Amino Acids In Brain Research Articles

Energetics of Excitatory and Inhibitory Neurotransmission in Aluminum Chloride Model of Alzheimer's Disease: Reversal of Behavioral and Metabolic Deficits by Rasa Sindoor.

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder, characterized by progressive loss of cognitive functions and memory. Excessive intake of aluminum chloride in drinking water is associated with amyloid plaques and neurofibrillary tangles in the brain, which are the hallmark of AD. We have evaluated brain energy metabolism in aluminum chloride (AlCl3) mouse model of AD. In addition, effectiveness of Rasa Sindoor (RS), a formulation used in Indian Ayurvedic medicine, for alleviation of symptoms of AD was evaluated. Mice were administered AlCl3 (40 mg/kg) intraperitoneally once a day for 60 days. The memory of mice was measured using Morris Water Maze test. The 13C labeling of brain amino acids was measured ex vivo in tissue extracts using 1H-[13C]-NMR spectroscopy with timed infusion of [1,6-13C2]glucose. The 13C turnover of brain amino acids was analyzed using a three-compartment metabolic model to derive the neurotransmitter cycling and TCA cycle rates associated with glutamatergic and GABAergic pathways. Exposure of AlCl3 led to reduction in memory of mice. The glutamatergic and GABAergic neurotransmitter cycling and glucose oxidation were found to be reduced in the cerebral cortex, hippocampus, and striatum following chronic AlCl3 treatment. The perturbation in metabolic rates was highest in the cerebral cortex. However, reduction in metabolic fluxes was higher in hippocampus and striatum following one month post AlCl3 treatment. Most interestingly, oral administration of RS (2 g/kg) restored memory as well as the energetics of neurotransmission in mice exposed to AlCl3. These data suggest therapeutic potential of RS to manage cognitive functions and memory in preclinical AD.

Quantification accuracy of neuro-oncology PET data as a function of emission scan duration in PET/MR compared to PET/CT

ObjectivesTo evaluate and compare the effect of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging. MethodsTwenty min 18F-FDG phantom measurements and 10min 18F-FET brain scans were acquired in a Biograph-True-Point-True-View PET/CT (n=8) and a Biograph mMR PET/MR (n=16). Listmode data were repeatedly split into frames of 1min to 10min length and reconstructed using two different reconstruction settings of a 3D-OSEM algorithm: with post-filtering (“OSEM”), and without post-filtering but with resolution recovery (“PSF”). Recovery coefficients (RCmax, RCA50) and standard uptake values (SUVmax, SUVA50) were evaluated. ResultsRCmax (phantom) and SUVmax (patients) increased significantly when reducing the frame duration. Significantly lower deviations were observed for RCA50 and SUVA50, respectively, making them more appropriate to compare PET studies at different number of counts. No statistical significant differences were observed when using post-filtering and reducing the frame time to 4min (RCA50, reference 20min, phantom) and to 3min (SUVA50, reference 10min, patients). ConclusionsFor hybrid aminoacid brain imaging, frame duration (or injected activity) can potentially be reduced to 30% of the standard used in clinical routine without significant changes on the quantification accuracy of the PET images if adequate reconstruction settings and quantitative measures are used. Frame times below 4min in the NEMA phantom are not advisable to obtain quantitative and reproducible measures.

Amalaki Rasayana improved memory and neuronal metabolic activity in AbPP-PS1 mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by progressive loss of memory and cognitive function. The cerebral metabolic rate of glucose oxidation has been shown to be reduced in AD. The present study evaluated efficacy of dietary Amalaki Rasayana (AR), an Ayurvedic formulation used in Indian traditional system, in AbPP-PS1 mouse model of AD in ameliorating memory and neurometabolism, and compared with donepezil, a standard FDA approved drug for AD. The memory of mice was measured using Morris Water Maze analysis. The cerebral metabolism was followed by 13C labelling of brain amino acids in tissue extracts ex vivo using 1H-[13C]-NMR spectroscopy together with a short time infusion of [1,6-13C2]glucose to mice. The intervention with Amalaki Rasayana showed improved learning and memory in AbPP-PS1 mice. The 13C labelings of GluC4, GABAC2 and GlnC4 were reduced in AbPP-PS1 mice when compared with wild-type controls. Intervention of AR increased the 13C labelling of amino acids suggesting a significant enhancement in glutamatergic and GABAergic metabolic activity in AbPP-PS1 mice similar to that observed with donepezil treatment. These data suggest that AR has potential to improve memory and cognitive function in AD.

