Metoclopramide as a Potential Antipsychotic Against Long-Term Methionine Exposure in Zebrafish.

Methionine (MET) contributes to brain function and is required for proper functioning of the central nervous system. However, exceptionally high levels of MET and its metabolites in plasma have been found to be toxic and can lead to cell alterations. Long-term exposure to MET has been shown to mimic psychotic symptoms in schizophrenic patients and rodents. The present study evaluated behavioral and neurochemical effects of long-term exposure to MET in zebrafish. Five groups of zebrafish were exposed to MET at a concentration of 4.5 mM for 7 days, along with acute exposure to 25 µM of clozapine and 750, 1000, and 1250 µM of metoclopramide. In contrast, the normal group was exposed to only water and dimethyl sulfoxide. After the treatment, social interaction, anxiety, memory, and locomotion of zebrafish and serotonin levels in zebrafish brains were evaluated. Our results showed that metoclopramide was not only beneficial in improving MET-induced cognitive impairment but it also prevented social withdrawal in zebrafish exposed to MET. In addition, metoclopramide reversed anxiety-like behavior, as indicated by significant changes in locomotion activity. Despite slight changes in serotonin levels in the zebrafish brain, an in vitro serotonin assay failed to demonstrate significant differences between the disease control, normal, and two treatment groups. Finally, results from the study showed that repeated administration of MET induced schizophrenia-like symptoms, although metoclopramide ameliorated the MET-mediated negative symptoms and cognitive deficits in zebrafish. Overall, our findings suggest a new perspective to further explore the antipsychotic properties of metoclopramide.

Paternal exposure to excessive methionine altered behavior and neurochemical activities in zebrafish offspring.

An increase in plasma L-methionine (Met) levels, even if transitory, can cause important toxicological alterations in the affected individuals. Met is essential in the regulation of epigenetic mechanisms and its influence on the subsequent generation has been investigated. However, few studies have explored the influence of a temporary increase in Met levels in parents on their offspring. This study evaluated the behavioral and neurochemical effects of parental exposure to high Met concentration (3 mM) in zebrafish offspring. Adult zebrafish were exposed to Met for 7 days, maintained for additional 7 days in tanks that contained only water, and then used for breeding. The offspring obtained from these fish (F1) were tested in this study. During the early stages of offspring development, morphology, heart rate, survival, locomotion, and anxiety-like behavior were assessed. When these animals reached the adult stage, locomotion, anxiety, aggression, social interaction, memory, oxidative stress, and levels of amino acids and neurotransmitters were analyzed. F1 larvae Met group presented an increase in the distance and mean speed when compared to the control group. F1 adult Met group showed decreased anxiety-like behavior and locomotion. An increase in reactive oxygen species was also observed in the F1 adult Met group whereas lipid peroxidation and antioxidant enzymes did not change when compared to the control group. Dopamine, serotonin, glutamate, and glutathione levels were increased in the F1 adult Met group. Taken together, our data show that even a transient increase in Met in parents can cause behavioral and neurochemical changes in the offspring, promoting transgenerational effects.

Novel effective mosquito larvicide DL-methionine: Lack of toxicity to non-target aquatic organisms.

Mosquito larvicides are an effective tool for reducing numbers of adult females that bite and potentially spread pathogenic organisms. Methionine, an essential amino acid in humans, has been previously demonstrated to be a highly effective larvicide against four (4) mosquito species in three (3) genera, Anopheles, Culex and Aedes. The aim of the present study was to determine the potential impact on non-target aquatic organisms of methionine applied as a mosquito larvicide. DL-methionine concentrations ranging from 0.06% to 1.00% were used; wherein the highest concentration of 1.00% would result in 100% mortality within 48 h in mosquitoes. Acute toxicity assays were conducted in accordance with the US Environmental Protection Agency (US EPA) guidelines for the water flea (Daphnia magna Straus; Cladocera: Daphniidae) and the fathead minnow (Pimephales promelas Rafinesque; Cypriniformes: Cyprinidae). Water fleas and fish were placed directly into the solutions in glass containers and tanks for 48-hours and 96-hours, respectively. When applied within the above-mentioned range of effective mosquito larvicide concentrations, DL-methionine meets US EPA criteria as a "practically non-toxic" pesticide for both species. These results suggest that methionine is a viable alternative to current mosquito larvicide options, which are typically classified as moderately to highly toxic and may be a valuable addition to a mosquito integrated pest management program.

