The role of peptide yy and ghrelin in regulating energy homeostasis and reproductive function in young exercising women
Open Access
- Author:
- Scheid, Jennifer L
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 20, 2012
- Committee Members:
- Mary Jane De Souza, Dissertation Advisor/Co-Advisor
Nancy Williams, Committee Member
James Anthony Pawelczyk, Committee Member
Leann L Birch, Committee Member - Keywords:
- Peptide YY
Ghrelin
Reproductive Function
Exercising Women - Abstract:
- The primary purpose of this dissertation was to understand the physiological relevance of alterations in ghrelin and PYY in healthy populations of premenopausal women. The specific goals of this dissertation were to understand if PYY and ghrelin are involved in the long-term regulation of body weight in normal weight premenopausal healthy women (Study 1), to understand if alterations in PYY and ghrelin are related to reproductive function in premenopausal healthy women (Study 2 and 4), and to determine if college-aged women with different eating behavioral phenotypes, i.e., high vs normal dietary restraint, differ with respect to circulating concentrations of gastrointestinal hormones during and following a test meal (Study 3). Study 1 was designed to examine changes in fasting PYY and ghrelin in non-obese premenopausal women following an exercise and diet program with and without weight loss. We demonstrated that exercising women who lost weight increased ghrelin concentrations. Study 2 was designed to examine if elevations in 24 hour circulating ghrelin concentrations following a ~3 month exercise and diet program associated with diet- and exercise-induced weight loss are associated with a decrease in luteinizing hormone (LH) pulsatility in premenopausal women. We demonstrated that elevated ghrelin concentrations were associated with the suppression of LH pulsatility in premenopausal women. The purpose of Study 3 was to determine if college-aged women with different eating behavioral phenotypes, i.e., high vs normal dietary restraint, differ with respect to circulating concentrations of gastrointestinal hormones during and following a test meal. We demonstrated that PYY3-36 concentrations were suppressed in the women with high dietary restraint compared to the women with normal dietary restraint, indicating low PYY3-36 concentrations following a test meal may be indicative of a blunted appetite reduction after a meal and, over time, lead to an increased risk of weight gain. The purpose of Study 4 was to determine if ghrelin and PYY are associated with the recovery of menses in women with exercise associated menstrual cycle disturbances (EAMD). We demonstrated that women with EAMD who experienced menstrual recovery experience significant decreases in fasting ghrelin concentrations compared to women with EAMD who did not resume menses. We speculate that decreases in ghrelin may be necessary, likely in conjunction with changes in other metabolic hormones, for exercising women with EAMD, to recover menstrual function. Overall, ghrelin is likely an important signal involved the regulation of the hypothalamic pituitary ovarian axis in premenopausal women, while PYY is related to eating behavior phenotypes after a meal.