Progressive loss of phasic, but not tonic, GABAA receptor-mediated inhibition in dentate granule cells in a model of post-traumatic epilepsy in rats.
Neuroscience
; 194: 208-19, 2011 Oct 27.
Article
em En
| MEDLINE
| ID: mdl-21840377
ABSTRACT
Traumatic brain injury (TBI) is a risk factor for the development of epilepsy, which can occur months to years after the insult. The hippocampus is particularly vulnerable to the pathophysiological effects of TBI. Here, we determined whether there are long-term changes in inhibition in the dentate gyrus that could contribute to the progressive susceptibility to seizures after TBI. We used severe lateral-fluid percussion brain injury to induce TBI in rats. In this model, spontaneous seizure activity, which involves the hippocampus, appears after a long latent period, resembling the human condition. We demonstrate that synaptic GABA(A) receptor-mediated inhibition is profoundly reduced in ipsilateral dentate granule cells 1 month after TBI. Moreover, synaptic inhibition decreases over time, and by 6 months after TBI, it is also significantly decreased contralaterally. Progressive loss of synaptic inhibition is paralleled by a decline in the number of parvalbumin-positive interneurons, but, in contrast to status epilepticus models, GABA(A) receptor subunit expression is largely unaltered. At both time points, the magnitude of tonic GABA(A) receptor-mediated currents after TBI is maintained, indicating a preservation of the inhibitory constraint of granule cells through tonic inhibition. Our results extend the time window during which strategies to target epileptogenesis may be effective.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Lesões Encefálicas
/
Receptores de GABA-A
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Giro Denteado
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Epilepsia do Lobo Temporal
/
Interneurônios
/
Inibição Neural
Tipo de estudo:
Etiology_studies
/
Prognostic_studies
/
Risk_factors_studies
Limite:
Animals
Idioma:
En
Revista:
Neuroscience
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Reino Unido