Featured Research

from universities, journals, and other organizations

Long-term hormone treatment increases synapses in female rats' prefrontal cortex

Date:
July 9, 2012
Source:
University of Illinois at Urbana-Champaign
Summary:
A new study of aged female rats found that long-term treatment with estrogen and a synthetic progesterone known as MPA increased levels of a protein marker of synapses in the prefrontal cortex, a brain region known to suffer significant losses in aging. The new findings appear to contradict the results of the Women's Health Initiative, a long-term study begun in 1991 to analyze the effects of hormone therapy on a large sample of healthy postmenopausal women aged 50 to 79.

A new study of aged female rats found that long-term treatment with estrogen and a synthetic progesterone known as MPA increased levels of a protein marker of synapses in the prefrontal cortex, a brain region known to suffer significant losses in aging.

The new findings appear to contradict the results of the Women's Health Initiative, a long-term study begun in 1991 to analyze the effects of hormone therapy on a large sample of healthy postmenopausal women aged 50 to 79. Among other negative findings, the WHI found that long-term exposure to estrogen alone or to estrogen and MPA resulted in an increased risk of stroke and dementia. More recent research, however, suggests that starting hormone replacement therapy at the onset of menopause, rather than years or decades afterward, yields different results.

The new study, from researchers at the University of Illinois, is the first to look at the effects of long-term treatment with estrogen and MPA on the number of synapses in the prefrontal cortex of aged animals. The researchers describe their findings in a paper in the journal Menopause.

"The prefrontal cortex is the area of the human brain that loses the most volume with age," said U. of I. psychology professor and Beckman Institute affiliate Janice Juraska, who led the study with doctoral student Nioka Chisholm. "So understanding how anything affects the prefrontal cortex is important."

The prefrontal cortex, just behind the forehead in humans, governs what researchers call "executive function" -- planning, strategic thinking, working memory (the ability to hold information in mind just long enough to use it), self-control and other functions that tend to decline with age.

Most studies of the effects of hormone treatments on the brain have focused on the hippocampus, a structure important to spatial navigation and memory consolidation. The studies tend to use young animals exposed to hormones for very brief periods of time (one or two days to a few weeks at the most). They have yielded mixed results, with most research in young female animals indicating an increase in hippocampal synapses and hippocampal function after exposure to estrogen and MPA.

"For some reason, a lot of researchers still look at the effects of hormones in young animals," Chisholm said. "And there's a lot of evidence now saying that the aged brain is different; the effect of these hormones is not going to be the same."

The new study followed middle-aged rats exposed to estrogen alone, to no additional hormones, or to estrogen in combination with MPA for seven months, a time period that more closely corresponds to the experience of women who start hormone therapy at the onset of menopause and continue into old age. The researchers removed the rats' ovaries just prior to the hormone treatment (or lack of treatment) to mimic the changes that occur in humans during menopause.

"Our most important finding is that estrogen in combination with MPA can result in a greater number of synapses in the prefrontal cortex than (that seen) in animals that are not receiving hormone replacement," Chisholm said. "Estrogen alone marginally increased the synapses, but it took the combination with MPA to actually see the significant effect."

"Our data indicate that re-examining the effects of estrogen and MPA, when first given to women around the time of menopause, is merited," Juraska said.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Journal Reference:

  1. Chisholm NC, Juraska JM. Effects of long-term treatment with estrogen and medroxyprogesterone acetate on synapse number in the medial prefrontal cortex of aged female rats. Menopause, 2012 Jul;19(7):804-11 [link]

Cite This Page:

University of Illinois at Urbana-Champaign. "Long-term hormone treatment increases synapses in female rats' prefrontal cortex." ScienceDaily. ScienceDaily, 9 July 2012. <www.sciencedaily.com/releases/2012/07/120709142802.htm>.
University of Illinois at Urbana-Champaign. (2012, July 9). Long-term hormone treatment increases synapses in female rats' prefrontal cortex. ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/2012/07/120709142802.htm
University of Illinois at Urbana-Champaign. "Long-term hormone treatment increases synapses in female rats' prefrontal cortex." ScienceDaily. www.sciencedaily.com/releases/2012/07/120709142802.htm (accessed August 22, 2014).

Share This




More Health & Medicine News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Cadavers, a Teen, and a Medical School Dream

Cadavers, a Teen, and a Medical School Dream

AP (Aug. 21, 2014) Contains graphic content. He's only 17. But Johntrell Bowles has wanted to be a doctor from a young age, despite the odds against him. He was recently the youngest participant in a cadaver program at the Indiana University NW medical school. (Aug. 21) Video provided by AP
Powered by NewsLook.com
American Ebola Patients Released: What Cured Them?

American Ebola Patients Released: What Cured Them?

Newsy (Aug. 21, 2014) It's unclear whether the American Ebola patients' recoveries can be attributed to an experimental drug or early detection and good medical care. Video provided by Newsy
Powered by NewsLook.com
Lost Brain Cells To Blame For Sleep Problems Among Seniors

Lost Brain Cells To Blame For Sleep Problems Among Seniors

Newsy (Aug. 21, 2014) According to a new study, elderly people might have trouble sleeping because of the loss of a certain group of neurons in the brain. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins