To create a stressful environment, researchers housed three young male mice together for several weeks. After the mice established a stable social hierarchy, researchers introduced an older aggressive male into the residence for a couple of hours. The intruder exhibits aggressive behavior posturing, fighting, wounding, pursuit that results in submissive behaviors and social defeat in the younger resident mice. This procedure was repeated for three consecutive nightly two-hour sessions with one night off, followed by an additional three nightly sessions. To keep the mice from getting used to the intruder, a new intruder was introduced for each session.
What they found was this stress appears to elevate levels of IL-6, which subsequently increases the severity of the MS-like illness. Furthermore, using specific IL-6 neutralizing antibody treatments during the stress exposure can prevent the stress-related worsening of the disease, said the authors.
In one experiment, they showed that mice exposed to social disruption had elevated central and peripheral levels of IL-6. However, infusing the neutralizing antibody into the brain prevented this stress-induced increase in IL-6. This demonstrated that the antibody could effectively reverse the stress-related increases in IL-6 in brain and in circulating blood.
Results from a second experiment showed that administering the IL-6 neutralizing antibody during the stress exposure prevented worsening of the TMEV infection. By blocking the stress-induced elevation of IL-6, TMEV infection was weakened, which lessened some of the disease symptoms, such as motor impairment, inflammation in the brain and spinal cord, and the viral level in the central nervous system. Based on these findings, Dr. Mary Meagher, the lead researcher, proposes that the adverse effects of stress-induced IL-6 on TMEV infection are enough to create
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American Psychological Association