EFFECTS OF CHRONIC PORTO-CAVAL ANASTOMOSIS ON BRAIN TRYPTOPHAN, TYROSINE AND 5-HYDROXYTRYPTAMINE |
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| Authors: | G. Curzon Bharati D. Kantamaneni J. C. Fernando Margaret S. Woods J. B. Cavanagh |
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| Affiliation: | Departments of Neurochemistry and Neurobiology, Institute of Neurology, London W.C.1, U.K. |
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| Abstract: | —Three weeks after porto-caval anastomosis, tryptophan and 5-hydroxyindolylacetic acid concentrations were-greatly increased in rat brain regions. 5-Hydroxytryptamine showed smaller increases. Midbrain tyrosine and muscle tyrosine and tryptophan concentrations were also increased. Striatal dopa-mine concentration was not significantly changed. Unlike previous results from acute liver failure, brain tryptophan changes in this chronic study did not simply reflect plasma-free tryptophan changes. Midbrain tryptophan/plasma-free tryptophan ratio and midbrain tyrosine/plasma tyrosine ratio both rose, suggesting increased effectiveness of uptake of these amino acids from plasma by brain. Corresponding muscle/plasma ratios were unaltered by the porto-caval anastomosis. Uptake of tryptophan from buffer by cerebral cortex slices was unaffected. Results on control animals illustrate the importance of plasma-free tryptophan in the normal physiological control of brain tryptophan. |
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