5 minute lightning oral presentation (and poster) ESA-SRB 2023 in conjunction with ENSA

The effect of menstrual cyclicity on brown adipose tissue activity in eumenorrheic women (#212)

Anne Nicole De Jesus 1 , Belinda A. Henry 2
  1. Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Clayton, VIC, Australia
  2. Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Clayton, VIC, Australia

Aims: Brown adipose tissue (BAT) expends energy via adaptive thermogenesis. Recently, BAT activation has also been shown to improve glucose clearance. However, it remains unknown as to whether BAT function changes across the menstrual cycle in women. We aimed to characterise changes in BAT activity, glucose tolerance and circulating levels of 17β-estradiol and progesterone in women during the luteal and follicular phases of the menstrual cycle.

Methods: Menstrual cyclicity was monitored in women (18-39 years) and studies were conducted in the follicular (n= 10) and luteal (n= 13) phases of the cycle. Weight, height, BMI, waist circumference and fat mass were measured. In fasted participants, resting energy expenditure (REE) and respiratory quotient (RQ) were determined. Infrared thermography was used to measure cutaneous supraclavicular temperature as an index of BAT temperature in response to either cold exposure (15oC) or an oral glucose tolerance test (oGTT). Continuous glucose monitors (Freestyle Libre) were used to measure transcutaneous glucose concentrations. A single blood sample was collected to measure 17β-estradiol, progesterone and insulin concentrations.

Results: There was no effect of the menstrual phase on REE, RQ and anthropometric parameters. The plasma concentrations of progesterone (p<0.01), 17β-estradiol (p<0.05) and insulin (p<0.01) were increased during the luteal phase of the menstrual cycle. Cold-induced BAT temperature was lower during the luteal phase (p<0.0001). Furthermore, glucose levels were increased (p<0.05) during the oGTT in luteal phase women, and this coincided with an attenuated increase in BAT temperature, but this was not statistically significant.

Conclusion: Our findings suggest that thermogenesis in BAT is attenuated during the luteal phase of the menstrual cycle. Moreover, this coincided with impaired glucose tolerance and reduced insulin sensitivity.  This study shows that innate variation in BAT activity in women across the menstrual cycle may not only influence energy expenditure but also glycaemic control.