Central corticotropin-releasing hormone reduces cellular immunity.

Corticotropin-releasing hormone (CRH) acts within the brain to elicit changes in neuroendocrine, autonomic, and behavioral activity similar to those observed after stress. A reduction of splenic natural killer (NK) activity has also been described following the central administration of CRH. In this study, we examined whether other in vitro measures of cellular immunity, including peripheral and splenic NK activity, lymphocyte responses to mitogen stimulation, and numbers of splenic T and NK cell subpopulations, are altered following CRH. Synthetic rat CRH (1.0 microgram) microinjected into the lateral ventricle reduced splenic and peripheral blood NK activity, lymphocyte responses to mitogenic stimulation, and percentage of splenic NK cell numbers. Numbers of splenic lymphocytes and T cell subpopulations were not altered by central CRH. These findings suggest that central CRH acts to reduce a number of in vitro cellular immune measures similar to the effects of inescapable stress.