Treatment With Resveratrol Ameliorates Mitochondrial Dysfunction During the Acute Phase of Status Epilepticus in Immature Rats

The aim of the present study was to elucidate the effect of resveratrol (natural polyphenol) on seizure activity, production of ROS, brain damage and mitochondrial function in the early phase of status epilepticus (SE), induced in immature 12 day-old rats by substances of a different mechanism of action (Li-pilocarpine, DL-homocysteic acid, 4-amino pyridine, and kainate). Seizure activity, production of superoxide anion, brain damage and mitochondrial function were assessed by EEG recordings, hydroethidium method, FluoroJadeB staining and Complex I activity measurement. A marked decrease of complex I activity associated with the acute phase of SE in immature brain was significantly attenuated by resveratrol, given i.p. in two or three doses (25 mg/kg each), 30 min before, 30 or 30 and 60 min after the induction of SE. Increased O2.– production was completely normalized, brain damage partially attenuated. Since resveratrol did not influence seizure activity itself (latency, intensity, frequency), the mechanism of protection is likely due to its antioxidative properties. The findings have a clinical relevance, suggesting that clinically available substances with antioxidant properties might provide a high benefit as an add-on therapy during the acute phase of SE, influencing also mechanisms involved in the development of epilepsy.

Effects of Alzheimer-Like Pathology on Homocysteine and Homocysteic Acid Levels—An Exploratory In Vivo Kinetic Study

Hyperhomocysteinemia has been suggested potentially to contribute to a variety of pathologies, such as Alzheimer’s disease (AD). While the impact of hyperhomocysteinemia on AD has been investigated extensively, there are scarce data on the effect of AD on hyperhomocysteinemia. The aim of this in vivo study was to investigate the kinetics of homocysteine (HCys) and homocysteic acid (HCA) and effects of AD-like pathology on the endogenous levels. The mice received a B-vitamin deficient diet for eight weeks, followed by the return to a balanced control diet for another eight weeks. Serum, urine, and brain tissues of AppNL-G-F knock-in and C57BL/6J wild type mice were analyzed for HCys and HCA using LC-MS/MS methods. Hyperhomocysteinemic levels were found in wild type and knock-in mice due to the consumption of the deficient diet for eight weeks, followed by a rapid normalization of the levels after the return to control chow. Hyperhomocysteinemic AppNL-G-F mice had significantly higher HCys in all matrices, but not HCA, compared to wild type control. Higher serum concentrations were associated with elevated levels in both the brain and in urine. Our findings confirm a significant impact of AD-like pathology on hyperhomocysteinemia in the AppNL-G-F mouse model. The immediate normalization of HCys and HCA after the supply of B-vitamins strengthens the idea of a B-vitamin intervention as a potentially preventive treatment option for HCys-related disorders such as AD.

A Functional Polymorphism in HIF-3α Is Related to an Increased Risk of Ischemic Stroke

Hypoxia-inducible factor-3α (HIF-3α), a member of HIF family, can mediate adaptive responses to low oxygen and ischemia. It is believed that HIF plays crucial roles in stroke-related diseases. However, there are no reports on the association between HIF-3α genetic variants and ischemic stroke (IS) susceptibility. Therefore, we examined the association between HIF-3α gene polymorphisms (rs3826795, rs2235095, and rs3764609) and IS risk. The study population included 302 controls and 310 patients with ischemic stroke. Three polymorphisms in HIF-3α (rs3826795, rs2235095, and rs3764609) were genotyped using SNPscan technique. Our study showed a strong association of rs3826795 in HIF-3α with the risk of IS. The genotype and allele frequencies were shown to differ between the two groups. The rs3826795 in an intron of HIF-3α was related to a prominent increased IS risk (AA vs GG adjusted odd ratio [OR], 2.21; 95% confidence intervals [95% CI], 1.10–4.44; P = 0.03; AA vs AG/GG OR = 1.74, 95% CI, 1.02–2.97, P = 0.04; A vs G OR = 1.48, 95% CI, 1.05–2.07, P = 0.02). Logistic regression analysis suggested that rs3826795 posed a risk factor for IS in addition to common factors. Furthermore, when compared to controls, increased levels of homocysteic acid and level of non-esterified fatty acid were found in the cases (P < 0.01). However, no significant association was found between rs2235095 or rs3264609 and IS risk. These findings indicated that the rs3826795 polymorphism may be a potential target for predicting the risk of IS.

Impact of Hyperhomocysteinemia and Different Dietary Interventions on Cognitive Performance in a Knock-in Mouse Model for Alzheimer’s Disease

Background: Hyperhomocysteinemia is considered a possible contributor to the complex pathology of Alzheimer’s disease (AD). For years, researchers in this field have discussed the apparent detrimental effects of the endogenous amino acid homocysteine in the brain. In this study, the roles of hyperhomocysteinemia driven by vitamin B deficiency, as well as potentially beneficial dietary interventions, were investigated in the novel AppNL-G-F knock-in mouse model for AD, simulating an early stage of the disease. Methods: Urine and serum samples were analyzed using a validated LC-MS/MS method and the impact of different experimental diets on cognitive performance was studied in a comprehensive behavioral test battery. Finally, we analyzed brain samples immunohistochemically in order to assess amyloid-β (Aβ) plaque deposition. Results: Behavioral testing data indicated subtle cognitive deficits in AppNL-G-F compared to C57BL/6J wild type mice. Elevation of homocysteine and homocysteic acid, as well as counteracting dietary interventions, mostly did not result in significant effects on learning and memory performance, nor in a modified Aβ plaque deposition in 35-week-old AppNL-G-F mice. Conclusion: Despite prominent Aβ plaque deposition, the AppNL-G-F model merely displays a very mild AD-like phenotype at the investigated age. Older AppNL-G-F mice should be tested in order to further investigate potential effects of hyperhomocysteinemia and dietary interventions.

