A study from the University of Jyväskylä has found that low oestrogen can affect the body’s systemic signalling in response to exercise.
Menopause is associated with several negative changes in health that cannot be counteracted with exercise alone. Menopause causes low oestrogen, which can lead to an increase in metabolic and cardiovascular diseases.
Currently, scientists do not understand why high levels of physical activity do not diminish some of the negative impacts of menopause, such as blood lipids. It has not yet been studied whether low oestrogen can affect systemic responses to exercise.
The effect of oestrogen deficiency on blood circulation
The researchers examined how the body reacts to exercise differently in people with oestrogen deficiency and when oestrogen is obtained from hormone therapy.
“We investigated the effect of oestrogen deficiency on two signalling molecules in blood circulation; extracellular vesicles (EV) and high-density lipoprotein (HDL) particles,” said Sira Karvinen, the principal investigator of the ErROR-study.
“EVs are membrane-bound transport vehicles sent by cells, which are used in communication between tissues. The best-known function of HDL particles is reverse cholesterol transport, by which the body removes excess cholesterol from peripheral tissues. Recent studies have shown that HDL particles can also act as inter-tissue messengers,” she added.
A total of 18 postmenopausal women took part in the study, half of whom underwent oestrogen-based hormone replacement therapy. The participants conducted a maximal oxygen uptake test on a bicycle ergometer in order to induce a systemic response to exercise.
The researchers took blood plasma samples from each participant before and after the exercise test. These samples were analysed to see if exercise affected the number of messenger molecules carried via EVs or HDL particles.
How exercise can affect signal carriers
“Our study is the first in which the messenger molecule content carried via EV and HDL particles have been accurately compared to each other and showed differences between these two signal carriers,” explained associate professor and researcher on the EsmiRs study, Eija Laakkonen.
“When we studied the contents of the messenger molecules in samples taken before and after exercise, we found that the contents change in response to exercise in both EV and HDL particles,” she continued.
The researchers found that hormone replacement therapy affected the body’s communication. They emphasised that more research is needed to establish whether this unresponsiveness to exercise in oestrogen-deficient women has any wider health implications.
“Exercise typically causes clear changes in the number of micro-RNA molecules in the blood, as we have previously shown. Based on our new results, the oestrogen level affects exercise-induced signalling in EV and HDL particles and can affect the metabolism of postmenopausal women during exercise via micro-RNA molecules,” said Karvinen.
“It is possible that the differences in systemic communication in response to exercise is part of the reason why vigorous exercise is not enough to diminish the negative changes in health associated with menopause,” she concluded.
