Some findings have suggested that individuals with heart failure are two to three times more likely to suffer from depression. The myocardial infarction (MI) is believed to cause increased neuroinflammation in the brain. Going further, additional studies have suggested that post-menopausal women with heart disease have a greater risk of depression than younger women and men of all ages.
A team from the University of Ottawa Heart Institute and Brain and Mind Institute in Canada has conducted a study that investigates the sex differences in depression-like behavior following a heart attack. The work, carried out in a rat model, is published recently in the American Journal of Physiology—Heart and Circulatory Physiology.
To mimic menopause, the team compared adult female rats without ovaries to adult males and normal adult females. Half of the "menopausal" rats received then received estrogen supplements while the other half did not. In test groups of rats, MI was induced by blocking an artery. All animals were then given several standardized tests to measure depression-like behavior, learning, memory and the ability to experience pleasure. Blood samples were also taken for measuring neuroinflammation.
Eight weeks after MI, the team found that the male, but not female, rats with heart failure displayed signs of depression and brain inflammation. In contrast, the menopausal females showed higher rates of depression-like behavior than all of the males studied. Surprisingly, the menopausal rats that were given estrogen showed no depression, with results comparable to rats with ovaries.
“These results suggest that estrogens prevent depression-like behavior induced by [heart failure] post MI in young adult female rats by inhibiting pro-inflammatory cytokines production and actions in the prefrontal cortex,” the team concluded in their paper.
"Understanding the mechanisms contributing to these sex-specific and estrogen-dependent responses may contribute to new therapies that may be sex-specific."