Combined Intraperitoneal and Intrathecal Etanercept Reduce Increased Brain Tumor Necrosis Factor-Alpha and Asymmetric Dimethylarginine Levels and Rescues Spatial Deficits in Young Rats after Bile Duct Ligation

Role of astrocytes and microglia in hepatic encephalopathy associated with advanced chronic liver disease: lessons from animal studies

Hepatic encephalopathy, defined as neuropsychiatric dysfunction secondary to liver disease, is a frequent decompensating event in cirrhosis. Its clinical impact is highlighted by a notable increase in patient mortality rates and a concomitant reduction in overall quality of life. Systemically, liver disease, liver function failure, portosystemic shunting, and associated multi-organ dysfunction result in the increase of disease-causing neurotoxins in the circulation, which impairs cerebral homeostasis. Key circulating neurotoxins are ammonia and inflammatory mediators. In the brain, pathophysiology is less well understood, but is thought to be driven by glial cell dysfunction. Astrocytes are the only brain resident cells that have ammonia-metabolizing machinery and are therefore putatively most susceptible to ammonia elevation. Based on a large body of mostly in vitro evidence, ammonia-induced cellular and molecular disturbances include astrocyte swelling and oxidative stress. Microglia, the brain resident macrophages, have been linked to the translation of systemic inflammation to the brain microenvironment. Recent evidence from animal studies has provided novel insights into old and new downstream effects of astrocyte and microglial dysfunction such as toxin clearance disruption and myeloid cell attraction to the central nervous system parenchyma. Furthermore, state of the art research increasingly implicates neuronal dysfunction and possibly even irreversible neuronal cell death. Cell-type specific investigation in animal models highlights the need for critical revision of the contribution of astrocytes and microglia to well-established and novel cellular and molecular alterations in hepatic encephalopathy. In this review, we therefore give a current and comprehensive overview of causes, features, and consequences of astrocyte and microglial dysfunction in hepatic encephalopathy, including areas of interest for future investigation.

Hypoxemia exerts detrimental effects on the choroid plexuses and cerebrospinal fluid system in rats

BACKGROUND

Hypoxemia can cause secondary acute brain injury, but the mechanisms behind it are not entirely clear and could involve disturbances in the brain extracellular fluids. We aimed to explore the effects of hypoxemia on the choroid plexus (CPs) and cerebrospinal fluid (CSF) system in rats.

METHODS

Male Sprague Dawley rats were kept in O2 control in vivo cabinet with either 21% (normoxia) or 8% O2 (hypoxemia) for up to 48 h. In some cases, signaling of selected cytokines was inhibited prior to hypoxemia. CSF and blood samples were collected by Cisterna Magna puncture and through venous catheters, respectively. The percentages of dead cells in the CPs and ependymal layers (EL) after hypoxemia or normoxia was estimated using TUNEL staining. CP's ultrastructure was analyzed by transmission electron microscopy. Protein concentration in the CSF and plasma was measured and the CSF albumin-to-total protein ratios were estimated. Concentrations of hypoxia-related cytokines in the CSF and plasma samples were estimated using the multiplex immunoassay. Data was analyzed by one-way ANOVA followed by either Bonferroni or Tukey's multiple comparison tests, or Student's t-test. Results are presented as mean ± SD; p < 0.05 was considered statistically significant.

RESULTS

Duration of hypoxemia exerted significant effects on the cell viability in the CPs (p < 0.01) and EL (p < 0.01) and caused apoptosis-related changes in the CP. Hypoxemia had significant effects on the protein concentration in the CSF (p < 0.05), but not in plasma (p > 0.05), with a significant increase in the CSF albumin-to-total protein ratio after 6 h hypoxemia (p < 0.05). Thirty-two cytokines were detected in the CSF. Hypoxemia caused a statistically significant reduction in the concentrations of 12 cytokines, while concentrations of erythropoietin (EPO) and vascular endothelial growth factor (VEGF) increased significantly. Exposure to hypoxemia after inhibitions of EPO, VEGF, or tumor necrosis factor alpha (TNFα) signaling resulted in more dead cells (p < 0.01), less dead cells (p < 0.01) and more dead cells (p < 0.01) in the CPs, respectively, when compared to the number of dead cells when these cytokines were not inhibited. The density of macrophages in the CPs decreased significantly during hypoxemia; that effect was cancelled out by TNFα inhibition.