Differences in activity levels as well as in brain amino acid levels and monoamine metabolisms, that exist between the Djungarian hamster（P. sungorus）and the Roborovskii hamster（P. roborovskii）are scarcely influenced by social isolation

Differences in activity levels as well as in brain amino acid levels and monoamine metabolisms, that exist between the Djungarian hamster（P. sungorus）and the Roborovskii hamster（P. roborovskii）are scarcely influenced by social isolation

An amino acid mystery

Right-handed amino acids—found in small doses in nature—are largely a mystery. In humans, most linger at low concentrations yet play unknown roles in the body. A new survey of right- and left-handed amino acids in mouse brains thickens the plot. The study’s findings imply that the brain tightly regulates the levels of right-handed amino acids and that undiscovered enzymes might flip lefties to righties (ACS Chem. Neurosci. 2017, DOI: 10.1021/acschemneuro.6b00398). Ubiquitous left-handed l-amino acids serve as the building blocks of all proteins. The roles of their right-handed counterparts, d-amino acids, are still not fully understood. In 2000, scientists figured out that one of them, d-serine, is a neurotransmitter. But, to find the functions of others, scientists must conduct baseline surveys that determine normal levels of d- and l-amino acids in various parts of the body, says Daniel W. Armstrong of the University of Texas, Arlington. Armstrong’s group collaborated with Adam

Gut microbiota of mice putatively modifies amino acid metabolism in the host brain.

Recently, it has been found that the gut microbiota influences functions of the host brain by affecting monoamine metabolism. The present study focused on the relationship between the gut microbiota and the brain amino acids. Specific pathogen-free (SPF) and germ-free (GF) mice were used as experimental models. Plasma and brain regions were sampled from mice at 7 and 16 weeks of age, and analysed for free d- and l-amino acids, which are believed to affect many physiological functions. At 7 weeks of age, plasma concentrations of d-aspartic acid (d-Asp), l-alanine (l-Ala), l-glutamine (l-Gln) and taurine were higher in SPF mice than in GF mice, but no differences were found at 16 weeks of age. Similar patterns were observed for the concentrations of l-Asp in striatum, cerebral cortex and hippocampus, and l-arginine (l-Arg), l-Ala and l-valine (l-Val) in striatum. In addition, the concentrations of l-Asp, d-Ala, l-histidine, l-isoleucine (l-Ile), l-leucine (l-Leu), l-phenylalanine and l-Val were significantly higher in plasma of SPF mice when compared with those of GF mice. The concentrations of l-Arg, l-Gln, l-Ile and l-Leu were significantly higher in SPF than in GF mice, but those of d-Asp, d-serine and l-serine were higher in some brain regions of GF mice than in those of SPF mice. In conclusion, the concentration of amino acids in the host brain seems to be dependent on presence of the gut microbiota. Amino acid metabolism in the host brain may be modified by manipulating microbiota communities.

Impaired Amino Acid Transport at the Blood Brain Barrier Is a Cause of Autism Spectrum Disorder

Autism spectrum disorders (ASD) are a group of genetic disorders often overlapping with other neurological conditions. We previously described abnormalities in the branched-chain amino acid (BCAA) catabolic pathway as a cause of ASD. Here, we show that the solute carrier transporter 7a5 (SLC7A5), a large neutral amino acid transporter localized at the blood brain barrier (BBB), has an essential role in maintaining normal levels of brain BCAAs. In mice, deletion of Slc7a5 from the endothelial cells of the BBB leads to atypical brain amino acid profile, abnormal mRNA translation, and severe neurological abnormalities. Furthermore, we identified several patients with autistic traits and motor delay carrying deleterious homozygous mutations in the SLC7A5 gene. Finally, we demonstrate that BCAA intracerebroventricular administration ameliorates abnormal behaviors in adult mutant mice. Our data elucidate a neurological syndrome defined by SLC7A5 mutations and support an essential role for the BCAA in human brain function.

