Lowered ω3 polyunsaturated fatty acids in serum phospholipids and cholesteryl esters of depressed patients

Abstract

Depression is associated with a lowered degree of esterification of serum cholesterol, an increased C20:4ω6/C20:5ω3 ratio and decreases in ω3 fractions in fatty acids (FAs) or in the red blood cell membrane. The aims of the present study were to examine: (i) serum phospholipid and cholesteryl ester compositions of individual saturated fatty acids (SFAs), monounsaturated FAs (MUFAs) and polyunsaturated FAs (PUFAs) in major depressed patients vs. healthy volunteers; (ii) the relationships between the above FAs and lowered serum zinc (Zn), a marker of the inflammatory response in depression; and (iii) the effects of subchronic treatment with antidepressants on FAs in depression. The composition of the FAs was determined by means of thin layer chromatography in conjunction with gas chromatography. Lipid concentrations were assayed by enzymatic colorimetric methods. The oxidative potential index (OPI) of FAs was computed in 34 major depressed inpatients and 14 normal volunteers. Major depression was associated with: increased MUFA and C22:5ω3 proportions and increased C20:4ω6/C20:5ω3 and C22:5ω6/C22:6ω3 ratios; lower C22:4ω6, C20:5ω3 and C22:5ω3 fractions in phospholipids; lower C18:3ω3, C20:5ω3 and total (Σ)ω3 FAs, and higher C20:4ω6/C20:5ω3 and Σω6/Σω3 ratios in cholesteryl esters; lower serum concentrations of phospholipids and cholesteryl esters; and a decreased OPI. In depression, there were significant and positive correlations between serum Zn and C20:5ω3 and C22:6ω3 fractions in phospholipids; and significant inverse correlations between serum Zn and the Σω6/Σω3, C20:4ω6/C20:5ω3, and C22:5ω6/C22:6ω3 ratios in phospholipids. There was no significant effect of antidepressive treatment on any of the FAs. The results show that, in major depression, there is a deficiency of ω3 PUFAs and a compensatory increase in MUFAs and C22:5ω6 in phospholipids. The results suggest that: (i) there is an abnormal metabolism of ω3 PUFAs in depression; (ii) the FA alterations in depression are related to the inflammatory response in that illness; and (iii) the disorders may persist despite successful antidepressant treatment.