Myoinositol and phosphatidylinositol metabolism in synaptosomes from galactose-fed rats.
The effects of experimental galactose toxicity on inositol and phosphatidylinositol (PtdIns) metabolism in synaptosomes from 0- to 30-day-old rats were investigated. Galactose toxicity was induced by feeding mothers a 40% galactose diet from the 12th day of pregnancy until 19 days postpartum when the offspring were weaned onto the maternal diet. There was no decrease in myoinositol concentrations and only a small decrease in PtdIns in synaptosomes from galactose-fed rats relative to glucose-fed controls. Synaptosomes from rats on the two diets converted equivalent amounts of [U-14C]glucose to inositol and PtdIns. Acetylcholine stimulated [2-3H]inositol incorporation into PtdIns while producing a net decrease in PtdIns concentration in synaptosomes from 22- to 30-day-old rats. However, the phospholipid response to acetylcholine in synaptosomes from galactose-fed rats was impaired. Thus, the acetylcholine-stimulated labeling of PtdIns was 40--50% lower in these synaptosomes while the effect on PtdIns concentration was reduced by a maximum of 55%. The data suggest that galactose-fed rats may have either a deficiency in the number of acetylcholine receptors or a defect in some step between receptor-neurotransmitter interaction and PtdIns breakdown.
D000109:Acetylcholine / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D001921:Brain / Q000378:metabolism*; D004032:Diet; D005690:Galactose / Q000378:metabolism / Q000506:poisoning*; D005947:Glucose / Q000378:metabolism; D007294:Inositol / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D013574:Synaptosomes / Q000378:metabolism*
D010716:Phosphatidylinositols; D007294:Inositol; D005947:Glucose; D000109:Acetylcholine; D005690:Galactose