The effect of lamotrigine on learning in mice using the passive avoidance model

- Lamotrigine inhibits the release of glutamate via blocking sodium channels.
- LTG showed a positive effect on memory retrieval in the PA test.
- Higher doses of LTG had improving effect on memory retrieval.

IntroductionLamotrigine (LTG) is an antiepileptic drug that inhibits the release of glutamate by blocking sodium channels. The present study was conducted to evaluate the effect of LTG in different stages of memory using a passive avoidance learning task in mice.MethodsMale albino mice in the weight range 20-25 g were used. They were divided into four groups (control group and three groups receiving various doses of LTG). LTG was given in three doses of 10, 25, and 50 mg/kg as intraperitoneal (IP) injections. The doses of LTG were used in three injection groups: before acquisition, after consolidation, and before retrieval at 24 h. The retention latency times in each group were recorded using a step-through passive avoidance task 24 h and one week after consolidation.ResultsRetention latency in the group receiving a high dose of LTG (25 mg/kg) after one week was significantly increased in comparison to the group receiving a low dose of LTG (10 mg/kg) (267 ± 49.96 vs. 198.87 ± 57.22, P = 0.015). With injection of LTG after consolidation, the retention latency times were increased in all doses after a one-week retrieval compared to the control (P = 0.023). Kaplan-Mayer surveillance analysis also showed significant differences in the latencies of the LTG-receiving group after 24 h and one week's retrieval (P = 0.041). Administration of LTG before retrieval at 24 h showed a significant difference in retention latency time, which was increased for two doses of LTG (10 and 50 mg/kg) after one week (203.5 ± 63.67 vs. 270.25 ± 19.78, P = 0.024).ConclusionLTG at higher doses may facilitate the learning process in mice and appears to improve memory function at different stages.