Cln3^lacZ/lacZ mice exhibit enhanced susceptibility to seizures. Cln3^lacZ/lacZ and Cln3^+/+ mice were given PTZ at 30 mg/kg, and seizure onset, grade, and duration were recorded (n = 10 for each genotype). A, PTZ induced no to moderate seizures in wild-type mice, although the effect was more severe in Cln3^lacZ/lacZ mice. B, Histochemistry for β-galactosidase shows enhanced reporter expression in the hippocampus of a PTZ (50 mg/kg dose)-injected (bottom) compared with a control saline-injected (top) Cln3^lacZ/+ mouse.