title: Inhibitory role of regucalcin in the regulation of nitric oxide synthase activity in rat brain cytosol: involvement of aging.
abstract: Regucalcin is shown to play a regulatory role in intracellular signaling system in many cells. The protein has been reported to be present in rat brain neurons. The role of regucalcin in the regulation of nitric oxide (NO) synthase activity in the brain cytosol of female young and aged rats was investigated. The presence of regucalcin (10(-9) and 10(-8) M) in the enzyme reaction mixture caused a significant decrease in NO synthase activity in the absence or presence of both calcium chloride (10 micro M) and calmodulin (2.5 micro g/ml). The effect of regucalcin (10(-8) M) in decreasing brain cytosolic NO synthase activity was not seen in the presence of Nw-nitro-L-argine methyl ester (NAME) (10(-4) M), trifluoperazine (20 micro M) or EGTA (1 mM). Regucalcin protein levels were significantly lowered in the brain cytosol of aged (50 weeks old) rats as compared with that of young (5 weeks old) rats. Brain cytosolic NO synthase activity was significantly reduced with increasing age. In aged rat brain cytosol, regucalcin caused a significant decrease in NO synthase activity. The presence of anti-regucalcin monoclonal antibody (10-50 ng/ml) caused a significant increase in NO synthase activity in the brain cytosol of young and aged rats. This elevation was completely blocked by the addition of regucalcin (10(-8) M). The present study demonstrates that endogenous regucalcin has an inhibitory effect on NO synthase activity in the brain cytosol of young and aged rats.
authors.affiliation: Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, 52-1 Yada, Shizuoka, 422-8526, Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Tobisawa
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001923:Brain Chemistry; D002122:Calcium Chloride / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D002147:Calmodulin / Q000494:pharmacology; D002265:Carboxylic Ester Hydrolases; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000737:chemistry / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015238:Sulfotransferases; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D014268:Trifluoperazine; D019001:Nitric Oxide Synthase; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; D002122:Calcium Chloride; D019331:NG-Nitroarginine Methyl Ester