Functional imaging and pathology in brain of interictal cats kindled by pentylenetetrazol

ABSTRACT

Objective: To investigate the electroencephalogram (EEG) characteristics, cerebral blood fl ow, glucose metabolism, and pathological characteristics in cats kindled by pentylenetetrazol (PTZ). Methods: Ten adult male cats received intramuscular injections of PTZ at a sub-convulsive dose of 25 mg/kg once daily. Cats were considered to be kindled when a class V or above seizure was observed. Subsequently, scalp EEG, 99mTc-ECD-single-photon emission computed tomography (SPECT), 18FDG-positron emission tomography (PET), and Cresyl violet staining were employed to evaluate brain activity, cerebral blood fl ow, glucose metabolism, and pathological characteristics representing epileptic foci during interictal stages. Results: The EEG data revealed bilateral dissymmetry paroxysmal activity in the form of δ and θ waves, as well as paroxysmal spikes and sharp waves instead of symmetric highamplitude rhythm of 8-12 Hz in cats kindled by PTZ compared to controls. In addition, low blood perfusion and low glucose metabolism unilaterally in the temporal lobe were observed in PTZ-kindled cats, in contrast to the bilateral symmetrical blood perfusion and high glucose metabolism observed in control cats. Pathological examinations showed a thickening of white matter in the ipsilateral temporal region and a thinning of gray matter in PTZ-kindled cats. Microscopically, we observed a structure disturbance of hippocampal CA3 area in PTZ-kindled cats. Conclusion: Epileptic foci of PTZ-kindled cats were localized to the unilateral temporal lobe, in a manner highly similar to the pathophysiology of human temporal lobe epilepsy.