Complexity of the neuroendocrine system.

This paper summarizes briefly the numerous connections and mechanisms existing within the neuroendocrine system. In the last decades it became clear that besides the originally postulated basic mechanisms there are several other, such as autocrine and paracrine mechanisms within the glands, bidirectional neural connections between the target endocrine glands and the hypothalamus and lower brainstem, which are of functional significance. Further we learned that the organization of the neural structures involved is much more complicated than originally thought. In addition, it turned out that the neuroendocrine system and the immune system are closely and intimately linked to each other. The available informations indicate clearly that a physiological integration exists between the nervous, the endocrine and immune systems.