Multicompartment analysis of protein-restricted phenylketonuric mice reveals amino acid imbalances in brain.

The mainstay of therapy for phenylketonuria (PKU) remains dietary protein restriction. Developmental and neurocognitive outcomes for patients, however, remain suboptimal. We tested the hypothesis that mice with PKU receiving protein-restricted diets would reveal disruptions of brain amino acids that shed light on these neurocognitive deficits. Phenylalanine hydroxylase-deficient (PKU) mice and parallel controls (both wild-type and heterozygous) were fed custom diets containing 18, 6, and 4% protein for 3weeks, after which tissues (brain, liver, sera) were collected for amino acid analysis profiling. Phenylalanine (phe) was increased in all tissues (p < 0.0001) of PKU mice and improved with protein restriction. In sera, decreased tyrosine (p < 0.01) was corrected (defined as not significantly different from the level in control mice receiving 18% chow) with protein restriction, whereas protein restriction significantly increased many other amino acids. A similar trend for increased amino acid levels with protein restriction was also observed in liver. In brain, the effects of protein restriction on large neutral amino acids (LNAAs) were variable, with some deficit correction (threonine, methionine, glutamine) and no correction of tyrosine under any dietary paradigm. Protein restriction (4% diet) in PKU mice significantly decreased lysine, arginine, taurine, glutamate, asparagine, and serine which had been comparable to control mice under 18% protein intake. Depletion of taurine, glutamate, and serine in the brain of PKU mice with dietary protein restriction may provide new insight into neurocognitive deficits of PKU.

Ketone ester supplementation attenuates seizure activity, and improves behavior and hippocampal synaptic plasticity in an Angelman syndrome mouse model

Angelman syndrome (AS) is a rare genetic and neurological disorder presenting with seizures, developmental delay, ataxia, and lack of speech. Previous studies have indicated that oxidative stress-dependent metabolic dysfunction may underlie the phenotypic deficits reported in the AS mouse model. While the ketogenic diet (KD) has been used to protect against oxidative stress and has successfully treated refractory epilepsy in AS case studies, issues arise due to its strict adherence requirements, in addition to selective eating habits and weight issues reported in patients with AS. We hypothesized that ketone ester supplementation would mimic the KD as an anticonvulsant and improve the behavioral and synaptic plasticity deficits in vivo. AS mice were supplemented R,S-1,3-butanediol acetoacetate diester (KE) ad libitum for eight weeks. KE administration improved motor coordination, learning and memory, and synaptic plasticity in AS mice. The KE was also anticonvulsant and altered brain amino acid metabolism in AS treated animals. Our findings suggest that KE supplementation produces sustained ketosis and ameliorates many phenotypes in the AS mouse model, and should be investigated further for future clinical use.

Epileptic Activity Increases Cerebral Amino Acid Transport Assessed by 18F-Fluoroethyl-l-Tyrosine Amino Acid PET: A Potential Brain Tumor Mimic.

Ten patients with 11 episodes of serial seizures or status epilepticus, who underwent MRI and 18F-FET PET, were studied. The main diagnosis was glioma World Health Organization grade II-IV (n = 8); 2 patients suffered from nonneoplastic diseases. Immunohistochemical assessment of LAT1/LAT2/CD98 amino acid transporters was performed in seizure-affected cortex (n = 2) and compared with glioma tissues (n = 3). All patients exhibited increased seizure-associated strict gyral 18F-FET uptake, which was reversible in follow-up studies or negative shortly before and without any histologic or clinical signs of tumor recurrence. 18F-FET uptake corresponded to structural MRI changes, compatible with cortical vasogenic and cytotoxic edema, partial contrast enhancement, and hyperperfusion. Patients with prolonged postictal symptoms lasting up to 8 wk displayed intensive and widespread (≥ 1 lobe) cortical 18F-FET uptake. LAT1/LAT2/CD98 was strongly expressed in neurons and endothelium of seizure-affected brains and less in reactive astrocytosis. Seizure activity, in particular status epilepticus, increases cerebral amino acid transport with a strict gyral 18F-FET uptake pattern. Such periictal pseudoprogression represents a potential pitfall of 18F-FET PET and may mimic brain tumor. Our data also indicate a seizure-induced upregulation of neuronal, endothelial, and less astroglial LAT1/LAT2/CD98 amino acid transporter expression.

