Neuroprotection by taurine in ethanol-induced apoptosis in the developing cerebellum

Taurine Neuroprotection and Neurogenesis Effect in Chronic Ethanol-Induced Rats

Taurine (2-aminoethanesulfonic acid) is a non-protein β-amino acid essential for cellular homeostasis, with antioxidant, anti-inflammatory, and cytoprotective properties that are crucial for life maintenance. This study aimed to evaluate the effects of taurine administration on hippocampal neurogenesis, neuronal preservation, or reverse damage in rats exposed to forced ethanol consumption in an animal model. Wistar rats were treated with ethanol (EtOH) for a 28-day period (5% in the 1st week, 10% in the 2nd week, and 20% in the 3rd and 4th weeks). Two taurine treatment protocols (300 mg/kg i.p.) were implemented: one during ethanol consumption to analyze neuroprotection, and another after ethanol consumption to assess the reversal of ethanol-induced damage. Overall, the results demonstrated that taurine treatment was effective in protecting against deficits induced by ethanol consumption in the dentate gyrus. The EtOH+TAU group showed a significant increase in cell proliferation (145.8%) and cell survival (54.0%) compared to the EtOH+Sal group. The results also indicated similar effects regarding the reversal of ethanol-induced damage 28 days after the cessation of ethanol consumption. The EtOH+TAU group exhibited a significant increase (41.3%) in the number of DCX-immunoreactive cells compared to the EtOH+Sal group. However, this amino acid did not induce neurogenesis in the tissues of healthy rats, implying that its activity may be contingent upon post-injury stimuli.

Integrated Transcriptomics and Metabolomics Reveal Changes in Cell Homeostasis and Energy Metabolism in Trachinotus ovatus in Response to Acute Hypoxic Stress

Trachinotus ovatus is an economically important mariculture fish, and hypoxia has become a critical threat to this hypoxia-sensitive species. However, the molecular adaptation mechanism of T. ovatus liver to hypoxia remains unclear. In this study, we investigated the effects of acute hypoxic stress (1.5 ± 0.1 mg·L-1 for 6 h) and re-oxygenation (5.8 ± 0.3 mg·L-1 for 12 h) in T. ovatus liver at both the transcriptomic and metabolic levels to elucidate hypoxia adaptation mechanism. Integrated transcriptomics and metabolomics analyses identified 36 genes and seven metabolites as key molecules that were highly related to signal transduction, cell growth and death, carbohydrate metabolism, amino acid metabolism, and lipid metabolism, and all played key roles in hypoxia adaptation. Of these, the hub genes FOS and JUN were pivotal hypoxia adaptation biomarkers for regulating cell growth and death. During hypoxia, up-regulation of GADD45B and CDKN1A genes induced cell cycle arrest. Enhancing intrinsic and extrinsic pathways in combination with glutathione metabolism triggered apoptosis; meanwhile, anti-apoptosis mechanism was activated after hypoxia. Expression of genes related to glycolysis, gluconeogenesis, amino acid metabolism, fat mobilization, and fatty acid biosynthesis were up-regulated after acute hypoxic stress, promoting energy supply. After re-oxygenation for 12 h, continuous apoptosis favored cellular function and tissue repair. Shifting from anaerobic metabolism (glycolysis) during hypoxia to aerobic metabolism (fatty acid β-oxidation and TCA cycle) after re-oxygenation was an important energy metabolism adaptation mechanism. Hypoxia 6 h was a critical period for metabolism alteration and cellular homeostasis, and re-oxygenation intervention should be implemented in a timely way. This study thoroughly examined the molecular response mechanism of T. ovatus under acute hypoxic stress, which contributes to the molecular breeding of hypoxia-tolerant cultivars.

Suppression of Chronic Unpredictable Stress-Persuaded Increased Monoamine Oxidase Activity by Taurine Promotes Significant Neuroprotection in Zebrafish Brain

Neuropsychiatric upshots following chronic exposure to unpredictable adverse stressors have been well documented in the literature. Considering the significant impact of chronic unpredictable stress (CUS), the literature is elusive regarding the neuroprotective efficacy of taurine against CUS-induced oxidative stress and chromatin condensation in the zebrafish brain. In this study, to ameliorate CUS-persuaded neurological outcomes, waterborne treatment of taurine as a prophylactic intervention was undertaken. Further, our approach also focused on the gross neurobehavioral response of zebrafish, oxidative stress indices and neuromorphology of the zebrafish brain following CUS exposure with taurine treatment. Because taurine provides significant neuroprotection against oxidative insult, the cytosolic level of monoamine oxidase (MAO) in the zebrafish brain following CUS exposure is worth investigating. Further, as heightened MAO activity is associated with augmented oxidative and chromatin condensation, the focus of this study was on whether taurine provides neuroprotection by downregulating MAO levels in the brain. Our findings show that CUS-persuaded altered neurobehavioral response was significantly rescued by taurine. Moreover, our findings firmly support the hypothesis that taurine acts as a radical neuroprotector by restoring glutathione biosynthesis in the zebrafish brain subsequent to CUS exposure. Additionally, the rising level of brain MAO following chronic exposure to CUS is ameliorated by taurine treatment. These findings strongly advocate the role of taurine as a natural MAO inhibitor through the neuroprotection it provides against CUS-instigated oxidative stress in zebrafish. However, the fundamental neuroprotective mechanism of such natural compounds needs to be elucidated to determine their neuroprotective efficacy against stress regimens.

