neurosciencestuff:Glutamate, an essential food for the brainGlutamate is an amino acid with very dif

neurosciencestuff:Glutamate, an essential food for the brainGlutamate is an amino acid with very different functions: in the pancreas, it modulatesthe activity of the pancreatic ß-cells responsible for insulin production,whereas in the brain it is the mainexcitatory neurotransmitter. In recentyears, it has been suspected toplay an additional role in the functioning of the brain.By discovering how the brain usesglutamate to produce energy, researchersat the University of Geneva (UNIGE) confirm this hypothesis and highlight unexpected links with the rest of the body. To read in CellReports.Unlike other organs, the brain cannot draw its energyfrom lipids, an energy resourcewidely present in the body. The blood-brain barrier, which protects it from the pathogens and toxins circulating in the blood, indeed limitsthe passage of these lipids. Moreover,while most of the organs in the human body have the ability to store glucose by increasing theirmass, the brain, prisoner of the cranialbones, cannot count on these variations in volume. Unable to storeits food, it depends on sugar supplied in real-time by the rest of the body. This distribution of energy is controlled by the liver.Pierre Maechler, professor at the Faculty of Medicine at UNIGE, and histeam therefore decided to verify ifglutamate was indeed an energy source for the brain. To do so, the researchersanalyzed the role of the glutamate dehydrogenase enzyme in the brain. In mutantform, this enzyme, encoded by the Glud1 gene, is responsible for a congenitalhyperinsulinism syndrome, a severe disease affecting at the same time the endocrinepancreas, the liver and the brain. Individuals affected by this syndrome sufferfrom intellectual disability and have a high risk of epilepsy. “We have suppressedthe Glud1 gene in the brain of mice. In the absence of glutamate dehydrogenase,we observed that the brain was no longer able to convert glutamate into energy,even though the amino acid was present in the brain,” explains MelisKaraca, first author of this study.Priority to the brainDevoid of the energy supplied by cerebral glutamate, thebrain sends signals to theliver to requisitiona compensatory proportion of glucose, atthe expense of the rest of thebody. This is why the transgenic mice also showed a growth deficit and muscleatrophy. “This clearly shows how the brain works in a just-in-timemanner and that each percent of energy resources is essential for its proper functioning,” highlightsProfessor Pierre Maechler.“If a part of this energy disappears, the brain serves itself firstand the rest of the body suffers.The liver mustthen make more glucose by drawing upon muscleprotein, resulting in loss of musclemass. Knowing that the brain usesglutamate as an energy resource allows us to reflect on other ways to overcome a potentialshortfall. ”Scientists also suspecta correlation betweenthe Glud1 geneand some neurodevelopmentaldisorders, particularly epilepsy and schizophrenia. They are currently pursuingtheir research by introducing in mice the same Glud1 mutationdetected in epileptic patients. At the same time, another group is working with schizophrenicpatients to assess the way theirbrain uses glutamate. -- source link

More pics about