According to Science Daily, current scientific research into the origins of compulsive eating is focused on the nucleus accumbens, a brain area related to motivation. This little area is in charge of the pursuit of enjoyable events such as sex and recreational substances such as nicotine, alcohol, and food.
“These brain incentive areas arose to help people live; acquiring food and having sex is vital to the existence of an individual and of a species,” says Carrie Ferrario, Ph.D., associate professor in the Department of Pharmacology at the University of Michigan Medical School.
“Because of our abundant food supply, activities formerly beneficial when food was scarce are destructive and unhealthy. The problem is aggravated by the ubiquitous availability of highly processed, nutritionally poor foods that delight our taste buds but do nothing to keep our bodies running.
Most people can say “no” to third helpings, but when it comes to french fries or saving room for dessert, they may have difficulty saying “no.” The real problem is modifying the eating habits in the face of these temptations, “Ferruccio mentioned.
Given the enormous toll obesity has on practically all body systems, Ferrario, Peter Vollbrecht, Ph.D., of Western Michigan University, and colleagues are employing rat models to investigate possible brain abnormalities between animals prone to overeating and obesity and those who aren’t.
Ferrario’s team previously discovered differences in the nucleus accumbens between obese and lean rats. In their most recent work, published in the Journal of Neurochemistry, the researchers tracked the brain activity of these mice in real-time as they were given glucose, a form of sugar. The researchers’ tracer allowed them to calculate the quantity of this new sugar in the brain.
Brain cells rely on glucose for energy, and glucose metabolism produces glutamine, glutamate, and GABA, all of which play significant roles in modulating the activity of neurons in the central nervous system.” Carbons obtained from glucose breakdown are used to create new neurotransmitters. Over time, glutamate, glutamine, and GABA all show the presence of such tagged carbons “according to Vollbrecht.
Obese rats’ nucleus accumbens were shown to have decreased glucose sensitivity. Furthermore, when they tested glutamate, glutamine, and GABA levels, they revealed unusually high amounts of glutamate, an excitatory neurotransmitter. The researchers found indications of disruption in the neurotransmitter recycling process, carried out by star-shaped cells known as astrocytes, routinely maintained in the nervous system.
Glutamate is generally recycled to GABA or glutamate-producing cells by astrocytes, which remove it from the synapse (the area between two neurons) and convert it to glutamine. This sequence is required for neuron activation and inhibition. ‘The findings indicate that we are receiving an excessive amount of glutamate that is not being removed from the synapse,’ explains Vollbrecht.
Ferrario discovered that the glutamate-to-GABA (the principal inhibitory transmitter) ratio could impact cell activity in the nucleus accumbens. According to Vollbrecht, it is critical to demonstrate a causal link between whether these rats are genetically predisposed to obesity. We can rule out the potential influence of diet in this analysis.
