Characterization of benzodiazepine receptor binding in immature rat brain after kainic acid administration

Purpose: To evaluate the effects of status epilepticus on benzodiazepine (B DZ) receptor binding in immature rat brain. Methods: Twenty-four immature (15 days old) and six adult (90 days old) rat s were used in this study. Status epilepticus was induced in immature anima ls by administration of kainic acid (7 mg/kg intraperitoneal), whereas adul ts rats received saline. Animals were killed 72 hours or 35 days after trea tment, and their brains were used for in vitro autoradiography experiments to determine BDZ binding. Results: in basal conditions and compared with the adult group, immature an imals presented reduced BDZ binding in the entorhinal cortex, substantia ni gra pars reticulata, and periaqueductal gray. Seventy-two hours after kaini c acid-induced status epilepticus, immature rats showed significantly incre ased BDZ in the frontal (48%), cingulate (39%), sensorimotor (39%), pirifor m (57%), and entorhinal (59%) cortices, the medial (84%) and basolateral (2 7%) amygdaloid nuclei, the dentate gyrus (51%), and the substantia nigra pa rs reticulata (43%). Thirty-five days after status epilepticus, immature ra ts displayed decreased BDZ binding in the entorhinal cortex (48%), dentate gyrus (36%), and fields CA1, CA2, and CA3 of Ammon's horn (30%). Conclusions: The present study demonstrates that status epilepticus and tem poral lobe epilepsy produce a characteristic pattern of BDZ binding changes in the immature rat brain that differs from the one previously seen in adu lts.