Max-Planck-Institut für Neurobiologie, Am Klopferspitz 18, D-82152 Martinsried, Germany.
Curr Biol. 2013 Mar 18;23(6):507-14. doi: 10.1016/j.cub.2013.02.010. Epub 2013 Mar 7.
Motivation controls behavior [1]. A variety of food-related behaviors undergo motivational modulation by hunger, satiety, and other states [2-4]. Here we searched for critical satiation factors modulating approach to an odor associated with sugar reward in Drosophila melanogaster. We selectively manipulated different parameters associated with feeding, such as internal glucose levels, and determined which are required for suppressing conditioned odor approach. Surprisingly, glucose levels in the hemolymph, nutritional value, sweetness of the food, and ingested volume (above a minimal threshold) did not influence behavior suppression. Instead, we found that the total osmolarity of ingested food is a critical satiation factor. In parallel, we found that conditioned approach is transiently suppressed by artificial stimulation of adipokinetic hormone (AKH) expressing corpora cardiaca cells, which causes elevation of hemolymph carbohydrate and lipid concentrations [5, 6]. This result implies that a rise in hemolymph osmolarity, without the experience of feeding, is sufficient to satiate conditioned odor approach. AKH stimulation did not affect innate sugar preference, suggesting that multiple satiation signals control different sets of appetitive behaviors.
动机控制行为[1]。各种与食物相关的行为会受到饥饿、饱腹感和其他状态的动机调节[2-4]。在这里，我们在黑腹果蝇中寻找调节与糖奖励相关的气味接近的关键饱食因素。我们选择性地操纵与进食相关的不同参数，例如血液中的葡萄糖水平，并确定哪些参数对于抑制条件性气味接近是必需的。令人惊讶的是，血液中的葡萄糖水平、营养价值、食物的甜度和摄入的量（超过最小阈值）并不影响行为抑制。相反，我们发现摄入食物的总渗透压是一个关键的饱食因素。同时，我们发现人工刺激表达肾上腺素能激素（AKH）的心脏体细胞会暂时抑制条件性接近，这会导致血液中碳水化合物和脂质浓度升高[5,6]。这一结果表明，血液渗透压的升高，即使没有进食的体验，也足以满足条件性气味接近。AKH 刺激不会影响先天的糖偏好，这表明多种饱食信号控制着不同的食欲行为。
