The human brain consumes up to 10 times more energy than the rest of the body, “devouring” an average of 20 percent of its energy intake when we rest.
Even in coma patients who are said to be experiencing brain death, the brain still consumes a large amount of energy, only two to three times less than usual.
This is one of the great mysteries of neurology: why does an inactive organ still require so much strength? A new study seems to have finally given an answer to this question.
The process of sending information
When a brain cell transmits a signal to another neuron, it does so through a synapse, that is, a point of contact between the axons of one cell and the dendrites or axons of another.
First, the presynaptic neuron sends a stack of vesicles to the end of its axon, closest to the synapse. The vesicles then suck in neurotransmitters from the neurons, behaving like coatings in which an important message is transmitted.
These “shells” travel to the edge of the neuron, where they connect to the membrane, releasing neurotransmitters (message) into the synapse. We already know that this process requires a significant amount of energy.
Why does the brain at rest consume so much energy?
But what happens to this system when nervous activity decreases? So why does the brain continue to expend so much energy?
To understand this, scientists conducted several experiments on nerve endings and compared the metabolic status of active and inactive synapses. Even when the nerve endings did not send messages, the synaptic vesicles still had high demands on metabolic energy.
That is, it seems that the pump behind the proton thrust of the vesicles and the suction of the neurotransmitters never stops and that its operation requires a constant supply of energy.
This bomb, during the experiments, was responsible for half of the metabolic consumption of the synapse at rest, writes Science Alert.
The scientists explained that the reason is that this bomb can leak, so that the synaptic vesicles constantly expel protons through them, even if they are already full of neurotransmitters and if the neuron is not active.
Some neurons in the brain are probably more susceptible to energy loss, so it would be good to establish a reason why we could keep them as long as possible, even if they are deprived of oxygen or sugar.
“With these findings, we can better understand why the human brain is so vulnerable in situations of disruption or poor energy distribution,” said biochemist Timothy Ryan of Vail Cornel Medicine School in New York.
“If we had a safe way to reduce this energy output and thus slow down the brain’s metabolism, it could be very useful in a clinical sense,” he added.
Research called synaptic vesicle pools is a major metabolic load at rest of the nerve endings published in the journal Science Advances.