美國芝加哥市Rosalind Franklin醫(yī)學(xué)及科學(xué)大學(xué)的研究人員日前表示,，他們在小鼠實驗中發(fā)現(xiàn)，受到過某種精神刺激,，例如受到大老鼠欺負的小鼠,，大腦內(nèi)產(chǎn)生的壓力會導(dǎo)致新生的神經(jīng)細胞死亡，甚至導(dǎo)致產(chǎn)生憂郁的情緒,。研究人員表示,，這項發(fā)現(xiàn)有助于治療人類的憂郁癥。
研究顯示,，受到欺負的小鼠大腦內(nèi)關(guān)鍵的記憶和情緒區(qū)域也會產(chǎn)生新的神經(jīng)細胞,，但由于其承受巨大的壓力，導(dǎo)致大多數(shù)細胞死亡,。研究作者之一Daniel Peterson表示,，如果可以想辦法幫助小鼠大腦中新生的神經(jīng)細胞存活下來，我們就可以助其遏止憂郁情緒的出現(xiàn),。
在這項研究中,，研究人員將一只小鼠和兩只大的小鼠關(guān)在一個籠子里20分鐘，這段時間里,，大老鼠很快就占了上風(fēng),，它們不停地追咬小老鼠,，小老鼠變得很害怕，情緒也很低落,，分析顯示這時小老鼠體內(nèi)的壓力荷爾蒙,，是其它沒有這種經(jīng)歷的小老鼠的7倍。
當(dāng)他們對小鼠的大腦進行詳細掃描后發(fā)現(xiàn),，仍然有新的細胞生成,，但一周之后這些新細胞中僅有三分之一的細胞存活了下來。這意味著如果想幫助小老鼠避免新生細胞全部死亡,，還有一段時間可以進行治療,。
研究人員接著計劃找出可以保護新生神經(jīng)細胞的藥物，不過現(xiàn)在市場上大多數(shù)抗憂郁藥,，需要幾周的時間才能生效,，所以對保護新生細胞的功效可能不大。
(資料來源 : Bio.com)
原始出處：
Stress and Nerve Cells Survival in Rats; Finding may Open Window for Depression Treatment
03/14/07 -- A single, socially stressful situation can kill off new nerve cells in the brain region that processes learning, memory, and emotion, and possibly contribute to depression, new animal research shows.
Researchers found that in young rats, the stress of encountering aggressive, older rats did not stop the generation of new nerve cells?the first step in the process of neurogenesis. But stress did prevent the cells, located in the hippocampus, from surviving, leaving fewer new neurons for processing feelings and emotions. The hippocampus is one of two regions of the brain that continues to develop new nerve cells throughout life, in both rats and humans. The reduction of neurogenesis could be one cause of depression, says senior author Daniel Peterson, PhD, of the Rosalind Franklin University of Medicine and Science, near Chicago. His team reports their findings in the March 14 issue of The Journal of Neuroscience.
"This is strong evidence that the effects of social stress on neurogenesis occur after a delay of 24 hours or more, providing a possible time window for treatment after acute episodes of stress," says Henriette van Praag, PhD, of the Salk Institute for Biological Studies.
When Peterson and his research team put a young rat in a cage with two older rats for 20 minutes, the resident rats quickly pinned down and, in many cases, bit the intruder. The team reported that intruder rats were fearful and acted depressed around the bigger, more mature animals and had stress hormone levels six times as high as young rats that didn't experience a stressful encounter.
Examining the rats' brains under a microscope, the scientists discovered that even with high levels of stress hormones, the young, stressed rats generated as many new cells as their unstressed counterparts. Previous research had led some to think that hormone levels played a role in blocking the generation of new cells or caused them to die early on. But a week after the encounter, the team found that only a third of the cells generated under stress had survived. Long-term survival of nerve cells was also compromised: When Peterson's team marked newborn cells in the hippocampus, subjected rats to stress a week later, then examined brain tissue at the end of a month, they counted a third fewer fully developed nerve cells.
"The next step is to understand how stress reduced this survival," says Peterson. "We want to determine if anti-depressant medications might be able to keep these vulnerable new neurons alive."
Source: Society for Neuroscience