Perinatal sulfamonomethoxine exposure influences physiological and behavioral responses and the brain mTOR pathway in mouse offspring

Sulfamonomethoxine (SMM) is widely used in the veterinary field in China. Although some clinical surveys have revealed that sulfonamide antibiotics cause adverse nervous system symptoms, the related mechanisms of maternal SMM exposure on the neurobehavioral development of offspring remain unclear. Here, we investigated the effects of perinatal SMM exposure on the physiological and behavioral responses of pubertal offspring mice and the underlying mechanisms. We randomly allocated pregnant mice into the groups treated with SMM at different doses and the saline-treated groups. Maternal mice were orally administered SMM daily from gestational day 1 to postpartum day 21. On postnatal day (PND) 22, the parameters of growth, endocrine hormones, and brain amino acid composition were assessed, as well as the brain transcript levels of key genes involved in the mammalian target of rapamycin (mTOR) signaling pathway. From PND 50 to 55, a battery of behavioral tests relevant to anxiety and memory were then administered. Analysis of the results indicated that the pups, particularly the pubertal female offspring, showed anxiety-like behavior. Moreover, the pubertal offspring showed cognitive impairments and fat accumulation. Furthermore, the relative mRNA expression of genes involved in the mTOR signaling pathway in females on PND 22 was elevated, whereas the expression of N-methyl-d-aspartate receptor 2B (NR2B) was reduced. Together, the results showed that perinatal SMM exposure perturbs neuroendocrine functions, and further alters gene expression in the mTOR pathway and NR2B gene expression early in life, which may contribute to brain dysfunction in pubertal life.

Quantification of Rat Brain Amino Acids: Analysis of the Data Consistency

Background: Tissue amino acids are important markers to characterize (patho)physiology. As neurotransmitters or their precursors, they have special significance in brain. However, mass spectrometry (MS)-based quantifications of brain amino acids are rare and inconsistent. Methods: To reveal efficient procedures optimal for brain research purposes, free amino acids in the same extracts of rat cerebellum were quantified by published assays employing hybrid triple quadrupole-linear ion trap (QTRAP) MS or amino acid analyzer with ninhydrin derivatization. Results: Levels of four amino acids out of 14 quantified by the two methods were established to be perturbed in the QTRAP MS assay, with the ninhydrin-based quantification agreeing well with the published values obtained by non-MS approaches. The overestimation of Glu and Lys and underestimation of Gly and Tyr in brain extracts by QTRAP MS suggest interference of the co-eluting compounds and ion suppression effects, correspondingly. The MS-inherent artifacts presumably contribute to inconsistency of published MS data on the brain amino acid content, as our analysis of different studies indicated that the variability of the MS data greatly exceeds the biological variability. Conclusion: Evaluation of potential artifacts of the MS-based quantification of brain amino acids using the ninhydrin detection as a reference method, provides a solution for reliable quantification of the artifact-resistant amino acids, pointing to relatively good performance of the time- and cost-efficient QTRAP MS procedure employed. Keywords: Amino acid quantification, brain metabolism, hybrid triple quadrupole mass spectrometry, ninhydrin.

Metabolomics of biomarker discovery in ovarian cancer: a systematic review of the current literature.

