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【科普】1月19日-23日的PNAS新闻摘要
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Appetite suppression differs by gender
Speedy sperm in promiscuous fish
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月19日-23日的PNAS新闻摘要
论文要点
食欲抑制因性别而异
混杂交配的鱼的快速精子
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人工信息素引诱七鳃鳗
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Appetite suppression differs by gender
Men have a better ability to suppress their hunger than women when presented with food, a new study has found. This difference may help explain some of the gender differences in rates of obesity, according to Gene-Jack Wang and colleagues. In two experiments, 23 healthy, non-obese subjects fasted for 17 hours and then either focused on a favorite food or used a technique called cognitive inhibition to suppress thoughts of hunger and eating. When the subjects focused on their favorite food, the hunger and desire for food increased at a similar rate in both sexes, as shown in brain scans using positron emission tomography (PET). Although cognitive inhibition decreased hunger in both sexes, the technique significantly lowered desire for food only in men. PET brain scans showed that men using cognitive inhibition techniques showed a decrease in brain activation in the regions involved in emotional regulation, conditioning, and motivation. These regions are known to play a role in processing the conscious awareness of the drive to eat. The authors suggest that a greater ability to inhibit brain activation from food among men may provide an explanation for higher rates of obesity in women.
Article #08-07423: "Evidence of gender differences in the ability to inhibit brain activation elicited by food stimulation," by Gene-Jack Wang, Nora Volkow, Frank Telang, Millard Jayne, Yeming Ma, Kith Pradhan, Wei Zhu, Christopher Wong, Panayotis Thanos, Allan Geliebter, et al.
MEDIA CONTACT: Gene-Jack Wang, Brookhaven National Laboratory, Upton, NY; tel: 631-344-3608 (primary), 631-344-2837 (secondary); e-mail: gjwang@bnl.gov
食欲抑制因性别而异
一项新的研究发现，当面对食物的时候，男性比女性具有更好地抑制饥饿的能力。Gene-Jack Wang及其同事说，这种差异可能有助于解释肥胖率的一些性别差异。在两项实验中，23位健康、非肥胖的受试者禁食17小时，然后或者把注意力放在喜爱的食物上，或者利用一种称为认知抑制的技巧去抑制饥饿和进食的想法。当这些受试者把注意力放在他们喜爱的食物上的时候，男女受试者的饥饿以及对食物的渴望以类似的速率增加，这是由正电子发射断层扫描技术（PET）对大脑扫描显示的。尽管认知抑制让男女受试者都减少了饥饿，这种技巧仅仅显著降低了男性对食物的渴望。PET扫描显示表明利用认知抑制技巧的男性的大脑表现出了涉及感情调控、条件作用和动机的区域的激活减少。这些区域已知在处理进食冲动的自觉意识方面扮演着一个角色。这组作者提出，男性具有更强的抑制大脑因食物而激活的能力可能为女性更高的肥胖率提供一个解释。
论文#08-07423: "Evidence of gender differences in the ability to inhibit brain activation elicited by food stimulation," 作者 Gene-Jack Wang, Nora Volkow, Frank Telang, Millard Jayne, Yeming Ma, Kith Pradhan, Wei Zhu, Christopher Wong, Panayotis Thanos, Allan Geliebter, et al.
媒体联系人：Gene-Jack Wang，布鲁克黑文国家实验室
Brookhaven National Laboratory, Upton, NY
电话： 631-344-3608 (主要), 631-344-2837 (次要)
电子邮件：gjwang@bnl.gov
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Speedy sperm in promiscuous fish
Promiscuous species of African cichlids have larger, faster sperm, which likely affected the evolution of the fish, according to a new report. John Fitzpatrick and colleagues found that the sperm in the most promiscuous cichlids species have evolved to be faster in the race to the egg than in nonpromiscuous species. Although it seems obvious that sperm would evolve to become more competitive in species in which multiple males mate with a single female, the experimental evidence found to date has been mixed. The authors analyzed 29 closely related species of the cichlid from Lake Tanganyika in East Africa and identified phylogenetic evidence showing that the sperm competition in promiscuous species selects for increases in number, size, and longevity of sperm. They then correlated sperm speed with size, showing that larger sperm swam faster, which was expected because a longer tail should propel sperm faster. A computer reconstruction of cichlid ancestry confirmed that promiscuous behavior, and therefore mating competition, drove the evolution of the species' sperm traits.
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作者:admin@医学,生命科学 2011-06-15 17:11
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