The researchers studied sweet-blind mice and normal mice that didn't eat or drank anything for 20-22 hours.
The mice had access to two bottles of water. One bottle contained plain, unsweetened water. The other bottle contained water sweetened with sugar.
All of the mice preferred the sugary water. And after drinking the sugary water, brain levels of the pleasure chemical dopamine rose in the mice.
Next, the mice got a choice between plain water and water sweetened with sucralose, a no-calorie sweetener. The normal mice preferred the sweet water, but the sweet-blind mice had no preference.
And although dopamine levels rose when the sweet-blind mice drank water spiked with sugar, that didn't happen when they drank sucralose-sweetened water or unsweetened water.
Sugar's appeal may lie in its calories, as well as its taste, conclude Ivan de Araujo, PhD and colleagues; de Araujo, who worked on the study at Duke University, now works at Yale University's John B. Pierce Laboratory.
The study is "important and interesting," write Yale University's Zane Andrews, PhD, and Tamas Horvath, DVM, PhD, in an editorial published with the study in tomorrow's edition of Neuron.
Andrews and Horvath point out that since the mice were hungry and thirsty, they may have responded differently than under normal conditions.
The editorialists call for more research on the topic, since other studies have shown "cross talk" in the brain about food's pleasurable (taste) and practical (calories) aspects.