The prenatal use of agmatine prevents social behavior deficits in VPA-exposed mice by activating the ERK/CREB/BDNF signaling pathway.

BACKGROUND: According to reports, prenatal exposure to valproic acid can induce autism spectrum disorder (ASD)-like symptoms in both humans and rodents. However, the exact cause and therapeutic method of ASD is not fully understood. Agmatine (AGM) is known for its neuroprotective effects, and this study aims to explore whether giving agmatine hydrochloride before birth can prevent autism-like behaviors in mouse offspring exposed prenatally to valproic acid. METHODS: In this study, we investigated the effects of AGM prenatally on valproate (VPA)-exposed mice. We established a mouse model of ASD by prenatally administering VPA. From birth to weaning, we evaluated mouse behavior using the marble burying test, open-field test, and three-chamber social interaction test on male offspring. RESULTS: The results showed prenatal use of AGM relieved anxiety and hyperactivity behaviors as well as ameliorated sociability of VPA-exposed mice in the marble burying test, open-field test, and three-chamber social interaction test, and this protective effect might be attributed to the activation of the ERK/CREB/BDNF signaling pathway. CONCLUSION: Therefore, AGM can effectively reduce the likelihood of offspring developing autism to a certain extent when exposed to VPA during pregnancy, serving as a potential therapeutic drug.

Landscapes of gut bacterial and fecal metabolic signatures and their relationship in severe preeclampsia.

BACKGROUND: Preeclampsia is a pregnancy-specific disease leading to maternal and perinatal morbidity. Hypertension and inflammation are the main characteristics of preeclampsia. Many factors can lead to hypertension and inflammation, including gut microbiota which plays an important role in hypertension and inflammation in humans. However, alterations to the gut microbiome and fecal metabolome, and their relationships in severe preeclampsia are not well known. This study aims to identify biomarkers significantly associated with severe preeclampsia and provide a knowledge base for treatments regulating the gut microbiome. METHODS: In this study, fecal samples were collected from individuals with severe preeclampsia and healthy controls for shotgun metagenomic sequencing to evaluate changes in gut microbiota composition. Quantitative polymerase chain reaction analysis was used to validate the reliability of our shotgun metagenomic sequencing results. Additionally, untargeted metabolomics analysis was performed to measure fecal metabolome concentrations. RESULTS: We identified several Lactobacillaceae that were significantly enriched in the gut of healthy controls, including Limosilactobacillus fermentum, the key biomarker distinguishing severe preeclampsia from healthy controls. Limosilactobacillus fermentum was significantly associated with shifts in KEGG Orthology (KO) genes and KEGG pathways of the gut microbiome in severe preeclampsia, such as flagellar assembly. Untargeted fecal metabolome analysis found that severe preeclampsia had higher concentrations of Phenylpropanoate and Agmatine. Increased concentrations of Phenylpropanoate and Agmatine were associated with the abundance of Limosilactobacillus fermentum. Furthermore, all metabolites with higher abundances in healthy controls were enriched in the arginine and proline metabolism pathway. CONCLUSION: Our research indicates that changes in metabolites, possibly due to the gut microbe Limosilactobacillus fermentum, can contribute to the development of severe preeclampsia. This study provides insights into the interaction between gut microbiome and fecal metabolites and offers a basis for improving severe preeclampsia by modulating the gut microbiome.

Spurious High Platelet Count without PLT Flag(S) in a Patient with Severe Aplastic Anaemia.

BACKGROUND: Platelet (PLT) count is one of the most important parameters of automated hematology, as spurious PLT reports could affect medical judgement and bring significant risks. In most cases, spurious PLT will not be reported for review criteria, which will be triggered by abnormal PLT histograms and PLT flag(s). Here, we present a case of severe aplastic anemia after hematopoietic stem cell transplantation with spurious high platelet count with normal histogram and no PLT flag(s). METHODS: The electrical impedance channel (PLT-I) and the fluorescence channel (PLT-F) of Sysmex XN-series hematology analyzer was used to obtain PLT results. Then, the sample was retested by another hematology analyzer MINDRAY BC-7500 [NR] CRP, and incubation was performed to rule out cryoglobulin interference. Furthermore, a microscope was used to estimate the PLT count by the ratio of platelets to red blood cells and observe the morphology of cells. RESULTS: Both PLT-I and PLT-F test results were spuriously high, and microscopically assessed platelet counts were relatively reliable. The observed spiny cells and ghost cells caused by hemolysis may have contributed to the inaccuracy of instrumental counting in this case. CONCLUSIONS: For special hematologic patients, PLT-I with flags may not be sufficient for screening purposes and PLT-F is not always accurate. Multiple testing methods including manual microscopy are needed.

