Sensitive determination of monoamine neurotransmitters, their main metabolites and precursor amino acids in different mouse brain components by liquid chromatography–electrospray tandem mass spectrometry after selective sample clean‐up

Abstract

For the assessment of diets and supplements formulated for the treatment of phenylketonuria, a highly sensitive and selective method was developed and validated for the quantification of dopamine (DA), serotonin (5‐HT), 3,4‐dihydroxyphenylacetic acid (DOPAC), 5‐hydroxyindoleacetic acid (5‐HIAA), phenylalanine, tyrosine and tryptophan in mouse cerebellum, brain stem, hypothalamus, parietal cortex, anterior piriform cortex and bulbus olfactorius. Samples were extracted by deproteinization with acetonitrile, and the extracts were cleaned up by strong anion exchange and weak cation exchange applied sequentially. The substances were detected by rapid liquid chromatography tandem mass spectrometry. Matrix components were largely removed by the clean‐up, resulting in low matrix effects. The lower limits of quantification for an extracted tissue mass of 100 mg were 0.3, 0.3, 0.2 and 2 ng/g for DA, 5‐HT, 5‐HIAA and DOPAC, respectively. The mean true extraction recoveries were 80–102%. The relative intra‐laboratory reproducibility standard deviations were generally <11% at concentrations of 20–1000 ng/g for DA, 5‐HT, 5‐HIAA and DOPAC and 7% at concentrations of 5–50 μg/g for the amino acids. This method was successfully used in a phenylketonuria mice study including nearly 300 brain tissue samples and for small sample masses (for example, 2 mg of bulbus olfactorius).

Improving the Utility of a Dynorphin Peptide Analogue Using Mannosylated Glycoliposomes

“…Both dynantin concentrations resulted in dopamine levels that were significantly elevated with respect to the PBS control group (0.54 ± 0.07 ng/mg). Importantly, the levels of striatal dopamine measured in the PBS treated control group are within the normal range of baseline levels reported in the literature for mice [ 61 , 62 , 63 ], indicating that the dissection and extraction processes did not have any significant effect.…”

“…The ability of dynantin to antagonize the KOR and modulate dopamine levels was next investigated in vitro using homogenates of the fresh mouse brain striatum ( Figure 4 ) and LC/MS, a highly sensitive analytical technique that can be combined with a variety of different extraction methods for the analysis of neurotransmitter levels in rodent brain tissue [ 59 , 60 , 61 , 62 , 63 ]. The gently homogenized tissue was treated with either PBS or dynantin at 1 and 10 µM concentrations for 90 min, after which dopamine levels were analyzed.…”

Establishment of a Highly Sensitive Analytical Method For Measurement of Monoamine Neurotransmitters Using Mass Spectrometry

“…However, the detection of histamine in brain tissue by LC-MS/MS has not been reported. In addition, these methods require pretreatment such as ion-exchange solid-phase extraction and drying under nitrogen gas to achieve highly sensitive measurements 26,37,38 . The LOD (MDL) of the analytical method established in this study was 2.08 ppt for 3-MT, 24.9 ppt for DA, 9.82 ppt for histamine, and 1.51 ppt for serotonin, achieving much higher detection sensitivity than conventional methods.…”

“…There have been several previous studies on the detection of monoamines using LC-MS/MS [23][24][25][26] .…”

Simultaneous Analysis of Tryptophan and Its Metabolites in Human Plasma Using Liquid Chromatography–Electrospray Ionization Tandem Mass Spectrometry

“…Previous reports have used various columns for solid-phase extraction [18,24,26], and analysis were chosen for the selective determination of Trp metabolites. Using solid-phase extraction, contaminants can be removed from samples, but this process is time-consuming and results in recovery variation.…”