Homocysteic Acid in Blood Can Detect Mild Cognitive Impairment: A Preliminary Study

Background: In the treatment of Alzheimer’s disease (AD), it is thought to be most effective to intervene at the earliest and mildest stages. For diagnosis at the earliest and mildest stages, it is desirable to use a biomarker that can be detected by a minimally invasive, cost-effective technique. Recent research indicates the potential clinical usefulness of plasma amyloid-β (Aβ) biomarkers in predicting brain Aβ burden at an individual level. However, it is as yet unproven that accumulation of Aβ necessarily leads to the development of AD. Objective: Homocysteic acid (HCA) is useful as an early diagnostic marker for mild cognitive impairment (MCI), a pre-stage of AD. Methods: We measured the concentration of HCA, tumor necrosis factor alpha, cortisol, tau, and phosphorylated tau (p-tau) in patients’ plasma of 22 AD, 23 MCI, and 9 negative control (NC) cases. Results: Plasma HCA was shown to be very high in areas under the receiver operating characteristic curves (AUC), distinguished between MCI and NC; when 0.116μM was chosen as the analyte concentration cut-off, the sensitivity was 95.7% and the specificity was 70%. Conclusion: Our results suggest that plasma HCA may be a useful indicator as an early diagnostic marker for MCI. HCA seems to be upstream from neurodegeneration in the AD pathology because it is known that an overactive NMDA receptor promotes amyloid polymerization and tau phosphorylation in AD.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) dysregulates hepatic one carbon metabolism during the progression of steatosis to steatohepatitis with fibrosis in mice

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental contaminant, induces steatosis that can progress to steatohepatitis with fibrosis, pathologies that parallel stages in the development of non-alcoholic fatty liver disease (NAFLD). Coincidently, one carbon metabolism (OCM) gene expression and metabolites are often altered during NAFLD progression. In this study, the time- and dose-dependent effects of TCDD were examined on hepatic OCM in mice. Despite AhR ChIP-seq enrichment at 2 h, OCM gene expression was not changed within 72 h following a bolus dose of TCDD. Dose-dependent repression of methionine adenosyltransferase 1A (Mat1a), adenosylhomocysteinase (Achy) and betaine-homocysteine S-methyltransferase (Bhmt) mRNA and protein levels following repeated treatments were greater at 28 days compared to 8 days. Accordingly, levels of methionine, betaine, and homocysteic acid were dose-dependently increased, while S-adenosylmethionine, S-adenosylhomocysteine, and cystathionine exhibited non-monotonic dose-dependent responses consistent with regulation by OCM intermediates and repression of glycine N-methyltransferase (Gnmt). However, the dose-dependent effects on SAM-dependent metabolism of polyamines and creatine could not be directly attributed to alterations in SAM levels. Collectively, these results demonstrate persistent AhR activation disrupts hepatic OCM metabolism at the transcript, protein and metabolite levels within context of TCDD-elicited progression of steatosis to steatohepatitis with fibrosis.

Do Stereoisomers of Homocysteic Acid Exhibit Different Convulsant Action in Immature Rats?

Mechanism of ictogenesis of D- and L-stereroisomers of homocysteic acid was studied in 12-day-old rats by means of antagonists of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. There was no qualitative difference between the two stereoisomers in generation of emprosthotonic (flexion) as well as generalized tonic-clonic seizures. Moderate differences were observed in the first, nonconvulsive effects of the two isomers. As generation of the two types of seizures is concerned, NMDA and AMPA participate in generalized tonic-clonic seizures whereas NMDA receptors play a dominant role in generation of flexion seizures.

Crystal structures and snapshots along the reaction pathway of human phosphoserine phosphatase

The equilibrium between phosphorylation and dephosphorylation is one of the most important processes that takes place in living cells. Human phosphoserine phosphatase (hPSP) is a key enzyme in the production of serine by the dephosphorylation of phospho-L-serine. It is directly involved in the biosynthesis of other important metabolites such as glycine and D-serine (a neuromodulator). hPSP is involved in the survival mechanism of cancer cells and has recently been found to be an essential biomarker. Here, three new high-resolution crystal structures of hPSP (1.5–2.0 Å) in complexes with phosphoserine and with serine, which are the substrate and the product of the reaction, respectively, and in complex with a noncleavable substrate analogue (homocysteic acid) are presented. New types of interactions take place between the enzyme and its ligands. Moreover, the loop involved in the open/closed state of the enzyme is fully refined in a totally unfolded conformation. This loop is further studied through molecular-dynamics simulations. Finally, all of these analyses allow a more complete reaction mechanism for this enzyme to be proposed which is consistent with previous publications on the subject.