NMDA Receptor Antagonist Memantine Ameliorates Experimental Autoimmune Encephalomyelitis in Aged Rats

Area of Science:

• Neuroimmunology
• Aging Research
• Multiple Sclerosis Pathogenesis

Background:

• Aging populations are increasing, leading to a rise in elderly patients with multiple sclerosis (MS).
• N-methyl-D-aspartate receptors (NMDARs) are present on both neurons and immune cells, suggesting a role in neuroinflammatory conditions like MS.
• Experimental autoimmune encephalomyelitis (EAE) is a common animal model for studying MS.

Purpose of the Study:

• To investigate the role of NMDARs in the EAE model in young versus aged rats.
• To evaluate the therapeutic potential of memantine, an NMDAR antagonist, in aged rats with EAE.

Main Methods:

• Administration of memantine to young and aged Dark Agouti rats post-immunization for EAE induction.
• Assessment of clinical disease, immune cell reactivation, apoptosis, and molecular markers in brain tissue.
• Analysis of NMDAR expression, fractalkine receptor CX3CR1, Nrf2 pathway activation, and oxidative stress markers.

Main Results:

• Memantine treatment showed more significant benefits in aged EAE rats regarding clinical symptoms, disease reactivation, and CD4+ T cell apoptosis.
• Increased expression of CX3CR1 and enhanced Nrf2 and Nrf2-regulated enzymes' mRNA were observed, particularly in aged rats treated with memantine.
• Reduced oxidative stress markers (superoxide anion radicals, malondialdehyde, advanced oxidation protein products) were consistent with therapeutic effects.

Conclusions:

• NMDARs appear to play a more critical role in the pathogenesis of EAE in aged rats compared to young rats.
• Targeting NMDARs with memantine may be a promising therapeutic strategy for older individuals with MS or similar neuroinflammatory conditions.
• The findings highlight age-dependent differences in NMDAR involvement in neuroinflammation and suggest potential for age-specific therapeutic interventions.