Intraperitoneal administration of NMDA-Subunit NR1-Receptor antibodies does not improve long-term outcome in a murine MCAostroke model

Carolin Albrecht^1,2*Christoph Harms^2,3,4Jakob Kreye^2,5Matthias Endres^2,3,4,5,6Susannne Müller^2,4,7Philipp Boehm-Sturm^2,4,7Stefan P Koch^2,4,7Dorette Freyer^2,8Harald Prüss^2,5Samuel Knauss^2,3

• ¹Technical University of Munich, Munich, Germany
• ²Charité University Medicine Berlin, Berlin, Baden-Wurttemberg, Germany
• ³German Center for Cardiovascular Research (DZHK), Berlin, Berlin, Germany
• ⁴Center for Stroke Research Berlin, Charité University Medicine Berlin, Berlin, Berlin, Germany
• ⁵German Center for Neurodegenerative Diseases, Helmholtz Association of German Research Centers (HZ), Bonn, North Rhine-Westphalia, Germany
• ⁶German Center for Mental Health (DZPG), partner site, Berlin, Germany
• ⁷Charité Core Facility Experimental MRIs, Berlin, Germany
• ⁸Department of Experimental Neurology, Clinic for Neurology with Experimental Neurology, Charité University Medicine Berlin, Berlin, Baden-Wurttemberg, Germany

Ischemic stroke is a major cause of disability worldwide, and current treatment is largely limited to thrombolytics. Therefore, additional therapeutic strategies are warranted. Previous evidence suggests that NMDA receptor antibodies targeting specific subunits may reduce excitotoxicity and lesion size. This study evaluates the effects of a specific NMDAR-NR1 antibody in both in vitro and in vivo models of ischemic stroke. Neuronal cultures were treated with NMDAR-NR1-AB, a control antibody (mGO-AB) or phosphate-buffered saline followed by NMDA exposure or oxygen-glucose deprivation (OGD). Cell death was measured by lactate dehydrogenase assay. NMDA and OGD significantly increased cell death, but NMDAR-NR1-AB did not exert neuroprotective effects in vitro. In vivo, C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAo) for 45 minutes and treated intraperitoneally with NMDAR-NR1-AB or mGO-AB. Lesion size and neurobehavioral outcomes were assessed at 24 and 72 hours and 28 days after MCAo. No differences in lesion sizes or long-term neuroprotective effects were evident at 24 hours and 28 days post-MCAo. These findings underscore both the potential and limitations of targeting NMDAR-mediated excitotoxicity in ischemic stroke therapy and highlight the need for further research into the longterm efficacy of NMDAR-NR1-AB.