The neuroendocrine and immune systems are linked through bidirectional communication pathways that enable modification and coordination of physiological, behavioural and immunological responses upon changing internal and external conditions. It is now realized that this delicate balance between neuroendocrine and immune systems is one of the most important factors conditioning homeostasis and as consequence animal health and welfare. Fish represent more than one-half of all extant vertebrate species and their ability to continuously adapt to altered and altering circumstances by co-ordinated neuroendocrine and immune responses must have contributed to this success. The present multi-disciplinary project, combining the knowledge from immunology, neurobiology, endocrinology and fish biology, will identify the phylogeny and functions of molecules involved in homeostasis. It will yield a fundamentally better understanding of the mechanisms underlying protective immune responses in fish and, will provide essential knowledge to improve aquaculture. The different types of adrenergic receptors will be characterised, and influence of neuroendocrine mediators on the immune response and vice versa, the effect of immunomediators on neuroendocrine system will be established. Accomplishment of the proposed project will guarantee transfer of knowledge and techniques to the host institution. An excellent molecular and proteomics laboratory, dedicated to immunology and neuroendocrinology will be made operational. The project will support complete reintegration of the fellow within the host institute and will assure her job stability and professional independence. Moreover, the reintegration grant will strengthen the fruitful and intensive collaboration with the Cell Biology and Immunology Group, Wageningen University and the Department of Physiology, Nijmegen University as initiated during the present Marie-Curie fellowship.