LEVETIRACETAM REDUCES CAFFEINE-INDUCED INTRACELLULAR CALCIUM TRANSIENTS IN CULTURED RAT HIPPOCAMPAL NEURONS
Abstract number :
1.271
Submission category :
Year :
2002
Submission ID :
1844
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Mikael ängehagen, Doru Georg Margineanu, Lars Rönnbäck, Elisabeth Hansson, Henrik Klitgaard, Elinor Ben-Menachem. Institute of Clinical Neuroscience, Göteborg University, Göteborg, Sweden; Preclinical CNS Research, UCB S.A., Pharma Sector, Braine-l[ssquot
RATIONALE: Levetiracetam (LEV; Keppra[reg]) is a novel anti-epileptic drug (AED) with proven efficacy in controlling refractory partial seizures in adults. LEV has been reported to exert several non-conventional effects on neurons. Specifically, LEV was previously shown to antagonize a non-GABA[sub]A[/sub] receptor-associated epileptiform effect of bicuculline in rat hippocampus (Margineanu and Wülfert, [italic]Br. J. Pharmacol.[/italic] 1997;122:1146), and thapsigargin, a depletor of intracellular Ca2+ stores, mimicked that anti-bicuculline effect (Wülfert and Margineanu, [italic]Neurosci. Lett.[/italic] 1998; 243:141). Therefore, we investigated whether LEV opposes the release of Ca2+ from intraneuronal stores.
METHODS: The effect of LEV on the caffeine, 10 mM (CAF)-induced intracellular calcium ([Ca2+][sub]i[/sub]) response was investigated in cultures of rat hippocampal cells, treated with cytosine-1-[beta]-D-arabinofuranoside to suppress the growth of glial cells and to promote neuronal survival. Ca2+ imaging was performed with a Photon Technology System using the calcium sensitive probe fura-2.
RESULTS: In 9 [ndash] 10 days old neuronal cultures, LEV reduced significantly the CAF-induced [Ca2+][sub]i[/sub] response. Compared to control values (means [plusminus] SEM), this was apparent after incubation with both 10 [mu]M of LEV (7.5 [plusminus] 1.8 vs. 4.6 [plusminus] 1.1; n=25), 32 [mu]M (4.0 [plusminus] 0.5 vs. 1.9 [plusminus] 0.4; n=22) and 100 [mu]M (6.3 [plusminus] 0.8 vs. 4.7 [plusminus] 0.5; n=23) while a concentration of 1 [mu]M was inactive (5.7 [plusminus] 0.4 vs. 5.6 [plusminus] 0.5; n=30). In contrast, incubation of cultured neurons with 32 [mu]M of the inactive R-enantiomer of LEV had no effect on CAF-induced [Ca2+][sub]i[/sub] response (4.8 [plusminus] 0.7 vs. 4.6 [plusminus] 0.5; n=18). Similarly, the reference AEDs carbamazepine (50 [mu]M) and clonazepam (1 [mu]M) were also devoid of significant effects on CAF-induced [Ca2+][sub]i[/sub] response.
CONCLUSIONS: These data suggest that LEV inhibits caffeine-induced release of Ca2+ from intraneuronal stores. This excitability-reducing effect might contribute to the antiepileptic activity of the drug. Further investigations are warranted in order to characterize the sub-cellular mechanisms by which LEV may modulate intraneuronal Ca2+ release.
[Supported by: UCB S.A. Pharma Sector]; (Disclosure: Grant - UCB S.A.)