Hajnal Andras, Smith Gerard P, Norgren Ralph
Department of Neural and Behavioral Sciences H181, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Am J Physiol Regul Integr Comp Physiol. 2004 Jan;286(1):R31-7. doi: 10.1152/ajpregu.00282.2003. Epub 2003 Aug 21.
Although taste can influence meal size and body weight, the neural substrate for these effects remains obscure. Dopamine, particularly in the nucleus accumbens, has been implicated in both natural and nonnatural rewards. To isolate the orosensory effects of taste from possible postingestive consequences, we investigated the quantitative relationship between sham feeding of sucrose and extracellular dopamine in the nucleus accumbens with microdialysis in rats. Sucrose intake linearly increased as a function of concentration (0.03 M, 18.07 +/- 2.41 ml; 0.1 M, 30.92 +/- 2.60 ml; 0.3 M, 43.28 +/- 2.88 ml). Sham feeding also stimulated accumbens dopamine overflow as a function of sucrose solution concentration (0.03 M, 120.76 +/- 2.6%; 0.1 M, 140.28 +/- 7.8%; 0.3 M, 146.27 +/- 5.05%). A second experiment used the same protocol but clamped the amount of sucrose ingested and revealed a similar, concentration-dependent dopamine activation in the nucleus accumbens. This is the first demonstration of a quantitative relationship between the concentration-dependent rewarding effect of orosensory stimulation by sucrose during eating and the overflow of dopamine in the nucleus accumbens. This finding provides new and strong support for accumbens dopamine in the rewarding effect of sucrose.
尽管味觉可影响进食量和体重，但这些作用的神经基质仍不清楚。多巴胺，尤其是伏隔核中的多巴胺，与自然奖赏和非自然奖赏均有关联。为了将味觉的口感觉效应与可能的摄食后后果区分开来，我们采用微透析技术研究了大鼠假饲蔗糖与伏隔核细胞外多巴胺之间的定量关系。蔗糖摄入量随浓度呈线性增加（0.03M，18.07±2.41ml；0.1M，30.92±2.60ml；0.3M，43.28±2.88ml）。假饲也会刺激伏隔核多巴胺释放，且与蔗糖溶液浓度有关（0.03M，120.76±2.6%；0.1M，140.28±7.8%；0.3M，146.27±5.05%）。第二个实验采用相同方案，但控制了蔗糖摄入量，结果显示伏隔核中多巴胺的激活同样呈浓度依赖性。这首次证明了进食期间蔗糖对口感觉刺激的浓度依赖性奖赏效应与伏隔核中多巴胺释放之间的定量关系。这一发现为伏隔核多巴胺在蔗糖奖赏效应中的作用提供了新的有力支持。
