Recent research in the journal “Hypertension” has found that young women with obesity are more prone to heart diseases. The study has shown that a hormone (progesterone) in females that helps them to get and stay pregnant can increase the early risk of CVD. Whereas, the results are similar in both, animal models and the human blood vessels.
Progesterone increases the expression of aldosterone receptors
Premenopausal women are believed to be protected from CVD. But the recent evidence shows that some factors in young women with obesity can negate those benefits. And in fact, it can place them at higher risk of heart diseases than men.
In this study, the research team has recorded an increase in levels of receptors for the aldosterone. This hormone can damage the endothelial cells lining the blood vessels. While the hormone progesterone is responsible for the expression of these receptors at high levels.
Females have naturally higher levels of aldosterone. But its expression further increases in the case of young women with obesity. Such a high level of aldosterone found in obesity has a bad impact on blood vessels. It directly affects blood pressure and induces inflammation, stiff and scarred arteries, and heart enlargement.
The fact that fat produces leptin (satiety hormone) may be a starting point for this storm. With obesity, both women and men produce more leptin due to the presence of more fat. But the leptin produced per ounce of fat in women is more than men. After some time, the brain stops listening to leptin’s signal about being full.
And the CV system becomes more responsive. In males, leptin stimulates the sympathetic nervous system (fight or flight response). That increases the rate of heartbeat and blood pressure. In contrast, this system doesn’t activate in younger females, even with obesity. And a sky-high level of aldosterone was detected in them.
Progesterone and blood vessels dysfunction
A cardiothoracic surgeon at AU Medical Centre has stated that in recent years, one-third of the patients he has operated on were females. And often, the females were young with excess body weight. Also, there was a presence of some other confounding factors like smoking and diabetes.
For a better understanding of sex differences in this disease process, the research team deleted either mineralocorticoid or progesterone receptors in female mice. And found that both deletions have prevented dysfunction of the blood vessels.
But, in reality, it was progesterone that derived the sex differences during the expression of mineralocorticoid receptors. So, a suppression in aldosterone receptors was present, even with the deletion of progesterone receptors only. In further analysis, the team removed the ovaries of female mice.
That are responsible for the production of progesterone and estrogen in females. After the removal of ovary, the numbers of aldosterone receptors were found equal in both female and male mice. Later, the team gave these hormones to female mice, both separately and together.
And found that it was rather the progesterone and not estrogen that has led to an increase in expression of aldosterone receptors in females. Whereas, adding progesterone to the endothelial cells of human have also given the same response. Overall, the study implies that when obesity isn’t a factor, the high level of both hormones isn’t a bad thing.
Still, there isn’t much evidence about how the increase in levels of progesterone is related to obesity. But previous data suggests that obesity can lead to an imbalance in the levels of various hormones. There may be other factors involved in high levels of aldosterone receptors. However, up till now, it’s only happening in females.