A Lipid-Based Nanocarrier Containing Active Vitamin D3 Ameliorates NASH in Mice via Direct and Intestine-Mediated Effects on Liver Inflammation.

The gut-liver axis may be involved in non-alcoholic steatohepatitis (NASH) progression. Pathogen-associated molecular patterns leak through the intestinal barrier to the liver via the portal vein to contribute to NASH development. Active vitamin D3 (1,25(OH)2D3) is a potential therapeutic agent to enhance the intestinal barrier. Active vitamin D3 also suppresses inflammation and fibrosis in the liver. However, the adverse effects of active vitamin D3 such as hypercalcemia limit its clinical use. We created a nano-structured lipid carrier (NLC) containing active vitamin D3 to deliver active vitamin D3 to the intestine and liver to elicit NASH treatment. We found a suppressive effect of the NLC on the lipopolysaccharide-induced increase in permeability of an epithelial layer in vitro. Using mice in which NASH was induced by a methionine and choline-deficient diet, we discovered that oral application of the NLC ameliorated the permeability increase in the intestinal barrier and attenuated steatosis, inflammation and fibrosis in liver at a safe dose of active vitamin D3 at which the free form of active vitamin D3 did not show a therapeutic effect. These data suggest that the NLC is a novel therapeutic agent for NASH.

Maternal Hyperhomocysteinemia Induces Neuroinflammation and Neuronal Death in the Rat Offspring Cortex.

Maternal hyperhomocysteinemia is one of the common complications of pregnancy that causes offspring cognitive deficits during postnatal development. In the present work, we evaluated the effect of prenatal hyperhomocysteinemia on structural and ultrastructural organization, neuronal and glial cell number, apoptosis (caspase-3 content and activity), inflammatory markers (tumor necrosis factor-α, interleukin-6, and interleukin-1ß), and p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation in the offspring brain cortex in early ontogenesis. Wistar female rats received methionine (0.6 g/kg body weight) by oral administration during pregnancy. Histological and biochemical analyses of 5- and 20-day-old pups' cortical tissue were performed. Lysosome accumulation and other neurodegenerative changes in neurons of animals with impaired embryonic development were investigated by electron microscopy. Neuronal staining (anti-NeuN) revealed a reduction in neuronal number, accompanied by increasing of caspase-3 active form protein level and activity. Maternal hyperhomocysteinemia also elevated the number of astroglial and microglial cells and increased expression of interleukin-1ß and p38 MAPK phosphorylation, which indicates the development of neuroinflammatory processes.

Edaravone protects from memory impairment induced by chronic L-methionine administration.

Hyperhomocysteinemia is a well-known cause of cognitive impairment and neurodegeneration. Increased oxidative stress in the brain has a major possible role in hyperhomocysteinemia-induced pathogenesis. Edaravone is a potent free radical scavenger that has a neuroprotective effect against memory impairment in several experimental models. The current study investigated the possible protective effect of edaravone in L-methionine-induced vascular dementia in a rat model. L-methionine was given (1.7 mg/kg/day) through oral gavage, while edaravone was given (6 mg/kg/day) intraperitoneally. The administration of methionine and edaravone started concomitantly and continued for a total of 9 weeks. Spatial learning and memory were assessed using the radial arm water maze (RAWM). Changes in the oxidative stress-related biomarkers in the hippocampus were assessed using enzymatic assays. Chronic L-methionine administration resulted in short-term and long-term memory impairment, whereas edaravone prevented such effect. Furthermore, edaravone ameliorated L-methionine induced decrease in the activity of the antioxidant enzymes catalase and glutathione peroxidase as well as the ratio of reduced glutathione to oxidized glutathione (GSH/GSSG ratio). Edaravone also prevented increase in the oxidized glutathione (GSSG) secondary to chronic L-methionine administration. In conclusion, the current study suggests that memory impairment and oxidative stress secondary to chronic L-methionine administration can be prevented by edaravone, probably via enhancing antioxidant mechanisms in the hippocampus.

Methionine dietary supplementation potentiates ionizing radiation-induced gastrointestinal syndrome.

