Brain sulfatide and non-lipid sulfate metabolism in hypothyroid rats

Neonatal hypothyroidism reduced the concentration of sulfatide in myelin and synaptosomes isolated from brains of 20-21 day old rats. The in vivo incorporation of ³⁵SO₄ into sulfatide of myelin, microsomal, mitochondrial and synaptosomal fractions was also decreased in these animals, as was the incorporation of the isotope into non lipid sulfate (sulfated glycoproteins and mucopolysaccharides) of microsomal and synaptosomal fractions. In contrast, when animals were made hypothyroid at one month of age, no depletion of brain sulfatide or alteration of incorporation of ³⁵SO₄ into sulfatide was found, although incorporation of the isotope into non lipid sulfate of myelin, mitochondria and synaptosomes was increased by this treatment. These results indicate that the metabolism of sulfatide and non lipid sulfate of brain membranes is much more susceptible to alteration by hypothyroidism in neonatal than in older animals. Furthermore, they suggest that neonatal hypothyroidism may alter the metabolism of sulfatide and non lipid sulfate in neuronal as well as myelin membranes.