Taurine Supplementation as a Neuroprotective Strategy upon Brain Dysfunction in Metabolic Syndrome and Diabetes

Obesity, type 2 diabetes, and their associated comorbidities impact brain metabolism and function and constitute risk factors for cognitive impairment. Alterations to taurine homeostasis can impact a number of biological processes, such as osmolarity control, calcium homeostasis, and inhibitory neurotransmission, and have been reported in both metabolic and neurodegenerative disorders. Models of neurodegenerative disorders show reduced brain taurine concentrations. On the other hand, models of insulin-dependent diabetes, insulin resistance, and diet-induced obesity display taurine accumulation in the hippocampus. Given the possible cytoprotective actions of taurine, such cerebral accumulation of taurine might constitute a compensatory mechanism that attempts to prevent neurodegeneration. The present article provides an overview of brain taurine homeostasis and reviews the mechanisms by which taurine can afford neuroprotection in individuals with obesity and diabetes. We conclude that further research is needed for understanding taurine homeostasis in metabolic disorders with an impact on brain function.

Methylsulfonylmethane protects against ethanol-induced brain injury in mice through the inhibition of oxidative stress, proinflammatory mediators and apoptotic cell death

Excessive ethanol consumption causes brain injury through oxidative stress, inflammation and apoptotic cell death. Methylsulfonylmethane (MSM) is a natural compound that has therapeutic effects on oxidative and inflammatory disorders. The aim of this study was to investigate the protective effect and underlying mechanisms of MSM on ethanol-induced brain injury in an experimental model. Male C57BL/6 mice were exposed to binge ethanol (5 g/kg/day, orally) and treated with MSM (200 and 400 mg/kg/day) concomitantly for 12 days. At the end of the experiment brain tissues were removed for histological and biochemical analysis. The results showed that MSM reduced ethanol-mediated oxidative stress by decreasing the levels of malondialdehyde (MDA) and carbonyl protein. The Nrf2/HO-1 pathway and the levels of cytoprotective antioxidants superoxide dismutase (SOD), catalase and glutathione (GSH) were increased by MSM in the brain tissue. MSM treatment reduced the ethanol-induced inflammatory factors including myeloperoxidase (MPO), iNOS/NO, cyclooxygenase (COX)-2, nuclear factor kappa B (NF-κB), NLRP3 inflammasome and proinflammatory cytokines including TNF-α, IL-1β, IL-6 and MCP-1. MSM also decreased the levels of pro-apoptotic caspase-3 and TUNEL positive cells while increased the level of anti-apoptotic Bcl-2 in the brain tissue. Our findings demonstrated that MSM protects against ethanol-induced brain injury by improving anti-oxidant defense mechanism and reducing ethanol-mediated inflammation and apoptosis. Therefore, MSM may be a potential protective approach for brain damage caused by high levels of alcohol.

Metabolomics Applied to Cord Serum in Preeclampsia Newborns: Implications for Neonatal Outcomes

Preeclampsia (PE) is one of the leading causes of maternal and perinatal morbidity and mortality. However, it is still uncertain how PE affects neonate metabolism. We conducted an untargeted metabolomics analysis of cord blood to explore the metabolic changes in PE neonates. Umbilical cord serum samples from neonates with preeclampsia (n = 29) and non-preeclampsia (non-PE) (n = 32) pregnancies were analyzed using the UHPLC-QE-MS metabolomic platform. Different metabolites were screened, and pathway analysis was conducted. A subgroup analysis was performed among PE neonates to compare the metabolome between appropriate-for-gestational-age infants (n = 21) and small-for-gestational-age (SGA) infants (n = 8). A total of 159 different metabolites were detected in PE and non-PE neonates. Creatinine, N4-acetylcytidine, sphingomyelin (D18:1/16:0), pseudouridine, uric acid, and indolelactic acid were the most significant differential metabolites in the cord serum of PE neonates. Differential metabolite levels were elevated in PE neonates and were involved in the following metabolic pathways: glycine, serine, and threonine metabolism; sphingolipid, glyoxylate, and dicarboxylate metabolism; and arginine biosynthesis. In PE neonates, SGA neonates showed increased levels of hexacosanoyl carnitine and decreased abundance of 3-hydroxybutyric acid and 3-sulfinoalanine. Taurine-related metabolism and ketone body-related pathways were mainly affected. Based on the UHPLC-QE-MS metabolomics analysis, we identified the metabolic profiles of PE and SGA neonates. The abundance of metabolites related to certain amino acid, sphingolipid, and energy metabolism increased in the umbilical cord serum of PE neonates.

The Role of Taurine in Mitochondria Health: More Than Just an Antioxidant

Taurine is a naturally occurring sulfur-containing amino acid that is found abundantly in excitatory tissues, such as the heart, brain, retina and skeletal muscles. Taurine was first isolated in the 1800s, but not much was known about this molecule until the 1990s. In 1985, taurine was first approved as the treatment among heart failure patients in Japan. Accumulating studies have shown that taurine supplementation also protects against pathologies associated with mitochondrial defects, such as aging, mitochondrial diseases, metabolic syndrome, cancer, cardiovascular diseases and neurological disorders. In this review, we will provide a general overview on the mitochondria biology and the consequence of mitochondrial defects in pathologies. Then, we will discuss the antioxidant action of taurine, particularly in relation to the maintenance of mitochondria function. We will also describe several reported studies on the current use of taurine supplementation in several mitochondria-associated pathologies in humans.

Serum metabolomic patterns in young patients with ischemic stroke: a case study

BACKGROUND

Ischemic stroke is one of the leading causes of death and adult disability. The incidence of ischemic stroke continues to rise in young adults. This study aimed to provide a comprehensive evaluation of metabolic changes and explore possible mechanisms in young ischemic stroke patients without common risk factors.

