Scientists have found out what makes us eat, even if we are full
Appetite by cable
Nadezhda Markina, <url>Researchers have figured out the mechanisms of gluttony, obesity, bulimia and anorexia.
To do this, it was necessary to stimulate the neurons of mice via a fiber-optic cable. But now they have been able to complete the research that began back in the 1950s.
The key to overeating and all kinds of eating disorders is in the brain. This, in fact, became clear 60 years ago, when during an experiment, physiologists stimulated an area in the mouse brain with a weak electric current and this caused the rodent to have an attack of gluttony, regardless of whether he was hungry or full.
But only now, specialists from the University of North Carolina School of Medicine have been able to figure out the mechanism of triggering eating behavior. Using the most modern high-tech methods, they saw what was happening in the brain at the level of neurons at that time. The researchers wrote about the results in the latest issue of the journal Science: Jennings et al., The Inhibitory Circuit Architecture of the Lateral Hypothalamus Orchestrates Feeding.
A summary of the article (An on-off switch for eating) can be read in the journal Science News – VM.
When scientists stimulated the brains of rats or mice in the 1950s, they only knew that they were stimulating an area called the lateral hypothalamus. This area of the brain is connected with the basic functions of the body, and it is here that the "hunger center" is located. But in those experiments, the electric current activated a variety of groups of neurons.
Now, neurophysiologists have focused on one group of cells, which is located in the amygdala (amygdala), the area of the brain most associated with emotions. These cells, called BNST, send their long processes – axons – from the amygdala to the lateral hypothalamus. There, these neurons form contacts – synapses – with the neurons of the lateral hypothalamus and send signals there.
To excite these neurons, the researchers used the method of optogenetics. First, they obtained genetically modified mice by inserting a yellow fluorescent protein gene derived from algae into BNST neurons. This led to the fact that when light hit them, the cells were excited and fluoresced. The mice were operated on by implanting a thin fiber-optic cable into their brains. When the neurons were exposed to light through this cable, the neurons were excited and the behavior of the mice changed.
Rodents immediately attacked the food, even if they had been fed recently and were full before. Stimulated by BNST light, neurons sent activating stimuli through synapses to the neurons of the lateral hypothalamus, which triggered eating behavior. Moreover, the mice stimulated in this way began to prefer more fatty and high-calorie foods.
"They consumed half of their daily allowance in 20 minutes," recalls Staber. This led scientists to conclude that the neural pathway from BNST cells plays a key role in food consumption and eating disorders.
Stimulation of BNST neurons was accompanied by activation of the "reinforcement system" of the brain, the main participant of which is the neurotransmitter dopamine.
This confirms that the mice enjoyed eating. When the researchers blocked the activation of these neurons, the rodents stopped paying attention to food, even when they were hungry.
The experiment sheds light on the mechanisms of obesity and various eating disorders – from bulimia to anorexia, which have recently become more and more. Scientists believe that they may be associated with a violation of the normal functioning of BNST neurons. Excessive activation or blocking of this pathway can lead to gluttony or refusal of food, regardless of the physiological need.
By the way, it is no coincidence that BNST neurons are located in the amygdala, which confirms the great role of emotions in eating behavior.
"Our work proves that obesity and other eating disorders have a neurological basis," says first author of the study Garrett Staber, associate professor at the faculties of psychiatry, cell biology and psychology. "In the future, we are going to figure out how to regulate the activity of neurons in this area of the brain and thereby regulate eating behavior."
In particular, scientists are going to study the genetic profile of excited neurons. Having found out which genes work at the same time, they will understand which proteins are synthesized at this moment – so you can find a way to drug correction of food disorders.
Portal "Eternal youth" http://vechnayamolodost.ru30.09.2013