Corticotropin-Releasing Hormone Microinfusion in the Central Amygdala Enhances Active Behaviour Responses in the Conditioned Defensive Burying Paradigm

The central nucleus of the amygdala (CeA) is known to be involved in the regulation of autonomic, neuroendocrine, and behavioural responses in stress situations. The CeA contains large numbers of corticotropin-releasing hormone (CRH) cell bodies, terminals and functional recognition sites. In the present study, the effects of locally infused CRH (30 ng) into the CeA, of freely moving Wistar rats in the conditioned defensive burying paradigm were examined. CRH administered into the CeA increases active (defensive burying and gnawing) behaviour towards a previously electrified probe, which was blocked by pretreatment of α-hCRH, the CRH receptor antagonist. This study clearly shows that the CeA CRH system is involved in the modulation of the CRH-induced behavioural stress response. These findings are discussed in terms of an enhancement of an anxiety response or a shift in coping style balance.