Abstract
Galacosemia is one of the inherited metabolic disorder which may lead to death early in in fancy or survival with varing degrees of mental retardation. Kalckar have found the defect in galactosemia as a deficiency of the enzyme, galactose-1-phosphate uridyl transferase. However, the full explanation of mental retardation in this disorder have not yet appeared because of difficulties and lacks of studies on the problem.
The author analyzed brain lipids of galaco semic rats, which were made galactosemic with feeding the diet Containg 35% galactose, for elucidating the pathogenosis of mental retardation in this condition. There are low levels of. free myo-inositol and phosphatidyl inositol in the brains 1 to 3 weeks old rats fed with galactose containing diet. Further, analyses of diand triphosphoinositides from frozen rat brains with liquid nitrogen showed some changes in developing brains of both groups of animals. The increasing amount of sphingomyelin and cerebroside during the course of growth in galactosemic rat brains were considerably lower than that of the sucrose fed rat brains, and these results indicated 1 week retardation of myelination in the former.
It has been noted that the inositol phosphatide may act an important role on ion trnsport or menbrane permeability. Especially, interesting work that triphosphoinositide-protein-ion complex release, the ions by adding acetylcholin in vitro (Hayashi, 1968), suggests some relation of this lipids to the functions of neural tissues. The low levels of these lipids in' brains of experimental galactosemic rats might support the idea that these relate to mental retardation.