Efficacy of Agmatine Treatment in Experimental Acute Pancreatitis Rat Model.

BACKGROUND/AIMS: Acute pancreatitis which is characterized by pancreatic inflammation can sometimes be difficult to treat because of limited therapeutic options. The purpose of the study was to assess the effects of agmatine in the acute pancreatitis experimental rat model. MATERIALS AND METHODS: An acute pancreatitis model was created with the administration of cerulein in 40 female Sprague-Dawley rats. Agmatine was administered as a protective agent at 5 mg/kg (low dose) and 10 mg/kg (high dose). The rats were divided into 5 groups, each with 8 rats: group 1 (acute pancreatitis); group 2 (acute pancreatitis+low-dose agmatine 5 mg/kg); group 3 (acute pancreatitis+high-dose agmatine 10 mg/kg); group 4 (placebo, acute pancreatitis+saline); and group 5 (sham and saline infusion). All rats were sacrificed 24 hours after the last injection, and the levels of superoxide dismutase, interleukin-1 beta, and tumor necrosis factor-alpha were assessed in blood samples collected via cardiac puncture. Histopathological examination was performed by a pathologist, who was blind to the groups, according to the Schoenberg's pancreatitis scoring index. RESULTS: The amylase (16.67 and 37.89 U/L), glutathione peroxidase (13.62 and 18.44 ng/mL), tumor necrosis factor-α (39.68 and 64 ng/mL), interleukin-1 (484.73 and 561.83 pg/mL), and transforming growth factor-ß (110.52 and 126.34 ng/L) levels were significantly lower and superoxide dismutase (1.29 and 0.98 ng/L) and malondialdehyde (0.99 and 0.96 nmol/mL) levels were significantly higher in group 3 compared to group 1 (P < .05). Moreover glutathione peroxidase, tumor necrosis factor-α, and transforming growth factor-ß levels were lower, and malondialdehyde levels were higher in the group 3 compared to group 2 (P < .05). Although the Schoenberg's pancreatitis scoring index was not significantly different between the high- and low-dose treatment groups, rats who received high-dose treatment had significantly lower scores compared to those with acute pancreatitis group. CONCLUSION: This is the first study that evaluated the efficacy of agmatine in an experimental model of acute pancreatitis. Agmatine, an anti-inflammatory and antioxidant agent, had a protective effect in an experimental rat model of acute pancreatitis.

Caldomycin, a new guanidopolyamine produced by a novel agmatine homocoupling enzyme involved in homospermidine biosynthesis.

An extreme thermophilic bacterium, Thermus thermophilus produces more than 20 unusual polyamines, but their biosynthetic pathways, including homospermidine, are not yet fully understood. Two types of homospermidine synthases have been identified in plants and bacteria, which use spermidine and putrescine or two molecules of putrescine as substrates. However, homospermidine synthases with such substrate specificity have not been identified in T. thermophilus. Here we identified a novel agmatine homocoupling enzyme that is involved in homospermidine biosynthesis in T. thermophilus. The reaction mechanism is different from that of a previously described homospermidine synthase, and involves conjugation of two molecules of agmatine, which produces a diamidino derivative of homospermidine (caldomycin) as an immediate precursor of homospermidine. We conclude that there is a homospermidine biosynthetic pathway from agmatine via caldomycin synthase followed by ureohydrolase in T. thermophilus. Furthermore, it is shown that caldomycin is a novel compound existing in nature.

Agmatine as a novel intervention for Alzheimer's disease: Pathological insights and cognitive benefits.