CONCLUSION

Hypoxemia had detrimental effects on the CPs and CSF system, which was modulated by hypoxia- and inflammation-related cytokines.

Edaravone reduces brain injury in hepatic encephalopathy by upregulation of Nrf2/HO-1 and inhibition of NF-κB, iNOS/NO and inflammatory cytokines

BACKGROUND

Brain damage is the most important complication in patients with hepatic encephalopathy (HE). Oxidative stress and inflammation are essential factors in the progression of brain injury caused by HE. The aim of this study was to investigate the potential therapeutic effect of edaravone and its underlying mechanisms against brain injury associated with HE in mice.

METHODS AND RESULTS

HE was induced by the injection of thioacetamide (200 mg/kg) for 2 days and then mice treated with edaravone (10 or 20 mg/kg/day, ip) for four consecutive days. The brain tissues were dissected for histopathological, biochemical, ELISA, RT-qPCR and immunofluorescence analysis. The results showed that edaravone improved the locomotor function and ameliorated brain histopathological changes in mice with HE. Edaravone inhibited oxidative stress markers by increasing the levels of glutathione, catalase, superoxide dismutase, glutathione reductase and the upregulation of nuclear erythroid 2-related factor (Nrf2)/HO-1 pathway in the brain tissue. Administration of edaravone significantly decreased the expression of p-NF-κB and iNOS. Edaravone treatment reduced the levels of NO, MPO and MMP-9 in the brain of mice. Additionally, the brain levels and expressions of inflammatory cytokines IL-1β, IL-6, TNF-α and IFN-γ were downregulated in mice treated with edaravone.

CONCLUSIONS

These results suggest that edaravone exerts significant neuroprotection by modulating of inflammatory and oxidative responses in HE and may serve as a promising agent for the treatment of brain injury associated with HE.

Increased Circulating ADMA in Young Male Rats Caused Cognitive Deficits and Increased Intestinal and Hippocampal NLRP3 Inflammasome Expression and Microbiota Composition Alterations: Effects of Resveratrol

Endothelial dysfunction is characterized by disturbances in nitric oxide (NO) bioavailability and increased circulating asymmetric dimethylarginine (ADMA) due to the enormous release of free radicals. Increased circulating ADMA may cause endothelial dysfunction and a variety of clinical disorders, such as liver and kidney disease. Young male Sprague-Dawley rats at postnatal day 17 ± 1 received continuous ADMA infusion via an intraperitoneal pump to induce endothelial dysfunction. Four groups of rats (n = 10 per group) were allocated: control, control and resveratrol, ADMA infusion, and ADMA infusion and resveratrol groups. Spatial memory, NLR family pyrin-domain-containing 3 (NLRP3) inflammasome, cytokine expression, tight junction proteins in the ileum and dorsal hippocampus, and microbiota composition were examined. We found cognitive deficits; increased NLRP3 inflammasome in the plasma, ileum, and dorsal hippocampus; decreased ileum and dorsal hippocampal cytokine activation and tight junction proteins; and microbiota composition alterations in the ADMA-infusion young male rats. Resveratrol had beneficial effects in this context. In conclusion, we observed NLRP3 inflammasome activation in peripheral and central dysbiosis in young male rats with increased circulating ADMA, and found that resveratrol had beneficial effects. Our work adds to the mounting evidence that inhibiting systemic inflammation is a promising therapeutic avenue for cognition impairment, probably via the gut-brain axis.

Melatonin protects against methotrexate hepatotoxicity in young rats: Impact of PI3K/Akt/mTOR signaling

With the improvement in children's acute lymphoblastic leukemia (ALL) care, the survival rate in children ALL has improved much. Methotrexate (MTX) plays an essential role in the success of children's ALL treatment. Since hepatotoxicity is commonly reported in individuals treated with intravenous or oral MTX, our study further examined the hepatic effect following intrathecal MTX treatment, which is an essential treatment for leukemia patients. Specifically, we examined the pathogenesis of MTX hepatotoxicity in young rats and explored the impact of melatonin treatment in protection against MTX hepatotoxicity. Successfully, we found that melatonin was able to protect against MTX hepatotoxicity.

