Prolonged exposure to lead lowers the threshold of pentylenetetrazole-induced seizures in rats

Purpose: The aim of this work was to study the effects of prolonged exposure to lead on the threshold of experimental seizures induced by pentylenetetrazole (PTZ). Methods: The 120 Wistar male rats were allocated randomly into four groups; (A) controls, and lead-treatment groups (B, C, and D) that received lead acetate in the drinking water for a period of 30 days at concentrations of 250, 500, and 1,000 ppm, respectively. After exposure, a trial of PTZ-induced seizures was conducted in all groups, and blood contents of lead were determined by atomic absorption spectrophotometry. Results: Blood lead contents increased in a dose-dependent manner. Time elapsed to develop the first myoclonic jerk and the tonic-clonic seizure was less in all lead-exposed groups than in controls. This effect was greater in the groups administered 500 and 1,000 ppm of lead. The required doses of PTZ to induce myoclonic jerks and tonic-clonic seizures were lower in lead-exposed rats than in controls. Conclusions: We found a reduction in the threshold for seizures in rats whose blood contents of lead were similar to those of humans from some areas of urban centers with high levels of air pollution.