METHODS

This study investigated serum metabolomics in 50 young patients with newly suffered ischemic stroke and 50 age-, sex-, and body mass index-matched healthy controls. Liquid chromatography coupled with a Waters Xevo TQ-S mass spectrometer with an electrospray ionization (ESI) source was used to analyze amino acid or bile acid, and free fatty acid or lipid was analyzed by liquid chromatography coupled with a Qtrap5500 mass spectrometer with an ESI source. The metabolomic data were analyzed by performing a multivariate statistical analysis.

RESULTS

A total of 197 metabolites, including amino acids, bile acids, free fatty acids, and lipids, were identified in all participants. Multivariate models showed significant differences in serum metabolomic patterns between young patients with ischemic stroke and healthy controls. The stroke patients had increased L-methionine, homocysteine, glutamine, uric acid, GCDCA, and PE (18:0/20:4, 16:0/22:5), and decreased levels of L-citrulline, taurine, PC (16:2/22:6, 16:2/20:5, 15:0/18:2), and SM (d18:1/23:0, d20:0/19:1, d18:1/22:0, d16:0/26:1, d16:0/18:0, d16:0/22:1, d18:1/19:1, d16:0/17:1, d16:1/24:1, d18:1/19:0). Based on the identified metabolites, the metabolic pathways of arginine biosynthesis, glycerophospholipid metabolism, and taurine and hypotaurine metabolism were significantly enriched in the young patients with ischemic stroke.

CONCLUSIONS

Serum metabolomic patterns were significantly different between young patients with ischemic stroke and healthy controls. Our study is beneficial in providing a further view into the pathophysiology of young patients with ischemic stroke.

New solutions for old challenges in glaucoma treatment: is taurine an option to consider?

Glaucoma is a range of progressive optic neuropathies characterized by progressive retinal ganglion cell loss and visual field defects. It is recognized as a leading cause of irreversible blindness affecting more than 70 million people worldwide. Currently, reduction of intraocular pressure, a widely recognized risk factor for glaucoma development, is the only pharmacological strategy for slowing down retinal ganglion cell loss and disease progression. However, retinal ganglion cell death and visual field loss have been observed in normotensive glaucoma, suggesting that the disease process is partially independent of intraocular pressure. Taurine is one of the agents that have attracted attention of researchers recently. Taurine has been shown to be involved in multiple cellular functions, including a central role as a neurotransmitter, as a trophic factor in the central nervous system development, as an osmolyte, as a neuromodulator, and as a neuroprotectant. It also plays a role in the maintenance of the structural integrity of the membranes and in the regulation of calcium transport and homeostasis. Taurine is known to prevent N-methyl-D-aspartic acid-induced excitotoxic injury to retinal ganglion cells. A recently published study clearly demonstrated that taurine prevents retinal neuronal apoptosis both in vivo and in vitro. Protective effect of taurine may be attributed to direct inhibition of apoptosis, an activation of brain derived neurotrophic factor-related neuroprotective mechanisms and reduction of retinal oxidative and nitrosative stresses. Further studies are needed to fully explore the potential of taurine as a neuroprotective agent, so that it can be applied in clinical practice, particularly for the treatment of glaucoma. The objective of current review was to summarize recent evidence on neuroprotective properties of taurine in glaucoma.

Dexmedetomidine attenuates ethanol-induced inhibition of hippocampal neurogenesis in neonatal mice

BACKGROUND/AIMS

Ethanol (EtOH) exposure during a period comparable to the third trimester in human results in obvious neurotoxicity in the developing hippocampus and persistent deficits in hippocampal neurogenesis. Dexmedetomidine (DEX), a highly selective α-2-adrenergic agonist has been demonstrated to restore the impaired neurogenesis and neuronal plasticity in the dentate gyrus (DG) that follows neurological insult. However, the protective roles of DEX in the EtOH-induced deficits of postnatal neurogenesis in the hippocampus are still unknown.

METHODS

Mice were pretreated with DEX prior to EtOH exposure to determine its protective effects on impaired postnatal hippocampal neurogenesis. Six-day-old neonatal mice were treated with DEX (125 μg/kg) or saline, followed by EtOH at a total of 5 g/kg or an equivalent volume of saline on P7. Immunohistochemistry and immunofluorescence were used to evaluate the neurogenesis and activated microglia in the DG. Quantitative real time PCR (qRT-PCR) was utilized to assess the expression of inflammatory factors in the hippocampus.

RESULTS

DEX pretreatment attenuated the inhibition of EtOH-mediated hippocampal neurogenesis and the reduction of hippocampal neural precursor cells (NPCs). We further confirmed that DEX pretreatment reversed the EtOH-induced microglia activation in the DG as well as the upregulation of the hippocampal TNFα, MCP-1, IL-6, and IL-1β mRNA levels.

CONCLUSION

Our findings indicate that DEX pretreatment protects against EtOH-mediated inhibition of hippocampal neurogenesis in postnatal mice and reverses EtOH-induced neuroinflammation via repressing microglia activation and the expression of inflammatory cytokines.

Taurine Treatment Provides Neuroprotection in a Mouse Model of Manganism

Manganese (Mn) is a trace element involved in many physiological processes. However, excessive Mn exposure leads to neurological complications. Although no precise mechanism(s) has been found for Mn-induced neurotoxicity, oxidative stress and mitochondrial injury seem to play a relevant role in this complication. On the other hand, there is no protective strategy against Mn neurotoxicity so far. Taurine is an amino acid with significant neuroprotective properties. The current study was designed to evaluate the effect of taurine supplementation and its potential mechanism(s) of action in a mouse model of manganism. Animals were treated with Mn (100 mg/kg, s.c) alone and/or in combination with taurine (50, 100, and 500 mg/kg, i.p, for eight consecutive days). Severe locomotor dysfunction along with a significant elevation in brain tissue biomarkers of oxidative stress was evident in Mn-exposed mice. On the other hand, it was revealed that mitochondrial indices of functionality were hampered in Mn-treated animals. Taurine supplementation (50, 100, and 500 mg/kg, i.p) alleviated Mn-induced locomotor deficit. Moreover, this amino acid mitigated oxidative stress biomarkers and preserved brain tissue mitochondrial indices of functionality. These data introduce taurine as a potential neuroprotective agent against Mn neurotoxicity. Antioxidative and mitochondria protecting effects of taurine might play a fundamental role in its neuroprotective properties against Mn toxicity.

