We have examined the effects of swim stress on gamma-aminobutyric acidA (GABAA), GABAB and benzodiazepine (BZD) receptors in synaptic membranes from rat brain. Acute, but not repeated, stress increased the number of BZD receptors in the cerebral cortex. The stress manipulation did not change BZD receptors either in the hippocampus or cerebellum. Furthermore, both GABAA and GABAB receptors did not change in the cerebral cortex, hippocampus or cerebellum after acute and repeated stress. GABA-stimulated BZD binding was not changed following acute or repeated stress. These results suggest that cortical BZD receptors are closely related to responses to acute stress.