Rapid and reliable quantitation of amino acids and myo-inositol in mouse brain by high performance liquid chromatography and tandem mass spectrometry

The L-enantiomer is the predominant type of amino acid in all living systems. However, D-amino acids, once thought to be “unnatural”, have been found to be indigenous even in mammalian systems and increasingly appear to be functioning in essential biological and neurological roles. Both D- and L-amino acid levels in the hippocampus, cortex, and blood samples from NIH Swiss mice are reported. Perfused brain tissues were analyzed for the first time, thereby eliminating artifacts due to endogenous blood, and decreased the mouse-to-mouse variability in amino acid levels. Total amino acid levels (L-plus D-enantiomers) in brain tissue are up to 10 times higher than in blood. However, all measured D-amino acid levels in brain tissue are typically ~10 to 2000 times higher than blood levels. There was a 13% reduction in almost all measured D-amino acid levels in the cortex compared to those in the hippocampus. There is an approximate inverse relationship between the prevalence of an amino acid and the percentage of its D-enantiomeric form. Interestingly, glutamic acid, unlike all other amino acids, had no quantifiable level of its D-antipode. The bioneurological reason for the unique and conspicuous absence/removal of this D-amino acid is yet unknown. However, results suggest that D-glutamate metabolism is likely a unidirectional process and not a cycle, as per the L-glutamate/glutamine cycle. The results suggest that there might be unreported D-amino acid racemases in mammalian brains. The regulation and function of specific other D-amino acids are discussed.

show abstract

“…14,15 Since the early 2000s, there have been additional reports of free D-amino acids in various mammalian tissues. 16–18 …”

Section: Introductionmentioning

confidence: 99%

d-Amino Acid Levels in Perfused Mouse Brain Tissue and Blood: A Comparative Study

Weatherly

Parpia

et al. 2017

ACS Chem. Neurosci.

104

View full text Add to dashboard Cite

show abstract

“…A majority of brain metabolism studies employ targeted analysis of small set of known, well defined metabolites (Bathena, et al, 2012; Ivanisevic, et al, 2013; Yanes, et al, 2011). For example, 1 H-NMR has been used to uncover specific highly abundant metabolites (N-acetyl-aspartate, myo-inositol, glutamate, glutamine, creatine, choline and GABA).…”

Section: Introductionmentioning

confidence: 99%

Brain Region Mapping Using Global Metabolomics

Ivanišević¹,

Epstein²,

Kurczy³

et al. 2014

Chemistry & Biology

View full text Add to dashboard Cite

SUMMARY Historically, studies of brain metabolism have been based on targeted analyses of a limited number of metabolites. Here we present a novel untargeted mass spectrometry-based metabolomics approach that has successfully uncovered differences in broad array of metabolites across anatomical regions of the mouse brain. The NSG immunodeficient mouse model was chosen because of its ability to undergo humanization leading to numerous applications in oncology and infectious disease research. Metabolic phenotyping by hydrophilic interaction liquid chromatography and nanostructure imaging mass spectrometry revealed unique water-soluble and lipid metabolite patterns between brain regions. Neurochemical differences in metabolic phenotypes were mainly defined by various phospholipids and several intriguing metabolites including carnosine, cholesterol sulfate, lipoamino acids, uric and sialic acid whose physiological roles in brain metabolism are poorly understood. This study lays important groundwork by defining regional homeostasis for the normal mouse brain to give context to the reaction to pathological events.

show abstract

“…Although some volatile ion‐pairing reagents have been used in LC‐MS analysis, ion suppression and other issues related to method ruggedness have been reported using these volatile ion pairing reagents . An alternative strategy is to use a hydrophilic interaction LC (HILIC) system, which improves the retention of polar analytes, but HILIC is limited for certain NT groups and requires high cost of HILIC columns . Hence, ODS‐EP columns, which have similar functions with HILIC columns but at a lower price, have been developed for analysis of polar compounds.…”

Section: Introductionmentioning

confidence: 99%

Rapid analysis of neurotransmitters in rat brain using ultra‐fast liquid chromatography and tandem mass spectrometry: application to a comparative study in normal and insomnic rats

Jia

et al. 2013

J. Mass. Spectrom.

View full text Add to dashboard Cite

Neurotransmitters and their metabolites in central nervous system were known to play a significant role in sedation and hypnosis. A rapid and sensitive UFLC-MS/MS method for simultaneous determination of serotonin, 5-hydroxyindole acetic acid (5-HIAA), tryptophan (Try), dopamine (DA), norepinephrine (NE), γ-aminobutyric acid (GABA), glutamic acid (Glu) and acetylcholine (Ach) in rat brain without derivatization, ion-pairing reagent or pre-concentration was developed. Analytes and IS were separated on a Inertsil ODS-EP column (150 mm × 4.6 mm, 5 µm particles) and analyzed in a single chromatographic run in less than 9.0 min, using gradient elution with the mobile phase consisting of methanol and 0.01% acetic acid in water at a flow rate of 1.2 ml min(-1) . The detection of the analytes was performed on 4000Q UFLC-MS/MS system with turbo ion spray source in positive ion and multiple reaction monitoring mode. The developed method provided excellent linear calibration curves for the assay of analytes (R(2) ≥ 0.9915). Limits of quantification were in the range of 1.0 ng ml(-1) to 1.0 µg ml(-1) for the analytes in rat brain. Intra- and inter-day precision and accuracy of analytes were well within acceptance criteria (15%). Mean extraction recoveries of analytes and IS from rat brain were all more than 80.0%. Furthermore, the validated method was successfully applied to comparing profiles of analytes in normal and insomnic rat brains. Results indicated that there were statistically significant differences for serotonin, 5-HIAA, DA, NE, Glu and Ach, but no significant difference for Try and GABA between two groups.

show abstract

Rapid and reliable quantitation of amino acids and myo-inositol in mouse brain by high performance liquid chromatography and tandem mass spectrometry

Cited by 31 publications

References 35 publications

d-Amino Acid Levels in Perfused Mouse Brain Tissue and Blood: A Comparative Study

d-Amino Acid Levels in Perfused Mouse Brain Tissue and Blood: A Comparative Study

Brain Region Mapping Using Global Metabolomics

Rapid analysis of neurotransmitters in rat brain using ultra‐fast liquid chromatography and tandem mass spectrometry: application to a comparative study in normal and insomnic rats

Contact Info

Product

Resources

About