Metabolomics is the emerging member of "omics" sciences advancing the understanding, diagnosis and treatment of many cancers, including ovarian cancer (OC). To systematically identify the metabolomic abnormalities in OC detection, and the dominant metabolic pathways associated with the observed alterations. An electronic literature search was performed, up to and including January 15th 2016, for studies evaluating the metabolomic profile of patients with OC compared to controls. QUADOMICS tool was used to assess the quality of the twenty-three studies included in this systematic review. Biological samples utilized for metabolomic analysis include: serum/plasma (n = 13), urine (n = 4), cyst fluid (n = 3), tissue (n = 2) and ascitic fluid (n = 1). Metabolites related to cellular respiration, carbohydrate, lipid, protein and nucleotide metabolism were significantly altered in OC. Increased levels of tricarboxylic acid cycle intermediates and altered metabolites of the glycolytic pathway pointed to perturbations in cellular respiration. Alterations in lipid metabolism included enhanced fatty acid oxidation, abnormal levels of glycerolipids, sphingolipids and free fatty acids with common elevations of palmitate, oleate, and myristate. Increased levels of glutamine, glycine, cysteine and threonine were commonly reported while enhanced degradations of tryptophan, histidine and phenylalanine were found. N-acetylaspartate, a brain amino acid, was found elevated in primary and metastatic OC tissue and ovarian cyst fluid. Further, elevated levels of ketone bodies including 3-hydroxybutyrate were commonly reported. Increased levels of nucleotide metabolites and tocopherols were consistent through out the studies. Metabolomics presents significant new opportunities for diagnostic biomarker development, elucidating previously unknown mechanisms of OC pathogenesis.

Differential modulation of GABAA and NMDA receptors by α7-nicotinic receptor desensitization in cultured rat hippocampal neurons.

To explore the modulatory effect of desensitized α7-containing nicotinic receptors (α7-nAChRs) on excitatory and inhibitory amino acid receptors in cultured hippocampal neurons and to identify the mechanism underlying this effect. Whole-cell patch-clamp recordings were performed on cultured rat hippocampal neurons to measure α7-nAChR currents and to determine the role of desensitized α7-nAChRs on brain amino acid receptor activity. Pulse and perfusion applications of the α7-nAChR agonist choline were applied to induce different types of α7-nAChR desensitization in cultured hippocampal neurons. After a brief choline pulse, α7-nAChR was desensitized as a result of receptor activation, which reduced the response of the A type γ-aminobutyric acid (GABAA) receptor to its agonist, muscimol, and enhanced the response of the NMDA receptor to its agonist NMDA. By contrast, the responses of glycine or AMPA receptors to their agonists, glycine or AMPA, respectively, were not affected. Pretreatment with the α7-nAChR antagonist methyllycaconitine (MLA, 10 nmol/L) blocked the choline-induced negative modulation of the GABAA receptor and the positive modulation of the NMDA receptor. The regulation of the GABAA and NMDA receptors was confirmed using another type of α7-nAChR desensitization, which was produced by a low concentration of choline perfusion. The negative modulation of the GABAA receptor was characterized by choline-duration dependency and intracellular calcium dependency, but the positive modulation of the NMDA receptor was not associated with cytoplasmic calcium. Brain GABAA and NMDA receptors are modulated negatively and positively, respectively, by desensitized α7-nAChR as a result of choline pretreatment in cultured hippocampal neurons.

Oral Administration of L-serine Modifies Amino Acid Metabolism in the Brain of Rats

Objective: Whether orally administered L-serine influences amino acid metabolism in the brain was investigated. Methods: L-Serine (6 mmol/10 ml/kg) was orally administered to rats after a 9 hr fast and plasma and brain samples were obtained at 30, 60 and 120 min in Experiment 1. In Experiment 2, the effect of L-serine and glycine on brain amino acid metabolism was compared. Results: In Experiment 1, plasma serine rapidly increased 30 min after administration and then decreased, but serine in both the cerebral cortex and hippocampus gradually increased with time. Plasma taurine and glutamine were positively and leucine, phenylalanine and lysine were negatively correlated with plasma serine concentration. Cerebral cortex glutamine, citrulline, tyrosine, β-alanine, and tryptophan were negatively and α-amino adipic acid and glycine were positively correlated with serine concentration. In the hippocampus, glutamine and tyrosine were negatively correlated with L-serine. In Experiment 2, threonine concentrations were significantly decreased by L-serine treatment compared with the control (distilled water) and glycine in both brain regions. Serine concentrations in both brain regions were greatly increased by L-serine treatment, but were also moderately increased by glycine. Similarly, glycine in both regions was increased by glycine treatment and by L-serine treatment. Cysteine in both regions was increased by glycine treatment. Tyrosine in both regions was decreased by both L-serine and glycine treatments. Conclusion: Orally administered L-serine greatly influenced brain amino acid metabolism. L-Serine and glycine influenced each other, but the effect on brain amino acid metabolism was somewhat different between the two amino acids.

