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Anthropometric and metabolic correlates of sympathetic nervous system activation in women with polycystic ovary syndrome

Lansdown, Andrew John 2016. Anthropometric and metabolic correlates of sympathetic nervous system activation in women with polycystic ovary syndrome. MD Thesis, Cardiff University.
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Abstract

Background: Polycystic ovary syndrome (PCOS) is associated with increased metabolic risk and hypertension, which may relate to enhanced sympathetic nervous system (SNS) activation. The cerebral pathways involved in this process are not known. Aims: (1) To compare blood pressure and SNS activation in response to isometric forearm contraction (IFC) between PCOS and control groups. (2) To identify and compare the neuronal signatures of this response. (3) To investigate metabolic and anthropometric correlates of SNS activation. Methods: 20 PCOS (age 29.8 yrs, BMI 26.1 kg/ m²) and 20 matched controls (age 29.7 yrs, BMI 26.1 kg/ m²; p=NS) were studied. Out-of-scanner tests: measurement of mean blood pressure (MAP) and heart rate (HR) responses to 30% IFC for 180 seconds; baseline and post-task catecholamines, and microneurography (MSNA) in a subgroup of 8 PCOS and 8 controls. In-scanner: Blood oxygen level dependent (BOLD) fMRI using an identical block paradigm design for IFC, BOLD signalcorrelating to MAP responses (threshold Z>2.3, corrected cluster threshold p=0.05). Results: IFC elicited an increase in HR and MAP in PCOS and controls but these did not differ between groups (p=0.16[HR] and p=0.06[MAP]). Adrenaline increased significantly post-IFC in PCOS (0.68 to 1.23ng/mL p<0.001) but not in controls (0.77 to 0.99ng/mL p=0.14). MSNA burst frequency increased by 68% in the PCOS group compared to 11.9% in controls (p=0.002). Brain activation indexed by the BOLD signal in response to IFC was significantly greater in the PCOS group compared to the control group in the right orbitofrontal cortex (p<0.0001), left angular gyrus and lateral occipital cortex (p=0.04). When the BOLD signal was separately corrected for insulin sensitivity, BOLD signal in the right orbitofrontal cortex was no longer significant. Conclusions: PCOS is associated with enhanced SNS activation and increased regional brain activation in response to IFC. The right orbitofrontal cortex BOLD signal change in the PCOS group is associated with insulin sensitivity.

Item Type: Thesis (MD)
Status: Unpublished
Schools: Medicine
Subjects: R Medicine > RG Gynecology and obstetrics
Date of First Compliant Deposit: 17 May 2017
Last Modified: 05 Jun 2017 05:55
URI: http://orca.cf.ac.uk/id/eprint/100609

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