Inhibitory effects of angiotensin on NMDA-induced cytotoxicity in primary neuronal cultures

Primary cultures from the hypothalamus/thalamus/septum/midbrain (HTSM) region of 1-day-old mice were used to investigate the effects of angiotensin on NMDA excitotoxicity. Cell viability was determined following exposure to 1-10mM glutamate or 0.01-10mM NMDA. Cells exposed to 1mM glutamate or 1mM NMDA for 24h showed a significant increase in cell death as determined by propidium iodide staining. HTSM cultures treated with 0.1mM NMDA revealed both DNA laddering and positive staining for TUNEL, suggesting apoptosis as the primary mechanism for the cell death. We also determined whether angiotensin II (Ang II) modulated NMDA-induced cell death in HTSM-cultured neurons. Cells pre-treated with 10nM Ang II showed a decrease in NMDA-induced cytotoxicity, TUNEL staining and DNA laddering. NMDA-induced cell death was also reduced when cells were pre-treated with the AT₁ receptor antagonist losartan. In this study, we have shown that NMDA and glutamate induce cell death through the NMDA receptor, and that Ang II, acting primarily through the AT₂ receptor, can attenuate this response.