Immunity and brain
Scientists from Russia have found out how immunity affects memory and intelligence
The lack of anti-inflammatory molecules in the brain and other problems with immunity can impair memory and learning ability, say Russian scientists who published an article in the journal Neuroreport (Arkhipov et al., Deficiency of transforming growth factor-β signaling disrupts memory processes in rats).
In recent years, scientists have been actively interested in what role the immune system plays in the work of the brain and other regions of the nervous system. Just over the past decade, neurophysiologists and molecular biologists have found many hints that excessive immune activity and associated inflammation can cause serious brain disorders, including multiple sclerosis or Alzheimer's disease.
Vladimir Arkhipov, a neurophysiologist from the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences in Pushchino, and his colleagues tried to understand why almost all people begin to think poorly and remember new information worse at those moments in time when they have the flu or any other serious illness.
As scientists explain, when the influenza virus or other pathogens appear in the body, an inflammatory reaction begins, putting the body into a kind of "state of emergency". At this time, immune cells begin to attack any suspicious objects especially aggressively, and secrete a large set of signaling molecules that change the behavior of other body tissues.
Some of them contribute to the development of inflammation, while others, on the contrary, suppress them. If the balance between these substances is disturbed, inflammation can flow into the chronic stage and cause a lot of problems for the human body or animals.
According to Arkhipov, relatively recently his team found out, experimenting on rats, that molecules that contribute to the development of inflammation significantly impair the intellectual abilities of rodents and prevent them from remembering new information. This discovery led them to the idea that a decrease in the number of anti-inflammatory substances secreted by cells, even in a healthy body, can cause similar changes.
They tested this idea by observing how the behavior of rats changed, into whose body they injected large amounts of a substance that blocked the work of TGF-beta protein molecules, one of the key anti-inflammatory signals.
The biologists checked the memory of rodents by putting them in a cage whose floor beat them with an electric current. As a rule, rats almost immediately remember the place where they received electricity discharges, and bypass it. They start moving especially slowly in its vicinity, checking every step.
When scientists blocked TGF-beta, the caution of rodents decreased markedly. The animals began to stop much less often and began to remember the position of electrified areas of the floor worse than their relatives from the control group. Interestingly, this behavior persisted even on the seventh day of the experiment, which indicates serious violations in the memory of rats.
Similar results of experiments, according to Arkhipov and his colleagues, suggest that the immune system unexpectedly strongly affects the work of memory and intelligence. Further study of these connections will help to understand how the brain can be protected from such changes and improve its performance at the onset of old age or Alzheimer's disease, the authors conclude.
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