Environmental, toxicological and related aspects of tryptophan metabolism with particular reference to the central nervous system.

Abstract

AbstractIX. SUMMARYTryptophan is unique among the amino acids as it is present largely in the plasma bound to albumin. The binding is decreased by various drugs and unesterified fatty acids. As synthesis of the latter substance is influenced by sympathetic nervous activity, the binding of plasma tryptophan can be markedly dependent on changes of environmental and internal milieu. One consequence of these relationships is that changes of plasma tryptophan binding may lead to changes of brain tryptophan concentration and, thus, to altered synthesis of the neurotransmitter 5-hydroxytryptamine and, hence, to the possibility of altered behavior. Other mechanisms, such as competition between tryptophan and other plasma amino acids for uptake by the brain, can also influence brain tryptophan concentration.Various components of behavior such as sleep, motor activity, food intake, pain sensitivity, and aggression respond to changes of brain 5-hydroxy -tryptamine synthesis. In general, these behavioral parameters i...