The brain has a sweet tooth
Experiments on mice have shown that the brain determines the calorie content of food regardless of its taste. This discovery will help specialists to understand the mechanisms of obesity development.
Scientists at Duke University (Durham, North Carolina), working under the guidance of Dr. Ivan de Araujo, have created genetically modified mice whose taste buds are deprived of one of the key components and are unable to taste sweet.
After that, they conducted a series of behavioral tests to compare the preferences of normal and transgenic mice who were offered solutions of sugar and the non-calorie sweetener sucralose. Both groups of animals, regardless of their ability to taste sweet, invariably preferred high-calorie sugar water.
Analysis of the functioning of the animals' brains showed that the reward mechanism was triggered in them in response to the intake of calories into the body, regardless of the ability to taste. According to the results of the analysis, the level of dopamine in the brain, which is the main activator of the reward mechanism, increased with the intake of calories into the body. In addition, electrophysiological studies have demonstrated that neurons of the nucleus accumbens, a region of the brain that plays a key role in obtaining pleasant sensations for humans and animals, including when eating, in transgenic and ordinary mice were equally activated in response to the intake of calories.
A significant point is the fact that the preference for sucrose over sucralose developed only 10 minutes after the start of feeding, while the neurons of the reward system reacted with the same delay.
In other words, the authors demonstrated that dopamine-triggered mechanisms responsible in the brain for the feeling of pleasure, including when assessing the attractiveness of pleasant-tasting compounds, react to the caloric value of sucrose in the absence of signals from taste receptors. Thus, the brain not only reacts to pleasant sensations experienced when eating, but also performs previously unknown functions, including registration of digestive and metabolic signals.
The scientific questions raised by the discovery of the brain's ability to respond to the intake of calories are extremely important for understanding the pathogenesis of human obesity. For example, based on the data obtained, it can be assumed that high-calorie food causes a stronger activation of the reward system and, accordingly, a stronger desire to continue enjoying food. The authors believe that, in any case, their results stimulate the work of the scientific community to study the participation of cognitive centers of the brain in the regulation of food intake and weight control.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
27.03.2008