The Effects Of NMDAR In CNTF Unknown Transduction Pathway

Our past experiments have proved that N-methyl-D-aspartate (NMDA) played an important role in the damage to the hippocampal neurons induced by stress and ciliary neurotrophic factor (CNTF) showed an improving effect with both slow and rapid effect in weakening the damage process. The signal transduction pathway of slow effect of CNTF is clear but that of rapid effect was unclear. In this study, the rapid neuro-protective effects of CNTF on hippocampal neurons and its mechanism via unknown transduction pathway were investigated. Damaged hippocampal neurons, which induced by ionotropic glutamate receptor agonist NMDA, were used as damaged models. Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STATs) inhibitor protein tyrosine phosphatase inhibior-2 (PTPi-2) were used to block the classical transduction pathway of CNTF. The main results were as follows:1. The methyl thiazole tetrazolium (MTT) colorimetric analysis results proved CNTF can protect the damaged hippocampal neurons induced by NMDA regardless JAK/STATs pathway was blocked or not.2. The results of detection of intracellular free Ca²⁺ showed that intracellular free Ca²⁺ concentration ([Ca²⁺];) was rapidly increased after administration of NMDA to hippocampal neurons and CNTF could significantly suppress the increment of [Ca²⁺]j induced by NMDA. CNTF can still inhibit the increment of [Ca²⁺];induced by NMDA after the JAK/STATs pathway was blocked by PTPi-2. And CNTF can inhibit the increment of [Ca²⁺];induced by Tg blocking endoplasmic reticulum Ca²⁺-ATPase.3. Whole cell patch-clamp recording results showed NMDA evoked an inward current. CNTF can rapidly suppress the current peaks evoked by NMDA. After the JAK/STATs pathway was blocked by PTPi-2, CNTF still can inhibit the currents evoked by NMDA.In brief, the results proved that the rapid protective effects of CNTF on hippocampal neurons were performed via other unknown rapid pathway. The pathwayexists in the upstream of JAK/STATs in the classic signal transduction and is related to intracellular Ca2+. In this unknown pathway, NMDAR is one of important elements at least in the signal transduction pathway.