The novel coronavirus can relieve pain, according to a new study published in PAIN, the journal of the International Association for the Study of Pain. The finding, the researchers say, may explain why so many people who get Covid-19 show few or no symptoms, although they are able to spread the disease.
“It made a lot of sense to me that perhaps the reason for the unrelenting spread of Covid-19 is that in the early stages, you’re walking around all fine as if nothing is wrong because your pain has been suppressed. You have the virus, but you don’t feel bad because your pain is gone. If we can prove that this pain relief is what is causing Covid-19 to spread further, that’s of enormous value,” researcher Rajesh Khanna of the University of Arizona College of Medicine said in a statement
It is well-known that SARS-CoV-2 spike protein uses the ACE2 receptor to enter the body. But in June, two papers pointed to neuropilin-1 as a second receptor for SARS-CoV-2. “That caught our eye because for the last 15 years my lab has been studying a complex of proteins and pathways that relate to pain processing that are downstream of neuropilin. So we stepped back and realised this could mean that maybe the spike protein is involved in some sort of pain processing,” Dr Khanna said.
One of the biological processes through which the body feels pain, one is through a protein named VEGF-A19. When VEGF-A binds to neuropilin, it initiates a series of events resulting in the hyper-excitability of neurons, which leads to pain.
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The research team found that the SARS-CoV-2 spike protein binds to neuropilin in exactly the same location as VEGF-A. The team used VEGF-A as a trigger to excite neurons, which creates pain, then they added the SARS-CoV-2 spike protein.
“The spike protein completely reversed the VEGF-induced pain signalling. It didn’t matter if we used very high doses of spike or extremely low doses – it reversed the pain completely,” Dr Khanna said.
Scientists will now continue research into the role of neuropilin in the spread of Covid-19. They will examine neuropilin as a new target for non-opioid pain relief. During the study just published, the researchers tested existing neuropilin inhibitors developed to suppress tumour growth in certain cancers, and found they provided the same pain relief as the SARS-CoV-2 spike protein when binding to neuropilin.
The research was funded by the National Institute of Neurological Disorders and Stroke, a unit of the US National Institutes of Health (NIH), and the National Institute on Drug Abuse, also an NIH unit.
Source: University of Arizona
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