Posted by jrbecker on August 2, 2004, at 10:34:41
In reply to Re: CORLUX (Mifepristone), posted by jrbecker on August 2, 2004, at 10:27:27
from the headlines today. interesting...
http://www.newscientist.com/news/news.jsp?id=ns99996226
Hormone levels turn mouse mums fearless05:00 01 August 04
NewScientist.com news service
Mouse mothers become fearless when levels of a particular hormone drop, reveals a new study. This gives mothers the courage to ferociously attack any would-be assailants to their offspring.In response to scary or stressful situations, the brain secretes corticotropin-releasing hormone (CRH), which triggers a complex cascade of hormones that ready the body for action, such as raising blood sugar levels. It also feeds into the part of the brain which generates feelings of fear and anxiety. Elevated levels of CRH have been linked with symptoms of depression in both rodents and humans.
But lactating females have chronically low levels of CRH in the brain, which is thought to make them generally less anxious. For example, studies in humans show that nursing women are less perturbed, both physiologically and emotionally, by stressful situations.
Stephen Gammie and colleagues at the University of Wisconsin, Madison, US wondered if lowered CRH might also be responsible for a mother’s fearless bravery.
To test their theory, the team injected three different concentrations of CRH or a saline solution into the brains of nursing mothers and then placed a male her nesting cage. Compared to controls, who immediately assaulted the male, mice injected with the two higher doses of CRH showed almost no maternal aggression. Their response was delayed, their attacks less frequent and much shorter.
Stressful jobs
Mothers with the lowest levels of CRH attacked intruding males more than 20 times for the duration of about 45 seconds.“Low levels CRH seem to be necessary for maternal protective behaviour. It makes evolutionary sense for mothers to increase aggression because it’s critical for them just to keep the kids alive,” says Gammie. Unbalanced levels of CRH in humans may also be connected with post-partum depression, he says.
For the past few years, pharmaceutical companies have been working to develop CRH receptor blockers, like antalarmin, as a treatment for anxiety disorders, depression and post traumatic stress disorder. The drugs could have a performance-enhancing effect on people with extremely stressful jobs.“In war, soldiers are under high stress constantly,” says Tracy Bale, who works on CRH and depression at University of Pennsylvania. “In those cases, a CRH blocker might help.”
However, results with animal studies suggest that responses could be highly sex-dependant. And, adds Bale, the dose would be critical because CRH is involved with many other bodily functions, including glucose metabolism. Blocking too much CRH might hinder performance more than it helps.
Journal reference: Behavioral Neuroscience (DOI: 10.1037/0735-7044.118.4.000)
Anna Gosline
poster:jrbecker
thread:371835
URL: http://www.dr-bob.org/babble/20040730/msgs/373144.html