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive cognitive decline and a significant societal burden. Despite extensive research and efforts of the multidisciplinary scientific community, to date, there is no cure for this debilitating disease. Moreover, the existing pharmacotherapy for AD only provides symptomatic support and does not modify the course of the illness or halt the disease progression. This is a significant limitation as the underlying pathology of the disease continues to progress leading to the deterioration of cognitive functions over time. In this milieu, there is a growing need for the development of new and more efficacious treatments for AD. Agmatine, a naturally occurring molecule derived from L-arginine, has emerged as a potential therapeutic agent for AD. Besides this, agmatine has been shown to modulate amyloid beta (Aß) production, aggregation, and clearance, key processes implicated in AD pathogenesis. It also exerts neuroprotective effects, modulates neurotransmitter systems, enhances synaptic plasticity, and stimulates neurogenesis. Furthermore, preclinical and clinical studies have provided evidence supporting the cognition-enhancing effects of agmatine in AD. Therefore, this review article explores the promising role of agmatine in AD pathology and cognitive function. However, several limitations and challenges exist, including the need for large-scale clinical trials, optimal dosing, and treatment duration. Future research should focus on mechanistic investigations, biomarker studies, and personalized medicine approaches to fully understand and optimize the therapeutic potential of agmatine. Augmenting the use of agmatine may offer a novel approach to address the unmet medical need in AD and provide cognitive enhancement and disease modification for individuals affected by this disease.

Agmatine ameliorates valproic acid-induced depletion of parvalbumin-positive neuron.

Autism spectrum disorder (ASD) is a widespread neurodevelopmental disorder with unknown etiology. Dysfunction of several brain areas including the prefrontal cortex (PFC), hippocampus, and cerebellum is involved in cognitive and behavioral deficits associated with ASD. Several studies have reported a reduction in the number of parvalbumin-immunoreactive (PV+) neurons in brain areas of ASD patients and animal models such as a shank mutant mouse model and rodents receiving fetal valproic acid (VPA) administration. Developing therapeutic interventions that restore PV interneurons can be the future therapeutic approach to ASD. The present study examined the possible effect of agmatine (AG), an endogenous NMDA antagonist, on the number of PV+ neurons in a VPA animal model of autism. The therapeutic effects of AG in ameliorating ASD-like behaviors were previously reported in VPA rats. AG was gavaged at dosages of 0.001, 0.01, and 0.1 mg/kg from gestational day (GD) 6.5 to 18.5, and the number of PV interneurons was analyzed by immunohistochemistry in the 1-month-old rats. Prenatal VPA (GD 12.5) or AG led to a decrease of PV neurons in the PFC, Cornu ammonia (CA1), and molecular layers (MLs) of the cerebellum. However, exposure to AG restored the PV population induced by VPA. AG may modify underlying neuronal mechanisms resulting in the increased survival or restoration of the PV population.

Performance evaluation of a novel platelet count parameter, hybrid platelet count, on the BC-780 automated hematology analyzer.

OBJECTIVES: Automated hematology analysis is expected to improve the performance of platelet counting. We evaluated the performance of a new platelet counting, hybrid (PLT-H) and also impedance (PLT-I) and optical (PLT-O) on the BC-780 automated hematology analyzer compared to the international reference method (IRM) in blood samples with thrombocytopenic and platelet interference. METHODS: The basic platelet count performance of the BC-780 automated hematology analyzer was evaluated according to the requirements of the Clinical Laboratory and Standards Institute (CLSI) Document H26-A2. Additionally, the thrombocytopenic (low PLT count) blood samples and the platelet interference blood samples including fragmented red blood cells (RBCs), microcytes or small RBCs, and giant platelets were determined with the BC-780 hematology analyzer compared to the IRM. RESULTS: Blank counting and the carry-over contamination rate of platelet count using the BC-780 both met the manufacturers' claim. For both 123 thrombocytopenic and 232 platelet interference blood samples (72 fragmented RBCs, 91 microcytes and 51 giant platelets), all three platelet counting methods exhibited high comparability with the IRM (the lowest correlation (r)=0.916). Interestingly, the comparability of PLT-H (r=0.928-0.986) with the IRM was better than that of PLT-I (r=0.916-0.979). CONCLUSIONS: The performance of PLT-H in the BC-780 met the manufacturer's specifications. PLT-H exhibits better reproducibility than did PLT-I, correlates well with the PLT-O for thrombocytopenic samples and demonstrates good anti-interference ability. PLT-H counting is therefore recommended as a zero-cost alternative platelet counting method for platelet interference samples in clinical settings.

