Biomaterial Database

The respective roles of tryptophan uptake and tryptophan hydroxylase in the regulation of serotonin synthesis in the central nervous system. 1981

M Hamon, and S Bourgoin, and F Artaud, and S El Mestikawy

1. The rate limiting enzyme for the synthesis of serotonin (5-HT) in brain, tryptophan hydroxylase, is not saturated under normal physiological conditions. 2. Therefore, any decrease or increase in brain tryptophan levels results in a reduction or a stimulation of 5-HT synthesis respectively. Thus, mechanisms controlling brain tryptophan levels, i.e. the concentration of free tryptophan in serum and the intrinsic activity of the tryptophan carrier in neuronal membranes, exert in fact a tonic regulation of 5-HT synthesis in central serotoninergic neurons. 3. Changes in the rate of 5-HT synthesis can also involve modifications in the intrinsic activity of tryptophan hydroxylase. This occurs in vivo following the intrastriatal injection of kainic acid and in vitro during the depolarization of brain slices. In both cases, an activation of tryptophan hydroxylase due to an increase in its apparent Vmax is detected in soluble extracts. 4. The depolarization-induced activation of tryptophan hydroxylase in brain slices very likely involves a Ca2+-dependent phosphorylation process. 5. Rapid changes in tryptophan hydroxylase activity produced by a phosphorylation-dephosphorylation process may be involved in the phasic regulation of 5-HT synthesis in serotoninergic neurons.

UI	MeSH Term	Description	Entries
D007608	Kainic Acid	(2S-(2 alpha,3 beta,4 beta))-2-Carboxy-4-(1-methylethenyl)-3-pyrrolidineacetic acid. Ascaricide obtained from the red alga Digenea simplex. It is a potent excitatory amino acid agonist at some types of excitatory amino acid receptors and has been used to discriminate among receptor types. Like many excitatory amino acid agonists it can cause neurotoxicity and has been used experimentally for that purpose.	Digenic Acid,Kainate,Acid, Digenic,Acid, Kainic
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D011494	Protein Kinases	A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.	Protein Kinase,Kinase, Protein,Kinases, Protein
D001812	Blood-Brain Barrier	Specialized non-fenestrated tightly-joined ENDOTHELIAL CELLS with TIGHT JUNCTIONS that form a transport barrier for certain substances between the cerebral capillaries and the BRAIN tissue.	Brain-Blood Barrier,Hemato-Encephalic Barrier,Barrier, Blood-Brain,Barrier, Brain-Blood,Barrier, Hemato-Encephalic,Barriers, Blood-Brain,Barriers, Brain-Blood,Barriers, Hemato-Encephalic,Blood Brain Barrier,Blood-Brain Barriers,Brain Blood Barrier,Brain-Blood Barriers,Hemato Encephalic Barrier,Hemato-Encephalic Barriers
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia