We don’t think about spleens much these days, but ancient Greeks viewed the spleen as the . Today’s scientists know that the spleen is an important part of the , an armory where immune cells pick up antigens. If an antigen is recognized as an enemy (like a previously encountered virus), antibodies are sent off to battle.
Researchers removed nerves from the spleens of mice, then injected the mice with antigens that should produce the immune cells that trigger antibody release. Without brain-spleen communication, immune cell production shut down. Two brain regions sent the bulk of these signals: the central nucleus of the amygdala, and the paraventricular nucleus of the thalamus.
Both regions activate and regulate production of . When mice were placed in stressful situations (like standing on a high, transparent platform), stress hormones released from the brain slowed down antibody production in the spleen.
Ancient Greek physicians weren’t quite right, but they were on to something: the brain and the body (yes, even the spleen) are in constant communication, and we’re just beginning to understand their language.