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It was shown that the increased brain seizure readiness persisted within 6 months after termination of corazol kindling. Seizures of the same severity as during kindling (corazol injection in a dose of 20 mg/kg) were reproduced by corazol injection in a dose of 30 mg/kg. In contrast to the control rats, in this situation an autoenhancement of seizures was observed in the kindled animals. Acute corazol seizures induced a decrease in Bmax and Kd of 3H-diazepam binding with benzodiazepine receptors (BDR) in the cerebellum of the 10-months-old control rats white the young animals demonstrated only a decrease in Bmax of binding. In 6 months after kindling termination the BDR activity (Bmax) was reduced by one half. However, we think that the increase in Bmax is not responsible for persistence of the increased seizure readiness. It seems possible that down regulation of receptor activity develops independently of kindling but in response to long-lasting corazol application. Probably, Bmax spontaneously decreases after the termination of the long-term corazol application. The single dose of corazol (30 mg/kg) restores the changes in BDR density to the level when seizure readiness has been just fixed (6 months after kindling termination), independently of the primary receptor density.

The acute korazol (pentylenetetrazol) injection (50 mg/kg) induced seizures which were accompanied by a long-lasting (from 30 minutes to 3 days) decrease in benzodiazepine receptor (BDR) density (Bmax) in rat cerebellum without change in affinity. The density of the BDR was normalized on the 7th day after seizure termination. There were no differences in the initial BDR characteristics between the animals more sensitive to korazol (a dose of 25 mg/kg was sufficient for seizure induction) and less sensitive (30 mg/kg were ineffective). The chronic daily (for 24 days) administration of korazol in a subconvulsive dose led to an increase in seizure readiness (kindling). In 30 min after the last korazol injection the BDR density was decreased to the same extent as after the acute 50 mg/kg korasol administration. The BDR density was normalized on the 7th day after kindling. It was demonstrated that the high-dose-induced and after-kindling seizures were underlain by the same mechanisms. The results suggest that the development of kindling depends on the state of the long-lasting receptors rather than the development of kindling forms the long-lasting reactions. The process of summation is at the basis of kindling development. The long-lasting decrease in activity of BDR receptors induced by a subconvulsive dose of korazol is summed with the following effect of the same dose.