Changes in the activities of adenosine-metabolizing enzymes in six regions of the rat brain on chemical induction of hypothyroidism.
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.
Mazurkiewicz
D
D
Department of Biochemistry, University College London, U.K.
Saggerson
D
D
D015720:5'-Nucleotidase; D000243:Adenosine Deaminase / Q000378:metabolism*; D000248:Adenosine Kinase / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D007037:Hypothyroidism / Q000139:chemically induced / Q000201:enzymology*; D008297:Male; D009700:Nucleoside Deaminases / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011441:Propylthiouracil; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000201:enzymology
D011441:Propylthiouracil; D010770:Phosphotransferases; D000248:Adenosine Kinase; D009708:Nucleotidases; D015720:5'-Nucleotidase; D009700:Nucleoside Deaminases; D000243:Adenosine Deaminase