L-Ornithine is a potential acute satiety signal in the brain of neonatal chicks

Recently, we observed that neonatal chicks exhibit feeding behavior characterized by frequent food intake and short resting intervals, with changes detected in the brain amino acid and monoamine concentrations. In this study, we aimed to clarify further the relationship between the appetite of neonatal chicks and brain amino acid metabolism. In Experiment 1, changes were investigated in free amino acids in the brain under conditions of regulated appetite induced by fasting and subsequent short-term re-feeding. Chicks (5days old) were distributed into four treatment groups — namely, fasting for 3h, and fasting for 3h followed by re-feeding for 10, 20 or 30min. Brain samples were collected after treatment to analyze free amino acid concentrations. Amino adipic acid and proline in all brain parts as well as arginine and ornithine in all brain parts – except mesencephalic arginine and cerebellar ornithine – were increased in a time-dependent manner following re-feeding. In Experiment 2, we further examined the effect of exogenous administration of some amino acids altered in association with feeding behavior in Experiment 1. We chose l-arginine and its functional metabolite, l-ornithine, to analyze their effects on food intake in chicks. Intracerebroventricular injection (2μmol) of l-ornithine, but not l-arginine, significantly inhibited food intake in neonatal chicks. In Experiment 3, we found that central injection of l-ornithine (2, 4, and 6μmol) dose-dependently suppressed food intake in chicks. These results suggested that l-ornithine may have an important role in the control of food intake as an acute satiety signal in the neonatal chick brain.

Large Neutral Amino Acid Supplementation Exerts Its Effect through Three Synergistic Mechanisms: Proof of Principle in Phenylketonuria Mice.

BackgroundPhenylketonuria (PKU) was the first disorder in which severe neurocognitive dysfunction could be prevented by dietary treatment. However, despite this effect, neuropsychological outcome in PKU still remains suboptimal and the phenylalanine-restricted diet is very demanding. To improve neuropsychological outcome and relieve the dietary restrictions for PKU patients, supplementation of large neutral amino acids (LNAA) is suggested as alternative treatment strategy that might correct all brain biochemical disturbances caused by high blood phenylalanine, and thereby improve neurocognitive functioning.ObjectiveAs a proof-of-principle, this study aimed to investigate all hypothesized biochemical treatment objectives of LNAA supplementation (normalizing brain phenylalanine, non-phenylalanine LNAA, and monoaminergic neurotransmitter concentrations) in PKU mice.MethodsC57Bl/6 Pah-enu2 (PKU) mice and wild-type mice received a LNAA supplemented diet, an isonitrogenic/isocaloric high-protein control diet, or normal chow. After six weeks of dietary treatment, blood and brain amino acid and monoaminergic neurotransmitter concentrations were assessed.ResultsIn PKU mice, the investigated LNAA supplementation regimen significantly reduced blood and brain phenylalanine concentrations by 33% and 26%, respectively, compared to normal chow (p<0.01), while alleviating brain deficiencies of some but not all supplemented LNAA. Moreover, LNAA supplementation in PKU mice significantly increased brain serotonin and norepinephrine concentrations from 35% to 71% and from 57% to 86% of wild-type concentrations (p<0.01), respectively, but not brain dopamine concentrations (p = 0.307).ConclusionsThis study shows that LNAA supplementation without dietary phenylalanine restriction in PKU mice improves brain biochemistry through all three hypothesized biochemical mechanisms. Thereby, these data provide proof-of-concept for LNAA supplementation as a valuable alternative dietary treatment strategy in PKU. Based on these results, LNAA treatment should be further optimized for clinical application with regard to the composition and dose of the LNAA supplement, taking into account all three working mechanisms of LNAA treatment.

Attentional performance, impulsivity, and related neurotransmitter systems in apoE2, apoE3, and apoE4 female transgenic mice.

