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

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. Neurology Asia 2013; 18(1) : 9 – 15 Address correspondence to: Kaiyan Wang, No.12 Middle Wulumuqi Road, Jingan District, Shanghai 200040, China. Tel:+86-13917806739, Fax:+86-021-62483421, E-mail: [email protected] INTRODUCTION Animal seizure models provide useful evidence related to human seizure that can be obtained from clinical practice; such models have therefore played a fundamental role in our understanding of the basic mechanisms that underlie epileptogenesis. An improved overall understanding of seizure characteristics in a diversity of animal models will therefore facilitate the study of human seizures. The pentylenetetrazol (PTZ) kindling model is an ideal tool for the modeling of focal to generalized seizure attacks. However, the location of epileptic foci following PTZ administration, the impact upon measures of functional brain imaging, and the resultant pathological characteristics of PTZinduced kindling in this model remain poorly understood.