Corticosterone implants to the amygdala and type 1 CRH receptor regulation: effects on behavior and colonic sensitivity.

Corticosterone (CORT) micropellets were stereotaxically placed bilaterally at the dorsal margin of the central nucleus of the amygdala (CeA). Both behavioral and physiological responses were recorded (plus maze and colonic discomfort) at 7 days post-implantation. Corticosterone reduced the exploration of the plus maze and increased colonic distress. The ability of a CRH type 1 receptor antagonist, antalarmin, to block behavioral and colonic effects of central placement of CORT was also examined. The diminished exploration in the plus maze and colon distress observed in response to CORT placement at the CeA were averted by the administration of antalarmin. These results provide further evidence for the role of the CRH type 1 receptor to ameliorate both behavioral and physiological functions.