The apolipoprotein E (apoE) genotype influences cognitive performance in humans depending on age and sex. While the detrimental role of the apoE4 isoform on spatial learning and memory has been well-established in humans and rodents, less is known on its impact on the executive functions. We aimed to evaluate the effect of apoE isoforms (apoE2, apoE3, apoE4) on visuospatial attention and inhibitory control performance in female transgenic mice, and to determine the neurochemical and neuropharmacological basis of this potential relationship. Female mice carrying apoE2, apoE3, and apoE4 were trained in the five-choice serial reaction time task (5-CSRTT). Upon a stable performance, we manipulated the inter-trial interval and the stimulus duration to elicit impulsive responding and engage attention respectively. We further performed a pharmacological challenge by administering cholinergic and GABAergic agents. Finally, we analyzed the levels of brain amino acids and monoamines by using reversed phase high-performance liquid chromatography (HPLC). ApoE4 mice showed a deficient inhibitory control as revealed by increased perseveration and premature responding. When attention was challenged, apoE4 mice also showed a higher drop in accuracy. The adverse effect of scopolamine on the task was attenuated in apoE4 mice compared to apoE2 and apoE3. Furthermore, apoE4 mice showed less dopamine in the frontal cortex than apoE2 mice. We confirmed that the apoE genotype influences attention and inhibitory control in female transgenic mice. The influence of apoE isoforms in the brain neuromodulatory system may explain the cognitive and behavioral differences attributable to the genotype.

Determination of the levels of two types of neurotransmitter and the anti-migraine effects of different dose-ratios of Ligusticum chuanxiong and Gastrodia elata

Ligusticum chuanxiong (LC)–Gastrodia elata (GE) compatibility is widely used in the clinic for the treatment of migraine. It has been shown that the changes of neurotransmitters in the central nervous system are closely related to the pathogenesis of migraine; whether LC–GE compatibility might affect the neurotransmitters in migraine rats has not yet been studied. In this study, high performance liquid chromatography-fluorescence detector methods for quantification of serotonin (5-hydroxytryptamine, 5-HT) and excitatory amino acids (EAAs) in rat brain were developed. The 5-HT was measured directly, while EAAs were determined by using dansyl chloride as precolumn derivative reagent. The validation of the methods, including selectivity, linearity, sensitivity, precision, accuracy, recoveries, and stability were carried out and demonstrated to meet the requirements of quantitative analysis. Compared with the model group, the expression of 5-HT in migraine rat brain was enhanced from 30 minutes to 120 minutes and glutamate (L-Glu) was suppressed from 30 minutes to 60 minutes in an LC–GE (4:3) group compared with the model group (p < 0.05, p < 0.01, respectively). These findings showed that the analytical methods were simple, sensitive, selective, and low cost, and LC–GE 4:3 compatibility could have better efficacy for treating migraine through upregulating 5-HT levels and downregulating L-Glu levels.

Biochemical, Metabolic, and Behavioral Characteristics of Immature Chronic Hyperphenylalanemic Rats.

Phenylketonuria and hyperphenylalanemia are inborn errors in metabolism of phenylalanine arising from defects in steps to convert phenylalanine to tyrosine. Phe accumulation causes severe mental retardation that can be prevented by timely identification of affected individuals and their placement on a Phe-restricted diet. In spite of many studies in patients and animal models, the basis for acquisition of mental retardation during the critical period of brain development is not adequately understood. All animal models for human disease have advantages and limitations, and characteristics common to different models are most likely to correspond to the disorder. This study established similar levels of Phe exposure in developing rats between 3 and 16 days of age using three models to produce chronic hyperphenylalanemia, and identified changes in brain amino acid levels common to all models that persist for ~16 h of each day. In a representative model, local rates of glucose utilization (CMRglc) were determined at 25-27 days of age, and only selective changes that appeared to depend on Phe exposure were observed. CMRglc was reduced in frontal cortex and thalamus and increased in hippocampus and globus pallidus. Behavioral testing to evaluate neuromuscular competence revealed poor performance in chronically-hyperphenylalanemic rats that persisted for at least 3 weeks after cessation of Phe injections and did not occur with mild or acute hyperphenylalanemia. Thus, the abnormal amino acid environment, including hyperglycinemia, in developing rat brain is associated with selective regional changes in glucose utilization and behavioral abnormalities that are not readily reversed after they are acquired.