Oxygen Therapy for the Treatment of Experimental Autoimmune Encephalomyelitis

Background Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS). Experimental autoimmune encephalomyelitis (EAE) is a widely used animal model of MS. Oxygen therapy, such as hyperbaric oxygen (HBO) or normobaric oxygen (NBO), has been advanced as a potential treatment option to allay the motor and sensory deficits associated with MS. However, it is unclear whether any therapeutic benefits derived from treatment are a result of pressurized oxygen or simply pure oxygen administration. This study aimed to explore whether pressurized oxygen (HBO) or sea-level oxygen (NBO) would attenuate the motor and sensory deficits associated with EAE. Methods Forty-two male Harlan Lewis rats were randomly assigned to one of four conditions: MBP/HBO, MBP/NBO, MBP/no treatment, or a vehicle group. Injections of MBP or vehicle were administered on day 1, and animals were allowed one-week to recover. Following recovery, animals were administered HBO at 2.0 atmospheres absolute (ATA) or sea-level oxygen for 60-minutes daily. Mechanical paw withdrawal threshold (MPWT) testing was conducted on the first day and every alternate day after the start of treatment to assess the development of tactile allodynia. Motor impairment tests were performed twice daily (immediately prior to and after oxygen treatment) to assess for the presence of motor deficits or paralysis. Results On days 14 through 18, animals injected with MBP had a greater level of motor impairment compared to the vehicle control group. Interestingly, results also indicated that NBO was as effective as HBO in attenuating EAE symptoms. Conclusion In conclusion, these results underscore the need for further research to determine the ideal parameters of oxygen treatment, particularly whether pressurization is necessary to attenuate symptoms of EAE.