The effect of crocin on cholestasis-induced spatial memory impairment with respect to the expression level of TFAM and PGC-1α and activity of catalase and superoxide dismutase in the hippocampus

Large evidence has shown that cholestasis has a wide-range of deleterious effects on brain function, and also, on neurocognitive functions including learning and memory. On the other hand, crocin (derived from Crocus sativus) is a medicinal natural compound that induces neuroprotective and precognitive effects. In this study, we aimed to evaluate the effect of crocin on spatial learning and memory in cholestatic rats with respect to the level of mitochondrial transcriptional factor A (TFAM), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), catalase (CAT), and superoxide dismutase (SOD) in the hippocampus of male Wistar rats. Bile duct ligation (BDL) was used to induce cholestasis. Y-maze apparatus was used to assess spatial memory performance and real-time PCR was used to assess TFAM and PGC-1α gene expression. Also, crocin was injected intraperitoneal at the doses of 15, 20, and 30 mg/kg for thirty days. The results showed that BDL impaired spatial memory in rats. BDL also decreased SOD, TFAM, and PGC-1α level. In addition, crocin partially reversed the impairment effect of BDL on spatial memory. Crocin (30 mg/kg) also reversed the effect of BDL on SOD, TFAM, and PGC-1α. Of note, the effect of BDL on CAT activity was controversial. It seems that BDL can increase CAT activity. In addition, crocin (30 mg/kg) reversed the enhancement of CAT following BDL to its control level. In conclusion, crocin may induce a significant neuroprotective effect on cholestasis-induced memory impairment.

Neuroprotective and anti-neuroinflammatory activity of frankincense in bile duct ligaion-induced hepatic encephalopathy

Objectives

Hepatic encephalopathy induces cognitive disturbances. Patients show neuroinflammation due to accumulation of toxic substances. Frankincense has neuroprotective and anti-inflammatory properties. Accordingly, we intended to evaluate the impact of frankincense on memory performance, inflammation, and the amount of hippocampal neurons in bile duct-ligated rats.

Materials and Methods

The bile duct was ligated in three groups of adult male Wistar rats (BDL groups). In two of these groups, frankincense was administered (100 or 200 mg/kg; by gavage) starting from one week before surgery to 28 days after surgery. The third BDL group received saline. In the sham group, the bile duct was not ligated and the animals received saline. Twenty-eight days after surgery, spatial memory was evaluated by the Morris water maze test. Five rats from each group were sacrificed to measure the expression of the hippocampal tumor necrosis factor-alpha (TNF-α). Three rats from each group were perfused to determine the amount of hippocampal neurons.

Results

Bile duct ligation impaired memory acquisition, while frankincense amended it. Bile duct ligation significantly increased the expression of TNF-α. Frankincense reduced TNF-α in BDL rats, significantly. The number of neurons in the hippocampal CA₁ and CA₃ areas was significantly lower in the BDL group and in the group that received frankincense (100 mg/kg) equated to the sham group. Frankincense (200 mg/kg) augmented the amount of neurons in the CA₁ area, slightly and in the CA₃ area, significantly.

Conclusion

The results indicate the anti-inflammatory and neuroprotective effects of frankincense in bile duct ligation-induced hepatic encephalopathy.

Infliximab and/or MESNA alleviate doxorubicin-induced Alzheimer's disease-like pathology in rats: A new insight into TNF-α/Wnt/β-catenin signaling pathway

AIMS

The current study aimed to elucidate the neurotoxic potential of DOX to induce AD-like pathology paying attention to the role of wingless-integrated/β-catenin (Wnt/β-catenin) signaling pathway. A major aim was to evaluate the efficacy of infliximab (IFX) either individually or in combination with 2-mercaptoethane sulfonate sodium (MESNA) on the DOX-induced neurotoxicity in rats.