Methionine is an essential amino acid needed for a variety of processes in living organisms. Ionizing radiation depletes tissue methionine concentrations and leads to the loss of DNA methylation and decreased synthesis of glutathione. In this study, we aimed to investigate the effects of methionine dietary supplementation in CBA/CaJ mice after exposure to doses ranging from 3 to 8.5 Gy of 137Cs of total body irradiation. We report that mice fed a methionine-supplemented diet (MSD; 19.5 vs. 6.5 mg/kg in a methionine-adequate diet, MAD) developed acute radiation toxicity at doses as low as 3 Gy. Partial body irradiation performed with hindlimb shielding resulted in a 50% mortality rate in MSD-fed mice exposed to 8.5 Gy, suggesting prevalence of radiation-induced gastrointestinal syndrome in the development of acute radiation toxicity. Analysis of the intestinal microbiome demonstrated shifts in the gut ecology, observed along with the development of leaky gut syndrome and bacterial translocation into the liver. Normal gut physiology impairment was facilitated by alterations in the one-carbon metabolism pathway and was exhibited as decreases in circulating citrulline levels mirrored by decreased intestinal mucosal surface area and the number of surviving crypts. In conclusion, we demonstrate that a relevant excess of methionine dietary intake exacerbates the detrimental effects of exposure to ionizing radiation in the small intestine.NEW & NOTEWORTHY Methionine supplementation, instead of an anticipated health-promoting effect, sensitizes mice to gastrointestinal radiation syndrome. Mechanistically, excess of methionine negatively affects intestinal ecology, leading to a cascade of physiological, biochemical, and molecular alterations that impair normal gut response to a clinically relevant genotoxic stressor. These findings speak toward increasing the role of registered dietitians during cancer therapy and the necessity of a solid scientific background behind the sales of dietary supplements and claims regarding their benefits.

Hypermethioninemia induces memory deficits and morphological changes in hippocampus of young rats: implications on pathogenesis.

The aim of this study was to investigate the effect of the chronic administration of methionine (Met) and/or its metabolite, methionine sulfoxide (MetO), on the behavior and neurochemical parameters of young rats. Rats were treated with saline (control), Met (0.2-0.4 g/kg), MetO (0.05-0.1 g/kg), and/or a combination of Met + MetO, subcutaneously twice a day from postnatal day 6 (P6) to P28. The results showed that Met, MetO, and Met + MetO impaired short-term and spatial memories (P < 0.05), reduced rearing and grooming (P < 0.05), but did not alter locomotor activity (P > 0.05). Acetylcholinesterase activity was increased in the cerebral cortex, hippocampus, and striatum following Met and/or MetO (P < 0.05) treatment, while Na+, K+-ATPase activity was reduced in the hippocampus (P < 0.05). There was an increase in the level of thiobarbituric acid reactive substances (TBARS) in the cerebral cortex in Met-, MetO-, and Met + MetO-treated rats (P < 0.05). Met and/or MetO treatment reduced superoxide dismutase, catalase, and glutathione peroxidase activity, total thiol content, and nitrite levels, and increased reactive oxygen species and TBARS levels in the hippocampus and striatum (P < 0.05). Hippocampal brain-derived neurotrophic factor was reduced by MetO and Met + MetO compared with the control group. The number of NeuN-positive cells was decreased in the CA3 in Met + MetO group and in the dentate gyrus in the Met, MetO, and Met + MetO groups compared to control group (P < 0.05). Taken together, these findings further increase our understanding of changes in the brain in hypermethioninemia by elucidating behavioral alterations, biological mechanisms, and the vulnerability of brain function to high concentrations of Met and MetO.

Methionine and methionine sulfoxide induces neurochemical and morphological changes in cultured astrocytes: Involvement of Na+, K+-ATPase activity, oxidative status, and cholinergic and purinergic signaling.

