EFFECT OF THYROID DEFICIENCY ON THE LEVELS OF SEVERAL ENZYMES IN RAT BRAIN

—Activities of acid phosphatase, alkaline phosphatase and β-glucuronidase have been estimated in the brain tissues, using various subcellular particles, in growing thyroidectomized rats and also using cytoplasmic extracts free from debris and nuclear fraction in young hypothyroid animals. Hepatic glucose-6-phosphate dehydrogenase activity was markedly reduced after thyroidectomy but the enzyme was brought back to normal levels by thyroxine treatment. There was no change, however, in the activity of neural glucose-6-phosphate dehydrogenase after thyroidectomy. In the thyroidectomized animals an increase only in the free acid phosphatase activity in the neural synaptosomes was found and this increase in activity was not counteracted by administration of thyroxine. In the hypothyroid young animal β-glucuronidase, acid phosphatase and alkaline phosphatase activities were found to be affected during development.