Correlation of plasma homocysteine content in peripheral blood and mitochondrial DNA in healthy women

Hyperhomocysteinemia is an independent risk factor of cardiovascular diseas e and associated with insulin resistance, although their causal relationshi p remains unclear. A previous report has shown that high concentration of h omocysteine damages mitochondrial gene expression, function and structure. As we found recently, the mitochondrial DNA (mtDNA) contents are inversely correlated with insulin resistance parameters. Thus there is possibility th at plasma total homocysteine (tHcy) level is somewhat correlated with mtDNA content. Sixty healthy women (mean age 40.3 +/- 20.9 yr, range 18-78 yr) w ere recruited to investigate the correlation of plasma tHcy level and mtDNA content in peripheral blood. A significant negative correlation was found between plasma tHcy levels and mtDNA content (r = - 0.507, P < 0.01). Plasm a tHcy and mtDNA content have an independent effect on each other and on in sulin resistance (HOMA-insulin resistance (IR) score) respectively in multi ple regression model. Plasma tHcy showed positive correlations with age (r = 0.407), W/H ratio (r = 0.370), total cholesterol (r = 0.338), LDL-cholest erol (r=0.317) and insulin resistance (HOMA-IR score) (r=0.261); and a nega tive correlation with folate (r = - 0.273). MtDNA content showed negative c orrelations with age (r = - 0.407), BMI (r = - 0.440), W/H ratio (r = - 0.6 59), SBP (r = - 0.350), total cholesterol (r = - 0.340), triglyceride (r - 0.376), LDL-cholesterol (r = - 0.349), fasting plasma insulin (r = - 0.483) , and insulin resistance (HOMA-IR score) (r = 0.423); and a positive correl ation with folate (r = 0.299). In this study, there was a significant inver se correlation between plasma tHcy level and mtDNA content. Further study w ill be warranted to elucidate the mechanism by which two factors are associ ated. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.