Formation of free hydroxyl radicals after pentylenetetrazol-induced seizure and kindling.

The present study indicates that free radicals have been implicated in pentylenetetrazol (PTZ)-induced seizure and kindling. In our experiments we used a method in which free hydroxyl radicals (* OH) are trapped by systemically applied salicylate in vivo, resulting in the stable and quantifiable products, 2, 3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA. We investigated the formation of both 2,3- and 2,5-DHBA in the whole brain (without cerebellum) of rats treated with an acute seizure-inducing dose of 48 mg/kg PTZ and in PTZ-kindled animals which were injected with the kindling dose of 37.5 mg/kg PTZ at different times after the last PTZ injection. An increase of * OH was observed in kindled rats compared with acutely convulsing animals when the PTZ application was performed 1 min after the salicylate treatment. The amount of DHBAs increased significantly in both convulsed groups 30 min after the application of PTZ compared with animals treated with NaCl instead of PTZ. Sixty minutes after PTZ the DHBA levels normalized to NaCl control values.