Guanidinoacetate Methyltransferase Deficiency

Guanidinoacetate methyltransferase (GAMT) deficiency is an autosomal recessively inherited disorder of the metabolism of creatine that leads to depleted levels of creatine and excessive concentrations of guanidinoacetate (GAA). Patients affected develop neurological symptoms during childhood, such as muscular hypotonia, involuntary extrapyramidal movements, convulsions, slurred speech, and even autism. Although the pathophysiology of GAMT deficiency is unclear, neurological dysfunction is commonly found in this disease, and it has been mainly attributed to a reduction in creatine or/and an increase in GAA levels. Reports from literature suggest that GAA may interfere with neuronal γ-aminobutyric acid (GABA) receptors type A and cause epilepsy in human. Preclinical studies show that GAA increases free radical formation and decreases brain antioxidant defenses, inducing alteration in oxidative status. Guanidinoacetate also impairs energy metabolism in brain. The discussion of this review focuses on various and latest studies addressing GAMT deficiency and creatine metabolism, as well as addresses the question of neurotoxicity GAA

Homocysteine induces oxidative stress, inflammatory infiltration, fibrosis and reduces glycogen/glycoprotein content in liver of rats

Hyperhomocysteinemia has been related to various diseases, including homocystinuria, neurodegenerative and hepatic diseases. In the present study we initially investigated the effect of chronic homocysteine administration on some parameters of oxidative stress, named total radical-trapping antioxidant potential, total antioxidant reactivity, catalase activity, chemiluminescence, thiobarbituric acid-reactive substances, and total thiol content in liver of rats. We also performed histological analysis, evaluating steatosis, inflammatory infiltration, fibrosis, and glycogen/glycoprotein content in liver tissue sections from hyperhomocysteinemic rats. Finally, we evaluated the activities of aminotransferases in liver and plasma of hyperhomocysteinemic rats. Wistar rats received daily subcutaneous injection of Hcy from their 6th to their 28th day of life. Twelve hours after the last injection the rats were sacrificed, liver and plasma were collected. Hyperhomocysteinemia decreased antioxidant defenses and total thiol content, and increased lipid peroxidation in liver of rats, characterizing a reliable oxidative stress. Histological analysis indicated the presence of inflammatory infiltrate, fibrosis and reduced content of glycogen/glycoprotein in liver tissue sections from hyperhomocysteinemic rats. Aminotransferases activities were not altered by homocysteine. Our data showed a consistent profile of liver injury elicited by homocysteine, which could contribute to explain, at least in part, the mechanisms involved in human liver diseases associated to hyperhomocysteinemia. (C) 2009 ISDN. Published by Elsevier Ltd. All rights reserved.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq Brazil).Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Hypermethioninemia provokes oxidative damage and histological changes in liver of rats

In the present study we evaluated the effect of chronic methionine administration on oxidative stress and biochemical parameters in liver and serum of rats, respectively. We also performed histological analysis in liver. Results showed that hypermethioninemia increased chemiluminescence, carbonyl content and glutathione peroxidase activity, decreased total antioxidant potential, as well as altered catalase activity. Hypermethioninemia increased synthesis and concentration of glycogen, besides histological studies showed morphological alterations and reduction in the glycogen/glycoprotein content in liver. Serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and glucose were increased in hypermethioninemic rats. These findings suggest that oxidative damage and histological changes caused by methionine may be related to the hepatic injury observed in hypermethioninemia. (C) 2009 Elsevier Masson SAS. All rights reserved.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq-Brazil)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Experimental hyperprolinemia induces mild oxidative stress, metabolic changes, and tissue adaptation in rat liver

The present study investigated the effects of chronic hyperprolinemia on oxidative and metabolic status in liver and serum of rats. Wistar rats received daily subcutaneous injections of proline from their 6th to 28th day of life. Twelve hours after the last injection the rats were sacrificed and liver and serum were collected. Results showed that hyperprolinemia induced a significant reduction in total antioxidant potential and thiobarbituric acid-reactive substances. The activities of the antioxidant enzymes catalase and superoxide dismutase were significantly increased after chronic proline administration, while glutathione (GSH) peroxidase activity, dichlorofluorescin oxidation, GSH, sulfhydryl, and carbonyl content remained unaltered. Histological analyses of the liver revealed that proline treatment induced changes of the hepatic microarchitecture and increased the number of inflammatory cells and the glycogen content. Biochemical determination also demonstrated an increase in glycogen concentration, as well as a higher synthesis of glycogen in liver of hyperprolinemic rats. Regarding to hepatic metabolism, it was observed an increase on glucose oxidation and a decrease on lipid synthesis from glucose. However, hepatic lipid content and serum glucose levels were not changed. Proline administration did not alter the aminotransferases activities and serum markers of hepatic injury. Our findings suggest that hyperprolinemia alters the liver homeostasis possibly by induction of a mild degree of oxidative stress and metabolic changes. The hepatic alterations caused by proline probably do not implicate in substantial hepatic tissue damage, but rather demonstrate a process of adaptation of this tissue to oxidative stress. However, the biological significance of these findings requires additional investigation. J. Cell. Biochem. 113: 174183, 2012. (C) 2011 Wiley Periodicals, Inc.Conselho Nacional de Desenvolvimento Cientifico e TecnologicoConselho Nacional de Desenvolvimento Cientifico e TecnologicoConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq-Brazil)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), BrazilFundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS)Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS