Rutin improves glutamate uptake and inhibits glutamate excitotoxicity in rat brain slices.

Rutin is an important flavonoid consumed in the daily diet. It is also known as vitamin P and has been extensively investigated due to its pharmacological properties. On the other hand, neuronal death induced by glutamate excitotoxicity is present in several diseases including neurodegenerative diseases. The neuroprotective properties of rutin have been under investigation, although its mechanism of action is still poorly understood. We hypothesized that the mechanisms of neuroprotection of rutin are associated with the increase in glutamate metabolism in astrocytes. This study aimed to evaluate the protective effects of rutin with a focus on the modulation of glutamate detoxification. We used brain organotypic cultures from post-natal Wistar rats (P7-P9) treated with rutin to evaluate neural cell protection and levels of proteins involved in the glutamate metabolism. Moreover, we used cerebral cortex slices from adult Wistar rats to evaluate glutamate uptake. We showed that rutin inhibited the cell death and loss of glutamine synthetase (GS) induced by glutamate that was associated with an increase in glutamate-aspartate transporter (GLAST) in brain organotypic cultures from post-natal Wistar rats. Additionally, it was observed that rutin increased the glutamate uptake in cerebral cortex slices from adult Wistar rats. We conclude that rutin is a neuroprotective agent that prevents glutamate excitotoxicity and thereof suggest that this effect involves the regulation of astrocytic metabolism.

LDL Receptor Deficiency Does not Alter Brain Amyloid-ß Levels but Causes an Exacerbation of Apoptosis.

Familial hypercholesterolemia (FH) is a genetic disorder caused by dysfunction of low density lipoprotein receptors (LDLr), resulting in elevated plasma cholesterol levels. FH patients frequently exhibit cognitive impairment, a finding recapitulated in LDLr deficient mice (LDLr-/-), an animal model of FH. In addition, LDLr-/- mice are more vulnerable to the deleterious memory impact of amyloid-ß (Aß), a peptide linked to Alzheimer's disease. Here, we investigated whether the expression of proteins involved in Aß metabolism are altered in the brains of adult or middle-aged LDLr-/- mice. After spatial memory assessment, Aß levels and gene expression of LDLr related-protein 1, proteins involved in Aß synthesis, and apoptosis-related proteins were evaluated in prefrontal cortex and hippocampus. Moreover, the location and cell-specificity of apoptosis signals were evaluated. LDLr-/- mice presented memory impairment, which was more severe in middle-aged animals. Memory deficit in LDLr-/- mice was not associated with altered expression of proteins involved in Aß processing or changes in Aß levels in either hippocampus or prefrontal cortex. We further found that the expression of Bcl-2 was reduced while the expression of Bax was increased in both prefrontal cortex and hippocampus in 3- and 14-month-old LDLr-/-mice Finally, LDLr-/- mice presented increased immunoreactivity for activated caspase-3 in the prefrontal cortex and hippocampus. The activation of caspase 3 was predominantly associated with neurons in LDLr-/- mice. Cognitive impairment in LDLr-/- mice is thus accompanied by an exacerbation of neuronal apoptosis in brain regions related to memory formation, but not by changes in Aß processing or levels.

Naringenin complexed with hydroxypropyl-ß-cyclodextrin improves the sciatic nerve regeneration through inhibition of p75NTR and JNK pathway.

Peripheral nerve injuries are common conditions that often lead to dysfunctions. Although much knowledge exists on the several factors that mediate the complex biological process involved in peripheral nerve regeneration, there is a lack of effective treatments that ensure full functional recovery. Naringenin (NA) is the most abundant flavanone found in citrus fruits and it has promising neuroprotective, anti-inflammatory and antioxidant effects. This study aimed to enhance peripheral nerve regeneration using an inclusion complex containing NA and hydroxypropyl-ß-cyclodextrin (HPßCD), named NA/HPßCD. A mouse sciatic nerve crush model was used to evaluate the effects of NA/HPßCD on nerve regeneration. Sensory and motor parameters, hyperalgesic behavior and the sciatic functional index (SFI), respectively, improved with NA treatment. Western blot analysis revealed that the levels of p75NTR ICD and p75NTR full length as well phospho-JNK/total JNK ratios were preserved by NA treatment. In addition, NA treatment was able to decrease levels of caspase 3. The concentrations of TNF-α and IL-1ß were decreased in the lumbar spine, on the other hand there was an increase in IL-10. NA/HPßCD presented a better overall morphological profile but it was not able to increase the number of myelinated fibers. Thus, NA was able to enhance nerve regeneration, and NA/HPßCD decreased effective drug doses while maintaining the effect of the pure drug, demonstrating the advantage of using the complex over the pure compound.

Characterization of a novel antioxidant peptide from feather keratin hydrolysates.

Feather hydrolysates were obtained through submerged cultivation of 50 g/L feathers with Chryseobacterium sp. kr6. Culture supernatants, displaying antioxidant properties, as evaluated by the 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) radical scavenging method, were partially purified by gel-filtration chromatography. Fractions showing scavenging activity were pooled, lyophilized and tested at different concentrations (0.1-1.0 mg/mL) by the total reactive antioxidant potential (TRAP) method, showing promising antioxidant capacities. Antioxidant activities of the partially purified feather hydrolysate (PPFH; 24.5 µg) were demonstrated by its ability to scavenge hydroxyl radicals and to inhibit lipid peroxidation. In addition, PPFH (0.24-24.5 µg) was found to reduce ferric ion (Fe3+), but did not display Fe2+-chelating activity. Thus, the main antioxidant activities could be related to the donation of hydrogen atoms, electron transfer and scavenging of hydroxyl radicals. PPFH was analyzed by mass spectrometry and five peptides were identified and chemically synthesized. The antioxidant activity of one peptide LPGPILSSFPQ was confirmed by ABTS and TRAP. The structure of this keratin-derived bioactive peptide has not been previously described.

Comparison of the effects of two antioxidant diets on oxidative stress markers in triathletes.

Intense exercise generates an imbalance in the redox system. However, chronic exercise can yield antioxidant adaptations. A few studies with humans have investigated the effects of antioxidant diets on athletes. Therefore we compared the effects of two dietary interventions on oxidative stress in competitive triathletes. Thirteen male triathletes were selected and divided into 2 groups: one that had a regular antioxidant diet (RE-diet) and the other that had a high antioxidant diet (AO-diet). The diet period was 14 days and blood samples were collected before and after this period. The AO-diet provided twice the dietary reference intake (DRI) of α-tocopherol (30 mg), five times the DRI of ascorbic acid (450 mg), and twice the DRI of vitamin A (1800 g), while the RE-diet provided the DRI of α-tocopherol (15 mg), twice the DRI of ascorbic acid (180 mg) and the DRI of vitamin A (900 µg). The oxidative stress parameters evaluated were: thiobarbituric acid reactive substances (TBARS), total reactive antioxidant potential (TRAP), total sulfhydryl, carbonyl, superoxide dismutase (SOD) activity, hydrogen peroxide consumption and glutathione peroxidase (GPx) activity. We observed, after the diet period, an increase in sulfhydryl, TRAP, TBARS and SOD activity, and a decrease in carbonyl levels. However, no changes were found in hydrogen peroxide consumption or GPx activity. We concluded that antioxidant-enriched diets can improve the redox status of triathletes.

A longitudinal study of neurotrophic, oxidative, and inflammatory markers in first-onset depression in midlife women.

Prospective studies have shown during the years preceding and following menopause, also known as "menopause transition", that midlife women are at higher risk for developing first-onset major depressive disorder (MDD). The biological factors associated with risk and resilience in this population are, however, largely unknown. Considering the growing body of evidence suggesting that inflammation, oxidative stress, and brain-derived neurotrophic factor (BDNF) are associated with the pathophysiology of MDD, we investigated serum levels of protein carbonyl, lipid peroxidation (thiobarbituric acid reactive substances-TBARS), thiol group content, BDNF, 3-nitrotyrosine, and heat shock protein 70 (HSP70) in a longitudinal cohort of first-onset MDD. One hundred and forty-eight women from the Harvard Study of Moods and Cycles, a prospective study of midlife women monitored throughout the transition to menopause, were studied. Within- and between-groups analyses of these peripheral markers were conducted in 37 women who developed and 111 women that did not develop MDD during the 3-year follow-up period. In women who developed MDD, HSP70 and 3-nitrotyrosine were elevated at baseline, whereas TBARS were elevated 6 months prior to development of MDD, as compared to those who did not develop MDD. Within-group analyses showed that HSP70, 3-nitrotyrosine, and BDNF decreased over time, whereas protein carbonyl was elevated only at 12 months prior to development of MDD. In women who did not develop MDD, HSP70 and thiol decreased over time. The development of MDD in midlife women may be associated with a systemic cascade of pro-oxidative and pro-inflammatory events including increased HSP70, 3-nitrotyrosine, protein carbonyl, and lipid peroxidation and decreased BDNF.

Sperm quality and oxidative status as affected by homogenization of liquid-stored boar semen diluted in short- and long-term extenders.

Homogenization of diluted boar semen during storage has for a long time been regarded as beneficial. Recent studies indicated an adverse effect of homogenization on sperm quality for yet unknown reasons. This study aimed to verify the effect of homogenization on sperm parameters and to elucidate the impact of oxidative stress. Twenty-one normospermic ejaculates (21 boars) were diluted with Androstar® Plus (AND) and Beltsville Thawing Solution (BTS). Semen doses were submitted to no-homogenization (NoHom) or twice-a-day manual homogenization (2xHom) during storage at 17°C for 168h. NoHom and 2xHom were similar (P>0.05) for both short- and long-term extenders with respect to motility and kinematics parameters (CASA system), membrane viability (SYBR-14/PI), acrosome integrity, lipid peroxidation, protein oxidation, intracellular reactive oxygen species, sulfhydryl content, and total radical-trapping antioxidant potential. 2xHom reduced sperm motility and motion kinematics (VCL, VSL, VAP, BCF, and ALH) following the thermoresistance test and presented with a slight increase in pH along the storage (P=0.05) as compared to NoHom. Furthermore, 2xHom semen doses presented with a constant SOD and GSH-Px activity during storage whereas enzymatic activity increased for NoHom at the end of the storage. These findings confirm that homogenization of semen doses is detrimental to sperm quality. Moreover, it is shown that the effect of homogenization is unlikely to be primarily related to oxidative stress. Homogenization is not recommended for storage of liquid boar semen for up to 168h in both short- and long-term extenders.

Apoptotic signaling pathways induced by acute administration of branched-chain amino acids in an animal model of maple syrup urine disease.

Maple Syrup Urine Disease (MSUD) is an inborn error of metabolism caused by a deficiency of the branched-chain α-keto acid dehydrogenase complex activity. This blockage leads to accumulation of the branched-chain amino acids leucine, isoleucine and valine, as well as their corresponding α-keto acids and α-hydroxy acids. The affected patients present severe neurological symptoms, such as coma and seizures, as well as edema and cerebral atrophy. Considering that the mechanisms of the neurological symptoms presented by MSUD patients are still poorly understood, in this study, protein levels of apoptotic factors are measured, such as Bcl-2, Bcl-xL, Bax, caspase-3 and -8 in hippocampus and cerebral cortex of rats submitted to acute administration of branched-chain amino acids during their development. The results in this study demonstrated that BCAA acute exposure during the early postnatal period did not significantly change Bcl-2, Bcl-xL, Bax and caspase-8 protein levels. However, the Bax/Bcl-2 ratio and procaspase-3 protein levels were decreased in hippocampus. On the other hand, acute administration of BCAA in 30-day-old rats increase in Bax/Bcl-2 ratio followed by an increased caspase-3 activity in cerebral cortex, whereas BCAA induces apoptosis in hippocampus through activation and cleavage of caspase-3 and -8 without changing the Bax/Bcl-2 ratio. In conclusion, the results suggest that apoptosis could be of pivotal importance in the developmental neurotoxic effects of BCAA. In addition, the current studies also suggest that multiple mechanisms may be involved in BCAA-induced apoptosis in the cerebral cortex and hippocampus.

pH-dependent cytotoxic effects of extracts of the marine sponge Polymastia janeirensis on cancer cell lines.

The purpose of this work was to study the cytotoxic effects of marine sponge Polymastia janeirensis, which has been observed in the field to release an orange substance that is toxic to fish. The result showed that aqueous extract (pH 7.0) was highly cytotoxic to glioma (U87) and neuroblastoma (SHSY5Y) cancer cell lines (IC50 < 1.0 µg/mL). In addition, this extract showed potent antioxidant and procoagulant (decreased the clotting time by 1.7-fold) activities. Interestingly, the cytotoxic effects were pH-dependent since the viability of the cancer cells was not affected with the extract (pH 5.5). The close similarity between the aqueous extract (pH 7.0) and the orange liquid that is released by the sponge indicates that this potential chemical defence of P. janeirensis deserves further investigation.

Sphingosines Derived from Marine Sponge as Potential Multi-Target Drug Related to Disorders in Cancer Development.

Haliclona tubifera, marine sponge species abundant in Brazilian coastline, presents only a few papers published in the literature. Recently, we have reported the isolation of two modified C18 sphingoid bases: (2R,3R,6R,7Z)-2-aminooctadec-7-ene-1,3, 6-triol and and (2R,3R,6R)-2-aminooctadec-1,3,6-triol. In order to continue our research, in this work aimed at the biological investigation of fractions that led to the isolation of these compounds. We evaluated the cytotoxic effect of marine sponge H. tubifera fractions in glioma (U87) and neuroblastoma (SH-SY5Y) human cell lines. In addition, considering the link between cancer, imbalance of reactive oxygen species and coagulation disorders, we also investigated the in vitro effects on blood coagulation and their redox properties. We showed that the ethyl acetate (EtOAc) fraction, rich in sphingoid bases, had important cytotoxic effects in both cancer cell lines with an IC50 < 15 µg/mL and also can inhibit the production of peroxyl radicals. Interestingly, this fraction increased the recalcification time of human blood, showing anticoagulant properties. The present study indicates the sphingosines fraction as a promising source of chemical prototypes, especially multifunctional drugs in cancer therapy.

Redox-Active Profile Characterization of Remirea maritima Extracts and Its Cytotoxic Effect in Mouse Fibroblasts (L929) and Melanoma (B16F10) Cells.

Remirea maritima is a tropical plant with a reticulated root system belonging to the family Cyperaceae, also known to have biologically active secondary metabolites. However, very few data on R. maritima's biological actions are available and there are no reports regarding the redox-active profile of this plant. In this study, we examined the total phenolic content of Remirea maritima hydroalcoholic (RMHA) extracts, redox properties against different reactive species generated in vitro and their cytotoxic effect against fibroblasts (L929) and melanoma (B16F10) cells. Total reactive antioxidant potential index (TRAP) and total antioxidant reactivity (TAR) results revealed that RMHA at all concentrations tested showed significant antioxidant capacity. RMHA was also effective against hydroxyl radical formation, reduction of Fe3+ to Fe2+ and in scavenging nitric oxide (NO) radicals. In vitro, the level of lipid peroxidation was reduced by RMHA extract and the data showed significant oxidative damage protection. The RMHA cytotoxicity was evaluated by a neutral red assay in fibroblast (L929) and melanome (B16F10) cells. The obtained results showed that the RMHA (40 and 80 µg/mL, respectively) reduced 70% of the viable cells. In conclusion, this study represents the first report regarding the antioxidant and anti-proliferative potential of R. maritima against B16F10 melanoma cells.

Acute Administration of Branched-Chain Amino Acids Increases the Pro-BDNF/Total-BDNF Ratio in the Rat Brain.

Maple syrup urine disease (MSUD) is caused by an inborn error in metabolism resulting from a deficiency in the branched-chain α-keto acid dehydrogenase complex activity. This blockage leads to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine and valine, as well as their corresponding α-keto acids and α-hydroxy acids. High levels of BCAAs are associated with neurological dysfunction and the role of pro- and mature brain-derived neurotrophic factor (BDNF) in the neurological dysfunction of MSUD is still unclear. Thus, in the present study we investigated the effect of an acute BCAA pool administration on BDNF levels and on the pro-BDNF cleavage-related proteins S100A10 and tissue plasminogen activator (tPA) in rat brains. Our results demonstrated that acute Hyper-BCAA (H-BCAA) exposure during the early postnatal period increases pro-BDNF and total-BDNF levels in the hippocampus and striatum. Moreover, tPA levels were significantly decreased, without modifications in the tPA transcript levels in the hippocampus and striatum. On the other hand, the S100A10 mRNA and S100A10 protein levels were not changed in the hippocampus and striatum. In the 30-day-old rats, we observed increased pro-BDNF, total-BDNF and tPA levels only in the striatum, whereas the tPA and S100A10 mRNA expression and the immunocontent of S100A10 were not altered. In conclusion, we demonstrated that acute H-BCAA administration increases the pro-BDNF/total-BDNF ratio and decreases the tPA levels in animals, suggesting that the BCAA effect may depend, at least in part, on changes in BDNF post-translational processing.

Antioxidant properties of phenolic compounds from Baccharis articulata and B. usterii.

As a continuation of our research on the Baccharis genus, the evaluation of the antioxidant effect by TRAP and TBARS assays of three isolated compounds from n-butanol fractions of B. articulata and B. usterii is reported. The structures of these compounds were established as 4-O-beta-D-glucopyranosyl-3,5-dimethoxybenzyl-methanol (1), 5-O-[E]-dicaffeoylquinic acid (2), and 7-hydroxy-5,4'-dimethoxyflavone (3). In the TRAP assay it was possible to observe an antioxidant effect of both n-butanol fractions at 1.25 microg/mL. Among the isolated compounds, compound 2 displayed a remarkable contribution to the total antioxidant capacity of the n-butanol fraction of B. usterii. Moreover, the n-butanol fractions of both species, compounds 1 and 2 at 40.0 microg/mL were efficient in protection of lipid peroxidation in the TBARS experiment. They are promising lead compounds for use in medicinal chemistry studies.

Coadministration of branched-chain amino acids and lipopolysaccharide causes matrix metalloproteinase activation and blood-brain barrier breakdown.

Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a severe deficiency in the activity of the branched-chain α-keto acid dehydrogenase complex, leading to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine. Infections have a significant role in precipitating acute metabolic decompensation in patients with MSUD; however, the mechanisms underlying the neurotoxicity in this disorder are poorly understood. In this study, we subjected rats to the coadministration of lipopolysaccharide (LPS), which is a major component of gram-negative bacteria cell walls, and high concentrations of BCAA (H-BCAA) to determine their effects on the permeability of the blood-brain barrier (BBB) and on the levels of matrix metalloproteinases (MMP-2 and MMP-9). Our results demonstrated that the coadministration of H-BCAA and LPS causes breakdown of the BBB and increases the levels of MMP-2 and MMP-9 in the hippocampus of these rats. On the other hand, examination of the cerebral cortex of the 10- and 30-day-old rats revealed a significant difference in Evan's Blue content after coadministration of H-BCAA and LPS, as MMP-9 levels only increased in the cerebral cortex of the 10-day-old rats. In conclusion, these results suggest that the inflammatory process associated with high levels of BCAA causes BBB breakdown. Thus, we suggest that BBB breakdown is relevant to the perpetuation of brain inflammation and may be related to the brain dysfunction observed in MSUD patients.

Resveratrol induces pro-oxidant effects and time-dependent resistance to cytotoxicity in activated hepatic stellate cells.

Resveratrol (RSV) is known for its antioxidant properties; however, this compound has been proposed to have cytotoxic and pro-oxidant effects depending on its concentration and time of exposure. We previously reported the cell cycle arrest effect of low doses of RSV in GRX cells, an activated hepatic stellate cell model. Here, we evaluated the effects of RSV treatment (0.1-50 µM) for 24 and 120 h on GRX viability and oxidative status. Only treatment with 50 µM of RSV reduced the amount of live cells. However, even low doses of RSV induced an increased reactive species production at both treatment times. While being diminished within 24 h, RSV induced an increase in the SOD activity in 120 h. The cellular damage was substantially increased at 24 h in the 50 µM RSV-treated group, as indicated by the high lipoperoxidation, which may be related to the significant cell death and low proliferation. Paradoxically, this cellular damage and lipoperoxidation were considerably reduced in this group after 120 h of treatment while the surviving cells proliferated. In conclusion, RSV induced a dose-dependent pro-oxidant effect in GRX cells. The highest RSV dose induced oxidative-related damage, drastically reducing cell viability; but this cytotoxicity seems to be attenuated during 120 h of treatment.