METHODOLOGY

AD-like pathology was induced in adult male Wistar rats by intraperitoneal (i.p.) administration of DOX at a dose of 3.5 mg/kg twice a week for 3 weeks. DOX-injected rats were then treated with either INF at a single dose of 5 mg/kg i.p. (IFX group), MESNA at a dose of 160 mg/kg/day i.p. for 4 weeks (MESNA group) or their combination at the same specified doses (INF + MESNA group). At the end of the study period, behavioral assessment was performed and the brain tissue samples were harvested at sacrifice.

KEY FINDINGS

DOX-treated rats significantly exhibited AD-like brain injury, increased amyloid burden, enhanced neuroinflammation and apoptosis, and multifocal histological injury in the cerebral cortex with widespread vacuolations. IFX and MESNA significantly reversed all the aforementioned detrimental effects in the DOX-treated rats.

SIGNIFICANCE

The study has provided sufficient evidence of the potential of IFX and/or MESNA to ameliorate the DOX-induced neurotoxicity, with the best improvement observed with their combined administration. A new insight has been introduced into the critical role of Wnt/β-catenin activation.

Methotrexate Neurotoxicity Is Related to Epigenetic Modification of the Myelination Process

With the improvement of the survival rate of acute lymphoblastic leukemia (ALL) in children, some children ALL survivors reveal inferior intellectual and cognition outcome. Methotrexate (MTX), while serving as an essential component in ALL treatment, has been reported to be related to various neurologic sequelae. Using combined intrathecal (IT) and intraperitoneal (IP) MTX model, we had demonstrated impaired spatial memory function in developing rats, which can be rescued by melatonin treatment. To elucidate the impact of MTX treatment on the epigenetic modifications of the myelination process, we examined the change of neurotrophin and myelination-related transcriptomes in the present study and found combined IT and IP MTX treatment resulted in altered epigenetic modification on the myelination process, mainly in the hippocampus. Further, melatonin can restore the MTX effect through alterations of the epigenetic pathways.

Interplay of cardiovascular mediators, oxidative stress and inflammation in liver disease and its complications

The liver is a crucial metabolic organ that has a key role in maintaining immune and endocrine homeostasis. Accumulating evidence suggests that chronic liver disease might promote the development of various cardiac disorders (such as arrhythmias and cardiomyopathy) and circulatory complications (including systemic, splanchnic and pulmonary complications), which can eventually culminate in clinical conditions ranging from portal and pulmonary hypertension to pulmonary, cardiac and renal failure, ascites and encephalopathy. Liver diseases can affect cardiovascular function during the early stages of disease progression. The development of cardiovascular diseases in patients with chronic liver failure is associated with increased morbidity and mortality, and cardiovascular complications can in turn affect liver function and liver disease progression. Furthermore, numerous infectious, inflammatory, metabolic and genetic diseases, as well as alcohol abuse can also influence both hepatic and cardiovascular outcomes. In this Review, we highlight how chronic liver diseases and associated cardiovascular effects can influence different organ pathologies. Furthermore, we explore the potential roles of inflammation, oxidative stress, vasoactive mediator imbalance, dysregulated endocannabinoid and autonomic nervous systems and endothelial dysfunction in mediating the complex interplay between the liver and the systemic vasculature that results in the development of the extrahepatic complications of chronic liver disease. The roles of ageing, sex, the gut microbiome and organ transplantation in this complex interplay are also discussed.

Maternal Iron Deficiency Programs Offspring Cognition and Its Relationship with Gastrointestinal Microbiota and Metabolites

