Three neurosteroids as well as GABAergic drugs do not convert immediate postictal potentiation to depression in immature rats
Tóm tắt
Postictal potentiation presented immediately after cortical seizures in immature rats might be due to imbalance between excitation and inhibition. The aim of the present study was to determine whether augmentation of inhibition mediated by GABAA receptors could also suppress the postictal potentiation. Twelve-day old rats with implanted electrodes were used in our study. Five drugs were tested: the agonist muscimol, the positive modulator midazolam and three neurosteroids affecting GABAA receptors—allopregnanolone, pregnanolone sulphate and pregnanolone glutamate. None of the five drugs was able to suppress potentiation appearing immediately after cortical epileptic afterdischarges, but all of them exhibited delayed anticonvulsant action 10 (in the case of midazolam and muscimol) or 20 min (all three steroids) after cortical seizures. Our results support a role of GABA in augmentation of cortical after discharges after longer intervals, whereas immediate postictal potentiation is not affected by GABAergic drugs. Due to similar effect with GABAergic drugs, the main mechanism of action of the three steroids tested is potentiation of GABAergic inhibition.
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