Tag: Mackenzie Kehmeier

The effects of ovariectomy and soy diet on vascular function in female C57BL6 mice

Presenter: Aleena Khurana − Human Physiology

Faculty Mentor(s): Ashley Walker, Mackenzie Kehmeier

Session: (In-Person) Oral Panel—Stimuli and Response

As people begin to live longer, studying age-related disease becomes more important. Age is a major risk factor for Alzheimer’s disease (AD), a prominent neurodegenerative disease, and other cardiovascular diseases; Females develop AD at much higher rates and all signs point to sex hormones. Estrogen drastically decreases post menopause, and it has been suggested that estrogen deficiency is a contributing factor to the sex differences seen in AD and other age-related diseases. The vascular system plays an important role in aging. A characteristic of aging in the vascular system is stiffening of larger arteries. Large artery stiffening is detrimental due to the increase in pulse pressure and stress associated with stiffening. Decreased estrogen activity results in increased production of reactive oxygen species (ROS), causing tissue damage and dysfunction. Elevated ROS and oxidative stress increase inflammation in the brain, further explaining the potential effects estrogen loss has in relation to such diseases. Soy also has been seen to be a protective factor against symptoms of age-related disease due to its role as a phytoestrogen, thus showing the potential importance of soy. This study aimed to explore the effects of estrogen depletion post menopause and the effects of a soy diet in relation with estrogen loss. We utilized a mouse model including ovariectomies to mimic estrogen loss post menopause and studied cognitive function, motor coordination, and vascular function.

In vivo arterial stiffness, but not endothelial function, varies with the mouse estrus cycle

Presenter: Bradley Bedell − Multidisciplinary Science

Faculty Mentor(s): Mackenzie Kehmeier MS, Ashley Walker PhD

(In-Person) Poster Presentation 

Historically, females have been omitted from research due to their perceived variability. Hormones fluctuate throughout the estrus cycle in mice mimicking the human menstrual cycle. The endothelium plays a role in vascular function and arterial stiffness. Human endothelial function and arterial stiffness vary throughout the menstrual cycle, however this has yet to be investigated in the mouse model.

C56Bl/6J mouse estrus cycle stage was identified via vaginal cytology prior to testing. Arterial stiffness was assessed via aortic pulse wave velocity. Endothelial function and nitric oxide mediated dilation were assessed by dose responses in pressurized mesenteric (MA) and posterior cerebral arteries (PCAs). Gene expression in PCAs and MAs was assessed as well as aortic protein analysis.

Aortic pulse wave velocity was lowered for mice in estrus as compared to diestrus. PCA and MCA dose responses did not differ between stages of the estrus cycle. PCA Esr2 gene coding for estrogen receptor β (ERβ) expression was lowered for mice in estrus as compared to diestrus and proestrus.

The estrus phase in mice is associated with lower in vivo large artery stiffness. There were no differences between the estrus cycle phase in ex vivo resistance artery endothelial function. ER gene expression changes during the estrus cycle are limited to ERβ in the cerebral arteries. These results suggest that estrus phase should be considered when measuring in vivo arterial stiffness in young female mice.