Brain's 'sixth sense' for calories discoveredMarch 27, 2008The brain can sense the calories in food, independent of the taste mechanism, researchers have found in studies with mice. Their finding that the brain's reward system is switched on by this "sixth sense" machinery could have implications for understanding the causes of obesity. For example, the findings suggest why high-fructose corn syrup, widely used as a sweetener in foods, might contribute to obesity. Ivan de Araujo and colleagues published their findings in the March 27, 2008, issue of the journal Neuron, published by Cell Press. In their experiments, the researchers genetically altered mice to make them "sweet-blind," lacking a key component of taste receptor cells that enabled them to detect the sweet taste.
The researchers next performed behavioral tests in which they compared normal and sweet-blind mice in their preference for sugar solutions and those containing the noncaloric sweetener sucralose. In those tests, the sweet-blind mice showed a preference for calorie-containing sugar water that did not depend on their ability to taste, but on the calorie content. In analyzing the brains of the sweet-blind mice, the researchers showed that the animals' reward circuitry was switched on by caloric intake, independent of the animals' ability to taste. Those analyses showed that levels of the brain chemical dopamine, known to be central to activating the reward circuitry, increased with caloric intake. Also, electrophysiological studies showed that neurons in the food-reward region, called the nucleus accumbens, were activated by caloric intake, independent of taste. Significantly, the researchers found that a preference for sucrose over sucralose developed only after ten minutes of a one-hour feeding session and that neurons in the reward region also responded with the same delay. "In summary, we showed that dopamine-ventral striatum reward systems, previously associated with the detection and assignment of reward value to palatable compounds, respond to the caloric value of sucrose in the absence of taste receptor signaling," concluded the researchers. "Thus, these brain pathways do not exclusively encode the sensory-related hedonic impact of foods, but might also perform previously unidentified functions that include the detection of gastrointestinal and metabolic signals," they wrote. The scientific questions raised by the discovery of the brain's calorie-sensing system "are extremely important to understanding the pathogenesis and sociology of human obesity," wrote Zane Andrews and Tamas Horvath in a preview of the article in the same issue of Neuron. "For example, high-fructose corn syrup is a ubiquitous sweetener in American society, and evidence suggests that fructose is not as effective as sucrose in terminating a meal. It may be that fructose produces stronger activation of the reward system and that removing high-fructose corn syrup as a sweetener will curb some desire for these products. Regardless, the present study alone will further galvanize the scientific community to understand how higher cognitive centers in the brain control food intake and body weight regulation," wrote Andrews and Horvath. Cell Press Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Intelligence Dry Eye Syndrome Search Engine Inflammatory Bowel Disease Nanospheres Dopamine Cyclones Psoriasis Vitamin D Deficiency Mass Spectrometry Nausea Narcolepsy Meditation Chromatin Lung Injury Hepatitis Autism Marriage Bird Flu Pacemaker T Cells Caesarean Section Meningitis Caffeine Coronary Artery Disease
See More: Science News Tags | |||||||||||||||||||||
|
Related Calories Current Events and Calories News Articles Drinking milk in the morning may help stave off lunchtime hunger Now there's a new reason for the weight-conscious to drink fat free milk at breakfast time, suggests a new study published in the July issue of the American Journal of Clinical Nutrition. 'Shortcuts' of the mind lead to miscalculations of weight and caloric intake, says Penn study Psychologists at the University of Pennsylvania have identified a cognitive shortcut, or heuristic, they call "Unit Bias," which causes people to ignore vital, obvious information in their decision-making process, points to a fundamental flaw in the modern, evolved mind and may also play a role in the American population's 30 years of weight gain. Appetite-stimulating hormone is first potential medical treatment for frailty in older women Older women suffering from clinical frailty stand to benefit from the first potential medical treatment for the condition, according to a study presented today by Penn Medicine researchers at ENDO, The Endocrine Society's 91st Annual Meeting. Brain molecule reduces food intake Researchers at Imperial College London have identified a new appetite suppressant for promoting weight loss that they say works in rodents and may one day be used to develop an effective anti-obesity treatment. Fatty foods -- not empty stomach -- fire up hunger hormone New research led by the University of Cincinnati (UC) suggests that the hunger hormone ghrelin is activated by fats from the foods we eat-not those made in the body-in order to optimize nutrient metabolism and promote the storage of body fat. Study finds regular daily exercise does not increase total sleep time According to a research abstract that will be presented on Monday, June 8 at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies, days with increased activity were followed by nights with lower total sleep time (TST), while nights with lower TST were followed by increased activities during the next day. Study further expands understanding of leptin's role in brain neurocircuitry In investigating the complex neurocircuitry behind weight gain and glucose control, scientists have known that the hormone leptin plays a key role in the process. Researchers engineer metabolic pathway in mice to prevent diet-induced obesity In recent years, obesity has taken on epidemic proportions in developed nations, contributing significantly to major medical problems, early death and rising health care costs. New study finds lowfat chocolate milk is effective post-exercise recovery aid for soccer players Soccer players and exercise enthusiasts now have another reason to reach for lowfat chocolate milk after a hard workout. Carbohydrate restriction may slow prostate tumor growth Restricting carbohydrates, regardless of weight loss, appears to slow the growth of prostate tumors, according to an animal study being published this week by researchers in the Duke Prostate Center. More Calories Current Events and Calories News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||