Effect of naloxone on remote seizure susceptibility

To evaluate the effect of low dose naloxone on remote seizure susceptibility after repeated febrile seizures(FS) in developing age.Warm water induced rat FS model was developed in this study. Forty-nine SD rats were randomly divided into two groups: normal control group(n=10) and hyperthermic seizure group (n=39). The latter was further divided into FS control group (n=13) and naloxone-treated group (n=26). The dose of naloxone was different in the two naloxone-treated groups (13/each group). One group dose was 1 mg/kg, and the other 2 mg/kg. Each rat of hyperthermic seizure groups was induced to have 7 febrile seizures at the interval of 1 day. The rats were weighed and injected intraperitoneally with naloxone once the FS occurred in naloxone-treated group, while the rats of other groups were injected with 0.9% sodium chloride. After the seventh stimulation, all rats were left un-stimulated for 2 months, then re-stimulated. Re-stimulated seizure incidence rate, seizure duration and seizure grade in different groups were observed and compared with each other. Hippocampal mossy fiber sprouting was detected by Timm stain.In naloxone-treated group, the rats' seizure duration and seizure grade [(5.66+/-2.78) min, (2.97+/-1.18)] significantly decreased (t=5.035, P<0.01; t=3.343, P<0.01) compared with those in FS control group [(21.18+/-4.06) min, (4.54+/-0.78)], although no significant gap was observed on seizure incidence rate(57.7%,84.6% respectively) and seizure latency between them. In non-treated group, in which two rats developed status epilepsy, the incident rate of the fifth grade seizure was 69.3%, much higher than 19.3% of naloxone treated group. Timm-stain pattern showed that the straining in the IML (inner molecular layer) of treated group rats was much lighter than that of non-treated group [(2.33+/-1.03), (0.92+/-0.79), P<0.01].Low dose naloxone used on naive rat with repeated febrile seizures can efficiently decrease the seizure susceptibility in the mature period and lighten the neural damage by twice-hit seizure in the mature period as well.PubMed0157-603