[Effect of licorice flavonoids on kainic acid-induced seizure in mice].

Objective: To investigate the effect of licorice flavonoid (LF) on kainic acid (KA)-induced seizure in mice and its mechanism.

Methods: Male adult ICR mice were injected with 25 mg/kg KA to induce temporal lobe seizure. LF was administrated 7 d before seizure induction (pre-treatment) or 24 h after seizure induction (post-treatment) for 7 d. Acute seizure latency, seizure stage and duration were observed and compared between LF- and vehicle-treated mice. From d2 on, mice with status epilepticus were video-monitored for spontaneous seizures, 10 h/d for 6 w. Immunohistochemical analysis of BrdU and Timm staining was conducted to detect the neurogenesis and mossy fiber sprouting, respectively.

Results: No significant difference was observed in acute seizure latency, seizure stage and duration between LF-and vehicle-treated mice. KA-induced acute seizure resulted in spontaneous seizure in mice, and the seizure frequency was increased with time. Pre- and post-treatment with LF decreased seizure frequency from w3 after modeling [(0.58±0.15)/d, (0.38±0.38)/d vs (1.23±0.23)/d, P <0.05]. Furthermore, KA-induced seizure resulted in robust neurogenesis and mossy fiber sprouting, while treatment with LF both pre- and post- KA injection significantly inhibited neurogenesis (15.6±2.6, 17.1±3.1 vs 28.9±3.5, P <0.05) and mossy fiber sprouting (1.33±0.31, 1.56±0.42 vs 3.0±0.37, P <0.05).

Conclusion: LF has no significant anti-seizure effect. However, it can decrease epileptogenesis through inhibition of neurogenesis and mossy fiber sprouting.