Source: Hebrew University of Jerusalem
Date: 5 April 2009
Reaction to stress traced to genetic differences
Can people's differing reactions to situations of stress be attributed at least in part to genetic differences and do those differences affect men and women in different ways - with the edge seemingly favoring the women? Research conducted at the Hebrew University of Jerusalem would seem to indicate that the answer to both questions is yes.
Some people appear to be resilient to difficult conditions, whereas others react adversely to such challenges, incurring a range of physical and mental disorders. Much research has shown that the way in which the brain and body adapt to acute and chronic stress are critical for physical and mental health. Further, according to a recent report by the World Health Organization (WHO), stress will be the second leading cause of mortality worldwide over the next 20 years.
It is generally believed that the genetic code plays a prominent role in different responses to stress. It has been estimated that the heredity factor determines by some 62 percent the level of the stress hormone (cortisol) in our bodies. However, only a handful of investigations so far have documented the role of specific genetic variants on shaping the stress response among individuals.
In an effort to reveal a genetic basis for coping with stress, the Hebrew University researchers devised a laboratory-based social stress test. The trials were carried out on students at the Hebrew University Department of Psychology and at the Aaron Beare Research Laboratories at Herzog Hospital by Idan Shalev, a doctoral student of Hebrew University Psychology Prof. Richard Ebstein, and in collaboration with Dr. Marsha Kaitz of the Department of Psychology. The results were published recently online in the journal Psychoneuroendocrinology.
In the test, the researchers examined the salivary cortisol response in 97 university students via the Trier Social Stress Test (TSST) devised at Trier University in Germany. The TSST measures changes in salivary cortisol to assess stress reactivity to challenging social situations.
The students were told that they would play the role of an interviewee for a job and had five minutes to convince the interviewers to hire them. The interview was carried out with a microphone and camera in front of a panel of three straight-faced judges. Additionally, in a second phase of the interview, subjects were tested in a mental arithmetic task in which they were asked to count backwards (out loud) from 1,687 in multiples of 13 as quickly and accurately as possible. If the subject made a mistake he or she was asked to start the series again.
In addition to testing the cortisol level, mouthwash samples were taken and subjects were genotyped for the brain-derived neurotrophic factor (BDNF) gene, which is involved in supporting the growth and differentiation of brain cells. Importantly, animal studies show that BDNF expression is reduced in chronic stress and restored by antidepressant treatment.
The BDNF gene is characterized by a variant that codes for either the valine (Val) or methionine (Met) amino acids. Individuals carry two copies of each gene, with the Val variant being more common. In the study, subjects carrying two copies of the VAL variant (Val/Val), were compared in their cortisol response to those carrying one copy of the Val and one of the Met (Val/Met).
When looking at the responses of the subjects in the stress testing, it was seen that the Val/Met men and women carriers had nearly equal cortisol levels. However, the men with the Val/Val variant had a higher cortisol response (and therefore a higher reaction to social stress) than the men carrying the Val/Met variant. For the women, surprisingly, the opposite was found: the Val/Val women had a lower cortisol response than the Val/Met women. Why the Val/Val variant produces opposite stress reactions (raising it for the males and lowering it for the females) remains an enigma.
Because of the predominance of the Val/Val type for both sexes, the males showed overall greater stress in the testing than the females.
The Hebrew University researchers point out that their investigation shows the importance of genotyping as an aid in helping to resolve paradoxical observations related to stress-related sex differences and also in providing new insight into understanding how depression and other psycho-neurological illnesses may be the result of a combination of stressful life events and genetic factors.
In conclusion, say the researchers, the study specifically indicates that women with the BDNF Val/Met genotype and men with the Val/Val may be particularly vulnerable to social stress mediated by brain stress system activity.
"'I'll make old vases for you if you want them—will make them just as I made these.' He had visions of a room full of golden brown beard. It was the most appalling thing he had ever witnessed, and there was no trickery about it. The beard had actually grown before his eyes, and it had now reached to the second button of the Clockwork man's waistcoat. And, at any moment, Mrs. Masters might return! "Worth stealing," a Society journalist lounging by remarked. "I could write a novel, only I can never think of a plot. Your old housekeeper is asleep long ago. Where do you carry your latchkey?" "Never lose your temper," he said. "It leads to apoplexy. Ah, my fine madam, you thought to pinch me, but I have pinched you instead." How does that strike you, Mr. Smith? Fancy Jerusha Abbott, (individually) ever pat me on the head, Daddy? I don't believe so-- The confusion was partly inherited from Aristotle. When discussing the psychology of that philosopher, we showed that his active Nous is no other than the idea of which we are at any moment actually conscious. Our own reason is the passive Nous, whose identity is lost in the multiplicity of objects with which it becomes identified in turn. But Aristotle was careful not to let the personality of God, or the supreme Nous, be endangered by resolving it into the totality of substantial forms which constitute Nature. God is self-conscious in the strictest sense. He thinks nothing but himself. Again, the subjective starting-point of305 Plotinus may have affected his conception of the universal Nous. A single individual may isolate himself from his fellows in so far as he is a sentient being; he cannot do so in so far as he is a rational being. His reason always addresses itself to the reason of some one else—a fact nowhere brought out so clearly as in the dialectic philosophy of Socrates and Plato. Then, when an agreement has been established, their minds, before so sharply divided, seem to be, after all, only different personifications of the same universal spirit. Hence reason, no less than its objects, comes to be conceived as both many and one. And this synthesis of contradictories meets us in modern German as well as in ancient Greek philosophy. 216 "I shall be mighty glad when we git this outfit to Chattanoogy," sighed Si. "I'm gittin' older every minute that I have 'em on my hands." "What was his name?" inquired Monty Scruggs. "Wot's worth while?" "Rose, Rose—my dear, my liddle dear—you d?an't mean——" "I'm out of practice, or I shouldn't have skinned myself like this—ah, here's Coalbran's trap. Perhaps he'll give you a lift, ma'am, into Peasmarsh." Chapter 18 "The Fair-pl?ace." "Yes," replied Black Jack, "here they are," drawing a parchment from his pocket. "This is the handwriting of a retainer called Oakley." HoME大桥未久AV手机在线观看
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