Hypermethioninemia is an inherited metabolic disorder characterized by high concentration of methionine (Met) and its metabolites such as methionine sulfoxide (Met-SO), which may lead to development of neurological alterations. The aim of this study was to investigate the in vitro effects of Met or Met-SO on viability, proliferation, morphology, and neurochemical parameters in primary culture of cortical astrocytes, after treatment with 1 or 2 mM Met or 0.5 mM Met-SO, for 24, 48, and 72 h. Met or Met-SO did not affect cell viability and proliferation but induced astrocyte hypertrophy. Acetylcholinesterase activity was increased, while Na+, K+-ATPase activity was decreased by 2 mM Met, Met-SO, or Met (1 and 2 mM) + Met-SO (P < 0.05). ATP and AMP hydrolysis was decreased by Met (1 and 2 mM), Met-SO and Met (1 and 2 mM) + Met-SO treatment, while ADP hydrolysis was enhanced by Met-SO and Met (1 and 2 mM) + Met-SO (P < 0.05). Superoxide dismutase activity was increased by Met-SO and Met (1 and 2 mM) + Met-SO (P < 0.05). Catalase and glutathione S-transferase activities were reduced by Met or Met-SO treatment for 48 and 72 h (P < 0.05). Reactive oxygen species and total thiol content was reduced by Met or Met-SO treatment for 24, 48, and 72 h while nitrite and thiobarbituric acid reactive substance levels were increased under the same experimental conditions (P < 0.05). High concentrations of Met and Met-SO do not cause cell death but induced changes in astrocyte function. These alterations in astrocytic homeostasis may be associated with neurological symptoms found in hypermethioninemia.

Mitigation of Oxidation in Therapeutic Antibody Formulations: a Biochemical Efficacy and Safety Evaluation of N-Acetyl-Tryptophan and L-Methionine.

PURPOSE: Biotherapeutics can be susceptible to oxidation during manufacturing and storage. Free L-methionine is known to protect methionine residues in proteins from oxidation. Similarly, free tryptophan and other indole derivatives have been shown to protect tryptophan residues from oxidation. N-acetyl-DL-tryptophan was previously identified as a potentially superior antioxidant to tryptophan as it has a lower oxidation potential and produces less peroxide upon light exposure. This study sought to confirm the antioxidant efficacy and safety of N-acetyl-DL-tryptophan and L-methionine as formulation components for biotherapeutic drugs. METHODS: Antibodies were subjected to AAPH and light exposure in the presence of N-acetyl-DL-tryptophan and L-methionine. Oxidation in relevant CDR and Fc residues was quantified by peptide map. In silico, in vitro, and in vivo studies were performed to evaluate the safety of N-acetyl-DL-tryptophan and L-methionine. RESULTS: Peptide mapping demonstrated that N-acetyl-DL-tryptophan was effective at protecting tryptophans from AAPH stress, and that the combination of N-acetyl-DL-tryptophan and L-methionine protected both tryptophan and methionine from AAPH stress. The safety assessment suggested an acceptable safety profile for both excipients. CONCLUSIONS: N-acetyl-tryptophan and L-methionine effectively reduce the oxidation of susceptible tryptophan and methionine residues in antibodies and are safe for use in parenteral biotherapeutic formulations.

High methionine, low folate and low vitamin B6/B12 (HM-LF-LV) diet causes neurodegeneration and subsequent short-term memory loss.

Methionine is an essential amino acid found in rich quantities in average American diet such as meats, fish and eggs. Excessive consumption of such food often exceeds the normal requirement of the methionine in our body; which found to be related to the development of neurodegenerative disorders. However, the mechanistic pathways of methionine's influence on the brain are unclear. The present study is focus on the effects of high methionine, low folate and low vitamin B6/B12 (HM-LF-LV) diet on the dysfunction of neuronal and vascular specific markers in the brain. C57BL6/J male mice (8-10 week old) were fed with HM-LF-LV diet for a 6 week period. Cognitive function of mice was determine by measuring short-term memory using a Novel Object Recognition test (NORT). Neuronal dysfunction were evaluate by measuring the levels of Neuronal nuclear antigen (NeuN), Neuron-specific-enolase (NSE) and Fluoro-jade C(FJC) fluorescence; while cerebrovascular disruption were evaluate by assessing levels of endothelial junction proteins Vascular Endothelial-Cadherin (VE-Cadherin) and Claudin-5 in harvested brain tissue. Cerebrovascular permeability was assess by evaluating microvascular leakage of fluorescently labeled albumin in vivo. Endothelial and Neuronal Nitric Oxide Synthase (eNOS, nNOS) regulation and vascular inflammation (ICAM: intercellular adhesion molecules) were also evaluate in brain tissue. All assessments were conduct at weekly intervals throughout the study duration. NORT showed a significant temporal decrease in short-term memory of mice fed on HM-LF-LV diet for 6 weeks compared to the wild-type control group. Our experimental data showed that neuronal dysfunction (decreased NeuN levels and increased FJC positive neurons in brain) was more prominent in HM-LF-LV diet fed mice compared to normal diet fed control mice. In experimental mice, cerebrovascular disruption was found to be elevated as evident from increased pial venular permeability (microvascular leakage) and decreased in VE-Cadherin expression compared to control. Slight decrease in nNOS and increase in eNOS in experimental mice suggest a trend towards the decrease in potential for neuronal development due to the long-term HM-LF-LV diet fed. Collectively, our results suggest that a diet containing high methionine, low folate and low vitamin B6/B12 results in increased neuronal degeneration and vascular dysfunction, leading to short-term memory loss. Interestingly, significant neuronal damage precedes vascular dysfunction.

