Introduction & Objective: Morphine has both anti and proconvulsive actions on the epileptiform activity depending on the exact experimental conditions. Study of the contraversy effects of morphine on certain neural activities such as epilepsy leads to clearify some neural events and neuronal adaptations. This study was designed to determine the effect of morphine on seizure induced by Low Mg2+ Artificial Cerebrospinal Fluid (ACSF) in whole hippocampus preparation of mice.

Materials & Methods: C57/BL6 mice 11 to 19 days of age, were used. Animals anaesthetized and the brain was removed(n=25) and placed in ice-cold, continuously oxygenated ACSF for 3 min. Then the hippocampi were dissected and incubated in normal ACSF at room temperature for an hour before electrophysiologic recording. Seizure activity was induced by per fusing the hippocampus with Low Mg2+ ACSF. Extra cellular recordings were performed mainly in the CA1 pyramidal cell layer. Seizure activity was quantified by measuring the duration and number of the ictal events and the percent of seizure time.

Results: Both low and high doses of morphine(10, 200μM, respectively) suppressed seizure length and percent of seizure time, whereas moderate doses of morphine (30,100 μM) potentates them. Naloxone (10μM) not only inhibited the excitatory effects of morphine on seizure but also suppressed the Low Mg2+ ACSF induced epileptiform activities. Combined application of morphine and naloxone attenuated the seizure.

Conclusion: Our results indicate that morphine in moderate concentration of 30 and 100 μM may potentate seizure activity and it should be used with caution in epileptic patients, while naloxone has anticonvulsant actions and can probably be used in clinical trials especially to control temporal lob epilepsy.