Iron is an essential micronutrient for the brain development of the fetus. Altered intestinal microbiota might affect behavior and cognition through the so-called microbiota-gut-brain axis. We used a Sprague-Dawley rat model of a maternal low-iron diet to explore the changes in cognition, dorsal hippocampal brain-derived neurotrophic factor (BDNF) and related pathways, gut microbiota, and related metabolites in adult male offspring. We established maternal iron-deficient rats by feeding them a low-iron diet (2.9 mg/kg), while the control rats were fed a standard diet (52.3 mg/kg). We used a Morris water maze test to assess spatial learning and long-term memory. Western blot (WB) assays and a quantitative reverse-transcription polymerase chain reaction (qRT-PCR) were used to detect the BDNF concentration and related signaling pathways. We collected fecal samples for microbiota profiling and measured the concentrations of plasma short-chain fatty acids. The adult male offspring of maternal rats fed low-iron diets before pregnancy, during pregnancy and throughout the lactation period had (1) spatial deficits, (2) a decreased BDNF mRNA expression and protein concentrations, accompanied by a decreased TrkB protein abundance, (3) a decreased plasma acetate concentration, and (4) an enrichment of the Bacteroidaceae genus Bacteroides and Lachnospiraceae genus Marvinbryantia. Maternal iron deficiency leads to an offspring spatial deficit and is associated with alternations in gastrointestinal microbiota and metabolites.

Effects of Maternal Resveratrol on Maternal High-Fat Diet/Obesity with or without Postnatal High-Fat Diet

To examine the effects of maternal resveratrol in rats borne to dams with gestational high-fat diet (HFD)/obesity with or without postnatal high-fat diet. We first tested the effects of maternal resveratrol intake on placenta and male fetus brain in rats borne to dams with gestational HFD/obesity. Then, we assessed the possible priming effect of a subsequent insult, male offspring were weaned onto either a rat chow or a HFD. Spatial learning and memory were assessed by Morris water maze test. Blood pressure and peripheral insulin resistance were examined. Maternal HFD/obesity decreased adiponectin, phosphorylation alpha serine/threonine-protein kinase (pAKT), sirtuin 1 (SIRT1), and brain-derived neurotrophic factor (BDNF) in rat placenta, male fetal brain, and adult male offspring dorsal hippocampus. Maternal resveratrol treatment restored adiponectin, pAKT, and BDNF in fetal brain. It also reduced body weight, peripheral insulin resistance, increased blood pressure, and alleviated cognitive impairment in adult male offspring with combined maternal HFD and postnatal HFD. Maternal resveratrol treatment restored hippocampal pAKT and BDNF in rats with combined maternal HFD and postnatal HFD in adult male offspring dorsal hippocampus. Maternal resveratrol intake protects the fetal brain in the context of maternal HFD/obesity. It effectively reduced the synergistic effects of maternal HFD/obesity and postnatal HFD on metabolic disturbances and cognitive impairment in adult male offspring. Our data suggest that maternal resveratrol intake may serve as an effective therapeutic strategy in the context of maternal HFD/obesity.

Melatonin rescued methotrexate-induced spatial deficit and hyperhomocysteinemia and increased asymmetric dimethylarginine in plasma and dorsal hippocampus in developing rats

AIMS

With the improvement of the survival rates in children acute lymphoblastic leukemia (ALL), some children ALL survivors show impaired cognitive function. Methotrexate (MTX), an essential component in ALL treatment, has been reported to be related to neurologic sequelae and to increased oxidative stress through its interactions with enzymes in the folate pathway. Asymmetric dimethylarginine (ADMA) is the main endogenous inhibitor of nitric oxide synthase, and increased ADMA may result from increased oxidants. Melatonin is an antioxidant; however, its role in MTX neuropathy is not well studied. We developed a rat model mimicking child ALL treatment to explore peripheral and central homocysteine and ADMA regulation after MTX and found potential treatment choice.

MAIN METHODS

Preweaning male Sprague-Dawley rats were used in this study. Experiment 1 evaluated spatial performance in rats with intrathecal (IT) MTX, intraperitoneal (IP) MTX, or combined IT and IP MTX, protocols mimicking ALL treatment in children. Experiment 2 focused on rats with combined IT and IP MTX, evaluating spatial performance and plasma and dorsal hippocampal homocysteine and ADMA levels, their regulation, and the protective effect of melatonin.

KEY FINDINGS

Combined IT and IP MTX treatment caused in spatial deficits in developing rats, and melatonin restored the spatial performance. Alterations in peripheral and central homocysteine and ADMA concentrations and their regulation were found and could be alleviated by melatonin treatment.

