Diazepam binding in brain after sleep and wakefulness

Abstract

Membranes prepared from various regions of hamster brain following 50 min of non-rapid eye movement sleep or a comparable period of wakefulness exhibit no significant differences in [ 3H]diazepam binding. When 30,000 × g supernatant from the awake brain is added to the membrane the [ 3H]diazepam binding decreases drastically in the cerebral cortex. The binding decreases to a lesser extent in all other brain areas. The 30,000 × g supernatant obtained from the sleeping animals do not cause any such changes in the [ 3H]diazepam binding. Studies with membrane preparations (S 1 fraction) not separated from its own supernatant demonstrate similar benzodiazepam binding inhibition in awake brain. [ 3H]diazepam binding gradually increases as sleeping time is prolonged. Scatchard analysis of the binding data suggest that in the presence of the supernatant from awake animals, the affinity of the receptor for [ 3H]diazepam decreases significantly, with no change in the maximum number of binding sites. These studies suggest the presence of a benzodiazepine binding inhibitor in the 30,000 × g supernatant prepared from awake animals. This inhibitor may be an endogenous benzodiazepine-like substance. Using benzodiazepine binding as a simple assay method, we are attempting to identify and characterize this wakefulness-related diazepam binding inhibitor.