Levels of dopamine, 5-hydroxytryptamine and their metabolites in the striatum of rats of various strains receiving a high-calorie diet

The aim of this work was to study the effect of a high fat and carbohydrate diet (HFCD) and quercetin supplementation on the levels of dopamine (DA), serotonin (5-HT) and their metabolites in Wistar, DA transporter knockout (DAT-KO) and obese Zucker fa/fa rats. Animals received a control diet or HFCD for 62 days. Wistar and Zucker fa/fa rats received quercetin. The contents of DA, 5-HT, norepinephrine (NE), dioxyphenyl acetate (DOPAC), homovanillic acid (HVA) and 5-hydroxyindolyl acetate (5-HIIA) in the striatum were determined by high-performance liquid chromatography (HPLC). DAT-KO homozygotes had lowered DA and increased HVA and DOPAC compared to Wistar rats. HFCD did not affect the content of NE and 5-HT. 5-HT was increased in DAT-KO homozygotes compared with Wistar receiving a control diet. 5-HIIA accumulated in larger amounts in DAT-KO compared to Wistar with the exception of those receiving quercetin with a control diet. Quercetin did not affect the levels of DA, 5-HT and their metabolites.

PARKINSONISM SYNDROME FORMATION IN EXPERIMENTAL ANIMALS. NEUROINFLAMMATORY PENUMBRA

Much valuable information about the development of Parkinson’s disease (PD) has been obtained from studies on the laboratory animals. Objectives. To compare the development of neurotoxic and neuroinflammatory parkinsonism syndrome in laboratory animals. Material and methods. The number of rats in the group of neuroinflammatory model of parkinsonism syndrome (lipopolysaccharide) was 6, and in the group of neurotoxic model (rotenone) - 20. The control group consisted of 5 animals. The study was approved by the independent Ethics Committee. The development dynamics of parkinsonism syndrome of neurotoxic and neuroinflammatory genesis was assessed in the study of the motor activity of animals, as well as in the laboratory study of biomarkers of dopamine metabolism (dopamine and homovanillic acid) in blood serum and cerebrospinal fluid obtained in 7 and 21 days after the first administration of rotenone or lipopolysaccharide, and also after a single intravenous injection of allogeneic (rat) multipotent mesenchymal stromal cells (MMSC) carried out after 9 injections of rotenone. Results. A decrease in the levels of dopamine and homovanillic acid has been shown in laboratory animals on the development of Parkinson’s syndrome. In rats with a neuroinflammatory model of parkinsonism syndrome, a pre-motor stage of motor disorders development has been laboratorially confirmed. During the first weeks after the introduction of MMSC, regression of the motor symptoms of neurotoxic parkinsonism syndrome and a parallel increase in dopamine and homovanillic acid are determined. Conclusions. The effectiveness of MMSC in the early post-transplantation period is associated with the paracrine effect. It is proposed to call activated microglia, a potential therapeutic target in PD, neuroinflammatory penumbra.

Application of an LC–MS/MS Method for the Simultaneous Quantification of Homovanillic Acid and Vanillylmandelic Acid for the Diagnosis and Follow-Up of Neuroblastoma in 357 Patients

Homovanillic acid (HVA) and vanillylmandelic acid (VMA) are end-stage metabolites of catecholamine and are clinical biomarkers for the diagnosis of neuroblastoma. For the first time in Korea, we implemented and validated a liquid chromatography tandem mass spectrometry (LC–MS/MS) assay to measure urinary concentrations of HVA and VMA according to Clinical and Laboratory Standards Institute guidelines. Our LC–MS/MS assay with minimal sample preparation was validated for linearity, lower limit of detection (LOD), lower limit of quantification (LLOQ), precision, accuracy, extraction recovery, carryover, matrix effect, and method comparison. A total of 1209 measurements was performed to measure HVA and VMA in spot urine between October 2019 and September 2020. The relationship between the two urinary markers, HVA and VMA, was analyzed and exhibited high agreement (89.1% agreement, kappa’s k = 0.6) and a strong correlation (Pearson’s r = 0.73). To our knowledge, this is the first study to utilize LC–MS/MS for simultaneous quantitation of spot urinary HVA and VMA and analyze the clinical application of both markers on a large scale for neuroblastoma patients.

Differential Modulation of the Central and Peripheral Monoaminergic Neurochemicals by Deprenyl in Zebrafish Larvae

Zebrafish embryos and larvae are vertebrate models increasingly used in translational neuroscience research. Behavioral impairment induced by the exposure to neuroactive or neurotoxic compounds is commonly linked to changes in modulatory neurotransmitters in the brain. Although different analytical methods for determining monoaminergic neurochemicals in zebrafish larvae have been developed, these methods have been used only on whole larvae, as the dissection of the brain of hundreds of larvae is not feasible. This raises a key question: Are the changes in the monoaminergic profile of the whole larvae predictive of the changes in the brain? In this study, the levels of ten monoaminergic neurotransmitters were determined in the head, trunk, and the whole body of zebrafish larvae in a control group and in those treated for 24 h with 5 M deprenyl, a prototypic monoamine-oxidase B inhibitor, eight days post-fertilization. In control larvae, most of the monoaminergic neurochemicals were found at higher levels in the head than in the trunk. Significant changes were found in the distribution of some neurochemicals after deprenyl-treatment, with serotonin and norepinephrine increasing in both the head and the trunk, whereas dopamine, L-DOPA, and homovanillic acid levels were only modulated in the head. In fact, the highly significant increase in dopamine levels observed in the head after deprenyl-treatment was not detected in the whole-body analysis. These results indicate that the analysis of neurotransmitters in the zebrafish larvae whole-body should not be used as a general surrogate of the brain.