Female sex hormone fluctuations across the female life cycle and their influence on vascular function tests

Davies, Rebecca (2021). Female sex hormone fluctuations across the female life cycle and their influence on vascular function tests. University of Birmingham. M.Sc.

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Abstract

Vascular dysfunction in the cerebral and peripheral vasculature has implications for cardiovascular and cerebrovascular diseases. Fluctuations in the levels of female sex hormones across the menstrual cycle, and over the course of the menopause appear to alter several vascular responses. These changes may have implications for vascular related diseases, however the extent of this in the peripheral and cerebral circulations is not fully understood. Therefore, this thesis aims to compare cerebral and peripheral vascular function over the course of the menstrual cycle in pre-menopausal females, in comparison with the responses to postmenopausal females. Methods: Six pre-menopausal females at two phases of their menstrual cycle and six post-menopausal females underwent a CO2 inhalation cerebrovascular reactivity protocol and a flow-mediated dilation protocol to assess vascular function. Comparisons were made between the phases of the menstrual cycle in pre-menopausal females and these results were compared to post-menopausal females. Results: CVRMCAv and CVRPCAv values were comparable over the course of the menstrual cycle in pre-menopausal females. FMD% in premenopausal females was higher in the ML phase than the EF phase of the menstrual cycle (p = .046). CVR to hypercapnia was higher in pre-menopausal females when compared to postmenopausal females (p = .014) , yet FMD% was only higher in pre-menopausal females when compared to post-menopausal, when the former were in the ML phase of their menstrual cycle (p= .006). Conclusion: In pre-menopausal females, CVR responses were similar between the EF and ML phases of their menstrual cycles. As expected, CVR to hypercapnia and FMD measures were higher in pre-menopausal females when compared to post-menopausal females and these were dependent on menstrual cycle phase. More research is required to look into the cardioprotective mechanisms of female sex hormones on different cohorts (including those on HRT) and how these have implications for health and disease.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):