Delayed kindling epileptogenesis and increased neurogenesis in adult rats housed in an enriched environment

Auvergne, Romane; Leré, Carole; Bahh, Bouchaib El; Arthaud, Sébastien; Lespinet, Véronique; Rougier, Alain

doi:10.1016/s0006-8993(02)03355-3

Cited by 88 publications

(61 citation statements)

References 64 publications

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“…Finally, although with the present approach double-labeled cells appeared to be more common in epileptic animals, consistent with the neurogenic and survival-promoting effects of seizures (Parent et al, 1997(Parent et al, , 1998Scott and Burnham, 2006), sufficient numbers of control neurons were available without the need for other neurogenic stimuli such as wheel running or environmental enrichment (Kempermann et al, 1998;van Praag et al, 1999). Notably, these stimuli can also alter granule cell morphology (Eadie et al, 2005) and epileptogenesis (Young et al, 1999;Auvergne et al, 2002).…”

Section: Advantages and Limitations Of The Present Approachsupporting

confidence: 66%

Pilocarpine-Induced Seizures Cause Selective Time-Dependent Changes to Adult-Generated Hippocampal Dentate Granule Cells

Walter¹,

Murphy²,

Pun³

et al. 2007

J. Neurosci.

163

176

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Aberrantly interconnected granule cells are characteristic of temporal lobe epilepsy. By reducing network stability, these abnormal neurons may contribute directly to disease development. Only subsets of granule cells, however, exhibit abnormalities. Why this is the case is not known. Ongoing neurogenesis in the adult hippocampus may provide an explanation. Newly generated granule cells may be uniquely vulnerable to environmental disruptions relative to their mature neighbors. Here, we determine whether there is a critical period after neuronal birth during which neuronal integration can be disrupted by an epileptogenic insult. By bromodeoxyuridine birthdating cells in green fluorescent protein-expressing transgenic mice, we were able to noninvasively label granule cells born 8 weeks before (mature), 1 week before (immature), or 3 weeks after (newborn) pilocarpineepileptogenesis. Neuronal morphology was examined 4 and 8 weeks after pilocarpine treatment. Strikingly, almost 50% of immature granule cells exposed to pilocarpine-epileptogenesis exhibited aberrant hilar basal dendrites. In contrast, only 9% of mature granule cells exposed to the identical insult possessed basal dendrites. Moreover, newborn cells were even more severely impacted than immature cells, with 40% exhibiting basal dendrites and an additional 20% exhibiting migration defects. In comparison, Ͻ5% of neurons from normal animals exhibited either abnormality, regardless of age. Together, these data demonstrate the existence of a critical period after the birth of adult-generated neurons during which they are vulnerable to being recruited into epileptogenic neuronal circuits. Pathological brain states therefore may pose a significant hurdle for the appropriate integration of newly born endogenous, and exogenous, neurons.

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Section: Advantages and Limitations Of The Present Approachsupporting

confidence: 66%

Pilocarpine-Induced Seizures Cause Selective Time-Dependent Changes to Adult-Generated Hippocampal Dentate Granule Cells

Walter¹,

Murphy²,

Pun³

et al. 2007

J. Neurosci.

163

176

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“…From this perspective, it is tempting to conclude that enrichment induced improvements in learning and memory performance in rats that underwent SE is due to increased dentate neurogenesis, as this neurogenesis is considered important for hippocampal-dependent spatial memory functions (Kee et al, 2007). A similar increase in dentate neurogenesis has been observed in adult amygdala kindled rats with environmental enrichment (Auvergne et al, 2002). However, increased dentate neurogenesis at early timepoints (2-4 weeks) after the SE is a normal phenomenon observed in rats that undergo SE and housed in standard conditions (Hattiangady et al, 2004;Jessberger et al, 2007).…”

Section: Capability For Improving Cognitive Functionmentioning

confidence: 84%

Is exposure to enriched environment beneficial for functional post-lesional recovery in temporal lobe epilepsy?