Enhancing anti-tumor therapy with agmatine-cholesterol conjugate liposomes: in vitro and in vivo evidence.

In this study, we synthesized a novel compound, agmatine-cholesterol conjugate (AG-Chol), to enhance the anti-tumor activity of drug-loaded liposomes. We replaced cholesterol with AG-Chol in preparing doxorubicin hydrochloride (DOX) liposomes by using an active loading method for DOX. We assessed the physical and chemical properties of the resulting AG-Liposomes and evaluated their efficacy in vitro and in vivo. The results showed that AG-Liposomes were stable with high encapsulation efficiency. Compared with the control liposomes, AG-Liposomes exhibited a slower drug release rate in the release medium at pH 6.8. The in vitro cell experiments demonstrated that AG-Liposomes had higher tumor cell uptake rate, stronger migration inhibition rate, higher apoptosis rate, better anti-clonogenic ability, and higher lysosome escape ability than the control liposomes. In vivo distribution results demonstrate that liposomes prepared with AG-Chol instead of cholesterol can significantly enhance their tumor targeting abilities and reduce their distribution to non-targeted sites. In vivo tumor suppression experiments showed that AG-Liposomes had a higher tumor suppression rate than the control liposomes without causing apparent toxicity to normal tissues, as evidenced by histological staining. Therefore, substituting cholesterol with AG-Chol in the preparation of liposomes can result in enhanced lysosome escape, improved tumor targeting, and increased efficacy of anti-tumor drugs.

Neuroprotection by agmatine: Possible involvement of the gut microbiome?

Agmatine, an endogenous polyamine derived from L-arginine, elicits tremendous multimodal neuromodulant properties. Alterations in agmatinergic signalling are closely linked to the pathogeneses of several brain disorders. Importantly, exogenous agmatine has been shown to act as a potent neuroprotectant in varied pathologies, including brain ageing and associated comorbidities. The antioxidant, anxiolytic, analgesic, antidepressant and memory-enhancing activities of agmatine may derive from its ability to regulate several cellular pathways; including cell metabolism, survival and differentiation, nitric oxide signalling, protein translation, oxidative homeostasis and neurotransmitter signalling. This review briefly discusses mammalian metabolism of agmatine and then proceeds to summarize our current understanding of neuromodulation and neuroprotection mediated by agmatine. Further, the emerging exciting bidirectional links between agmatine and the resident gut microbiome and their implications for brain pathophysiology and ageing are also discussed.

Biodistribution of Agmatine to Brain and Spinal Cord after Systemic Delivery.

Agmatine, an endogenous polyamine, has been shown to reduce chronic pain behaviors in animal models and in patients. This reduction is due to inhibition of the GluN2B subunit of the N-methyl-D-aspartate receptor (NMDAR) in the central nervous system (CNS). The mechanism of action requires central activity, but the extent to which agmatine crosses biologic barriers such as the blood-brain barrier (BBB) and intestinal epithelium is incompletely understood. Determination of agmatine distribution is limited by analytical protocols with low sensitivity and/or inefficient preparation. This study validated a novel bioanalytical protocol using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) for quantification of agmatine in rat biologic matrices. These protocols were then used to determine the plasma pharmacokinetics of agmatine and the extent of distribution to the CNS. Precision and accuracy of the protocol met US Food and Drug Administration (FDA) standards in surrogate matrix as well as in corrected concentrations in appropriate matrices. The protocol also adequately withstood stability and dilution conditions. Upon application of this protocol to pharmacokinetic study, intravenous agmatine showed a half-life in plasma ranging between 18.9 and 14.9 minutes. Oral administration led to a prolonged plasma half-life (74.4-117 minutes), suggesting flip-flop kinetics, with bioavailability determined to be 29%-35%. Intravenous administration led to a rapid increase in agmatine concentration in brain but a delayed distribution and lower concentrations in spinal cord. However, half-life of agmatine in both tissues is substantially longer than in plasma. These data suggest that agmatine adequately crosses biologic barriers in rat and that brain and spinal cord pharmacokinetics can be functionally distinct. SIGNIFICANCE STATEMENT: Agmatine has been shown to be an effective nonopioid therapy for chronic pain, a significantly unmet medical necessity. Here, using a novel bioanalytical protocol for quantification of agmatine, we present the plasma pharmacokinetics and the first report of agmatine oral bioavailability as well as variable pharmacokinetics across different central nervous system tissues. These data provide a distributional rationale for the pharmacological effects of agmatine as well as new evidence for kinetic differences between brain and spinal cord.

