Bidirectional communication between neuroendocrine and immune systems through growth hormone, prolactin and hepcidin

It has been proposed that growth hormone (GH) and prolactin (PRL) may act as immunomodulators in infectious processes via specific receptors, revealing a connection between the immune and endocrine systems in the tissues where they act as cytokines through different signaling pathways. Similarly, hepcidin (HAMP), a hormone produced in hepatocytes in response to excess iron and inflammatory stimuli, is considered a link between mineral metabolism, host defense and inflammatory processes because of its ability to deprive microorganisms of iron. It is suggested that in an infectious process, synthesis, and regulation of GH secretion occurs through the production of cytokines such as necrosis factor?alpha (TNF?α) and interleukin?1 beta (IL?1β), which act in the hypothalamus by stimulating the release of either somatostatin or somatotropin hormones; on the other hand, it has been reported that lymphoid cells including T and B lymphocytes and dendritic cells produce GH, and biologically active PRL with immunoregulatory properties.