来自英国的一组科学家最近通过研究发现：一种主要负责调节食欲的激素在人体内通过大脑的两个不同区域发挥其作用。
伦敦大学的科学家分别分析了大脑视丘下部和前额叶皮质的活性，并且通过测量功能核磁共振获得的图像成功预测了参与到实验中的八位体重正常的男性进食量的多少。
参与测试的男性在14小时内没有进食，然后科学家们为他们静脉注射了被称为YY多肽的激素，或是安慰剂，注射后再对参与者的大脑进行扫描。接着小组测量了这些男性进食量的多少。
结果发现，每一位参与者在接受了YY多肽的注射之后进食量都变少了，但是对于那些注射了安慰剂的参与者，其大脑中视丘下部的活跃性能预测出这些男性进食量的多少。与此相比，注射了YY多肽的参与者，其大脑中前额叶皮质的活跃程度也能起到同样的预测作用。
研究项目负责人，来自UCL英国医学研究理事会的临床科学家Rachel Batterham表示，这些发现将有助于肥胖的治疗，她说：“肥胖是目前西方社会所面临的最大健康问题之一。”以上研究结果发表在《自然》（Nature）上。（ 教育部科技发展中心）
原文链接：http://www.physorg.com/news111943211.html
原始出处:
Nature advance online publication 14 October 2007 | doi:10.1038/nature06212; Received 31 May 2007; Accepted 31 August 2007; Published online 14 October 2007
PYY modulation of cortical and hypothalamic brain areas predicts feeding behaviour in humans
Rachel L. Batterham1, Dominic H. ffytche2, J. Miranda Rosenthal1, Fernando O. Zelaya2, Gareth J. Barker2, Dominic J. Withers1 & Steven C. R. Williams2
Centre for Diabetes and Endocrinology, Department of Medicine, University College London, London WC1E 6JJ, UK
Centre for Neuroimaging Sciences, King's College London, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF, UK
Correspondence to: Rachel L. Batterham1 Correspondence and requests for materials should be addressed to R.L.B. (Email: r.batterham@ucl.ac.uk).
The ability to maintain adequate nutrient intake is critical for survival. Complex interrelated neuronal circuits have developed in the mammalian brain to regulate many aspects of feeding behaviour, from food-seeking to meal termination. The hypothalamus and brainstem are thought to be the principal homeostatic brain areas responsible for regulating body weight1, 2. However, in the current 'obesogenic' human environment food intake is largely determined by non-homeostatic factors including cognition, emotion and reward, which are primarily processed in corticolimbic and higher cortical brain regions3. Although the pleasure of eating is modulated by satiety and food deprivation increases the reward value of food, there is currently no adequate neurobiological account of this interaction between homeostatic and higher centres in the regulation of food intake in humans1, 4, 5. Here we show, using functional magnetic resonance imaging, that peptide YY3–36 (PYY), a physiological gut-derived satiety signal, modulates neural activity within both corticolimbic and higher-cortical areas as well as homeostatic brain regions. Under conditions of high plasma PYY concentrations, mimicking the fed state, changes in neural activity within the caudolateral orbital frontal cortex predict feeding behaviour independently of meal-related sensory experiences. In contrast, in conditions of low levels of PYY, hypothalamic activation predicts food intake. Thus, the presence of a postprandial satiety factor switches food intake regulation from a homeostatic to a hedonic, corticolimbic area. Our studies give insights into the neural networks in humans that respond to a specific satiety signal to regulate food intake. An increased understanding of how such homeostatic and higher brain functions are integrated may pave the way for the development of new treatment strategies for obesity.
