Increased peripheral of brain-derived neurotrophic factor levels in phenylketonuric patients treated with l-carnitine.

Phenylketonuria (PKU) is the most common inherited metabolic disorders caused by severe deficiency or absence of phenylalanine hydroxylase activity that converts phenylalanine (Phe) to tyrosine. PKU patients were treated with a Phe restricted diet supplemented with a special formula containing l-carnitine (L-car), well-known antioxidant compound. The lack of treatment can cause neurological and cognitive impairment, as severe mental retardation, neuronal cell loss and synaptic density reduction. Although Phe has been widely demonstrated to be involved in PKU neurotoxicity, the mechanisms responsible for the CNS injury are still not fully known. In this work, we evaluated markers of neurodegeneration, namely BDNF (brain-derived neurotrophic factor), PAI-1 total (Plasminogen activator inhibitor-1 total), Cathepsin D, PDGF AB/BB (platelet-derived growth factor), and NCAM (neuronal adhesion molecule) in plasma of PKU patients at early and late diagnosis and under treatment. We found decreased Phe levels and increased L-car concentrations in PKU patients treated with L-car compared to the other groups, indicating that the proposed treatment was effective. Furthermore, we found increased BDNF levels in the patients under treatment compared to patients at early diagnosis, and a positive correlation between BDNF and L-car and a negative correlation between BDNF and Phe. Our results may indicate that in PKU patients treated with L-car there is an attempt to adjust neuronal plasticity and recover the damage suffered, reflecting a compensatory response to brain injury.

In vivo intracerebral administration of L-2-hydroxyglutaric acid provokes oxidative stress and histopathological alterations in striatum and cerebellum of adolescent rats.

Patients affected by L-2-hydroxyglutaric aciduria (L-2-HGA) are biochemically characterized by elevated L-2-hydroxyglutaric acid (L-2-HG) concentrations in cerebrospinal fluid, plasma, and urine due to a blockage in the conversion of L-2-HG to α-ketoglutaric acid. Neurological symptoms associated with basal ganglia and cerebelar abnormalities whose pathophysiology is still unknown are typical of this neurometabolic disorder. In the present study we evaluated the early effects (30min after injection) of an acute in vivo intrastriatal and intracerebellar L-2-HG administration on redox homeostasis in rat striatum and cerebellum, respectively. Histological analyses of these brain structures were also carried out 7 days after L-2-HG treatment (long-term effects). L-2-HG significantly decreased the concentrations of reduced (GSH) and total glutathione (tGS), as well as of glutathione peroxidase (GPx) and reductase (GR) activities, but did not change the activities of superoxide dismutase and catalase in striatum. Furthermore, the concentrations of oxidized glutathione (GSSG) and malondialdehyde (MDA), as well as 2',7'-dichlorofluorescein (DCFH) oxidation and hydrogen peroxide (H2O2) production, were increased, whereas carbonyl formation and nitrate plus nitrite concentrations were not altered by L-2-HG injection. It was also found that the melatonin, ascorbic acid plus α-tocopherol, and creatine totally prevented most of these effects, whereas N-acetylcysteine, the noncompetitive glutamate NMDA antagonist MK-801, and the nitric oxide synthase inhibitor L-NAME were not able to normalize the redox alterations elicited by L-2-HG in striatum. L-2-HG intracerebellar injection similarly provoked a decrease of antioxidant defenses (GSH, tGS, GPx, and GR) and an increase of the concentrations of GSSG, MDA, and H2O2 in cerebellum. These results strongly indicate that the major accumulating metabolite in L-2-HGA induce oxidative stress by decreasing the antioxidant defenses and enhancing reactive oxygen species in striatum and cerebellum of adolescent rats. Regarding the histopathological findings, L-2-HG caused intense vacuolation, lymphocyte and macrophage infiltrates, eosinophilic granular bodies, and necrosis in striatum. Immunohistochemistry revealed that L-2-HG treatment provoked an increase of GFAP and a decrease of NeuN immunostaining, indicating reactive astroglyosis and reduction of neuronal population, respectively, in striatum. Similar macrophage infiltrates, associated with less intense vacuolation and lymphocytic infiltration, were observed in cerebellum. However, we did not observe necrosis, eosinophilic granular bodies, and alteration of GFAP and NeuN content in L-2-HG-teated cerebellum. From the biochemical and histological findings, it is presumed that L-2-HG provokes striatal and cerebellar damage in vivo possibly through oxidative stress induction. Therefore, we postulate that antioxidants may serve as adjuvant therapy allied to the current treatment based on a protein-restricted diet and riboflavin and L-carnitine supplementation in patients affected by L-2-HGA.

Urinary biomarkers of oxidative damage in Maple syrup urine disease: the L-carnitine role.

Maple syrup urine disease (MSUD) is a disorder of branched-chain amino acids (BCAA). The defect in the branched-chain α-keto acid dehydrogenase complex activity leads to an accumulation of these compounds and their corresponding α-keto-acids and α-hydroxy-acids. Studies have shown that oxidative stress may be involved in neuropathology of MSUD. L-carnitine (L-car), which has demonstrated an important role as antioxidant by reducing and scavenging free radicals formation and by enhancing the activity of antioxidant enzymes, have been used in the treatment of some metabolic rare disorders. This study evaluated the oxidative stress parameters, di-tyrosine, isoprostanes and antioxidant capacity, in urine of MSUD patients under protein-restricted diet supplemented or not with L-car capsules at a dose of 50 mg kg(-1) day(-1). It was also determined urinary α-keto isocaproic acid levels as well as blood free L-car concentrations in blood. It was found a deficiency of carnitine in patients before the L-car supplementation. Significant increases of di-tyrosine and isoprostanes, as well as reduced antioxidant capacity, were observed before the treatment with L-car. The L-car supplementation induced beneficial effects on these parameters reducing the di-tyrosine and isoprostanes levels and increasing the antioxidant capacity. It was also showed a significant increase in urinary of α-ketoisocaproic acid after 2 months of L-car treatment, compared to control group. In conclusion, our results suggest that L-car may have beneficial effects in the treatment of MSUD by preventing oxidative damage to the cells and that urine can be used to monitorize oxidative damage in patients affected by this disease.