The effect of four weeks of physical activity in the enriched environment on inflammatory and anti-inflammatory factors in the dorsal horn of the spinal cord of mice with experimental autoimmune encephalomyelitis

An excessive increase in the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) and a decrease in the levels of Tumor necrosis factor beta1 (TGF-β1) are associated with creating an inflammatory environment, resulting in increasing pain hypersensitivity in Different models of nerve pain. This study aimed to investigate the effect of four weeks of physical activity in an enriched environment on TNF-α, IL-1β, and TGF-β1 in the dorsal horn of the spinal cord in the chronic course of Experimental autoimmune encephalomyelitis (EAE). 

Thirty female C57BL6 mice were divided into three groups: control, EAE, and enriched environment. After induction of EAE with MOG35-55, the environmental enrichment group lived in an enriched environment for four weeks. On day 30 post-induction (chronic period of the disease), pain sensitivity was assessed by tail immersion test in water, and then the animals were sacrificed and biopsied. TNF-α, IL-1β, and TGF-β1 protein levels were measured by immunohistochemistry. The data were analyzed by One-way analysis of variance at a significance level of 0.05.

The present study's findings showed that living in an enriched environment decreased the levels of TNF-α (p=0/00) and IL-1β (p=0/00) in the dorsal horn of the spinal cord and increased the level of TGF-β1 (p=0/00) protein compared to the EAE group. Also, physical activity in the enriched environment increased the delay time in extracting the tail from hot water in the chronic period of the disease (P = 0.00). 

Active lifestyle can reduce pain sensitivity in the animal model of MS disease (EAE) by reducing the levels of inflammatory factors TNF-α and IL-1β and increasing the levels of anti-inflammatory factor TGF-β1 in the dorsal horn of the spinal cord.