REGULATION OF THE ADRENOCORTICOTROPIN RESPONSE TO STRESS BY THE CENTRAL NUCLEUS OF THE AMYGDALA IN RATS DEPENDS UPON THE NATURE OF THE STRESSOR

The regulatory role of the medial (CeM) or the lateral (CeL) part of t he central nucleus of the amygdala on the hypothalamo-pituitary-adrena l axis response to stress was investigated in male rats. Basal and res traint- or lipopolysacharride (LPS)-induced plasma adrenocorticotrophi c hormone (ACTH) levers were measured 7 days after sham operation or l esion of the CeM or CeL. CeM or CeL lesion did not change basal ACTH c oncentrations. In control rats, restraint or LPS injection induced a r obust increase in ACTH secretion. CeL lesion did not modify the stress -induced increment in ACTH release. CeM lesion significantly decreased the ACTH response to restraint and potentiated the ACTH response to L PS injection. Our findings demonstrate that the CeM exerts complex inf luences on the corticotrophic response to stress, being either stimula tory or inhibitory, depending on the nature of the stressor.