The effect of hop extract supplementation on gut microbiota and metabolic function in ovariectomized mice
Date
2017
Authors
Hamm, Alison Kay, author
Weir, Tiffany L., advisor
Cox-York, Kimberly A., committee member
Broeckling, Corey D., committee member
Avens, John S., committee member
Bunning, Marisa L., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Estrogen decline with aging, or menopause, is associated with increased risk for cardiometabolic diseases primarily due to altered metabolism and weight gain. Standard treatment has traditionally been with 17β-estradiol (E2) prescription, although its use has declined over the last decade due to associated increase in breast and ovarian cancer risk. As a result, use of phytoestrogenic herbal supplements has increased, due to their perceived safety and effectiveness in treatment of menopausal side effects. The gut microbiota may also be important in terms of mitigating disease risk and hormone exposure during the menopause transition, as our gut microbiota are important modulators of local and systemic inflammation. Gut microbes also can metabolize hormones and dietary flavonoids, altering their bioactivity and bioavailability. In this study, we supplemented ovariectomized (OVX) or control sham-operated C57BL/6 mice, with oral E2, a flavonoid-rich extract from hops (Humulus lupulus), or placebo carrier oil, and observed differences in adiposity, inflammation, and gut bacteria composition. Hops extract (HE) did not protect against ovariectomy-associated weight gain or increased visceral adiposity, while E2-treated animals had similar body weights and fat depot sizes as Sham-operated animals. However, HE was protective against liver triglyceride accumulation, to levels similar to Sham control and OVX E2 groups. We found no evidence of OVX having a significant impact on the overall gut bacterial community structure in any of our treatment groups. We did find differences in abundance of two bacteria; Akkermansia muciniphila was lower with HE treatment in the Sham group, and Ruminococcus gnavus was higher with OVX compared to Sham control. Possible mechanisms of the interplay between gut bacteria, loss of estrogen, and hormone replacement will be discussed.