| Affiliation: | (1) Pennington Biomedical Research Center, Baton Rouge, LA, USA;(2) Department of Pharmacology, Toxicology, and Neuroscience, LSU Health Sciences Center-Shreveport, 1501 Kings Highway Shreveport, 71103, LA, USA |
| Abstract: | Changes in brain tryptophan concentrations may affect the synthesis of brain serotonin (5-hydroxytryptamine, 5-HT). Concentrations of tryptophan are regulated more than those of any other amino acid. Such stimuli as acute stress, carbohydrate ingestion, and treatment with various drugs increase the brain content of tryptophan. Treatment of rats and mice with interleukin-1 (IL-1), interleukin-6 (IL-6), lipopolysaccharide (LPS), and β-adrenoceptor agonists, as well as a variety of stressors, such as footshock and restraint, all increase brain concentrations of tryptophan. The peak effect following both acute stress and β-adrenoceptor agonist administration occurs within 30–60 min, whereas the peak effect following LPS and the cytokines occurs much later at around 4–8 h. Experiments using the ganglionic blocker chlorisondamine, and β-adrenoceptor antagonists suggest that the sympathetic nervous system plays an important role in the modulation of brain tryptophan concentrations. The mechanisms involved in the increases observed in brain tryptophan are discussed, as well as their possible biological significance. Special issue dedicated to Dr. Simo S. Oja |
