The variation in the levels of 18 amino acids in the cortex and plasma of cerebral ischemia C57BL/6 mice

Abstract

Emerging evidence suggests that amino acid (AA) neurotransmitters play important roles in the pathophysiological processes of cerebral ischemia. In this work, an HPLC with fluorescence detection (HPLC‐FLR) method was developed for the simultaneous determination of 18 AAs in the cortex and plasma after cerebral ischemia in mice. The ischemia model was prepared by bilateral common carotid artery occlusion, and then the cortex and plasma of the sham, ischemia, and naringenin groups were collected. Based on the protein precipitation method, a simple and effective sample preparation method was developed. The treated sample contained minimal proteins and lipids. The analysis of the sample was performed by the proposed HPLC‐FLR method in combination with o‐phthalaldehyde. The results showed a statistically significant increase in excitatory AAs (aspartic acid and glutamic acid), inhibitory AAs (glycine and 4‐aminobutyric acid), phenylalanine, citrulline, isoleucine, and leucine levels, and a decrease of glutathione and phenylalanine levels when compared with the sham group in the cortex. Besides, the administration of naringenin had significant effects on excitatory AAs, inhibitory AA (glycine), glutamine, tyrosine, phenylalanine, and leucine levels when compared with the sham group in the cortex. These findings could be utilized in studying and clarifying the mechanisms of ischemia.

Determination of 23 related analytes in bone marrow fluid and hippocampus of C57BL/6 mice following cerebral ischemia–reperfusion injury by HPLC‐FLD

“…Since most amino acids have no direct and obvious response in liquid chromatography–ultraviolet detector and fluorescence detectors, it is imperative to add derivatization reagents. The regularly used pre‐column derivatization reagents are O ‐phthalaldehyde (Li et al, 2021), 9‐fluorenylmethyl chloroformate (Haynes et al, 1991), dansyl chloride (Letertre et al, 2021), 4‐fluoro‐7‐nitro‐2,1,3‐benzoxadiazole (Zheng et al, 2015), phenyl isothiocyanate (PITC), etc. All of them have disadvantages, for example, O ‐phthalaldehyde can only derivatize primary amines, and the fluorescence response is unstable (Dai et al, 2014; Tcherkas et al, 2001).…”

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“…The increase in methionine content in TCI reflects the identified lack of activation of oxidative processes in this grade of cerebral ischemia [2,3,[8][9][10][11].…”

“…An increase in the level of L-arginine and citrulline reflects the active course of reactions associated with the cytoplasmic part of the ornithine cycle, with the exception of thoseinvolving arginine [2,3,7].…”

“…This is due not only to theircrucial role as the sources of synthesis of various biologically important compounds (proteins, mediators, lipids, biologically active amines), but also to their involvement in synaptic transmission as neurotransmitters and neuromodulators (glutamate, aspartate, glycine, GABA, taurine). Some AA are in charge of the formation of nervous system mediators: e.g., methionine (acetylcholine, DOPA, dopamine), tyrosine (catecholamines), serine and cysteine (taurine), tryptophan (serotonin), histidine (histamine), L-arginine (NO), glutamic acid (glutamate) [1,2,3].…”