Rapid, stress-induced modification of the benzodiazepine receptor-coupled chloride ionophore

Rapid changes in the chloride ionophore component of the benzodiazepine-GABA receptor complex were observed in cerebral cortical membranes from rats exposed to a brief, ambient temperature swim stress. These changes were manifest as: (1) an increase in both the efficacy and potency of chloride ions to enhance [³H]flunitrazepam binding, and (2) an increase in both the number of [³⁵S]t-butylbicyclophosphorothionate (a ligand that binds at or near the GABA_A receptor-gated chloride ionophore) binding sites and the apparent affinity of this radioligand. These studies demonstrate that the GABA-gated, benzodiazepine-coupled chloride ionophore, which can be considered the effector component of this 'supramolecular complex', is rapidly modulated by acute stress. Such changes could represent the compensatory response of an organism to stressful or anxiety provoking changes in the environment.