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

(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.