A Review on the Interaction between Neuroendocrinology and Immunology: Hypothalamic-Pituitary-Thyroid Axis in Immunoendocrinology

Immunoendocrinology is a novel area that focuses on the connection between the neurological, endocrine, and immunological systems. It is the study of interactions between neuroendocrinology and immunology. The interactions between sex- and stress-steroids are also involved in a neuroendocrine-immunological sexual dimorphism. Homeostasis, development, aging, metabolism, infection, and inflammation are all influenced by the crosstalk between these systems via hormones, cytokines, and neurotransmitters. The nervous system affects the immune system through either the hypothalamus-pituitary axes (adrenal, gonadal, thyroid, growth-hormone), neuropeptide and hormone signals or through autonomic nervous system signals of norepinephrine and acetylcholine. The immune system, on the other hand, provides feedback via cytokine type and concentration in the blood. Any of these systems that is out of balance increases the severity of metabolic, psychiatric, inflammatory, or autoimmune diseases. These two systems, neuroendocrinology and immunology, are complex in and of themselves, and even more so when they interact. As a result, the relationship between the immune system and the hypothalamus-pituitary-thyroid axis must be examined.