Dhanushkodi

Shetty

2008

Neuroscience & Biobehavioral Reviews

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Exposure to environmental enrichment has been shown to induce robust neuronal plasticity in both intact and injured adult central nervous system, including up-regulation of multiple neurotrophic factors, enhanced neurogenesis in the dentate gyrus of the hippocampus, and improved spatial learning and memory function. Neuronal plasticity, though mostly adaptive and abnormal, also occurs during certain neurodegenerative conditions such as the temporal lobe epilepsy (TLE). The TLE is characterized by hippocampal neurodegeneration, aberrant mossy fiber sprouting, spontaneous recurrent motor seizures, cognitive deficits, and abnormally enhanced neurogenesis during the early phase and dramatically declined neurogenesis during the chronic phase of the disease. As enrichment has been found to be beneficial for treating animal models of Alzheimer's, Parkinson's, and Huntington's diseases, there is considerable interest in determining the efficacy of this strategy for preventing or treating chronic TLE after the initial precipitating brain injury. This review first discusses the proof of principle behind the potential application of the environmental enrichment strategy for preventing or treating TLE after brain injury. The subsequent chapters confer the portrayed beneficial effects of enrichment for functional post-lesional recovery in TLE and the possible complications which may arise from housing epilepsy-prone or epileptic rats in enriched environmental conditions. The final segment discusses studies that are essential for further understanding the efficacy of this approach for preventing or treating TLE.

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“…Altogether, our results indicate that induction of EpoR gene expression in vulnerable brain areas by 3H is a prerequisite to optimize neuroprotective effects of rhEpo. Unfortunately, this concept could not be tested in the HiD, where EpoR gene expression is enhanced in rats raised in EC and subjected to 3H, due to the inhibitory effect of environmental enrichment on the development of brain excitability and SE (35,36).…”

Section: Discussionmentioning

confidence: 99%

Optimal neuroprotection by erythropoietin requires elevated expression of its receptor in neurons

Sanchez

Fares

Risso

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Erythropoietin receptor (EpoR) binding mediates neuroprotection by endogenous Epo or by exogenous recombinant human (rh)Epo.The level of EpoR gene expression may determine tissue responsiveness to Epo. Thus, harnessing the neuroprotective power of Epo requires an understanding of the Epo-EpoR system and its regulation. We tested the hypothesis that neuronal expression of EpoR is required to achieve optimal neuroprotection by Epo. The ventral limbic region (VLR) in the rat brain was used because we determined that its neurons express minimal EpoR under basal conditions, and they are highly sensitive to excitotoxic damage, such as occurs with pilocarpine-induced status epilepticus (Pilo-SE). We report that (i) EpoR expression is significantly elevated in nearly all VLR neurons when rats are subjected to 3 moderate hypoxic exposures, with each separated by a 4-day interval; (ii) synergistic induction of EpoR expression is achieved in the dorsal hippocampus and neocortex by the combination of hypoxia and exposure to an enriched environment, with minimal increased expression by either treatment alone; and (iii) rhEpo administered after Pilo-SE cannot rescue neurons in the VLR, unless neuronal induction of EpoR is elicited by hypoxia before Pilo-SE. This study thus demonstrates using environmental manipulations in normal rodents, the strict requirement for induction of EpoR expression in brain neurons to achieve optimal neuroprotection. Our results indicate that regulation of EpoR gene expression may facilitate the neuroprotective potential of rhEpo.hypoxia ͉ environmental enrichment ͉ epilepsy ͉ limbic system ͉ enviromimetic

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Delayed kindling epileptogenesis and increased neurogenesis in adult rats housed in an enriched environment

Cited by 88 publications

References 64 publications

Pilocarpine-Induced Seizures Cause Selective Time-Dependent Changes to Adult-Generated Hippocampal Dentate Granule Cells

Pilocarpine-Induced Seizures Cause Selective Time-Dependent Changes to Adult-Generated Hippocampal Dentate Granule Cells

Is exposure to enriched environment beneficial for functional post-lesional recovery in temporal lobe epilepsy?

Optimal neuroprotection by erythropoietin requires elevated expression of its receptor in neurons

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