Excessive activation of NMDA receptors (NMDARs) is implicated in pathological synaptic plasticity also known as post-ischemic long-term potentiation (i-LTP) which was produced by glutamate mediated excitotoxicity after stroke. In the past decades, many NMDARs inhibitors failed in clinical investigations due to severe psychotomimetic side effects. GLYX-13 is a NMDAR modulator with glycine site partial agonist properties and has potential protective effects on ischemic neuronal death. However, the underlying molecular mechanism of GLYX-13 attenuating the ischemic neuronal damage remains elusive. Our study was conducted to examine the molecular, cellular and behavioral actions of GLYX-13 in stroke, and further characterize the mechanism underlying the neuroprotective actions via modulation of the NMDAR subunit composition. In present study we found that in vitro oxygen-glucose deprivation (OGD) stroke model, GLYX-13 blocked i-LTP and restored the ratio of NR2A/NR2B subunit composition. The glycine site of NMDARs full coagonist D-serine completely blocked the effects of GLYX-13 on i-LTP. Besides, in vivo middle cerebral artery occlusion (MCAO) model, GLYX-13 decreased the cerebral infarct volume and reduced injury of hippocampus. Western analysis showed that GLYX-13 down-regulated the expression of phosphorylated NR2B (Tyr1472) and up-regulated phosphorylated NR2A (Tyr1325). Furthermore, GLYX-13 treatment along with NR2B specific antagonist (Ro256981) failed to exhibit any additional neuro-protective effects, whereas the application of NR2A antagonist (NVP-AAM007) abolished the neuroprotective effects of GLYX-13, which suggested that the protective action of GLYX-13 should be by its regulation of NMDAR subunit components. Our study provides important insights on the potential protective mechanism of GLYX-13 in ischemia and proposes the glycine site of NMDARs as a novel target for developing therapeutic strategies to store synaptic function in stroke.

Purpose: To investigate the effect of Shenxiong Drop Pill (SXDP) on cerebral infarction (CI) in rats, and the involvement of anti-inflammatory response in the process.Methods: Rats were sacrificed at three different time points, viz, 24, 48 and 72 h after establishment of CI model. Neurological deficit score (NDS) was determined using Bederson’s neurological behavioral scoring method, whereas triphenyltetrazolium chloride (TTC) staining was used to show brain injury. The integrated optical density (IOD) of Nissl bodies and caspase-3-positive nerve cells were measured with Nissl staining and SP kit, respectively. The mRNA expression of intercellular adhesion molecule 1(ICAM-1) was determined using reverse transcription-polymerase chain reaction (RT-PCR).Results: SXDP produced neuroprotective effect at high, medium, and low doses. The infarct volumes in the high-, medium- and low-dose SXDP, and cyclophosphamide groups were significantly reduced at each time point. Different doses of SXDP significantly reduced the mRNA expression of ICAM-1 and the IOD of caspase-3.Conclusion: These results indicate that SXDP exerts neuroprotective effects against ischemic injury by negatively regulating ICAM-1/caspase-3 downstream of inflammatory and apoptosis pathways.