Taurine and its analogs in neurological disorders: Focus on therapeutic potential and molecular mechanisms

Taurine is a sulfur-containing amino acid and known as semi-essential in mammals and is produced chiefly by the liver and kidney. It presents in different organs, including retina, brain, heart and placenta and demonstrates extensive physiological activities within the body. In the several disease models, it attenuates inflammation- and oxidative stress-mediated injuries. Taurine also modulates ER stress, Ca2+ homeostasis and neuronal activity at the molecular level as part of its broader roles. Different cellular processes such as energy metabolism, gene expression, osmosis and quality control of protein are regulated by taurine. In addition, taurine displays potential ameliorating effects against different neurological disorders such as neurodegenerative diseases, stroke, epilepsy and diabetic neuropathy and protects against injuries and toxicities of the nervous system. Several findings demonstrate its therapeutic role against neurodevelopmental disorders, including Angelman syndrome, Fragile X syndrome, sleep-wake disorders, neural tube defects and attention-deficit hyperactivity disorder. Considering current biopharmaceutical limitations, developing novel delivery approaches and new derivatives and precursors of taurine may be an attractive option for treating neurological disorders. Herein, we present an overview on the therapeutic potential of taurine against neurological disorders and highlight clinical studies and its molecular mechanistic roles. This article also addresses the neuropharmacological potential of taurine analogs.

Neuroprotection by Taurine on HBCD-Induced Apoptosis in PC12 Cells

Hexabromocyclododecane (HBCD) is a widely used brominated flame retardant (BFR). Because of their presence in human issues, including brain tissue, concern has been raised on their possible neurotoxicity. Presently, we explored the neuroprotection of taurine against HBCD-induced apoptotic damages in PC12 cells. Cells were pre-treated with taurine before HBCD exposure and the viability was assayed via the methyl-thiazolyl-tetrazolium (MTT) method. Apoptotic features were observed with Hoechst 33342 staining. Apoptotic ratio was measured using flow cytometry with Annexin V-FITC coupled propidium iodide (PI) double staining. The changes in the levels of Bcl-2 and Bax proteins were quantitated by the western blot. The activity of caspase-3 was tested and the results revealed that presence of HBCD decreased cell survival and led to apoptosis in the tested cells. Further, exposure of HBCD reduced protein expression of Bcl-2, increased expression in Bax protein and activity of caspase-3. Taurine attenuated HBCD-induced cell viability loss and cell apoptosis. Moreover, taurine significantly prevented from reducing Bcl-2 protein expression and elevating Bax protein expression and caspase-3 activity induced by HBCD. These results demonstrated that taurine can alleviate HBCD-induced apoptosis by altering Bcl-2 expression and Bax protein and Caspase-3 activity in PC12.

Taurine Ameliorates Arsenic-Induced Apoptosis in the Hippocampus of Mice Through Intrinsic Pathway

Our group previously reported that arsenic (As) exposure induced apoptosis in hippocampus neurons. The aim of the present study was to clarify the protective capacity of taurine (Tau) on As-induced neuronal apoptosis and the related mechanism in mouse hippocampus. Mice were divided into: control group, Tau control group, As exposure group and Tau protective group, randomly. The apoptotic rate of mouse hippocampus was determined by TUNEL staining. The levels of Bcl-2 and Bax gene and protein were analyzed by real time RT-PCR and WB, respectively. Furthermore, cytochrome c (Cyt C) release, and the activity of caspase-8 and caspase-3 were also determined. The results showed that Tau treatment induced the decrease of TUNEL-positive cells, prohibited the disturbance of Bcl-2 and Bax expression, and inhibited Cyt C release and caspase-8 and caspase-3 activation significantly. The results indicated that Tau supplement markedly ameliorates As-induced apoptosis by mitochondria-related pathway in mouse hippocampus.

Comparison of Toxicity of Taurine and GABA in Combination with Alcohol in 7-Day-Old Mice

Previously, we described the combined toxicity of taurine and alcohol, and assumed hypoglycemia to be one reason of this toxicity. To understand whether taurine-ethanol combined toxicity is exclusively connected to taurine or whether other inhibitory amino acids may have similar effects when combined with ethanol, we tested different doses of gamma-aminobutyric acid (GABA) in combination with ethanol in 7-day-old mice. The minimal dose of GABA in combination with 5 g/kg ethanol which could kill a mouse was 2 g/kg. GABA combined with ethanol at doses of 3 g/kg, 4 g/kg, 6 g/kg induced lethality of 30%, 90% and 100%, correspondingly. Taurine at the doses of 4 and 6 g/kg combined with ethanol induced death in 60 and 100% of mice. Ethanol (5 g/kg), taurine (6 g/kg), GABA (4 g/kg) administered alone and the combination of ethanol (5 g/kg) with taurine (3 g/kg) have no lethal effects. GABA (6 g/kg) applied alone induced 90% lethality. Taurine or GABA alone decreased blood glucose in a dose-depending manner. Ethanol potentiated GABA- and taurine-induced decrease in blood glucose and in some animals it dropped from 8.8 (intact) to a hypoglycemic level 3.1-3.3 mmol/L (GABA 4 g/kg, taurine 6 g/kg), but this may not be considered a single reason of death. We conclude that the combination of GABA and ethanol has a lethal effect and this is stronger than the combined toxicity of ethanol and taurine.

