Gene found key to brain chemical. (Neuroscience).The story of serotonin, a brain chemical associated with depression and anxiety, just became more complicated. German scientists have found that the mouse brain doesn't use the expected enzyme to create the neurotransmitter neurotransmitter, chemical that transmits information across the junction (synapse) that separates one nerve cell (neuron) from another nerve cell or a muscle. Neurotransmitters are stored in the nerve cell's bulbous end (axon). . The previously known serotonin-making enzyme is tryptophan hydroxylase Tryptophan hydroxylase (TPH) is an enzyme (EC 1.14.16.4) involved in the synthesis of the neurotransmitter serotonin. Function It is responsible for addition of the -OH group (hydroxylation) to the 5 position to form the amino acid 5-hydroxytryptophan (5-HTP), which is , or TPH TPH Transplacental hemorrhage . Recently, Diego J. Walther of the Max Delbruck Center for Molecular Medicine in Berlin-Buch and his colleagues created mutant mice that lack this enzyme. Surprisingly, the rodents still made serotonin in their brains. In other tissues, however, the chemical was almost nonexistent non·ex·is·tence n. 1. The condition of not existing. 2. Something that does not exist. non . The investigators soon discovered the explanation--mice have a gene encoding a second form of TPH, as do people. It's this version of TPH that's responsible for serotonin synthesis in the brains of mice and, presumably pre·sum·a·ble adj. That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. , people, the researchers report in the Jan. 3 Science. The many past efforts to link the original THP gene to psychiatric disorders now must be reevaluated, Walther and his colleagues suggest.--J.T. |
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