SIGNIFICANCES

Combined IP and IT MTX treatment caused spatial deficits in developing rats. Melatonin could restore spatial performance through alleviating the effects on the imbalance of oxidative stress.

Melatonin prevented spatial deficits and increases in brain asymmetric dimethylarginine in young bile duct ligation rats

Bile duct ligation (BDL) in young rats can cause impaired liver function and cognition deficits. Nitric oxide is implicated in hepatic encephalopathy and is also involved in cognition. In this study, we examined the role of brain asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, in young BDL rats with spatial deficits. Young male Sprague-Dawley rats aged 17 days were assigned to four groups: laparotomy (SHAM), laparotomy plus 5 mg melatonin delivered through a pellet (SHAMM) for 4 weeks, BDL for 4 weeks, and BDL plus 5 mg melatonin delivered through a pellet (BDLM) for 4 weeks. Their spatial memory was assessed using a Morris water-maze task. Plasma and brains were collected for biochemical and ADMA analyses. We found that the BDL group had significantly elevated levels of ADMA in the plasma, the prefrontal cortex, and the dorsal hippocampus, and worse spatial performance than that of the control groups. Melatonin administration prevented an increase in the ADMA levels in the plasma, prefrontal cortex, and dorsal hippocampus, and prevented spatial deficits in BDL rats. In addition, melatonin maintained brain-derived neurotrophic factor in the dorsal hippocampus at a level comparable with controls. We concluded that melatonin is effective in preventing spatial deficits and decreasing ADMA levels in the plasma, prefrontal cortex, and dorsal hippocampus in young BDL rats. Brain ADMA levels might play a role in BDL-induced spatial deficits.

Pathogenesis of Hepatic Encephalopathy in Chronic Liver Disease

Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome that occurs during chronic liver disease (CLD). While ammonia and other precipitating factors in liver disease including inflammation, bile acids, oxidative stress, and lactate play a role in the pathogenesis of HE, the exact mechanism that leads to HE is not fully understood. Notably, accumulating evidence points toward a synergic effect rather than independent actions among precipitating factors that contributes to the development and severity of HE in CLD. Hence, this review is aimed to briefly discuss the single and synergic interplay of pathological factors in the progression and severity of HE.

Combined maternal and postnatal high-fat diet leads to metabolic syndrome and is effectively reversed by resveratrol: a multiple-organ study

This study aimed to study the impact of a combination of maternal and post-weaning high-fat diets and whether resveratrol was beneficial. Sprague-Dawley dams were fed either chow or a high-fat diet, before mating, during pregnancy, and into lactation. At weaning, their offspring were randomly fed chow or a high-fat diet. Four experimental groups were generated: CC (maternal/postnatal chow diet), HC (maternal high-fat/postnatal chow diet), CH (maternal chow/postnatal high-fat diet), and HH (maternal/postnatal high-fat diet). A fifth group consisted of HH plus resveratrol. The 4 month-old offspring of HH group had higher body weight, higher levels of plasma triglycerides, leptin, angiotensin I and angiotensin II and abnormal intraperitoneal glucose tolerance test results, which fulfilled the features of metabolic syndrome. The dysregulation of the renin-angiotensin system was seen in multiple organs. Sirtuin 1 expression/abundance was reduced by a maternal/postnatal high-fat diet, in all the organs examined. Resveratrol ameliorated most of the features of metabolic syndrome and molecular alterations. The administration of a high-fat diet in both periods showed interactive metabolic effects in the plasma and many organs. Our results suggest that a maternal high-fat diet sensitizes offspring to the adverse effects of subsequent high-fat intake on multiple organs.