Taurine modulates acute ethanol-induced social behavioral deficits and fear responses in adult zebrafish

Ethanol (EtOH) is a central nervous system (CNS) depressant drug that modifies various behavioral domains (i.e., sociability, aggressiveness, and memory) by promoting disinhibition of punished operant behavior and neurochemical changes. Taurine (TAU) is a β-amino sulfonic acid with pleiotropic roles in the brain. Although exogenous TAU is found in energy drinks and often mixed with alcohol in beverages, the putative risks of mixing TAU and EtOH are poorly explored. Here, we investigated whether TAU modulates social and fear responses by assessing shoaling behavior, preference for conspecifics, and antipredatory behavior of adult zebrafish acutely exposed to EtOH. Zebrafish shoals (4 fish per shoal) were exposed to water (control), TAU (42, 150, and 400 mg/L), 0.25% (v/v) EtOH alone or in association with TAU for 1 h, and their behaviors were analyzed at different time intervals (0-5 min, 30-35 min, and 55-60 min). The effects of TAU and EtOH were further tested in a social preference test and during exposure to a predator. Both EtOH and TAU co-treated fish showed a higher shoal dispersion, while TAU 400/EtOH group shoal area had a similar profile when compared to control. However, in the social preference test, TAU 400/EtOH impaired the seeking for conspecifics. Regarding fear-like behaviors, TAU-cotreated fish showed a prominent reduction in risk assessments when compared to EtOH alone. Overall, we demonstrate that TAU modulates EtOH-induced changes in different behavioral domains, suggesting a complex relationship between social and fear-like responses.

Taurine prevents mitochondrial membrane permeabilization and swelling upon interaction with manganese: Implication in the treatment of cirrhosis-associated central nervous system complications

Brain tissue manganese (Mn) accumulation is a cirrhosis-associated complication. Cellular mitochondria are among the potential targets for Mn-induced cytotoxicity. Taurine is one of the most abundant amino acids with high concentrations in human brain tissue. Several pharmacological properties including regulation of mitochondrial function are attributed to taurine. The current investigation was designed to evaluate the effect of taurine on Mn-induced mitochondrial impairment in isolated mice brain mitochondria. The brain mitochondria were exposed to increasing concentrations of Mn (0.1-10 mM). Taurine (0.1, 1, and 10 mM) was added as the protective agent. The severe collapse of mitochondrial membrane potential, decreased mitochondrial dehydrogenases activity, mitochondrial swelling, and depleted mitochondrial adenosine triphosphate (ATP) were evident in Mn-exposed mitochondria. It was found that taurine administration preserved mitochondrial ATP, prevented mitochondrial depolarization and swelling, and increased mitochondrial dehydrogenases activity. These data suggest mitochondrial protection as an underlying mechanism for the protective effects of taurine against Mn toxicity.

Gut Microbiota and Relevant Metabolites Analysis in Alcohol Dependent Mice

Alcohol abuse is a major public health crisis. Relative evidences supported that the gut microbiota (GM) played an important role in central nervous system (CNS) function, and the composition of them had changed after alcohol drinking. We sought to explore the changes of GM in alcohol dependence. In our study, the GM of mice with alcohol administration was detected through analyzed 16S rRNA gene sequencing and the fecal metabolites were analyzed by LC-MS. The microbial diversity was significantly higher in the alcohol administration group, the abundance of phylum Firmicutes and its class Clostridiales were elevated, meanwhile the abundance of Lachnospiraceae, Alistipes, and Odoribacter showed significant differences among the three groups. Based on LC-MS results, bile acid, secondary bile acid, serotonin and taurine level had varying degrees of changes in alcohol model. From paraffin sections, tissue damage was observed in liver and colon. These findings provide direct evidence that alcohol intake affects the composition of GM, enable a better understanding of the function of GM in the microbiota-gut-brain (MGB) axis, and give a new thought for alcohol addiction treatment.

Acute effect of Ethanol and Taurine on frontal cortex absolute beta power before and after exercise

Ethanol (ET) is a substance that modulates the Central Nervous System (CNS). Frequently, ET intake occurs combined with energy drinks, which contain taurine (TA), an important amino acid found in the body (i.e brain and muscles). Although TA administration has been used in the improvement of physical performance, the impact of TA, ET and exercise remains unknown. This study aimed to analyze the acute effect of 6g of Taurine (TA), 0.6 mL∙kg^-1 of Ethanol (ET), and Taurine combined with Ethanol (TA+ET) ingestion on the electrocortical activity before and after a moderate intensity exercise in 9 subjects, 5 women (counterbalanced experimental design). In each of the 4 treatments (Placebo—PL, TA, ET and TA+ET), electroencephalography (EEG) tests were conducted in order to analyze changes in absolute beta power (ABP) in the frontal lobe in 3 moments: baseline (before ingestion), peak (before exercise) and post-exercise. In the PL treatment, the frontal areas showed decrease in ABP after exercise. However, in the ET+TA treatment, ABP values were greater after exercise, except for Fp1. The ET treatment had no effect on the Superior Frontal Gyrus area (F3, Fz and F4) and ABP decreased after exercise in Fp1 and Fp2. In the TA treatment, ABP increased after exercise, while it decreased at the peak moment in most of the frontal regions, except for Fp1, F3 and Fz. We concluded that after a moderate intensity exercise, a decrease in cortical activity occurs in placebo treatment. Moreover, we found a inhibitory effect of TA on cortical activity before exercise and a increased in cortical activity after exercise. A small ET dose is not enough to alter ABP in all regions of the frontal cortex and, in combination with TA, it showed an increase in the frontal cortex activity at the post-exercise moment.