Caffeine Prevents Memory Impairment Induced by Hyperhomocysteinemia.

L-Methionine chronic administration leads to impairment of memory. This impairment is due to the increase in the body oxidative stress, which damages neurons and prevents their firing. On the other hand, caffeine has antioxidant and neuroprotective effects that could prevent impairment of memory induced by L-methionine chronic administration. In the current study, this hypothesis was evaluated. L-methionine (1.7 g/kg/day) was orally administered to animals for 4 weeks and caffeine (0.3 g/L) treatment was added to the drinking water. The radial arm water maze (RAWM) was used to test spatial learning and memory. Antioxidant biomarkers were assessed in the hippocampus tissues using biochemical assay methods. Chronic L-methionine administration induced (short- and long-) term memory impairment (P < 0.05), while caffeine treatment prevented such effect. Additionally, L-methionine treatment reduced catalase and glutathione peroxidase (GPx") enzymatic activities, and reduced glutathione (GSH) to oxidized glutathione (GSSG) ratio. These effects were normalized by caffeine treatment. Activity of superoxide dismutase (SOD) was unchanged by either L-methionine or caffeine treatments. In conclusion, L-methionine induces impairment of memory, and caffeine treatment prevented this impairment probably through affecting hippocampus antioxidant mechanisms.

Cancer cell specific fluorescent methionine protected gold nanoclusters for in-vitro cell imaging studies.

Benefiting from the excellent photostability and biocompatibility, fluorescent nanoclusters have recently emerged as a highly attractive bio-sensing and imaging material, especially in early diagnosis of cancer. However, their clinic applications were limited by the unsatisfactory specificity and the complex synthesis. In this study, novel methionine coated gold nanoclusters (Met-AuNCs) have been prepared via an easily-achievable one-pot synthetic method. The prepared Met-AuNCs showed high imaging-specificity: after incubating with Met-AuNCs for 1 h, cancer cells (including A549, Hela, MCF-7, HepG2) were fluorescent, while the normal cells (WI-38 and CHO) showed no fluorescence. According to a series of controlled experiments, the reason for the high imaging-selectivity was proposed to originate from the specific recognition of L-type amino acid transporter overexpressed in cancer cells.

Safety of methionine, a novel biopesticide, to adult and larval honey bees (Apis mellifera L.).

Methionine is an essential/indispensible amino acid nutrient required by adult and larval honey bees (Apis mellifera L. [Hymenoptera: Apidae]). Bees are unable to rear broods on pollen deficient in methionine, and reportedly behaviorally avoid collecting pollen or nectar from florets deficient in methioinine. In contrast, it has been demonstrated that methionine is toxic to certain pest insects; thus it has been proposed as an effective biopesticide. As an ecofriendly integrated pest management agent, methionine boasts a novel mode of action differentiating it from conventional pesticides, while providing non-target safety. Pesticides that minimize collateral effects on bees are desirable, given the economic and ecological concerns about honey bee health. The aim of the present study was to assess the potential impact of the biopesticide methionine on non-target adult and larval honey bees. Acute contact adult toxicology bioassays, oral adult assessments and chronic larval toxicity assessments were performed as per U.S. Environmental Protection Agency (EPA) requirements. Our results demonstrated that methionine fits the U.S. EPA category of practically nontoxic (i.e. lethal dose to 50% mortality or LD50 > 11µg/bee) to adult honey bees. The contact LD50 was > 25µg/bee and the oral LD50 was > 100µg/bee. Mortality was observed in larval bees that ingested DL-methionine (effective concentration to 50% mortality or EC50 560µg/bee). Therefore, we conclude that methionine poses little threat to the health of the honey bee, due to unlikely exposure at concentrations shown to elicit toxic effects.