A maternal high-fat diet during pregnancy and lactation, in addition to a postnatal high-fat diet, leads to metabolic syndrome with spatial learning and memory deficits: beneficial effects of resveratrol

We tested the hypothesis that high-fat diet consumption during pregnancy, lactation, and/or post weaning, altered the expression of molecular mediators involved in hippocampal synaptic efficacy and impaired spatial learning and memory in adulthood. The beneficial effect of resveratrol was assessed. Dams were fed a rat chow diet or a high-fat diet before mating, during pregnancy, and throughout lactation. Offspring were weaned onto either a rat chow or a high-fat diet. Four experimental groups were generated, namely CC, HC, CH, and HH (maternal chow diet or high-fat diet; postnatal chow diet or high-fat diet). A fifth group fed with HH plus resveratrol (HHR) was generated. Morris water maze test was used to evaluate spatial learning and memory. Blood pressure and IPGTT was measured to assess insulin resistance. Dorsal hippocampal expression of certain biochemical molecules, including sirtuin 1, ERK, PPARγ, adiponectin, and BDNF were measured. Rats in HH group showed impaired spatial memory, which was partly restored by the administration of resveratrol. Rats in HH group also showed impaired glucose tolerance and increased blood pressure, all of which was rescued by resveratrol administration. Additionally, SIRT1, phospho-ERK1/2, and phospho-PPARγ, adiponectin and BDNF were all dysregulated in rats placed in HH group; administration of resveratrol restored the expression and regulation of these molecules. Overall, our results suggest that maternal high-fat diet during pregnancy and/or lactation sensitizes the offspring to the adverse effects of a subsequent high-fat diet on hippocampal function; however, administration of resveratrol is demonstrated to be beneficial in rescuing these effects.

Minocycline restores cognitive-relative altered proteins in young bile duct-ligated rat prefrontal cortex

AIMS

Bile duct ligation (BDL) model is used to study hepatic encephalopathy accompanied by cognitive impairment. We employed the proteomic analysis approach to evaluate cognition-related proteins in the prefrontal cortex of young BDL rats and analyzed the effect of minocycline on these proteins and spatial memory.

MAIN METHODS

BDL was induced in young rats at postnatal day 17. Minocycline as a slow-release pellet was implanted into the peritoneum. Morris water maze test and two-dimensional liquid chromatography-tandem mass spectrometry were used to evaluate spatial memory and prefrontal cortex protein expression, respectively. We used 2D/LC-MS/MS to analyze for affected proteins in the prefrontal cortex of young BDL rats. Results were verified with Western blotting, immunohistochemistry, and quantitative real-time PCR. The effect of minocycline in BDL rats was assessed.

KEY FINDINGS

BDL induced spatial deficits, while minocycline rescued it. Collapsin response mediator protein 2 (CRMP2) and manganese-dependent superoxide dismutase (MnSOD) were upregulated and nucleoside diphosphate kinase B (NME2) was downregulated in young BDL rats. BDL rats exhibited decreased levels of brain-derived neurotrophic factor (BDNF) mRNA as compared with those by the control. However, minocycline treatment restored CRMP2 and NME2 protein expression, BDNF mRNA level, and MnSOD activity to control levels.

SIGNIFICANCE

We demonstrated that BDL altered the expression of CRMP2, NME2, MnSOD, and BDNF in the prefrontal cortex of young BDL rats. However, minocycline treatment restored the expression of the affected mediators that are implicated in cognition.

Toxic Dimethylarginines: Asymmetric Dimethylarginine (ADMA) and Symmetric Dimethylarginine (SDMA)

Asymmetric and symmetric dimethylarginine (ADMA and SDMA, respectively) are toxic, non-proteinogenic amino acids formed by post-translational modification and are uremic toxins that inhibit nitric oxide (NO) production and play multifunctional roles in many human diseases. Both ADMA and SDMA have emerged as strong predictors of cardiovascular events and death in a range of illnesses. Major progress has been made in research on ADMA-lowering therapies in animal studies; however, further studies are required to fill the translational gap between animal models and clinical trials in order to treat human diseases related to elevated ADMA/SDMA levels. Here, we review the reported impacts of ADMA and SDMA on human health and disease, focusing on the synthesis and metabolism of ADMA and SDMA; the pathophysiological roles of these dimethylarginines; clinical conditions and animal models associated with elevated ADMA and SDMA levels; and potential therapies against ADMA and SDMA. There is currently no specific pharmacological therapy for lowering the levels and counteracting the deleterious effects of ADMA and SDMA. A better understanding of the mechanisms underlying the impact of ADMA and SDMA on a wide range of human diseases is essential to the development of specific therapies against diseases related to ADMA and SDMA.