Effect of combined genotype on seizure frequency. Animals were injected i.p. with 4 mg/kg nicotine and observed for seizure activity. Animals were subsequently genotyped for the α5 and α7 rflps, and we determined the effect on seizure frequency of changing the genotype of one of the subunit genes within a single genotype of the other subunit gene.

• HH, homozygous for the C3H variant of the specified gene; HD, heterozygous for the specified gene; DD, homozygous for the DBA variant of the specified gene.