1. Rats (4 weeks old) were made hypothyroid by treatment with propylthiouracil and a low-iodine diet for a further period of 4 weeks. Synaptosomal membranes, myelin and 105,000 g soluble fractions were obtained from six regions of the brain. 2. Hypothyroidism resulted in 2-5-fold increases in membrane-bound 5′-nucleotidase activity in synaptosomal fractions obtained from cerebellum, cortex, striatum and hippocampus. By contrast, myelin 5′-nucleotidase activity was slightly increased only in the medulla oblongata. 3. Hypothyroidism did not change adenosine deaminase activity, but decreased adenosine kinase activity by approx. 40% in soluble fractions obtained from cerebellum, hippocampus, striatum and hypothalamus. 4. It is suggested that these changes in hypothyroidism, in particular the increases in 5′-nucleotidase activity, could enhance the neuromodulatory effect of adenosine to decrease neurotransmitter release.
Changes in the activities of adenosine-metabolizing enzymes in six regions of the rat brain on chemical induction of hypothyroidism
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D Mazurkiewicz, D Saggerson; Changes in the activities of adenosine-metabolizing enzymes in six regions of the rat brain on chemical induction of hypothyroidism. Biochem J 15 July 1989; 261 (2): 667–672. doi: https://doi.org/10.1042/bj2610667
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