Neurovascular Coupling Across the Menstrual Cycle

Abstract

Vascular function is modulated in response to the changing hormonal patterns of the menstrual cycle. Sex hormones may also act on non‐vascular cells regulating blood flow, including astrocytes and neurons, which may alter cerebral blood flow responses. However, the impact of menstrual phase on cerebral neurovascular coupling has not been investigated. We hypothesized that the visually evoked cerebral blood flow response would be higher in the mid‐luteal phase of the menstrual cycle, corresponding to elevated estrogen levels.Nine normally menstruating women (Age = 28 ± 6 yrs, BMI = 25 ± 4kg/m2) underwent a visual stimulation test in the early follicular (EF) and mid‐luteal (ML) phase of the menstrual cycle. Beat‐by‐beat mean arterial pressure (MAP) was derived using photoplethysmography (Finometer) and posterior cerebral artery blood flow velocity (PCAVP) was measured using transcranial Doppler ultrasound (Multigon).At rest, MAP (EF: 86.8 ± 7.4mmHg, ML: 87.7 ± 6.2mmHg, p=0.78) and cerebral blood flow (EF: 36.5 ± 5.5cm/s; ML: 37.6 ±11.3cm/s, p=0.80) were similar between phases. Further, the magnitude (EF: 25.0 ± 6.0%, ML: 26.5 ±8.5%, p=0.38) and the timing (EF: 12.0 ± 1.4s, ML: 11.8 ± 1.9s, p=0.78) of the cerebral blood flow response to visual stimulation was similar between phases.These data suggest that contrary to our hypothesis, neurovascular coupling assessed by visual stimulation was not different across the menstrual cycle. Supported by the University of Alberta ‐ Human Performance Scholarship Fund.