Pound for Pound, the brain consumes much more energy than other organs, and mysteriously, it remains a fuel guzzler even if its neurons do not signal each other called neurotransmitters. Researchers at Weill Cornell Medicine have now discovered that the process of packaging neurotransmitters may be responsible for this energy expenditure.
In their study, on December 3rd Science Advances, They identified small capsules called synaptic vesicles as a major source of energy expenditure for inactive neurons. Neurons use these vesicles as containers for neurotransmitter molecules and fire from communication ports called synaptic terminals to signal other neurons.Packing neurotransmitters into vesicles is a consuming process Chemical energy, And researchers have found that this process is energetically inherently leaky. It is so leaky that it continues to consume significant energy even when the vesicles are filled and the synaptic ends are inactive.
“Why are these findings? Human brain Very vulnerable to its interruption or weakening fuel Supply “. Dr. Timothy Ryan, a senior author who is a professor of biochemistry and biochemistry in the anesthesiology department of Weil Cornell Medicine, said.
That observation brain It consumes large amounts of energy, even when it is relatively stationary, but dates back decades to studies of brain fuel use in coma and nutrition. These studies found that even in these highly inactive states, glucose consumption in the brain is usually reduced by about half of normal. This leaves the brain as a high energy consumer compared to other organs. The cause of its resting energy consumption is not fully understood.
Dr. Ryan and his lab have been very sensitive to interruptions in fuel supply in recent years, with neuronal synaptic terminations, bud-like growth that ignite neurotransmitters, being a major consumer of active energy. I showed that. In a new study, they looked at fuel use at synaptic terminals as follows: ofIt turned out to be active and still expensive.
This high resting fuel consumption they discovered is primarily explained by the pool of synaptic terminal vesicles. While the synapses are inactive, each vesicle is fully loaded with thousands of neurotransmitters, ready to launch these signaling payloads across the synapse to partner neurons.
why Synaptic vesicles Does it consume energy even when it is full?Researchers have discovered that there is essentially an energy leak Vesicle Membrane, “proton outflow”, such a special “Proton pump“The enzymes in the vesicles need to continue to function and consume fuel as such, even if the vesicles are already full of neurotransmitter molecules.
Experiments have pointed out a protein called a transporter as a possible cause of this proton leak. Transporters usually carry neurotransmitters to vesicles and transform to carry neurotransmitters, but at the same time allow protons to escape — as they do. Dr. Ryan speculates that the energy threshold for this transporter’s shape change was set lower by evolution to accelerate the reloading of neurotransmitters during synaptic activity and to accelerate thinking and behavior.
“The disadvantage of faster loading capacity is that even random thermal fluctuations cause the transporter to change shape, Neurotransmitters It’s loaded. “
Leakage per vesicle is negligible, but because there are at least hundreds of trillions of synaptic vesicles in the human brain energy Drain will really be summed, Dr. Ryan said.
This discovery is an important advance in understanding the basic biology of the brain. In addition, the vulnerability of the brain to fuel supply interruptions is a major neurological problem, and metabolic deficiencies have been noted in many common brain disorders, including Alzheimer’s disease and Parkinson’s disease. This series of investigations may ultimately help solve important medical puzzles and propose new treatments.
“If there is a safe way to lower this Energy consumption Therefore, it can have significant clinical consequences because it slows down the metabolism of the brain, “Dr. Ryan said.
Camila Pulido et al, the synaptic vesicle pool, is the major hidden resting metabolic load of nerve endings, Science Advances (2021). DOI: 10.1126 / sciadv.abi9027.. www.science.org/doi/10.1126/sciadv.abi9027
Weil Cornell Medical College
Quote: Scientists obtained from https: //medicalxpress.com/news/2021-12-scientists-neurons-consume-fuel-rest.html on December 3, 2021 at rest (December 3, 2021) But it explains why neurons consume so much fuel
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