Hyperpolarized [1-13C]pyruvate Magnetic Resonance Spectroscopy Shows That Agmatine Increased Lactate Production in the Brain of Type 2 Diabetic Mice.

PURPOSE: Type 2 diabetes mellitus (T2DM) is associated with a 2-fold increased risk of developing Alzheimer's disease. In earlier research, agmatine has been demonstrated to alleviate diabetes symptoms and increase cognitive performance. However, it is unclear whether the improvement of cognitive function is attributable to the reduction of diabetic symptoms or its direct influence on brain metabolism. Using hyperpolarized (HP) [1-13C]pyruvate magnetic resonance spectroscopy (MRS), this study intends to evaluate the influence of agmatine on brain metabolism. MATERIALS AND METHODS: ICR mice were fed a high-fat diet and injected with streptozotocin to develop a T2DM animal model. During a 2-week period, T2DM mice were treated with normal saline or 100 mg/kg of agmatine, and brain HP [1-13C]pyruvate MRS was performed. The effect of agmatine on lactate generation and NADH/NAD+ redox state was investigated using C6 and neuro-2a (N2a) cells. RESULTS: As a perfusion marker, the total 13C signals in the brain of T2DM mice (p=0.07) and agmatine-treated mice (p<0.05) were reduced. The conversion constant (Kpl) from [1-13C]pyruvate to [1-13C]lactate was not distinguishable in the brains of T2DM mice but was significantly increased in the brains of agmatine-treated T2DM mice. Treating C6 and N2a cells with agmatine increased NADH/NAD+ratio and lactate generation. CONCLUSION: Agmatine influences the NADH/NAD+ redox state in the brains of T2DM mice, which may be connected with enhanced cognitive performance and increased conversion of HP [1-13C]pyruvate to HP [1-13C]lactate.

Cholinergic deficit induced memory retrieval impairment and hippocampal CaMKII-alpha deregulation is counteracted by sub-chronic agmatine treatment in mice.

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disease characterized by brain cholinergic dysfunction. Evidence suggests the impairment of memory retrieval phase in AD. It has been shown that CaMKII-α expressing neurons are selectively reduced in the hippocampus in AD brains. The present study aimed to investigate the effect of scopolamine on the memory retrieval phase and the hippocampal CaMKII-α signaling. In addition, the effect of sub-chronic administration of agmatine against scopolamine induced memory and possible hippocampal CaMKII-α deregulation was investigated in mice. Adult male NMRI mice were administered with agmatine at the doses of 5, 10, 20, 30 and 40 mg/kg/i.p. or saline for 11 days. Acquisition and retrieval tests of passive avoidance task were performed on days 10 and 11, respectively (30 Min following agmatine treatment). Scopolamine (1 mg/kg/i.p.) was administered once, 30 Min before retrieval test. Upon completion of the behavioral tasks, the hippocampi were isolated for western blot analysis to detect the phosphorylated and total levels of CaMKII-α and beta actin proteins. The results showed that scopolamine induced memory retrieval deficit and decreased the phosphorylated level of hippocampal CaMKII-α. Sub-chronic agmatine treatment at the dose of 40 mg/kg prevented scopolamine induced memory retrieval deficit and restored the level of hippocampal phosphorylated CaMKII-α. This study suggests that hippocampal CaMKII-α might play a role in scopolamine induced amnesia and sub-chronic agmatine prevents the impairing effect of scopolamine on the retrieval phase of memory and the phosphorylation of hippocampal CaMKII-α protein.

