Analysis of Homocysteine in Plasma of Rats Exposed to High-fat Diet and Chronic Unpredictable Mild Stress by LC/ESI-MS/MS

Context: Homocysteine (Hcy) is an amino acid that occurs in the body as an intermediate in the metabolism of methionine and cysteine. Hcyinplasma is a disease risk factor associated with both atherosclerosis and depression. The relation between Hcy balance and complication of atherosclerosis and depression remains unclear. Determination of Hcy in plasma is important and necessary for the research on comorbidities of atherosclerosis and depression. Objective: To establish an LC/ESI-MS/MS method for measuring plasma Hcy levels in rats and to compare plasma Hcy levels in rats exposed to high-fat diet, unpredictable mild stress or its combination. Materials and Methods: Forty rats were randomized into control group, high-fat group (HFD), chronic unpredictable mild stress group (CMS) and CMS+HFD group (n=10 in each group). 8 weeks later, the rats were sacrificed and plasma was collected for determining Hcy by LC/ESI-MS/MS. All data were analyzed by using SPSS13.0 software. Results: Compared to the plasma Hcy levels of control group, neither HFD group nor CMS group had statistical significance. However, CMS+HFD group showed a significantly higher level of plasma Hcy than the other three groups. Conclusions: Only when exposed to both high fat diets and chronic unpredictable mild stress, rats showed a remarkably elevated Hcy level in their plasma, however, when exposed alone to either high fat diet or chronic unpredictable mild stress, rats had a normal Hcy level in their plasma. Our findings indicate that Hcy is increased in comorbidity of atherosclerosis and depression.