BEHAVIORAL ACTIVATION PRODUCED BY CRH BUT NOT ALPHA-HELICAL CRH (CRH-RECEPTOR ANTAGONIST) WHEN MICROINFUSED INTO THE CENTRAL NUCLEUS OF THE AMYGDALA UNDER STRESS-FREE CONDITIONS

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)-containing cell bodies and terminals. In the present study we examined (by continuous behaviour observations) the effects of a high dose of CRH (150 ng) and two doses of the CRH-receptor antagonist (alpha-hCRH: 1.0 and 0.1 mu g) after microinfusion into the CeA in freely moving male Wistar rats under stress-free conditions. In comparison with control, alpha-hCRH infusion did not cause any behavioural activation. In contrast CRH-infusion revealed a long-lasting increase in grooming and exploration with a concomitant decrease in behaviours specified as resting. These results indicate that the CRH system in the CeA does not seem to be activated in stress-free conditions, but its activation is of importance for active behavioural responses