The effect of acute cold-restraint stress on binding of [3H]rauwolscine to alpha 2-adrenoceptors was investigated in 10 regions of rat brain. Acute stress: significantly decreased the density but had no significant effect on the affinity of binding sites in the hippocampus; decreased density and increased affinity in the amygdala; and increased density and decreased the affinity in the midbrain. Seven other brain regions showed no significant changes in binding parameters in response to stress. These results, together with previous findings in this laboratory showed that alteration by restraint stress of noradrenaline levels in amygdala and hippocampus, but not other regions, indicate an association between neurotransmitter turnover and receptor function.