Arginine Is a Novel Drug Target for Arginine Decarboxylase in Human Colorectal Cancer Cells.

Colorectal cancer (CRC) has been proven to be highly reliant on arginine availability. Limiting arginine-rich foods or treating patients with arginine-depleting enzymes arginine deiminase (ADI) or arginase can suppress colon cancer. However, arginase and ADI are not the best drug candidates for CRC. Ornithine, the product of arginase, can enhance the supply of polyamine, which favors CRC cell growth, while citrulline, the product of ADI, faces the problem of arginine recycling due to the overexpression of argininosuccinate synthetase (ASS). Biosynthetic arginine decarboxylase (ADC), an enzyme that catalyzes the conversion of arginine to agmatine and carbon dioxide, may be a better choice as it combines both arginine depletion and suppression of intracellular polyamine synthesis via its product agmatine. ADC has anti-tumor potential yet has received much less attention than the other two arginine-depleting enzymes. In order to gain a better understanding of ADC, the preparation and the anti-cancer properties of this enzyme were explored in this study. When tested in vitro, ADC inhibited the proliferation of three colorectal cancer cell lines regardless of their ASS cellular expression. In contrast, ADC had a lesser cytotoxic effect on the human foreskin fibroblasts and rat primary hepatocytes. Further in vitro studies revealed that ADC induced S and G2/M phase cell-cycle arrest and apoptosis in HCT116 and LoVo cells. ADC-induced apoptosis in HCT116 cells followed the mitochondrial apoptotic pathway and was caspase-3-dependent. With all results obtained, we suggest that arginine is a potential target for treating colorectal cancer with ADC, and the anti-cancer properties of ADC should be more deeply investigated in the future.

Preventive putative effect of agmatine on cognitive and molecular outcomes in ventral tegmental area of male offspring following physical and psychological prenatal stress.

Prenatal stress (PS) results from a maternal experience of stressful events during pregnancy, which has been associated with an increased risk of behavioral disorders including substance abuse and anxiety in the offspring. PS is known to result in heightened dopamine release in the ventral tegmental area (VTA), in part through the effects of corticotropin-releasing hormone, which directly excites dopaminergic cells. It has recently been suggested that agmatine plays a role in modulating anxiety-like behaviors. In this study, we investigated whether agmatine could reduce negative cognitive outcomes in male mice prenatally exposed to psychological/physical stress, and whether this could be associated with molecular changes in VTA. Agmatine (37.5 mg/kg) was administrated 30 min prior to PS induction in pregnant Swiss mice. Male offspring were evaluated in a series of behavioral and molecular assays. Findings demonstrated that agmatine reduced the impairment in locomotor activity induced by both psychological and physical PS. Agmatine also decreased heightened conditioned place preference to morphine seen in PS offspring. Moreover, agmatine ameliorated the anxiety-like behavior and drug-seeking behavior induced by PS in the male offspring. Molecular effects were seen in VTA as the enhanced brain-derived neurotrophic factor (BDNF) induced by PS in the VTA was reduced by agmatine. Behavioral tests indicate that agmatine exerts a protective effect on PS-induced impairments in male offspring, which could be due in part to agmatine-associated molecular alterations in the VTA. Taken together, our data suggest that prenatal treatment with agmatine exerts protective effect against negative consequences of PS on the development of affective circuits in the offspring.

Agmatine prevents the memory impairment and the dysfunction of hippocampal GSK-3ß and ERK signaling induced by aluminum nanoparticle in mice.

