Biogenic amines in neuroendocrine systems: multiple sources, messages, targets and controls.

Biogenic amines are small chemical mediator molecules synthesized from amino acids by the body. Our research has centered on functions and controls of three categories of biogenic amines in neuroendocrine and neural systems of laboratory species of mammals as models of similar processes in the human body. Experimental analyses have been made of possible contributions of particular of these compounds, or their sources, to regulation of reproductive and 24-hour rhythms, and to responses and adaptations to stress. Results from this and related work, by many other investigators as well, have general implications for biomedical research, including: (A) Biogenic amines have multiple sources, messages, targets and possible controls, depending on species (genetics), developmental stage and age, and in relation to tissue regions and responses during both adaptations and disease states. (B) Functions or actions of biogenic amines in either the nervous or the neuroendocrine system go beyond what can be accommodated by the classical paradigms or terms of neurophysiology. Labeling these compounds in their various tissue sites as "neurotransmitters", or "neuromodulators", or "neurohormones" adds little to our understanding of their actions and roles. (C) Future understanding of how these chemical mediators function and are controlled in health and in disease should be enhanced by investigation of the spectrum of adaptive tissue changes in which these compounds and their control mechanisms participate. This suggested approach contrasts with the usual and classic paradigm in which primary, if not unitary, sources, actions and controls are emphasized to the exclusion and ignoring of others that may have vital significance at particular times or in particular circumstances.