Metabolic assessment of a migraine model using relaxation-enhanced 1 H spectroscopy at ultrahigh field

PURPOSE

This study evaluates biochemical imbalances in a rat model that reflects dysfunctional pathways in migraine. The high sensitivity and spectral dispersion available to 1 H MRS at 21.1 T expands metabolic profiling in this migraine model to include lactate (Lac), taurine (Tau), aspartate, and Gly-a mixture of glycine, glutamine, and glutamate.

METHODS

Sprague-Dawley male rats were administered in situ an intraperitoneal injection of nitroglycerin (NTG) to induce the migraine analogue or saline as a control. A selective relaxation-enhanced MR spectroscopy sequence was used to target upfield metabolites from a 4-mm3 voxel for 2.5 h after injection.

RESULTS

Significant increases were evident for Lac as early as 10 min after NTG injection, peaking over 50% compared with baseline and control (normalized Lac/N-acetyl aspartate with NTG = 1.54 ± 0.65 versus with saline = 0.99 ± 0.08). Tau decreased progressively in controls over 2 h after injection, but remained elevated with NTG, peaking at 105 min after injection (normalized Tau/N-acetyl aspartate with NTG = 1.10 ± 0.18 versus with saline = 0.85 ± 0.14). Total creatine under NTG showed significant decreases with time and compared with saline; Gly demonstrated temporal increases for NTG.

CONCLUSIONS

These changes indicate an altered metabolic profile in the migraine analogue consistent with early changes in neural activity and/or vasodilation consistent with progressively enhanced neuroprotection and osmoregulation. Magn Reson Med 79:1266-1275, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Taurine protects against retinal and optic nerve damage induced by endothelin-1 in rats via antioxidant effects

Endothelin-1 (ET-1), a potent vasoconstrictor, is involved in retinal vascular dysregulation and oxidative stress in glaucomatous eyes. Taurine (TAU), a naturally occurring free amino acid, is known for its neuroprotective and antioxidant properties. Hence, we evaluated its neuroprotective properties against ET-1 induced retinal and optic nerve damage. ET-1 was administered intravitreally to Sprague-Dawley rats and TAU was injected as pre-, co- or post-treatment. Animals were euthanized seven days post TAU injection. Retinae and optic nerve were examined for morphology, and were also processed for caspase-3 immunostaining. Retinal redox status was estimated by measuring retinal superoxide dismutase, catalase, glutathione, and malondialdehyde levels using enzyme-linked immuosorbent assay. Histopathological examination showed significantly improved retinal and optic nerve morphology in TAU-treated groups. Morphometric examination showed that TAU pre-treatment provided marked protection against ET-1 induced damage to retina and optic nerve. In accordance with the morphological observations, immunostaining for caspase showed a significantly lesser number of apoptotic retinal cells in the TAU pre-treatment group. The retinal oxidative stress was reduced in all TAU-treated groups, and particularly in the pre-treatment group. The findings suggest that treatment with TAU, particularly pre-treatment, prevents apoptosis of retinal cells induced by ET-1 and hence prevents the changes in the morphology of retina and optic nerve. The protective effect of TAU against ET-1 induced retinal and optic nerve damage is associated with reduced retinal oxidative stress.

Iron Oxide Nanoparticles Induce Dopaminergic Damage: In vitro Pathways and In Vivo Imaging Reveals Mechanism of Neuronal Damage

Various iron-oxide nanoparticles have been in use for a long time as therapeutic and imaging agents and for supplemental delivery in cases of iron-deficiency. While all of these products have a specified size range of ∼ 40 nm and above, efforts are underway to produce smaller particles, down to ∼ 1 nm. Here, we show that after a 24-h exposure of SHSY-5Y human neuroblastoma cells to 10 μg/ml of 10 and 30 nm ferric oxide nanoparticles (Fe-NPs), cellular dopamine content was depleted by 68 and 52 %, respectively. Increases in activated tyrosine kinase c-Abl, a molecular switch induced by oxidative stress, and neuronal α-synuclein expression, a protein marker associated with neuronal injury, were also observed (55 and 38 % percent increases, respectively). Inhibition of cell-proliferation, significant reductions in the number of active mitochondria, and a dose-dependent increase in reactive oxygen species (ROS) were observed in neuronal cells. Additionally, using a rat in vitro blood-brain barrier (BBB) model, a dose-dependent increase in ROS accompanied by increased fluorescein efflux demonstrated compromised BBB integrity. To assess translational implications, in vivo Fe-NP-induced neurotoxicity was determined using in vivo MRI and post-mortem neurochemical and neuropathological correlates in adult male rats after exposure to 50 mg/kg of 10 nm Fe-NPs. Significant decrease in T 2 values was observed. Dynamic observations suggested transfer and retention of Fe-NPs from brain vasculature into brain ventricles. A significant decrease in striatal dopamine and its metabolites was also observed, and neuropathological correlates provided additional evidence of significant nerve cell body and dopaminergic terminal damage as well as damage to neuronal vasculature after exposure to 10 nm Fe-NPs. These data demonstrate a neurotoxic potential of very small size iron nanoparticles and suggest that use of these ferric oxide nanoparticles may result in neurotoxicity, thereby limiting their clinical application.

