Many stress-related mental illnesses, including depression and post-traumatic stress disorder (PTSD), occur at least twice as often in women as in men. While social and cultural factors certainly may contribute to this statistic, potential neurobiological reasons for this discrepancy have been inadequately investigated. Depression and PTSD are characterized by dysfunction of an area of the brain called the prefrontal cortex (PFC), which is known to govern higher cognitive abilities like concentration and short-term memory. These functions have been shown in lab animals to be disrupted after exposure to stress. However, the experiments have largely been done only in male animals, and sex differences in how the PFC responds to stress are unknown. A better understanding of such processes may help to elucidate the reason that women are more susceptible to stress-related disorders, and lead to the development of better anti-depressant treatments.
To examine the effects of stress on PFC function, male and female rats were exposed to different levels of mild stress, and then tested on a short-term memory task. The authors found that without stress, males and females performed equally well on the task. Likewise, after exposure to higher levels of stress, both males and females made significant memory errors. However, after exposure to a moderate level of stress, females were impaired, but males were not, suggesting that females were more sensitive to the PFC-impairing effects of stress. When the authors monitored the female rats’ estrus cycles, they found that the rats showed this sensitivity only when they were in a high-estrogen phase. To further investigate the role of estrogen in this effect, Shansky et al removed the ovaries of a new group of female rats, thus eliminating any circulating estrogen. A time-release capsule containing either estrogen or placebo was implanted and the experiment repeated. Estrogen replacement had the same effect as naturally circulating estrogen--animals with estrogen capsules displayed the same sensitivity to stress that females in the high-estrogen estrus phase did, while animals with placebo capsules were unaffected.
Together, these results suggest that high levels of estrogen can act to enhance the stress response, causing greater stress-related cognitive impairments. It is important to note, however, that estrogen had no effect on cognitive performance under non-stressful conditions. The idea that estrogen could contribute to the higher prevalence of stress-related disorders in women is consistent with reports that the discrepancy first arises at puberty, maintains through the child-bearing years, and then declines, such that it is equally likely to occur in post-menopausal women as in men of the same age. The mechanisms by which estrogen may be producing these effects are to date unknown, but currently under investigation. It is known that estrogen can interact with molecular processes involved in the stress response, and that certain genetic variations have been demonstrated in clinically depressed women. However, how these factors might combine to produce the glaring disparity in the prevalence of this disorder awaits discovery. Such knowledge will hopefully lead to the development of new, more effective treatments for depression.
Aimee Midei | EurekAlert!
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The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
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Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
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