glycogen and Congenital-Hypothyroidism

We investigated the effect of hyperthyroidism and hypothyroidism on the myocardial glycogen metabolism by quantitating 125I-insulin binding, glycogen content, glycogen synthase and phosphorylase enzyme activities in the newborn rabbit. Although an increase in 125I-insulin binding was observed in response to hyperthyroidism (p less than 0.01), a decrease in myocardial glycogen (p less than 0.01) along with no change in the synthase and phosphorylase enzyme activity was demonstrated. On the other hand, propylthiouracil-induced hypothyroxinemia did not affect the 125I-insulin binding, glycogen content or the two enzyme systems. We conclude that the depletion of myocardial glycogen secondary to hyperthyroidism is independent of an increase in 125I-insulin binding or any change in the major glycogen enzyme activities (synthase and phosphorylase). We speculate that this decline in neonatal heart glycogen may be secondary to thyroxine-induced altered glucose uptake or modified postinsulin receptor events.

Topics: Animals; Animals, Newborn; Blood Glucose; Congenital Hypothyroidism; Female; Fetal Diseases; Glycogen; Hyperthyroidism; Hypothyroidism; Insulin; Myocardium; Pregnancy; Rabbits; Thyroid Hormones; Thyroxine

Topics: Action Potentials; Child; Child, Preschool; Congenital Hypothyroidism; Creatine Kinase; Electromyography; Female; Fructose-Bisphosphate Aldolase; Glycogen; Humans; Hypertrophy; Hypothyroidism; L-Lactate Dehydrogenase; Lipid Metabolism; Male; Microscopy, Electron; Mitochondria, Muscle; Muscles; Muscular Diseases; Neuromuscular Junction; Sarcoplasmic Reticulum; Syndrome; Thyroxine

Topics: Congenital Hypothyroidism; Female; Glycogen; Humans; Ichthyosis; Infant; Intellectual Disability; Linoleic Acids; Lipid Metabolism; Liver; Liver Glycogen; Microscopy, Electron; Muscle Spasticity; Myxedema; Palmitic Acids; Retinal Degeneration

Topics: Child, Preschool; Congenital Hypothyroidism; Glycogen; Histocytochemistry; Humans; Hypertrophy; Hypothyroidism; Male; Muscles; Muscular Diseases

Topics: Congenital Hypothyroidism; Down Syndrome; Glycogen; Humans; Intellectual Disability; Myotonia