Comparison of the effect of four weeks of forced and voluntary exercise on glutamatergic synapse in the spinal dorsal horn of female C57BL6 mice with experimental autoimmune encephalomyelitis

Abstract

Introduction: The decrease of GLT-1 is associated with the activation and increased expression of the glutamate receptor subunit, NR1, which causes neuropathic pain in multiple sclerosis (MS) by increasing basal cell activity. This study aimed to compare the effect of four weeks of swimming and living in an enriched environment on GLT-1, NR1, and c-FOS, a marker of neuronal activity, in the dorsal horn of the spinal cord in experimental autoimmune encephalomyelitis (EAE), an animal model used to study of MS. Materials and Methods: forty female C57BL6 mice were randomly divided into four groups: EAE, control, swimming exercise, and enriched environment. The healthy control group received a saline injection, other groups were induced with myelin oligodendrocyte glycoprotein (MOG35-55). After the induction of EAE, the swimming group performed swimming for 30 minutes, 5 days a week for four weeks, and the environmental enrichment group lived in an enriched environment for four weeks. On day 30 post-induction, the mice were sacrificed, and the spinal cord tissue was removed. GLT-1, NR1, and c-FOS protein levels were measured by immunohistochemistry. Results: The findings showed that living in an enriched environment and swimming exercise both significantly increased GLT-1 levels and significantly decreased NR1 and c-FOS levels compared to the EAE group. Although, living in an enriched environment compared to swimming exercise, showed that the first was a more effective method. Conclusion: Exercise, in addition to reducing disease severity, can reduce pain sensitivity in the EAE mice and increase their quality of life by increasing GLT-1, and decreasing NR1 and c-FOS in the spinal dorsal horn.