The growing usage of aluminum nanoparticles (Al-NP) and their exposure may influence body function. Considering the proposed relationship between Al and the pathogenesis of Alzheimer's disease and the concern about the effect of this nanoparticle on brain health and cognitive function, the use of neuroprotective agents might be helpful. According to the reported neuroprotective effects of agmatine, in the present study, the possible protective effect of agmatine was assessed in mice model of Al-NP-induced memory impairment. In addition, due to the roles of hippocampal Glycogen synthase kinase-3 beta (GSK-3ß) and ERK signaling in memory and its disorders, these pathways were also investigated. Al-NP (10 mg/kg/p.o.) with/without agmatine (5 or 10 mg/kg/i.p.) was administered to adult male NMRI mice for 5 days. Novel object recognition (NOR) test session was used to assess cognitive function. Following the behavioral assessments, the hippocampi were used to determine the phosphorylated and total levels of GSK-3ß and ERK as well as GAPDH using western blot analysis. The results showed that Al-NP impaired NOR memory in mice while agmatine 10 mg/kg prevented the memory deficit induced by Al-NP. Furthermore, Al-NP activated GSK-3ß as well as ERK signals within the hippocampus while agmatine prevented the effects of Al-NP on GSK-3ß and ERK signals within the hippocampus. Besides supporting the neuroprotective effects of agmatine, these findings suggest the possibility of the connection of hippocampal GSK-3ß and ERK signaling in the neuroprotective effect of this polyamine against Al-NP.

Administration of agmatine prior to physical or psychological stress in pregnant mice ameliorates behavioural and cognitive deficits in female offspring.

Physical or psychological stress experienced by a mother during gestation is often associated with serious behavioural and cognitive deficits in newborns. Investigations of protective agents, which could prevent the adverse outcomes of prenatal stress (PS), are warranted. Agmatine is a neurotransmitter putatively involved in the physiological response to stress, and exogenous administration of agmatine has been shown to produce a variety of neuroprotective effects. In this study, we aimed to assess whether prenatal agmatine exposure could ameliorate behavioural and cognitive deficits in female offspring born to prenatally stressed mice. Pregnant Swiss Webster (SW) mice were exposed to physical or psychological stress from the 11th to 17th days of gestation. Agmatine (37.5 mg/kg, i.p.) was administrated 30 min before the induction of stress for seven consecutive days. The pups were assessed using a variety of behavioural tests and molecular assays on postnatal days 40 to 47. Agmatine attenuated impairments in locomotor activity, anxiety-like behaviour, and drug-seeking behaviour associated with both physical and psychological PS. Furthermore, agmatine reduced PS-induced impairments in passive avoidance memory and learning. Neither PS nor agmatine treatment affected the mRNA expression level of hippocampal brain-derived neurotrophic factor (BDNF) or tyrosine hydroxylase (TH) in the ventral tegmental area (VTA). Taken together, our findings highlight the protective effects of prenatally administered agmatine on PS-mediated behavioural and cognitive deficits of the offspring. Future studies are needed to elucidate the underlying mechanisms, which could allow for more targeted prenatal treatments.

Agmatine-IRF2BP2 interaction induces M2 phenotype of microglia by increasing IRF2-KLF4 signaling.

BACKGROUND: Following central nervous system (CNS) injury, the investigation for neuroinflammation is vital because of its pleiotropic role in both acute injury and long-term recovery. Agmatine (Agm) is well known for its neuroprotective effects and anti-neuroinflammatory properties. However, Agm's mechanism for neuroprotection is still unclear. We screened target proteins that bind to Agm using a protein microarray; the results showed that Agm strongly binds to interferon regulatory factor 2 binding protein (IRF2BP2), which partakes in the inflammatory response. Based on these prior data, we attempted to elucidate the mechanism by which the combination of Agm and IRF2BP2 induces a neuroprotective phenotype of microglia. METHODS: To confirm the relationship between Agm and IRF2BP2 in neuroinflammation, we used microglia cell-line (BV2) and treated with lipopolysaccharide from Escherichia coli 0111:B4 (LPS; 20 ng/mL, 24 h) and interleukin (IL)-4 (20 ng/mL, 24 h). Although Agm bound to IRF2BP2, it failed to enhance IRF2BP2 expression in BV2. Therefore, we shifted our focus onto interferon regulatory factor 2 (IRF2), which is a transcription factor and interacts with IRF2BP2. RESULTS: IRF2 was highly expressed in BV2 after LPS treatment but not after IL-4 treatment. When Agm bound to IRF2BP2 following Agm treatment, the free IRF2 translocated to the nucleus of BV2. The translocated IRF2 activated the transcription of Kruppel-like factor 4 (KLF4), causing KLF4 to be induced in BV2. The expression of KLF4 increased the CD206-positive cells in BV2. CONCLUSIONS: Taken together, unbound IRF2, resulting from the competitive binding of Agm to IRF2BP2, may provide neuroprotection against neuroinflammation via an anti-inflammatory mechanism of microglia involving the expression of KLF4.

