Scientists from the University of Calgary have discovered a new oxygen sensing system in a small group of spinal cord neurons that can protect the brain and other important organs from hypoxia (low oxygen).
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When blood oxygenation reduces, mammals trigger a cardiorespiratory response and ensure oxygen supply to important organs. The scientists identified that the kick-starter to that rescue response are spinal oxygen sensors (SOS), which initiate the stimulation of the sympathetic and respiratory nervous systems.
Understanding how the central nervous system regulates oxygen supply is of considerable scientific and medical importance. Hypoxia can lead to cognitive decline, memory impairment and in extreme circumstances such as heart attack, stroke or sudden infant death syndrome (SIDS), can be fatal.
Dr. Nicole Barioni, PhD, Study First Author, University of Calgary
The research is the first to conclusively show the presence of SOS. This is the outcome of 8 years of research by Dr. Barioni and principal investigator, Dr. Richard Wilson, Ph.D. Details of the study have been published in Science Advances.
What started with a late-night experiment in the lab with some mates and a post-pizza surprise discovery turned into an epic multi-year international science project to determine mechanism. Without the tireless energy and brilliance of Nicole and the rest of the team, this important contribution would not have been possible.
Dr. Richard Wilson, PhD., Principal Investigator, University of Calgary
Owing to the exclusive way in which the SOS function, they are vital for extensive physiological regulation in chronic disease, health, cardiorespiratory crisis and spinal cord injury.
The research puts forward that the SOS uses a unique oxygen sensing platform comprising two yin and yang-like oxygen-dependent enzymes. These enzymes contest for the same molecules. When oxygen is plentiful one enzyme triumphs.
Only when the oxygen decreases, the other enzyme takes charge, using the residual oxygen to produce signaling factors. These signaling factors then trigger a flow of events resulting in neuronal excitation and sympathetic activation.
Unlike brainstem neuronal networks controlling breathing, which are largely suppressed by acute hypoxia, sympathetic networks are strongly excited. Prior to this study identifying the sensors, the way in which these sympathetic networks function in low to no oxygen was not well understood.
Dr. Richard Wilson, PhD., Principal Investigator, University of Calgary
Using a number of innovative experimental methods that separate various parts of the rodent nervous system to test physiological responses to spinal cord oxygen levels, this research establishes that the SOS influence sympathetic activation and, under extreme situations, are very essential for auto resuscitative reflexes.
Journal Reference:
Barioni, N. O., et al. (2022) Novel oxygen sensing mechanism in the spinal cord involved in cardiorespiratory responses to hypoxia. Science Advances. doi.org/10.1126/sciadv.abm1444.