Role of corticotropin-releasing factor and urocortin within the basolateral amygdala of rats in anxiety and panic responses

The amygdala is a critical temporal lobe structure involved in the expressi on of anxiety and stress responses. The basolateral nucleus (BLA) of the am ygdala in particular, may play a key role in anxiety. Furthermore, corticot ropin-releasing factor (CRF), a 41 amino acid peptide, has been strongly im plicated in the regulation of stress and anxiety responses. Centrally admin istered CRF has been shown to increase the anxiety-like behaviors of rodent s in several animal models. A recently cloned related peptide, Urocortin (U cn), appears to have similar affinity for the CRF1 receptor, but higher aff inity at the CRF2 receptor. When microinjected into the BLA, we found Ucn w as substantially more potent than CRF in producing anxiogenic-like behavior as assessed in the social interaction test. Furthermore, repetitive admini stration of subthreshold doses of Ucn and CRF resulted in 'priming'. Once p rimed, these animals exhibited behavioral and cardiovascular responses to i ntravenous sodium lactate, a panicogenic agent in susceptible human patient s. These results suggest central CRF and Ucn play a role in generating anxi ety which may be similar to that seen in pathological conditions such as pa nic disorder. (C) 1999 Elsevier Science B.V. All rights reserved.