Abstract
Male albino rats were injected with 25 mg/kg of phenytoin (PHT) every day for 20 consecutive days and were tested on days 21 and 28 for their response to 1 or 2 mg/kg of muscimol, a GABA receptor agonist. Rats treated with PHT showed a decreased responsiveness to muscimol-induced catalepsy (2 mg/kg) on day 21 but not on day 28. Acutely administered PHT, on the contrary, had a tendency to potentiate muscimol-induced catalepsy. Muscimol-induced catalepsy was not antagonized by acute treatment with bicuculline (0.5–2.0 mg/kg). It is proposed that withdrawal after long-term administration of PHT reduces the sensitivity of a GABA receptor site not sensitive to bicuculline.
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Lalonde, R., Botez, M.I. Subsensitivity to muscimol-induced catalepsy after long-term administration of phenytoin in rats. Psychopharmacology 86, 77–80 (1985). https://doi.org/10.1007/BF00431687
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DOI: https://doi.org/10.1007/BF00431687