Convulsant properties of GABA antagonists and anticonvulsant properties of ethanol in selectively bred Long- and Short-Sleep mice

The convulsant potency of bicuculline, a GABA antagonist, was shown to be greater in Short-Sleep (SS) mice than in Long-Sleep (LS) mice. LS mice, selectively bred for lengthy ethanol-induced narcosis, had longer latencies to myoclonus and clonus following administration of bicuculline and picrotoxin than did ethanol-resistant SS mice. SS mice were also more susceptible to pentylenetetrazol-induced myoclonus, but not clonus. F₁ hybrids showed bicuculline seizure sensitivity intermediate to the two parent lines. Ethanol weakly inhibited bicuculline-induced myoclonus in both LS and SS mice. Clonus was clearly antagonized by ethanol in both lines, but to a similar degree. These data provide evidence for a GABAergic role in geno-type-dependent sensitivity to ethanol.