Exercise intervention attenuates hyperhomocysteinemia-induced aortic endothelial oxidative injury by regulating SIRT1 through mitigating NADPH oxidase/LOX-1 signaling.

Coronary artery disease (CAD) is a critical cardiovascular disease and a cause of high morbidity and mortality in this world. Hyperhomocysteinemia (HHcy) has been suggested as a risk factor for CAD. In addition, SIRT1 (sirtuin 1) has been reported to play a protective role in a variety of diseases, especially in the cardiovascular system. The main purpose of this study was to investigate the effects of exercise training on apoptosis and inflammation in HHcy animals. We also tested whether exercise protected against Hhcy-induced dysfunction of endothelium through modulation of SIRT1. C57BL mice (8 in each group) were fed with or without 1% L-methionine (w/w) in water for 4 months to induce HHcy. We found that Hhcy repressed SIRT1 and AMPK expression and increased NADPH oxidase activity. Plasma MDA, endothelium LOX-1 and p-p38 were up-regulated by Hhcy induction. NF-κB and it downstream molecules were activated under Hhcy situation, thereby promoting pro-inflammatory responses. Moreover, we also reported that Hhcy caused endothelium apoptosis involving Akt inhibition and mitochondria-dependent apoptotic pathways. Exercise training significantly protected against endothelium from Hhcy caused oxidative injuries. In addition, EX527 (SIRT1 inhibitor) reduced the therapeutic effects by exercise. Our results had indicated that exercise training prevent the development of atherosclerosis through SIRT1 activation and oxidative stress inhibition under Hhcy situation.

Acute administration of methionine and/or methionine sulfoxide impairs redox status and induces apoptosis in rat cerebral cortex.

High plasma levels of methionine (Met) and its metabolites such as methionine sulfoxide (MetO) may occur in several genetic abnormalities. Patients with hypermethioninemia can present neurological dysfunction; however, the neurotoxicity mechanisms induced by these amino acids remain unknown. The aim of the present work was to study the effects of Met and/or MetO on oxidative stress, genotoxicity, cytotoxicity and to evaluate whether the cell death mechanism is mediated by apoptosis in the cerebral cortex of young rats. Forty-eight Wistar rats were divided into groups: saline, Met 0.4 g/Kg, MetO 0.1 g/Kg and Met 0.4 g/Kg + MetO 0.1 g/Kg, and were euthanized 1 and 3 h after subcutaneous injection. Results showed that TBARS levels were enhanced by MetO and Met+MetO 1 h and 3 h after treatment. ROS was increased at 3 h by Met, MetO and Met+MetO. SOD activity was increased in the Met group, while CAT was reduced in all experimental groups 1 h and 3 h after treatment. GPx activity was enhanced 1 h after treatment by Met, MetO and Met+MetO, however it was reduced in the same experimental groups 3 h after administration of amino acids. Caspase-3, caspase-9 and DNA damage was increased and cell viability was reduced by Met, MetO and Met+MetO at 3 h. Also, Met, MetO and Met+MetO, after 3 h, enhanced early and late apoptosis cells. Mitochondrial electrochemical potential was decreased by MetO and Met+MetO 1 h and 3 h after treatment. These findings help understand the mechanisms involved in neurotoxicity induced by hypermethioninemia.

Neuroprotective Effects of Simvastatin and Cilostazol in L-Methionine-Induced Vascular Dementia in Rats.

