Endocrine Interactions
Bidirectional crosstalk between the stress and sex hormone systems
The systems that govern the hormonal response to stress and “reproductive” hormones in women engage in bidirectional interactions. One direction of this interaction is arguably more well-known to scientific and non-scientific audiences: high levels of chronic stress can interrupt the reproductive cycle in women. This makes sense when considering survival, under conditions of long-term stress (e.g., starvation) reproduction ceases to be a biological priority and so resources typically reserved for such functions are diverted elsewhere.
The interaction between these systems, the hypothalamic-pituitary-adrenal axis and hypothalamic-adrenal-ovarian axis, is not limited to the inhibitory action of cortisol on reproduction. Estradiol and progesterone also impact the cortisol response to stress. Arguably, this direction of the bidirectional interaction of these systems has more day-to-day influence on women than the effects of chronic stress on reproductive function.
Women experience monthly fluctuations of estradiol and progesterone (and the gonadotropins). These fluctuations become more erratic during the perimenopause. Cycling ceases and estradiol and progesterone levels plumet after the menopause transition. That estradiol and progesterone can influence the cortisol response to stress suggests that the way in which women respond to stressors may change over the course of the month and the adult lifespan. Of course, this also means that women could experience other shifts in physiological stress reactivity, such as during pregnancy, the postpartum period, lactation, and using hormonal contraceptives.
Stress plays integral roles in maintaining homeostasis, cognition, brain health and function, and aging. In my research, I aim to understand how these different hormone profiles affect the physiological stress response. I am particularly interested in how understanding the impact of estradiol and progesterone levels on the cortisol response may help promote cognitive processes and brain function with age.