The effects of naloxone and interstimulation interval on post-ictal depression in kindled seizures

Two experiments were conducted to investigate the effects of naloxone hydrochloride on seizure thresholds seizure afterdischarges (thresholds and durations) and on post-ictal depression. Experiment 1 examined the effects of naloxone dosage and interstimulation interval (ISI) on kindled seizures. Eight male hooded rats were exposed to a factorial combination of two ISIs (30 and 60 s) and 3 naloxone doses (2, 10 mg/kg and a saline control) during a threshold testing procedure. Naloxone was found to significantly shorten motor seizure duration and post-ictal depression. Experiment 2 examined the effects of naloxone on a subsequent suprathreshold-stimulation-induced seizure following an initial suprathreshold stimulation. A factorial combination of 3 naloxone doses (2, 5 and 10 mg/kg) and a saline control and two ISIs (2 and 6 min) separating the two stimulations was employed. While no main effects for either naloxone or ISI were found in the subsequent seizure activity, there was a significant interaction between naloxone and ISI for the subsequent motor seizure duration. It was concluded from the results of the present experiments that the direction and consistency of naloxone's effects on kindled seizures were present but not very strong. However, the effects of ISI on seizure activity were found to be consistent with the previous literature.