Acute brain inflammation and oxidative damage are related to long-term cognitive deficits and markers of neurodegeneration in sepsis-survivor rats.

Survivors from sepsis present long-term cognitive deficits and some of these alterations resemble the pathophysiological mechanisms of neurodegenerative diseases. For this reason, we analyzed beta-amyloid peptide (Aß) and synaptophysin levels in the brain of rats that survived from sepsis and their relation to cognitive dysfunction and to acute brain inflammation. Sepsis was induced in rats by cecal ligation and puncture, and 30 days after surgery, the hippocampus and prefrontal cortex were isolated just after cognitive evaluation by the inhibitory avoidance test. The immunocontent of Aß and synaptophysin were analyzed by Western blot analysis. Aß increased and synaptophysin decreased in septic animals both in the hippocampus and prefrontal cortex concurrent with the presence of cognitive deficits. Prefrontal levels of synaptophysin correlated to the performance in the inhibitory avoidance. Two different treatments known to decrease brain inflammation and oxidative stress when administered at the acute phase of sepsis decreased Aß levels both in the prefrontal cortex and hippocampus, increased synaptophysin levels only in the prefrontal cortex, and improved cognitive deficit in sepsis-survivor animals. In conclusion, we demonstrated that brain from sepsis-survivor animals presented an increase in Aß content and a decrease in synaptophysin levels and cognitive impairment. These alterations can be prevented by treatments aimed to decrease acute brain inflammation and oxidative stress.

Resveratrol-loaded lipid-core nanocapsules treatment reduces in vitro and in vivo glioma growth.

The development of novel therapeutic strategies to treat gliomas remains critical as a result of the poor prognoses, inef-. ficient therapies and recurrence associated with these tumors. In this context, biodegradable nanoparticles are emerging as efficient drug delivery systems for the treatment of difficult-to-treat diseases such as brain tumors. In the current study, we evaluated the antiglioma effect of trans-resveratrol-loaded lipid-core nanocapsules (RSV-LNC) based on in vitro (C6 glioma cell line) and in vivo (brain-implanted C6 cells) models of the disease. In vitro, RSV-LNC decreased the viability of C6 glioma cells to a higher extent than resveratrol in solution. Interestingly, RSV-LNC treatment was not cytotoxic to hippocampal organotypic cultures, a model of healthy neural cells, suggesting selectivity for cancer cells. RSV-LNC induced losses in glioma cell viability through induction of apoptotic cell death, as assessed by Annexin-FITC/PI assay, which was preceded by an early arrest in the S and G1 phases of the cell cycle. In brain-implanted C6 tumors, treatment with RSV-LNC (5 mg/kg/day, i.p.) for 10 days promoted a marked decrease in tumor size and also reduced the incidence of some malignant tumor-associated characteristics, such as intratumoral hemorrhaging, intratumoral edema and pseudopalisading, compared to resveratrol in solution. Taken together, the results presented herein suggest that nanoencapsulation of resveratrol improves its antiglioma activity, thus providing a provocative foundation for testing the clinical usefulness of nanoformulations of this natural compound as a new chemotherapeutic strategy for the treatment of gliomas.

Exploring the multifactorial nature of autism through computational systems biology: calcium and the Rho GTPase RAC1 under the spotlight.

Autism is a neurodevelopmental disorder characterized by impaired social interaction and communication accompanied with repetitive behavioral patterns and unusual stereotyped interests. Autism is considered a highly heterogeneous disorder with diverse putative causes and associated factors giving rise to variable ranges of symptomatology. Incidence seems to be increasing with time, while the underlying pathophysiological mechanisms remain virtually uncharacterized (or unknown). By systematic review of the literature and a systems biology approach, our aims were to examine the multifactorial nature of autism with its broad range of severity, to ascertain the predominant biological processes, cellular components, and molecular functions integral to the disorder, and finally, to elucidate the most central contributions (genetic and/or environmental) in silico. With this goal, we developed an integrative network model for gene-environment interactions (GENVI model) where calcium (Ca(2+)) was shown to be its most relevant node. Moreover, considering the present data from our systems biology approach together with the results from the differential gene expression analysis of cerebellar samples from autistic patients, we believe that RAC1, in particular, and the RHO family of GTPases, in general, could play a critical role in the neuropathological events associated with autism.

