Estrogen has probably given soon after menopause is the protection of stroke

Estrogen replacement therapy for stroke to the protection, it must be likely to drop quickly after the planes because of menopause or surgical removal of ovaries, the researchers report in the Journal of Neuroscience will be granted.

Animal studies indicate a "critical period" for replacement therapy of estrogen and that if treatment is delayed, are estrogen receptor in brain cells significantly promotes neuroprotection by estrogen in general as well as decreased Research Medical College of Georgia, North China Coal Medical University and the University of Texas Health Science Center at San Antonio.

"We, the controversy about whether estrogen is after a long period without it being useful and have found the answer seems" not seen,''said Dr. Darrell W. Brann, chief of neurobiology program development and MCG The author of the study.

He is referencing the controversy arose from an Initiative for Women's Health, a 12-year study of 161,808 women aged 50-79 who have examined the health benefits of hormone replacement therapy. One of the surprising findings was that estrogen and estrogen and progesterone increases the risk of stroke therapy more effective than decreasing. Critics, who had a problem with the study that many women for years without HRT.

Animal studies show that they could be right, at least in terms of the ability of estrogen to protect the brain. Studies on the hippocampus, a center of learning and memory, where scientists have shown that estrogen was strongly protective against stroke addressed in rats treated with estrogen had a week after surgical removal of ovaries. As replacement therapy for 10 weeks after the move has been delayed - until a few years of life - estrogen is basically useless.

A closer examination of the rats, which exceeded 10 weeks, without the mediation of estrogen receptor alpha probably neuroprotective effects of estrogen were reduced by 50 percent or more.

"So, could not meet the receivers," said Brann, who also associate director of the Institute of MCG for molecular medicine and genetics. "It seems that the adjustment of the data it makes little estrogen is necessary to keep the receiver at a reasonable level."

Interestingly, estrogen receptors were still intact and open to the uterus, is another important objective of estrogen. "We try to know why there is a difference in tissue," says Brann.

But inside the brain, there were other signs of collateral damage of estrogen deficiency. CA3, a region of the hippocampus, which resistance tends to be a stroke, was prone to stroke in rats, was the long term without estrogen. "Estrogen have to do something that is very important for the protection of CA3, and we believe it is to remove the production of NADPH oxidase, says Dr. Brann. NADPH oxidase, an enzyme that makes the free radical superoxide, which is abundant in the CA1 region near, but at low levels in CA3. The two regions, he noted, are crucial for learning and memory.

In case of stroke, helps to suppress estrogen production of free radicals in CA1 cells can be lethal to a further increase. Studies have shown the CA1 and CA3 regions are also susceptible to stroke animals that have a long time without estrogen.

"If this is true in humans, only with surgical menopause, for example, women want to be in order when they arrived to severe stress," Dr. Brann, noting that stress is not only a severe blow, but also emotional stress or simple aging. It may also explain why women who undergo surgical menopause have an increased risk of cognitive impairment and dementia. "This is what we believe, based on these data," says Dr. Brann.

The next steps are to investigate the status of estrogen receptors in the brain of aged rats by nature - the equivalent of more than 70 years in humans - see what happens with the normal age, the loss of estrogen and waited a moment, then put estrogen back to see if there is no advantage.

You want to examine the neuroprotective benefits of estrogen produced locally in the brain compared to the evaluation of the ovaries, the main source of estrogen. In the last decade, scientists have learned that neurons and supporting glial cells to produce estrogen locally in the brain by the enzyme aromatase. Men and women have estrogen receptors in the brain and the scientific consensus is that the brains of people also produce estrogen.