Symptoms of insect bites and stings. An insect bite or sting often causes a small lump to develop, which is usually very itchy. A small hole, or the sting itself, may also be visible. The lump may have an inflamed (red and swollen) area around it that may be filled with fluid. This is called a weal.
Hormones and the Brain. That's not to say estrogen isn't a major player in regulating moods. Estrogen acts everywhere in the body, including the parts of the brain that control emotion. Some of estrogen's effects include: 1  Increasing serotonin, and the number of serotonin receptors in the brain.
Most Common Cause. A lack of estrogen is the most common cause of postmenopausal spotting in women not taking hormone therapy. Estrogen production drops to a low level after menopause, causing the tissues of both the vagina and uterus can become dry, thin and fragile. This is known as atrophy, which can cause bleeding.