Determination of monoamine and amino acid neurotransmitters and their metabolites in rat brain samples by UFLC–MS/MS for the study of the sedative-hypnotic effects observed during treatment with S. chinensis

Abstract Schisandra chinensis (Turcz.) Baill. has been used as a sedative and hypnotic agent in traditional Chinese medicine for centuries. The purpose of this study was to reveal the influence of insomnia on the levels of the neurotransmitters: glutamate (Glu), γ -aminobutyric acid (GABA), noradrenaline (NE), dopamine (DA), serotonin (5-HT) and their metabolites (5-HIAA, DOPAC and HVA), and to study the role of S. chinensis in the treatment of insomnia. To achieve this goal, an efficient, sensitive and selective method was developed and validated for the simultaneous determination of these five neurotransmitters and their metabolites in rat brain samples using ultra fast liquid chromatography/tandem mass spectrometry (UFLC–MS/MS). The analysis was performed on a Synergi Fusion-RP 80A ODS column (150 mm × 2.0 mm, 4.0 μm) using gradient elution, with the mobile phase consisting of acetonitrile and 0.05% formic acid in water. The method was validated using rat brain homogenate samples and showed a good linearity over a wide concentration range ( r 2  > 0.99) with a lower limit of quantification (LLOQ) at 4–16 ng mL −1 . The intra and inter-day assay variability was less than 15% for all analytes. The results indicated that the condition of insomnia elevated GABA, NE, DA, DOPAC and HVA, and reduced 5-HT, 5-HIAA levels in rat brain. The oral administration of S. chinensis (7.5 g kg −1  day −1 , eight days) influenced insomnia by significantly increasing or reducing the levels of the neurotransmitters parameters mentioned above. These results suggested that S. chinensis could alter the levels of these brain neurotransmitters and their metabolites through its sedative-hypnotic effects.