Agmatine improves liver function, balance performance, and neuronal damage in a hepatic encephalopathy induced by bile duct ligation.

INTRODUCTION: In the current study, we investigate whether oral administration of agmatine (AGM) could effectively reduce motor and cognitive deficits induced by bile duct ligation (BDL) in an animal model of hepatic encephalopathy (HE) through neuroprotective mechanisms. METHODS: The Wistar rats were divided into four groups: sham, BDL, BDL+ 40 mg/kg AGM, and BDL+ 80 mg/kg AGM. The BDL rats were treated with AGM from 2 weeks after the surgery for 4 consecutive weeks. The open field, rotarod, and wire grip tests were used to assess motor function and muscle strength. The novel object recognition test (NOR) was performed to evaluate learning and memory. Finally, blood samples were collected for the analysis of the liver markers, the animals were sacrificed, and brain tissues were removed; the CA1 regions of the hippocampus and cerebellum were processed to identify apoptosis and neuronal damage rate using caspase-3 immunocytochemistry and Nissl staining. RESULTS: The serological assay results showed that BDL severely impaired the function of the liver. Based on histochemical findings, BDL increased the neuronal damage in CA1 and Purkinje cells, whereas apoptosis was significantly observed only in the cerebellum. AGM treatment prevented the increase of serum liver enzymes, balance deficits, and neuronal damage in the brain areas. Apoptosis partially decreased by AGM, and there were no differences in the performance of animals in different groups in the NOR. CONCLUSIONS: The study suggests AGM as a potential treatment candidate for HE because of its neuroprotective properties and/or its direct effects on liver function.

Analysis of Regulatory Mechanism of AcrB and CpxR on Colistin Susceptibility Based on Transcriptome and Metabolome of Salmonella Typhimurium.

With the increasing and inappropriate use of colistin, the emerging colistin-resistant isolates have been frequently reported during the last few decades. Therefore, new potential targets and adjuvants to reverse colistin resistance are urgently needed. Our previous study has confirmed a marked increase of colistin susceptibility (16-fold compared to the wild-type Salmonella strain) of cpxR overexpression strain JSΔacrBΔcpxR::kan/pcpxR (simplified as JSΔΔ/pR). To searching for potential new drug targets, the transcriptome and metabolome analysis were carried out in this study. We found that the more susceptible strain JSΔΔ/pR displayed striking perturbations at both the transcriptomics and metabolomics levels. The virulence-related genes and colistin resistance-related genes (CRRGs) were significantly downregulated in JSΔΔ/pR. There were significant accumulation of citrate, α-ketoglutaric acid, and agmatine sulfate in JSΔΔ/pR, and exogenous supplement of them could synergistically enhance the bactericidal effect of colistin, indicating that these metabolites may serve as potential adjuvants for colistin therapy. Additionally, we also demonstrated that AcrB and CpxR could target the ATP and reactive oxygen species (ROS) generation, but not proton motive force (PMF) production pathway to potentiate antibacterial activity of colistin. Collectively, these findings have revealed several previously unknown mechanisms contributing to increased colistin susceptibility and identified potential targets and adjuvants for potentiating colistin treatment of Salmonella infections. IMPORTANCE Emergence of multidrug-resistant (MDR) Gram-negative (G-) bacteria have led to the reconsideration of colistin as the last-resort therapeutic option for health care-associated infections. Finding new drug targets and strategies against the spread of MDR G- bacteria are global challenges for the life sciences community and public health. In this paper, we demonstrated the more susceptibility strain JSΔΔ/pR displayed striking perturbations at both the transcriptomics and metabolomics levels and revealed several previously unknown regulatory mechanisms of AcrB and CpxR on the colistin susceptibility. Importantly, we found that exogenous supplement of citrate, α-ketoglutaric acid, and agmatine sulfate could synergistically enhance the bactericidal effect of colistin, indicating that these metabolites may serve as potential adjuvants for colistin therapy. These results provide a theoretical basis for finding potential new drug targets and adjuvants.