Effect of taurine on seizures induced by 4‐aminopyridine

Abstract

The effect of intraperitoneally injected taurine against the convulsive activity induced by 4-aminopyridine (4-AP) was studied in 12- to 15-day-old mice. At a dose of 2.6 mg/kg, taurine increased the latency of clonic seizures from 7 to 20 minutes, reduced the incidence of tonic seizures from 92% to 30% and the postconvulsive mortality from 80% to 31%. The injection of EDTA prior to the administration of taurine prevented the protective effect of the amino acid. GABA and glycine at the same doses did not protect against 4-AP-induced seizures. 4-AP caused a small increase (19%) in ⁴⁵Ca accumulation by mice brain synaptosomes incubated in a Krebs-HEPES medium containing low CaCl₂ (0.1 mM) and also slightly potentiated the veratrine and potassium-induced increase in calcium accumulation. 4-AP at concentrations of 1–2 mM caused a marked increase (100%–500%) of ⁴⁵Ca acculation by synaptosomes incubated in a Krebs-bicarbonate medium containing 2.5 mM CaCl₂. This increase was completely antagonized by taurine but not by GABA or glycine. The present observations suggest that the anticonvulsant effect of taurine might be mediated by 4-AP-calcium-taurine interactions.