MECHANISM OF THE ANTICONVULSANT EFFECT OF PROPRANOLOL

In mice, propranolol(0.025～1 mg/kg sc) produced a dose-dependent reduction in the rate of semicarbazide seizures(SCZS). Following pretreatment with saline, semicarbazide and amino-oxyacetic acid, ED₅₀ of propranolol against the seizure induced by maximum electroshock(MES) was 10.7±1.6, 15.7±2.3, and 3.8±0.9 mg/kg, respectively. Propranolol(10 mg/kg) administered intraperitoneally caused no significant changes in brain GABA, taurine, glycine, aspartate and glutamate contents in mice pretreated with AOAA. Taurine, a GABA analogue, facilitated SCZS, and showed no significant effect on MES.These results suggest that the action of propranolol at low doses against SCZS may be mediated via blocking the central β-adrenoceptor, its action against MES is closely related to the function of GABA-ergic system that taurine could not substitute for GABA to inhibit the convulsion when brain GABA content was reduced.