A role of the novel, non‐AT1, non‐AT2 angiotensin binding site in neuronal cell death

Abstract

The novel, non‐AT1, non‐AT2 angiotensin binding site is a yet unknown protein found in rodent and human brain membranes with pharmacological specificity and tissue distribution different from the type 1 and 2 angiotensin receptors and key enzymes involved in proteolytic processing of angiotensins. Here we report a summary of our recent studies indicating a correlation between the density of the novel binding site in primary neurons and neuronal cell death. 125I‐Sar1, Ile8 angiotensin II binding studies were carried out according to previously established procedures in mouse primary cortical neuronal membranes. Unmasking of the novel angiotensin binding site was carried out by 10 μM p‐chloromercuribenzoic acid (PCMB) in the presence of 10 μM PD123319 and 1 μM ZD7155 (AT1 & AT2 receptor antagonists). 12 in‐vitro‐day‐old primary neurons were challenged in three in vitro models of apoptosis (oxygen‐glucose deprivation for 3 hr, exposure to sodium azide (3 mM) or NMDA (0.5 mM) for 30 min in glucose free EBSS) followed by 24 hr recovery in normal medium. Density of the novel angiotensin binding site in neuronal membranes was estimated by saturation binding assays. The results indicated that the number of novel angiotensin binding sites was significantly elevated in neuronal membranes from all treatment groups, where the viability of neurons was significantly decreased. Supported by TTUHSC SOP start‐up funds to VTK.