SHBG and endothelial function in older subjects

BACKGROUND: Endothelial dysfunction is predictor of cardiovascular diseases that have different prevalence in men and women before menopause. Sex hormones and sex hormone binding globulin (SHBG), novel risk factors for diabetes and cardiovascular diseases even in older individuals, might explain this difference. However, the relationship between these hormones and endothelial function has never been addressed in the elderly. METHODS AND RESULTS: 430 men and,424 women 70years older of Prospective Study of the Vasculature in Uppsala Seniors study, with complete data on SHBG, testosterone(T), estradiol(E2), endothelium-independent vasodilation (EIDV), endothelium-dependent vasodilation(EDV), flow-mediated vasodilation (FMD) and the pulse wave analysis (reflection index, RI) were evaluated. Multivariate regression analysis adjusted for confounders was used to assess the relationship between T, E2, SHBG and endothelial function. In men we found a positive relationship between SHBG and EDV (β±SE 3.60±0.83, p<0.0001), EIDV (2.42±0.58, p<0.0001) but not with FMD. The relationship between SHBG and EDV and EIDV was maintained after adjustment for sex (1.64±0.47, p<0.001 and 1.79±0.35, p<0.0006, respectively). After adjustment for confounders, the relationship between SHBG and EDV and EIDV was still statistically significant (2.63±0.90 and 1.86±0.63, p=0.004 for both). In women SHBG and EIDV were positively associated (1.58±0.46; p=0.0007), and this relationship was independent of sex (1.79±0.35; p<0.001). No significant interaction SHBG∗SEX was found for EIDV (p=0.72). In a combined analysis in two sexes, SHBG and EIDV were positively associated (1.13±0.45; p=0.01). SHBG was not associated with EDV, FMD and RI. No significant relationship was found between T or E2 and EDV, EIDV, FMD or RI in both sexes. CONCLUSIONS: In older men SHBG, but not T and E2, is positively and independently associated with EDV in resistance arteries. In both sexes, SHBG was positively and independently associated with EIDV.