Effects of pilocarpine- and kainate-induced seizures on thyrotropin-releasing hormone biosynthesis and receptors in the rat brain.
J Neural Transm (Vienna)
; 106(5-6): 395-407, 1999.
Article
em En
| MEDLINE
| ID: mdl-10443546
ABSTRACT
The expression of mRNA coding for prepro-thyrotropin releasing hormone (preproTRH) was estimated in the rat brain in two animal models of limbic seizures, evoked by systemic administration of pilocarpine (400 mg/kg ip) or kainate (12 mg/kg ip). As shown by an in situ hybridization study, after 24h both pilocarpine- and kainate-induced seizures profoundly increased the preproTRH mRNA level in the dentate gyrus. After 72h, the preproTRH mRNA level was back to control values. Kainate-treated rats showed an elevated level of TRH in the hippocampus, septum, frontal and occipital cortex after 24 and 72h, whereas in the striatum and amygdala the TRH level was raised after 72h only. In the hypothalamus, TRH levels was lowered after 3 and 24h, and returned to the control after 72h. Pilocarpine-induced seizures also elevated the TRH level after 72h in the majority of the above structures, except for the hypothalamus and amygdala where no changes were found at any time point. A radioreceptor assay showed that kainate decreased the Bmax value of TRH receptors in the striatum and hippocampus after 3 and 24h, respectively, and had no effect on the Kd values. In contrast, pilocarpine-induced seizures lowered the Bmax of TRH receptors in the striatum, hippocampus and piriform cortex after 72h only, and decreased Kd values in the striatum, amygdala and frontal cortex. These data showed that pilocarpine- and kainate-induced seizures enhanced likewise preproTRH mRNA in the dentate gyrus; on the other hand, they differed with respect to time- and structure-related changes in TRH tissue levels and TRH receptors. These differences may have functional significance in TRH-dependent control mechanism of the seizure activity in these two models of limbic epilepsy.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pilocarpina
/
Convulsões
/
Transcrição Gênica
/
Encéfalo
/
Regulação da Expressão Gênica
/
Hormônio Liberador de Tireotropina
/
Receptores do Hormônio Liberador da Tireotropina
/
Ácido Caínico
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Neural Transm (Vienna)
Ano de publicação:
1999
Tipo de documento:
Article