Choline Ameliorates Deficits in Balance Caused by Acute Neonatal Ethanol Exposure

Fetal alcohol spectrum disorder (FASD) is estimated to occur in 1 % of all live births. The developing cerebellum is vulnerable to the toxic effects of alcohol. People with FASD have cerebellar hypoplasia and developmental deficits associated with cerebellar injury. Choline is an essential nutrient, but many diets in the USA are choline deficient. In rats, choline given with or following alcohol exposure reduces many alcohol-induced neurobehavioral deficits but not those associated with cerebellar function. Our objective was to determine if choline supplementation prior to alcohol exposure would ameliorate the impact of ethanol on a cerebellar-associated behavioral test in mice. Pregnant C57Bl6/J mice were maintained on a choline-deficient diet from embryonic day 4.5. On postnatal day 1 (P1), pups were assigned to one of eight treatment groups: choline (C) or saline (S) pre-treatment from P1 to P5, ethanol (6 g/kg) or Intralipid(®) on P5, C and or S post-treatment from P6 to P20. On P30, balance and coordination were tested using the dowel crossing test. Overall, there was a significant effect of treatment and females crossed longer distances than males. Ethanol exposure significantly reduced the total distance crossed. Choline pre-treatment increased the distance crossed by males, and both pre- and post-treatment with choline significantly increased total distance crossed for females and males. There was no effect of choline on Intralipid®-exposed animals. This is the first study to show that choline ameliorates ethanol-induced effects on balance and coordination when given before ethanol exposure. Choline fortification of common foodstuffs may reduce the effects of alcohol.

Apoptosis of Purkinje and granular cells of the cerebellum following chronic ethanol intake

Ethanol alters motricity, learning, cognition, and cellular metabolism in the cerebellum. We evaluated the effect of ethanol on apoptosis in Golgi, Purkinje, and granule cells of the cerebellum in adult rats. There were two groups of 20 rats: a control group that did not consume ethanol and an experimental group of UChA rats that consumed ethanol at 10% (<2 g ethanol/kg body weight/day). At 120 days old, rats were anesthetized and decapitated, and their cerebella were collected and fixed. Cerebellar sections were subjected to immunohistochemistry for terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL), caspase-3, X-linked inhibitor of apoptosis protein (XIAP), and insulin-like growth factor 1-receptor (IGF-1R); real-time PCR (RT-PCR) to determine caspase-3, XIAP, and IGF-1R gene expression; and transmission electron microscopy (TEM). We identified fragmentation of DNA and an increase in caspase-3 protein and XIAP in Purkinje cells, whereas granule cells exhibited increased caspase-3 and XIAP. IGF-1R expression was unchanged. There was no significant difference in gene expression of caspase-3, XIAP, and IGF-1R. There were an increase in lipid droplets, a reduction in the cellular cytoplasm in electron-dense nuclei, and changes in the myelin sheath in the cerebellar cortex. In conclusion, our data demonstrated that ethanol induced apoptosis in the Purkinje and granule cells of the cerebellum of adult UChA rats.

Cellular commitment in the developing cerebellum

The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum.

Activation of liver X receptor is protective against ethanol-induced developmental impairment of Bergmann glia and Purkinje neurons in the mouse cerebellum

Cerebellar Purkinje cell and granule cell development are coordinated by Bergmann glia, and are particularly sensitive to ethanol (EtOH) exposure. The liver X receptor (LXR) plays important roles in Bergmann glial development. However, the effect of LXR activation on EtOH-mediated impairment of Bergmann glia and subsequently on Purkinje cell dendritogenesis remains undetermined. Therefore, using immunohistochemistry, quantitative real-time PCR and Western blot, we tested the possible protection of LXR agonist T0901317 (T0) on Bergmann glia and Purkinje cell dendritogenesis in mice exposed to ethanol. Results showed that a brief exposure of EtOH on postnatal day (PD 5) significantly decreased the average body weight of mice at PD 6 without alteration in the brain weight. In EtOH-exposed mice, the number of migrating granule cells in the molecular layer was significantly decreased, and this effect was attenuated by pretreatment of T0. EtOH exposure also resulted in the significant reduction of calbindin-labeled Purkinje cells, their maximum dendrite length, and impairment of Purkinje cell dendritogenesis. Furthermore, EtOH induced the activation of microglia in the Purkinje cell layer and impaired the development of Bergmann glia. However, pretreatment of T0 effectively blocked all of these responses. These responses were found to be mediated by the inhibition of upregulated levels of β-catenin and transcription factor LEF1 in the cerebellum. Overall, the results suggest that activating LXRs on postnatal mice exposed to EtOH is protective to Bergmann glia, and thus may play a critical role in preventing EtOH-induced defects during cerebellar development.

Long-lasting neural circuit dysfunction following developmental ethanol exposure

Fetal Alcohol Spectrum Disorder (FASD) is a general diagnosis for those exhibiting long-lasting neurobehavioral and cognitive deficiencies as a result of fetal alcohol exposure. It is among the most common causes of mental deficits today. Those impacted are left to rely on advances in our understanding of the nature of early alcohol-induced disorders toward human therapies. Research findings over the last decade have developed a model where ethanol-induced neurodegeneration impacts early neural circuit development, thereby perpetuating subsequent integration and plasticity in vulnerable brain regions. Here we review our current knowledge of FASD neuropathology based on discoveries of long-lasting neurophysiological effects of acute developmental ethanol exposure in animal models. We discuss the important balance between synaptic excitation and inhibition in normal neural network function, and relate the significance of that balance to human FASD as well as related disease states. Finally, we postulate that excitation/inhibition imbalance caused by early ethanol-induced neurodegeneration results in perturbed local and regional network signaling and therefore neurobehavioral pathology.

