Low levels of pro-inflammatory agent help cognition in rats

January 28, 2014
Jennifer Donegan, graduate student at The University of Texas Health Science Center at San Antonio, is lead author of a January 2014 report in the Journal of Neuroscience. The research found that neutralizing the cytokine interleukin-6 in the brain impaired reversal learning in both stressed and nonstressed rats. Reversal learning is a form of cognitive flexibility that is diminished in psychiatric diseases such as depression, schizophrenia and post-traumatic stress disorder. Cognitive flexibility is the ability to change previously learned thoughts and behaviors in response to changes in the environment. Cytokines are proteins produced by the immune system. Credit: UT Health Science Center at San Antonio

Although inflammation is frequently a cause of disease in the body, research from The University of Texas Health Science Center at San Antonio indicates that low levels of a pro-inflammatory cytokine in the brain are important for cognition. Cytokines are proteins produced by the immune system.

Jennifer Donegan, graduate student, and David Morilak, Ph.D., professor of pharmacology in the School of Medicine, found that neutralizing the cytokine interleukin-6 in the brain impaired reversal learning in both stressed and nonstressed rats. Reversal learning is a form of that is diminished in psychiatric diseases such as depression, schizophrenia and . Cognitive flexibility is the ability to change previously learned thoughts and behaviors in response to changes in the environment.

"When we started the project, we thought cognitive flexibility would be impaired by stress-induced in a region of the brain called the ," Donegan said. "We decided to block interleukin-6 during stress to prevent the cognitive deficit, and to our surprise this made things worse. This suggested that it may actually be beneficial to maintain a low level of this pro-inflammatory cytokine in the brain."

Low level corrected deficit

As a key next step, the scientists were then able to fix the caused by stress by restoring a low level of the cytokine specifically in the prefrontal cortex. Both scientists caution, however, that there is still much to learn about interleukin-6's role in cognition and in diseases like depression. "We've replicated just one piece of a very complex disease so we can understand the biology," Dr. Morilak said. "We found that, in one brain region, one cytokine facilitates cognitive flexibility and is beneficial after chronic stress. But we delivered the cytokine specifically into that brain region using a virus, which we cannot do in people. And its role in inflammation may be very different than in normal conditions. There's still a lot of work to do."

Donegan is on track to receive her Ph.D. later this year. She is lead author and Dr. Morilak is senior author of the study, published this month in the Journal of Neuroscience. The research is funded by the National Institute of Mental Health and the Brain & Behavior Research Foundation.

Related Stories

Researchers discover new way to block inflammation

July 1, 2013

Researchers at NYU Langone Medical Center have discovered a mechanism that triggers chronic inflammation in Alzheimer's, atherosclerosis and type-2 diabetes. The results, published today in Nature Immunology, suggest a common ...

The stressed out brain

November 8, 2013

Clinical studies of adolescents suffering from depression have shown an interesting connection between early life stress and the immune system. "Those who have experienced childhood trauma and adversity tend to have higher ...

Recommended for you

Improved memory thanks to irregular sleep-wake patterns

July 31, 2015

If you've had a good night's sleep, you are mentally more alert and your memory works more reliably. During sleep, a part of our forebrain called the prefrontal cortex remains active. It ensures that memories and learned ...

Take a trip through the brain (w/ Video)

July 30, 2015

A new imaging tool developed by Boston scientists could do for the brain what the telescope did for space exploration. In the first demonstration of how the technology works, published July 30 in the journal Cell, the researchers ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.