Abstract: A simple method was developed for the analysis of 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-β-carboline (6-OH-MTHβC), 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in rat brain by high performance liquid chromatography with electrochemical detection (HPLC-ECD). The separation of the sample was performed on a Discovery HS F5 column (250 mm×4.6 mm, 5 μm) with a mobile phase of the buffer（40 mmol/L citric acid+20 mmol/L Na2HPO4+0.3 mmol/L EDTA2Na, pH 4.0）-methanol （78∶22, v/v） at a flow rate of 1.0 mL/min. The electrochemical detector was Coularray Detector-4. This method showed good linearity (r>0.9992) for the quantification of 6-OH-MTHβC, 5-HT and 5-HIAA in the concentration range of 1.0-500.0 μg/L. The limits of detection were 0.56, 0.26 and 0.53 μg/L, respectively. The recoveries of 6-OH-MTHβC, 5-HT and 5-HIAA spiked in rat brain samples were 87.1%-98.2%, 87.0%-95.3%, 90.1%-97.7%, respectively, and the relative standard deviations of intra-day and inter-day determinations were both less than 6.1%. In comparison with the control, the analysis of alcohol-exposed neonatal rat brain samples revealed a significant difference in the level of 6-OH-MTHβC (P<0.05). The method was proved to be simple, highly sensitive, and could be applied in the analysis of 6-OH-MTHβC, 5-HT and 5-HIAA in the rat brain.

Key words: 5-hydroxyindole acetic acid, 5-hydroxytryptamine, 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-β-carboline, electrochemical detection (ECD), rat brain , high performance liquid chromatography (HPLC)