Reduction of 5'-Nucleotidase Activity in Rat Thyroid and Adenohypophysis following Methylthiouracil Treatment

Abstract

5'-Nucleotidase activity was determined in rat thyroid and some other organs employing a specific assay method. During the course of methylthiouracil (MTU) treatment, thyroid 5'-nucleotidase activity decreased significantly. This decrease was specific for this enzyme since the activity of neutral phosphatase did not change and the activity of alkaline phosphatase and Mg²⁺-activated adenosine triphosphatase increased markedly. The 5'-nucleotidase activity of the adenohypophysis also decreased following MTU treatment. This enzyme activity of the liver, heart and whole brain remained unchanged after the treatment. The role of this enzyme was discussed in relation to tissue growth and increased contents of RNA and DNA in the thyroid and adenohypophysis.