Review: taurine: a "very essential" amino acid

Taurine is an organic osmolyte involved in cell volume regulation, and provides a substrate for the formation of bile salts. It plays a role in the modulation of intracellular free calcium concentration, and although it is one of the few amino acids not incorporated into proteins, taurine is one of the most abundant amino acids in the brain, retina, muscle tissue, and organs throughout the body. Taurine serves a wide variety of functions in the central nervous system, from development to cytoprotection, and taurine deficiency is associated with cardiomyopathy, renal dysfunction, developmental abnormalities, and severe damage to retinal neurons. All ocular tissues contain taurine, and quantitative analysis of ocular tissue extracts of the rat eye revealed that taurine was the most abundant amino acid in the retina, vitreous, lens, cornea, iris, and ciliary body. In the retina, taurine is critical for photoreceptor development and acts as a cytoprotectant against stress-related neuronal damage and other pathological conditions. Despite its many functional properties, however, the cellular and biochemical mechanisms mediating the actions of taurine are not fully known. Nevertheless, considering its broad distribution, its many cytoprotective attributes, and its functional significance in cell development, nutrition, and survival, taurine is undoubtedly one of the most essential substances in the body. Interestingly, taurine satisfies many of the criteria considered essential for inclusion in the inventory of neurotransmitters, but evidence of a taurine-specific receptor has yet to be identified in the vertebrate nervous system. In this report, we present a broad overview of the functional properties of taurine, some of the consequences of taurine deficiency, and the results of studies in animal models suggesting that taurine may play a therapeutic role in the management of epilepsy and diabetes.

Potential protective effect of taurine against dibromoacetonitrile-induced neurotoxicity in rats

Dibromoacetonitrile (DBAN) is a disinfection by-product of water chlorination. Epidemiological studies indicate that it might present a potential hazard to human health. The present study aimed to investigate the possible neurotoxicity of DBAN in rats and possible protection by taurine. Based on initial dose-response experiment, DBAN (60 mg/kg) was administrated orally for 7 days. DBAN administration significantly impaired behavior of rats. Further, DBAN produced significant decrease of monoamines, γ-aminobutyric acid (GABA), glutamate contents, acetylcholinestrase (AChE) and aspartate aminotransferase (AST) activities, in rat brain. On the other hand, a significant increase in malondialdehyde (MDA), nitric oxide (NO) contents and lactic dehydrogenase (LDH) activity was observed. Co-administration of taurine (200mg/kg, i.p.) with DBAN mitigated most tested parameters. In conclusion, the present study indicates that DBAN has the propensity to cause significant oxidative damage in rat brain. However, taurine has a promising role in attenuating the obtained hazardous effects of DBAN.

In vivo monitoring of recovery from neurodegeneration in conditional transgenic SCA1 mice

Reliable and objective markers of neuronal function and pathology that can directly assess the effects of neuroprotective treatments in the brain are urgently needed for clinical trials in neurodegenerative diseases. Here we assessed the sensitivity of high field proton magnetic resonance spectroscopy ((1)H MRS) to monitor reversal of neurodegeneration by taking advantage of a well characterized conditional mouse model of spinocerebellar ataxia type 1 (SCA1), where the cerebellar pathology and ataxic phenotype are reversible by doxycycline administration. Transgene expression was suppressed by feeding the mice with chow that contains doxycycline from 6 to 12 weeks of age in an early stage group and from 12 to 24 weeks in a mid-stage group. Cerebellar neurochemical profiles of treated and untreated conditional mice were measured at 9.4 tesla (T) before and after treatment and compared to those of wild type (WT) controls, as well as to histology measures (molecular layer thickness in the primary fissure and a global pathological severity score). Concentrations of N-acetylaspartate (NAA) and myo-inositol in the treated mice trended toward normalization to WT levels in both the early and mid-stage groups. The NAA-to-myo-inositol ratio was significantly different between the treated vs. untreated SCA1 mice and demonstrated partial reversal to WT values both at early and mid-stage, consistent with the histological measures. Taurine and total creatine levels were completely normalized in early and mid-stage treatment groups, respectively. The MRS markers were a more sensitive measure of treatment response than the histological measures from the same volume-of-interest in the early stage group. NAA, myo-inositol and taurine levels were significantly correlated with the histology measures in data combined from all groups. These data demonstrate that MRS markers reliably detect rescue from neuronal pathology and imply that the neurochemical levels measured by MRS accurately reflect treatment efficacy. Therefore this study presents an important step in validating MRS biomarkers as potential surrogate markers to evaluate therapeutics in pre-clinical and clinical trials in SCA1.

Neuroprotective effects of the 17β-estradiol against ethanol-induced neurotoxicity and oxidative stress in the developing male rat cerebellum: biochemical, histological and behavioral changes

During particular periods of central nervous system (CNS) development, exposure to ethanol can decrease regional brain growth and can result in selective loss of neurons. Unfortunately, there are few effective means of attenuating damage in the immature brain. In this study, the possible antioxidant and neuroprotective properties of 17β-estradiol against ethanol-induced neurotoxicity was investigated. 17β-estradiol (600 μg/kg) was injected subcutaneously in postnatal day (PD) 4 and 5, 30 min prior to intraperitoneal injection of ethanol (6g/kg) in rat pups. Ninety minutes after injection of ethanol, the activities of several antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (Gpx) in vermis of cerebellum were assayed. Thiobarbituric acid reactive substance (TBARS) levels were also measured as a marker of lipid peroxidation. Behavioral studies, including rotarod and locomotor activity tests were performed in PD 21-23 and histological study was performed after completion of behavioral measurements in postnatal day 23. The results of the present work demonstrated that ethanol could induce lipid peroxidation, increase TBARS levels and decrease glutathione peroxidase levels in pup cerebellum. We also observed that ethanol impaired performance on the rotarod and locomotor activities of rat pups. However, treatment with 17β-estradiol significantly attenuated motoric impairment, the lipid peroxidation process and restored the levels of antioxidants. Histological analysis also indicated that ethanol could decrease vermis Purkinje cell count and 17β-estradiol prevented this toxic effect. These results suggest that ethanol may induce lipid peroxidation in the rat pups cerebellum while treatment with 17β-estradiol improves motor deficits by protecting the cerebellum against ethanol toxicity.