Chronic administration of branched-chain amino acids impairs spatial memory and increases brain-derived neurotrophic factor in a rat model.

Maple syrup urine disease (MSUD) is a neurometabolic disorder that leads to the accumulation of branched-chain amino acids (BCAAs) and their α-keto branched-chain by-products. Because the neurotoxic mechanisms of MSUD are poorly understood, this study aimed to evaluate the effects of chronic administration of a BCAA pool (leucine, isoleucine and valine). This study examined the effects of BCAA administration on spatial memory and the levels of brain-derived neurotrophic factor (BNDF). We examined both pro-BDNF and bdnf mRNA expression levels after administration of BCAAs. Furthermore, this study examined whether antioxidant treatment prevented the alterations induced by BCAA administration. Our results demonstrated an increase in BDNF in the hippocampus and cerebral cortex, accompanied by memory impairment in spatial memory tasks. Additionally, chronic administration of BCAAs did not induce a detectable change in pro-BDNF levels. Treatment with N-acetylcysteine and deferoxamine prevented both the memory deficit and the increase in the BDNF levels induced by BCAA administration. In conclusion, these results suggest that when the brain is chronically exposed to high concentrations of BCAA (at millimolar concentrations) an increase in BDNF levels occurs. This increase in BDNF may be related to the impairment of spatial memory. In addition, we demonstrated that antioxidant treatment prevented the negative consequences related to BCAA administration, suggesting that oxidative stress might be involved in the pathophysiological mechanism(s) underlying the brain damage observed in MSUD.

Exploring the mechanisms of alcohol-related damage in oral mucosa - is oxidative stress associated with the increase in cell proliferation in rat tongue epithelium?

CONTEXT: Alcohol consumption has been related to a cell proliferation increase in oral epithelium but its mechanism remains unclear. OBJECTIVE: The aim of this study was to investigate whether oxidative stress parameters are implicated in the induction of cell proliferation in rat tongue epithelium after different times of chronic alcohol consumption. MATERIALS AND METHODS: Cell proliferation was assessed in tongue epithelium using AgNOR (argyrophilic proteins related to active nucleolar organizer regions) quantification. Oxidative stress parameters [lipid peroxidation, protein carbonyls, superoxide dismutase activity and catalase (CAT) activity and immunocontent] and Nrf2 immunocontent were quantified in tongue homogenates. RESULTS AND DISCUSSION: Mean AgNOR numbers (mAgNOR) per nucleus was 2.22 ± 0.30 in ventral tongue epithelium after 120 days of alcohol consumption (vs. 1.87 ± 0.18 for control animals and 1.91 ± 0.23 for animals treated with alcohol for 60 days) indicating cell proliferation increase (p < 0.05, ANOVA followed by Tukey post hoc). Interestingly, 60 days of alcohol consumption induced changes in oxidative stress parameters, but no alteration in cell proliferation. Vitamin E co-treatment was conduced in order to evaluate its possible protective effects. The 120 day Tween + vitamin E + alcohol treatment induced an increase in mAgNORs when compared to the Tween + vitamin E treated group (respectively 2.10 ± 0.30 vs. 1.77 ± 0.11, p < 0.05, ANOVA followed by Tukey post hoc), showing that vitamin E co-treatment had no protective effects. In addition, an inverse association was observed between CAT activity and AgNORs quantity (R = -0.32; p < 0.05, Person's correlation) as well as the possible involvement of Nrf2 in alcohol-related damage. CONCLUSIONS: Our findings suggest that the increase in cell proliferation associated with alcohol-related damage has no direct relation with an imbalance in oxidative parameters. In contrast, our results indicate that hydrogen peroxide may be implicated in cellular signaling during proliferation in the oral mucosa.