Brain benzodiazepine receptors and their rapid changes after seizures in the Mongolian gerbil.

To elucidate the physiological role of benzodiazepine receptors in convulsion, these receptors were studied in the brain of the Mongolian gerbil (Meriones unguiculatus), an animal model used for the study of epilepsy. Benzodiazepine binding sites in the gerbil brain were demonstrated using [3H]diazepam. The binding was saturable and stereospecific. Benzodiazepines inhibited [3H]diazepam binding to the membranes and their ability to inhibit the binding closely correlated with their potency as anticonvulsants. These results showed that the characteristics of the benzodiazepine receptors in the Mongolian gerbil were similar to those obtained from rat and human brain. Seizures increase the specific binding of [3H]diazepam to the membranes of all regions of the gerbil brain, the most remarkable increase seen in the striatum. Time course studies showed that the increase reached a maximum 10 min after the seizure and the binding returned to the control level within 20 min. The increase in specific [3H]diazepam binding was due almost entirely to shifts in the affinity of [3H]diazepam for its receptors. Thus, the seizures may not be due to changes in the benzodiazepine receptors, and seizures produce an increase in receptor binding, which may be related to a physiological modification of excessive excitation.