Fig. 5. Dose–response curves for GABAAR antagonist-induced convulsive seizures in mGluR4−/− and mGluR4+/+ mice.A, Dose specificity of seizures induced by GABAAR antagonists in mGluR4+/+ mice.Seizure Grade refers to the type of seizure that was induced. One is absence, two is clonic, and three is tonic seizure. The dosage shown for PTZ is the CD100 rather than CD95 because only 10 animals were used to generate the absence seizure dose–response curve. B, The dose–response curve for GABAAR antagonist-induced clonic seizures in mGluR4−/− and mGluR4+/+ mice (n = 20 for each group). There was no significant difference between the mGluR4−/− and mGluR4+/+ mice in the CD95 of the GABAAR antagonists (p > 0.1, ANOVA; n = 20/group). The CD95 for the induction of clonic seizures with PTZ, bicuculline (BMI), and picrotoxin (PXN) in the mGluR4+/+ mice was 45, 4.5, and 1.8 mg/kg, respectively. The CD95 for the induction of clonic seizures with PTZ, bicuculline, and picrotoxin in the mGluR4−/− mice was 40, 5.0, and 1.9 mg/kg, respectively. SEM was <10% for all data points and is not shown. ●, mGluR4+/+ (PXN); ♦, mGluR4+/+(BMI); ▪, mGluR4+/+ (PTZ); ▿, mGluR4−/− (PXN); ⋄, mGluR4−/− (BMI); ■, mGluR4−/− (PTZ). C, The dose–response curve for GABAAR antagonist-induced tonic seizures in mGluR4−/− and mGluR4+/+ mice (n = 20 for each group). There was no significant difference between the mGluR4−/− and mGluR4+/+ mice in the CD95 of the GABAAR antagonists (p > 0.1, ANOVA; n = 20/group). In the mGluR4+/+ mice the CD95 for PTZ, bicuculline, and picrotoxin was 74, 5.5, and 2.2 mg/kg, respectively, whereas the CD95 for the induction of tonic seizures with PTZ, bicuculline, and picrotoxin in the mGluR4−/− mice was 70, 5.5, and 2.4, respectively. SEM was <10% for all data points and is not shown.