Researchers at the University of Colorado-Boulder may have discovered how human beings can avoid, or at least reduce, the effects of stress — with a shot. The researchers published their findings last month in the scientific journal, Brain, Behavior and Immunity, revealing that an injection of the probiotic “good” bacteria, Mycobacterium vaccae, reduced the type of inflammation that develops in the brain when a person is under stress. Preventing that inflammation may be able to lower the effects of stress-related disorders such as depression, anxiety, or even post-dramatic stress syndrome often experienced by soldiers in combat.
“There is a robust literature that shows if you induce an inflammatory immune response in people, they quickly show signs of depression and anxiety,” said the study’s lead author, Matthew Frank, of the university’s Psychology and Neuroscience Department, quoted by Science Daily. “Just think about how you feel when you get the flu.”
The study was conducted on lab rats, with male rats being injected just three times with the probiotic known as M. vaccae for short. Those rats showed higher levels of an anti-inflammatory protein in the region of the brain responsible for the emotions of fear and anxiety, the hippocampus, according to a report on the study by McClatchy News.
The effects, which also included lower levels of the stress-related protein alarmin in the rats’ brains, lasted more than a week after the final shot of the three that the rodents received. The rats also showed fewer signs of stress-related behavior patterns. The results were similar to an earlier study that showed when male rats were injected with M. vaccae, and then placed in a cage with a larger, more aggressive rat — normally a highly stressful situation for rats — they “exhibited less anxiety-like behavior and were less likely to suffer colitis or inflammation in their peripheral tissues,” according to the University of Colorado at Boulder web site.
But the previous study did not examine the effects of the probiotic injections on actual brain function.
“If you look at the field of probiotics generally, they have been shown to have strong effects in the domains of cognitive function, anxiety and fear,” said researcher Christopher Lowry, another author of the Colorado research paper, quoted in the Economic Times. “The study helps make sense of that by suggesting that these beneficial microbes, or signals derived from these microbes, somehow make their way to the hippocampus, inducing an anti-inflammatory state.”
Lowry said that the probiotic treatment creates hope that the injections cold someday be administered “to people at high risk of PTSD — such as soldiers preparing to be deployed or emergency room workers — to buffer the effects of stress on the brain and body,” Science Daily reported.