Vascular dementia (VaD) is a degenerative cerebrovascular disorder that leads to progressive decline in cognitive abilities and memory. Several reports demonstrated that oxidative stress and endothelial dysfunction are principal pathogenic factors in VaD. The present study was constructed to determine the possible neuroprotective effects of simvastatin in comparison with cilostazol in VaD induced by L-methionine in rats. Male Wistar rats were divided into four groups. Group I (control group), group II received L-methionine (1.7 g/kg, p.o.) for 32 days. The remaining two groups received simvastatin (50 mg/kg, p.o.) and cilostazol (100 mg/kg, p.o.), respectively, for 32 days after induction of VaD by L-methionine. Subsequently, rats were tested for cognitive performance using Morris water maze test then sacrificed for biochemical and histopathological assays. L-methionine induced VaD reflected by alterations in rats' behavior as well as the estimated neurotransmitters, acetylcholinesterase activity as well as increased brain oxidative stress and inflammation parallel to histopathological changes in brain tissue. Treatment of rats with simvastatin ameliorated L-methionine-induced behavioral, neurochemical, and histological changes in a manner comparable to cilostazol. Simvastatin may be regarded as a potential therapeutic strategy for the treatment of VaD. To the best of our knowledge, this is the first study to reveal the neuroprotective effects of simvastatin or cilostazol in L-methionine-induced VaD. Graphical Abstract ᅟ.

Mobilization and removing of cadmium from kidney by GMDTC utilizing renal glucose reabsorption pathway.

Chronic exposure to cadmium compounds (Cd(2+)) is one of the major public health problems facing humans in the 21st century. Cd(2+) in the human body accumulates primarily in the kidneys which leads to renal dysfunction and other adverse health effects. Efforts to find a safe and effective drug for removing Cd(2+) from the kidneys have largely failed. We developed and synthesized a new chemical, sodium (S)-2-(dithiocarboxylato((2S,3R,4R,5R)-2,3,4,5,6 pentahydroxyhexyl)amino)-4-(methylthio) butanoate (GMDTC). Here we report that GMDTC has a very low toxicity with an acute lethal dose (LD50) of more than 10,000mg/kg or 5000mg/kg body weight, respectively, via oral or intraperitoneal injection in mice and rats. In in vivo settings, up to 94% of Cd(2+) deposited in the kidneys of Cd(2+)-laden rabbits was removed and excreted via urine following a safe dose of GMDTC treatment for four weeks, and renal Cd(2+) level was reduced from 12.9µg/g to 1.3µg/g kidney weight. We observed similar results in the mouse and rat studies. Further, we demonstrated both in in vitro and in animal studies that the mechanism of transporting GMDTC and GMDTC-Cd complex into and out of renal tubular cells is likely assisted by two glucose transporters, sodium glucose cotransporter 2 (SGLT2) and glucose transporter 2 (GLUT2). Collectively, our study reports that GMDTC is safe and highly efficient in removing deposited Cd(2+) from kidneys assisted by renal glucose reabsorption system, suggesting that GMDTC may be the long-pursued agent used for preventive and therapeutic purposes for both acute and chronic Cd(2+) exposure.

Hyperhomocysteinemia induced by excessive methionine intake promotes rupture of cerebral aneurysms in ovariectomized rats.

BACKGROUND: Hyperhomocysteinemia (HHcy) is associated with inflammation and a rise in the expression of matrix metalloproteinase-9 (MMP-9) in the vascular wall. However, the role of HHcy in the growth and rupture of cerebral aneurysms remains unclear. METHODS: Thirteen-week-old female Sprague-Dawley rats were subject to bilateral ovariectomy and ligation of the right common carotid artery and fed an 8 % high-salt diet to induce cerebral aneurysms. Two weeks later, they underwent ligation of the bilateral posterior renal arteries. They were divided into two groups and methionine (MET) was or was not added to their drinking water. In another set of experiments, the role of folic acid (FA) against cerebral aneurysms was assessed. RESULTS: During a 12-week observation period, subarachnoid hemorrhage due to aneurysm rupture was observed at the anterior communicating artery (AcomA) or the posterior half of the circle of Willis. HHcy induced by excessive MET intake significantly increased the incidence of ruptured aneurysms at 6-8 weeks. At the AcomA of rats treated with MET, we observed the promotion of aneurysmal growth and infiltration by M1 macrophages. Furthermore, the mRNA level of MMP-9, the ratio of MMP-9 to the tissue inhibitor of metalloproteinase-2, and the level of interleukin-6 were higher in these rats. Treatment with FA abolished the effect of MET, suggesting that the inflammatory response and vascular degradation at the AcomA is attributable to HHcy due to excessive MET intake. CONCLUSIONS: We first demonstrate that in hypertensive ovariectomized rats, HHcy induced by excessive MET intake may be associated with the propensity of the aneurysm wall to rupture.