Benzodiazepine effect of I-125-iomazenil-benzodiazepine receptor binding and serum corticosterone level in a rat model

摘要

To test the change in free or unoccupied benzodiazepine receptor (BZR) density in response to diazepam, we investigated I-125-iomazenil (I-125-IMZ) binding and serum corticosterone levels in a rat model. Wistar male rats, which received psychological stress using a communication box for 5 days, were divided into two groups according to the amount of administered diazepam: no diazepam [D (0)] group and 10 mg/kg per day [D (10)] group of 12 rats each. The standardized uptake value (SUV) of I-125-IMZ of the D (10) group were significantly lower (P < .05) than those of the D (0) group in the frontal, parietal and temporal cortices, globus pallidus, hippocampus, amygdala and hypothalamus. The serum corticosterone level ratio in the D (10) group was significantly lower than that in the D (10) group (P < .05). From the change in serum corticosterone levels, diazepam attenuated the psychological stress produced by the physical stress to animals in adjacent compartments. From the reduced binding of I-125-IMZ. it is clear that diazepam competed with endogenous ligand for the free BZR sites, and the frontal, parietal and temporal cortices, globus pallidus, hippocampus, amygdala and hypothalamus are important areas in which I-125-IMZ binding is strongly affected by administration of diazepam. (C) 2005 Elsevier Inc. All rights reserved.