High-fat simple carbohydrate feeding impairs central and peripheral monoamine metabolic pathway triggering the onset of metabolic syndrome in C57Bl/6J mice

Background: Previous studies have shown disturbances in an individual monoamine pathway but have not studied metabolic pathways at the onset and progression of metabolic syndrome (MetS). Aims, Settings, and Design: The aim of this study was to investigate the effect of high-fat simple carbohydrate (HFSC) diet on central (hypothalamic) and peripheral (plasma and urine) monoamine metabolic pathways during the development of metabolic syndrome in C57BL/6J mice. Materials and Methods: Monoamines were analyzed in the 1^st, 2^nd, 3^rd, 4^th, and 5^th month after feeding mice the HFSC diet or the control diet using the high performance liquid chromatography (HPLC) system (Shimadzu, Japan). Data was statistically analyzed (by Student's t-test) using Graph Pad Instat Version 3.1. Post statistical analysis, Bonferroni correction was applied to the results of 2^nd, 3^rd, 4^th, and 5^th month in order to calculate the correct error in the study. Results: Significantly lower hypothalamic, plasma, and urine dopamine, and higher hypothalamic and plasma levels of norepinephrine and normetanephrine levels were observed in the HFSC diet fed C57BL/6J mice as compared to the control diet fed C57BL/6J mice after 5 months of feeding. No consistent changes were observed in other brain regions. The turnover ratio indicated that the lower dopamine levels in the HFSC diet fed C57BL/6J mice was due to the increased formation of norepinephrine and homovanillic acid. Conclusion: HFSC diet impairs the central and peripheral dopaminergic and noradrenergic pathways in mice as evidenced by the disturbances in their hypothalamic, plasma, and urine levels and this might be one of the early factors contributing towards the development of the MetS.