Abstract
Deficiency of ccystathionine may be a factor in the pathogenesis of the abnormalities in homocystinuria. Wong et al. [1968] showed that homocystinuric liver was able to synthesize cystathionine from homoserine and cysteine. Hence it may be possible to correct cystathionine deficiency in the brains of these patients.
(1) Homoserine, (2) cysteine, (3) homoserine + cysteine (7.5 μ/g) was injected intraperitoneally to mice. It was observed that brain tissue could concentrate these amino acids. At 5 h after injection, brain cystathionine (μm/g) was significantly higher in groups (1), (2) and (3) than in controls (4). (1) 0.042±0.013, (2) 0.069±0.017, (3) 0.143±0.022, (4) 0.023±0.011 (n – 6).
Ten groups of 25 weaning mice were fed with Purina Chow (PC) or PC + 5%, 2% or 1% of either homoserine or cysteine or both. Mice on diets containing 5% cysteine had initial weight loss and subsequent slow weight gain. These changes were correlated with poor intake. Light microscopy of organs was normal in all groups. Electronmicroscopy showed ‘adaptive’ changes in the liver of mice on diets with 2 to 5% cysteine. At 6 months, brain cystathionine (μm/g) in mice on homoserine was 0.018±0.005, 0.112+0.019, 0.054±0.007 and 0.040±0.003 respectively. The higher brain cystathionine in the experimental groups is signifacant.
It appears that prolonged feeding of homoserine and cysteine in moderate amounts to homocystinurics is harmless and that cystathionine deficiency may be corrected. Clinical trials to assess the role of homoserine in the treatment of homocystinuria are now justified.
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Wong, P., Fresco, R. & Hsia, D. Tissue Cystathionine in Mice Treated With Cysteine and Homoserine. Pediatr Res 4, 454 (1970). https://doi.org/10.1203/00006450-197009000-00080
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DOI: https://doi.org/10.1203/00006450-197009000-00080