Effect of pentylenetetrazol-induced convulsions on the development and expression of limbic kindled seizures.

Male Long-Evans rats experienced three convulsions induced by intravenously administered pentylenetetrazol (PTZ) and were then kindled by electrical stimulation of the olfactory bulb or amygdala. Pretreatment with PTZ did not alter the rate of kindling in either site but did enhance the expression of kindled seizures once generalization had occurred (PTZ-treated animals had significantly longer motor seizures, measured by clonus duration, than did saline-treated controls). This suggests that PTZ-induced convulsions have selective effects on areas of the brain that are involved in the expression of the motor seizure. In addition, rats treated with PTZ after kindling had convulsions that were significantly longer in duration than any of their three pre-kindling convulsions, indicating that kindling produced an increased sensitivity to PTZ's convulsant effects. Comparison of this experiment with previous research suggests that the ability of a drug treatment to generate a kindling-like effect is related to the pattern of seizure activity that it produces.