Interactions between gonadal hormones and neurovascular responses to the cold pressor test in young healthy females

Previously, we observed divergent vascular responses to the cold pressor test (CPT) among young healthy female participants. This short report examined circulating hormones as contributors to this variability in a larger cohort of female participants. We tested the hypothesis that gonadal hormones would be associated with vascular and muscle sympathetic nerve activity (MSNA) responses to the CPT. CPT responses from 20 young females tested in the early follicular phase of the menstrual cycle or placebo phase of oral contraceptive use were pooled for analyses. Venous blood samples were analyzed (radioimmunoassay; n = 18) for circulating total testosterone, 17β-estradiol, progesterone, sex hormone-binding globulin (SHBG), and free androgen index (FAI; total testosterone/SHBG). Mean arterial pressure (MAP; finger photoplethysmography), femoral blood flow (FBF; vascular ultrasound), femoral vascular conductance (FVC; FBF/MAP), and MSNA burst incidence [bursts/100 heartbeats (hb); peroneal microneurography] were assessed at baseline and during a hand CPT (3 min). The CPT induced increases in MSNA (baseline: 10 ± 5 vs. CPT: 28 ± 12 bursts/100 hb; P < 0.01) and MAP (86 ± 9 vs. 96 ± 7 mmHg; P < 0.01), whereas changes in FVC were not significant (2.6 ± 0.9 vs. 3.4 ± 0.6 mL/min/mmHg; P = 0.89). Neither 17β-estradiol (R = 0.07, P = 0.27) nor progesterone (R < 0.01, P = 0.73) was associated with CPT-induced increases in MSNA, whereas FAI was positively associated with increases in MSNA (R = 0.47; P < 0.01). Likewise, neither 17β-estradiol (R = 0.11, P = 0.65) nor progesterone (R = 0.01, P = 0.98) was associated with percent change in FVC (%FVC). However, there was a negative association between FAI and %FVC (R = 0.49, P < 0.01). These data suggest that bioavailable testosterone may be associated with CPT-induced increases in MSNA and peripheral vasoconstriction in young healthy females.NEW & NOTEWORTHY In this pooled cohort of young, healthy females assessed during the early follicular phase of the menstrual cycle or placebo phase of the oral contraceptive pill cycle, correlation analyses indicated that those with the highest free androgen index demonstrated 1) the greatest increases in sympathetic activity and 2) decreases in peripheral vascular conductance during the cold pressor test. These data suggest that bioavailable testosterone may be linked to sympathetic neurovascular responses to acute stress.