New University of Colorado Boulder study investigates how low cortisol levels affect long-term COVID-19

A new study from the University of Colorado Boulder finds that proteins that remain long after COVID-19 infection could help shed light on the causes of neurological changes. Long COVID.

Nearly five years after the COVID-19 pandemic began, researchers are learning more about the condition that has left millions of Americans plagued by lingering symptoms, including a foggy brain feeling and extreme fatigue.

These proteins are Cortisolis an important hormone that affects almost all organs and tissues and plays a key role in energy production, stress regulation, and inflammation suppression. Animal studies have shown that this protein can also induce inflammation in the nervous system and induce immune cells to respond strongly when another stressor strikes.

Previous studies have found that proteins released by the virus that causes COVID-19 remain in the blood for up to a year after infection and have also been found in the brains of long COVID patients who have died, according to a press release from the University of Colorado Boulder.

The researchers injected the S1 antigen, a small part of the famous spike protein of the COVID-19 virus, into the spinal fluid of rats. They examined several inflammatory responses in the brain and looked for effects on behavior and physiology.

After a week, rats exposed to the protein saw a sharp 31% drop in levels of corticosterone, the human equivalent of cortisol, in their hippocampus, an area of ​​the brain linked to memory, decision-making and learning. After nine days, levels dropped a further 37%.

“Cortisol has many beneficial properties, so reducing it can have many negative effects,” Matt Frank, a senior research scientist in the Department of Psychology and Neuroscience at the University of Colorado Boulder, said in a statement.

In a second experiment, the researchers added weakened bacteria as an immune stressor. They exposed different groups of rats to the bacteria and tracked their heart rates, body temperatures, and behavior, as well as the responses of immune cells in the brain.

“Does this protein change the brain in a way that makes it more vulnerable to subsequent stress or infection?” Frank asked in an interview with CPR News. Corticosterone acts like a brake on the immune system. “If you release that brake, the immune system may become more sensitive to subsequent stress.”

According to the publication, rats previously exposed to the S1 protein responded much more strongly to the stressor, “exhibiting significant changes in eating, drinking, behavior, core temperature, and heart rate, as well as increased neuroinflammation and enhanced glial cell activation.”

“We show for the first time that exposure to antigens left behind by this virus actually alters the immune response in the brain, potentially causing an overreaction to subsequent stress or infection,” Frank said.

He noted that more research is needed and that humans are obviously different from rats, but this study, coupled with more research being done around the world, could help scientists better understand the neurobiology of long COVID, which could lead to developing drugs and treatments in the future.

Cortisol is important for humans to produce energy for daily activities and exercise.

“So I really believe this could be related to the fatigue symptoms that most long COVID patients report,” he said, “And of course, cortisol is also involved in learning and memory. So if this is altered in any way in the brain, it could be affecting our ability to learn and remember.”

This study Polybio Research Foundationwas published in this week's journal Brain, behavior and immunity.

More than 700,000 Colorado residents May be affected by long COVID Still suffering from symptoms Or recovered.

This figure is for the state 2023 Report The long COVID report said about one in five infected people have severe symptoms that “significantly reduce their ability to carry out daily activities.” About 5% of U.S. adults say they currently have long COVID. U.S. Census Bureau Survey.