” period, i.e. the time between brain injury and the development of spontaneous seizure activity (Berdichevsky et al., 2012). Following microglial depletion, field potentials were recorded at DIV6, 12, and 22 (Fig. 3A). SLAs were observed in 83.3% (vs 50% in control, n = 6 each group, p = 0.24h), 83.3% (vs 66.7% in control, n = 6 each group, p = 0.52i), and 37.5% (vs 25.0% in control, n = 8 each group, p = 0.60j) in microglia-depleted slices on recoding at DIV6, 12, and 22, respectively. Overall, the proportions of epileptic slices, which were defined as having more than one seizure during the observation time, were not statistically different between the microglia-depleted and control groups (Fig. 3B). The values for SLA frequency, duty cycle, and duration are listed in Table 3. On recording at DIV6 and 22, there were no significant differences in these parameters between microglia-depleted and control slices. These three parameters tended to be increased in microglia-depleted slices at DIV12, but the differences did not reach significance between the groups (Fig. 3C−E). Overall, there were no statistical differences between groups or agesk.

Bottom Line: Organotypic hippocampal brain slices can be maintained in culture independently of the systemic inflammatory system, and the rapid course of epileptogenesis in these cultures supports the idea that inflammation is not necessary for epilepsy.However, this preparation still retains key cellular inflammatory mediators.These data support the idea that although the inflammatory system, neurons, and glia share key intercellular signaling molecules, neither systemic nor CNS-specific cellular elements of the immune and inflammatory systems are necessary components of epileptogenesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts 02129 ; Seoul Paik Hospital, Inje University , Seoul 100-032, South Korea.

ABSTRACT
Epileptogenesis in vivo can be altered by manipulation of molecules such as cytokines and complement that subserve intercellular signaling in both the inflammatory and central nervous systems. Because of the dual roles of these signaling molecules, it has been difficult to precisely define the role of systemic inflammation in epileptogenesis. Organotypic hippocampal brain slices can be maintained in culture independently of the systemic inflammatory system, and the rapid course of epileptogenesis in these cultures supports the idea that inflammation is not necessary for epilepsy. However, this preparation still retains key cellular inflammatory mediators. Here, we found that rodent hippocampal organotypic slice cultures depleted of T lymphocytes and microglia developed epileptic activity at essentially the same rate and to similar degrees of severity as matched control slice cultures. These data support the idea that although the inflammatory system, neurons, and glia share key intercellular signaling molecules, neither systemic nor CNS-specific cellular elements of the immune and inflammatory systems are necessary components of epileptogenesis.

No MeSH data available.


Related in: MedlinePlus