Central corticotropin-releasing hormone reduces cellular immunity

Area of Science:

• Neuroendocrinology
• Immunology
• Stress Physiology

Background:

• Corticotropin-releasing hormone (CRH) centrally regulates stress responses.
• Central CRH administration is known to reduce splenic natural killer (NK) cell activity.
• The impact of CRH on other cellular immunity measures requires further investigation.

Purpose of the Study:

• To investigate the effects of central CRH on various in vitro measures of cellular immunity.
• To determine if CRH alters peripheral and splenic NK activity, lymphocyte proliferation, and splenic T and NK cell populations.

Main Methods:

• Synthetic rat CRH was microinjected into the lateral ventricle of rats.
• In vitro assays measured splenic and peripheral blood NK activity.
• Lymphocyte responses to mitogen stimulation and splenic T/NK cell subpopulations were analyzed.

Main Results:

• Central CRH significantly reduced splenic and peripheral blood NK activity.
• Lymphocyte responses to mitogenic stimulation were decreased following CRH administration.
• The percentage of splenic NK cells decreased, but total lymphocyte and T cell numbers remained unchanged.

Conclusions:

• Central CRH administration suppresses key cellular immune functions, including NK cell activity and lymphocyte responsiveness.
• These immunosuppressive effects of CRH mirror those observed after inescapable stress.
• CRH plays a significant role in mediating stress-induced alterations in cellular immunity.