Contrasting Effects of Zonisamide and Acetazolamide on Amygdaloid Kindling in Rats
Article first published online: 12 JAN 2002
Volume 42, Issue 11, pages 1379–1386, November 2001
How to Cite
Hamada, K., Song, H.-K., Ishida, S., Yagi, K. and Seino, M. (2001), Contrasting Effects of Zonisamide and Acetazolamide on Amygdaloid Kindling in Rats. Epilepsia, 42: 1379–1386. doi: 10.1046/j.1528-1157.2001.26800.x
- Issue published online: 12 JAN 2002
- Article first published online: 12 JAN 2002
- Revision accepted January 23, 2001.
- Carbonic anhydrase;
- NMDA receptor
Summary: Purpose: Zonisamide (ZNS) and acetazolamide (AZM) are two antiepileptic drugs (AEDs) that differ in clinical efficacy. To elucidate the mechanisms of action of these compounds, we investigated their therapeutic and prophylactic effects in rats by using a kindling model of partial epilepsy.
Methods: Electrodes were implanted into the left amygdala of adult male Wistar rats. The animals were stimulated at the afterdischarge threshold until five stage 5 seizures were induced. The generalized seizure threshold was then determined. Therapeutic effects were examined in rats manifesting successive convulsions with near-threshold stimulation. To test prophylactic effects, drugs were administered intraperitoneally before daily kindling stimulation until the animal had a stage 5 seizure or reached day 18.
Results: ZNS (10–40 mg/kg; n = 6) suppressed kindled seizures in a dose-dependent manner. Repeated administration for 7 days produced tolerance to anticonvulsive effects. AZM (25–200 mg/kg; n = 7) showed limited therapeutic effect, alleviating only the clonic convulsion in stage 5 seizures and reducing afterdischarge duration. Secondary generalization was not significantly suppressed during repeated treatment (50–200 mg/kg; n = 6). ZNS, 25 or 40 mg/kg (n = 8), significantly retarded seizure development; 15.0 or 17.0 daily stimulations were required to produce a stage 5 seizure. AZM, 50–200 mg/kg (n = 6), also retarded seizure development, with 14.0–14.8 stimulations required.
Conclusions: ZNS exhibited modest therapeutic and prophylactic effects, whereas AZM showed mainly prophylactic effects. Hypotheses are presented that may explain the mechanisms of action of these drugs.