Neurobiology: How much oxygen does the brain need?

Date:
July 6, 2020
Source:
Ludwig-Maximilians-Universita"t Mu"nchen
Summary:
The brain has a high energy demand and reacts very sensitively
to oxygen deficiency. Neurobiologists have now succeeded for the
first time in directly correlating oxygen consumption with the
activity of certain nerve cells.



FULL STORY ==========================================================================
The brain has a high energy demand and reacts very sensitively to
oxygen deficiency. Ludwig-Maximilians-Universitaet (LMU) in Munich neurobiologists have now succeeded for the first time in directly
correlating oxygen consumption with the activity of certain nerve cells.


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The brain requires a disproportionate amount of energy compared to its
body mass. This energy is mainly generated by aerobic metabolic processes
that consume considerable amounts of oxygen. Therefore, the oxygen concentrations in the brain are an important parameter that influences
the function of nerve cells and glial cells. However, how much oxygen is consumed in the brain and how this is related to neuronal activity was
so far largely unknown. LMU neurobiologists Hans Straka, Suzan O"zugur
and Lars Kunz have now succeeded for the first time in directly measuring
this in the intact brain and correlating it with nerve cell activity. The scientists report on their results in the journal BMC Biology.

In an already established animal model -- tadpoles of the clawed
frog Xenopus laevis -- the scientists used electrochemical sensors to
determine the concentration of oxygen in the brain and in one of the
brain ventricles. They were able to specifically control the amount of
oxygen available to the brain as well as inhibit nerve cell activity
with the help of pharmacological substances. Using the example of
nerve cells that control eye movements, the scientists succeeded in
directly recording the relationship between oxygen consumption and
nerve cell activity. "We have found that the brain is anoxic in a normal air-saturated environment, which means that no oxygen can be measured,"
says Straka. The complete oxygen was therefore immediately used by
the cells to synthesize energy-rich substances. If more than twice the atmospheric oxygen concentration was available, the energy metabolism
was saturated and oxygen was abundantly present in the brain. "We were
also able to show that during normal operation only about 50 percent of
the oxygen is used for nerve cell activity," says Straka. "So the other
50 percent are required for glial cells and for maintaining the basic
metabolic rate of nerve cells.

However, nerve cells with increased activity consume more oxygen."
In order to better understand how information is processed in the
brain, knowledge of the relationship between oxygen availability and
brain activity is essential. The scientists' results provide initial
insight into this and are an important basis for further investigations
of the brain's energy balance in future experiments and for measuring
oxygen consumption for various nerve cell functions. This could also be relevant from a medical point of view, for example to better understand
the consequences of oxygen deficiency in the brain or to better interpret
the information on brain activity obtained with imaging techniques.


========================================================================== Story Source: Materials provided by
Ludwig-Maximilians-Universita"t_Mu"nchen. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Suzan O"zugur, Lars Kunz, Hans Straka. Relationship between oxygen
consumption and neuronal activity in a defined neural circuit. BMC
Biology, 2020; 18 (1) DOI: 10.1186/s12915-020-00811-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200706140847.htm

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