The 'sixth sense' of the brain detects calories

In an experiment with mice, scientists found that the brain can recognize calories in food independently of the taste mechanism. The brain's sensory system activated by this 'sixth sense' mechanism is significant in understanding the cause of obesity.

For example, this finding shows why fructose corn syrup, widely used as a sweetener in food, can contribute to obesity. Ivan de Araujo and colleagues published their findings in the March 27, 2008 issue of Neuron.

In their experiments, scientists have made genetic changes that make 'sweet-blind' mice, missing the key components of sensory cells, allow them to recognize sweetness. Next scientists carried out behavioral experiments, they compared 'sweet-blind' and normal mice when they gave them the freedom to choose no sugar and sucraloza sweetener solutions. calories. In those experiments, the "sweet-blind" mice chose a sugar solution containing calories, which was not dependent on the taste ability, but on the internal calorie content.

The mouse is eating a sweet plum (Photo: istockphoto)

Analyzing the brains of "sweet-blind" mice, the researchers showed that the delightful circuitry in these animals was triggered by the caloric intake, independent of their taste buds. These analyzes also showed that the chemical concentration of dopamine in the brain, known as the center to activate the sensory circuitry, also increased when calorie intake increased. At the same time, neurophysiological studies show that neurons in the food sensing region, called nucleus accumbens, are activated by caloric intake, independent of taste.

Significantly, the researchers also found that the preference of sucrose to sucralose was formed after ten minutes for an hour-long meal and that neurons in the sensory region also began to react after a similar delay.

'In short, we have shown that the dopamine sensing system, previously tasked with detecting the value of pleasure in compounds, reacts to the caloric value of sucrose even when a cold organ is missing. Get the taste buds, " the scientists concluded. 'So, these mechanisms of the brain not only encode the effects of taste sensation in food, but also perform functions that were not previously found, including detecting the signal of transfer. chemistry and metabolism ' .

According to an introduction to the article by Zane Andrews and Tamas Horvath in Neuron, the scientific questions given by exploring brain's calorie recognition system 'are extremely important to understand the origin. Pathogenesis and sociology of human obesity ' .

'For example, fructose-rich corn syrup is a popular sweetener in the United States, and the evidence suggests that fructose is not as effective as sucrose for a meal. Fructose can create a greater stimulus for the sensory system and eliminating fructose corn syrup can curb the need for these products. Despite this, the study will continue to motivate the scientific community to understand the extent to which brain cognitive centers control intake and body weight regulation, ' Andrews and Horvath wrote.

Researchers include Ivan E.de Araujo, Albino J. Oliverira - Maia;Tatyana D. Sotnikova;Raul R. Gainetdinov;Marc G. Caron;Miguel AL Nicolelis;Sidney A. Simon (Medical Center of Nuke University, Durham, NC) and Universidade do Porto University, Porto, Portugal.