Memantine Administration Enhances Glutamatergic and GABAergic Pathways in the Human Hippocampus of Alzheimer's Disease Patients

One of the traditional treatments in Alzheimer's disease (AD) is administration of memantine, the NMDA receptor antagonist. However, the molecular mechanism of the complex memantine action and the impact on the hippocampal proteome in humans is unknown. In this study, hippocampal proteins extracted from formalin-fixed paraffin-embedded post mortem tissues obtained from healthy donors (n = 15), AD patients not treated with memantine (n = 11), and AD patients treated with memantine (n = 8) were investigated using tandem mass tag (TMT)-based quantitative proteomics. Memantine medication induced subtle but distinct changes in the hippocampal proteome in AD patients. Although it did not prevent the metabolic and physiologic decline associated with AD pathology, memantine administration upregulated several mitochondrially encoded proteins and mitigated the proteomic pattern of activated phagocytes. Furthermore, memantine specifically enhanced the expression of postsynaptic glutamatergic and GABAergic receptors and components of the respective pathways without affecting presynaptic proteome. This suggests that memantine treatment in AD patients not only alleviates excitotoxic stress by inhibiting NMDA receptor activity, but also triggers broader adaptations in the synaptic signaling and plasticity.