Effect of morphine administration after status epilepticus on epileptogenesis in rats.

INTRODUCTION

Morphine is widely used in patients and has been reported to alter seizure threshold, but its role in the development of epilepsy is unknown. In this study, role of morphine administration in the development of epilepsy using the status epilepticus (SE) model was determined in rats.

METHODS

Rats experiencing SE with lithium-pilocarpine (LiP) were randomized into four groups- saline, morphine low dose (5 mg/kg, s.c.), morphine high dose (5-20 mg/kg, s.c.), and naloxone (1 mg/kg, s.c.). Treatments were started 90 min after termination of SE and repeated twice daily for next three days. Rats were video monitored daily for 21 days to determine onset and frequency of spontaneous convulsive seizures (SS).

RESULTS

Morphine in low doses increased frequency of SS (1.51 ± 0.15 vs LiP 0.60 ± 0.12 seizures/rat/day, p-value = 0.0026) and seizures occurred during handling (SDH) (0.08 ± 0.02 vs LiP control 0.01 ± 0.01) (p-value = 0.0018). In high doses, no significant change in SS and SDH was found as compared to LiP. No effect of morphine on the onset of SS and percentage of rats experienced SS was found. No effect of naloxone per se was found on SS.

CONCLUSION

Morphine administration after SE does not affect epileptogenesis as no change in the onset of SS and percentage of rats experiencing SS was found. However, it might alter the susceptibility and frequency of SS. As no other study is available with a similar finding, it needs further evaluation.