Sigma-1 Receptor (σ – 1R) Activation and Modulation of NMDA Receptor Surface Expression

Abstract

The sigma-1 receptors (σ-1Rs) are endoplasmic reticulum (ER) resident proteins shown to have chaperone-like functions, and are widely distributed throughout the central nervous system (CNS). They reside at a specialized membrane called mitochondria- associated ER-membrane (MAM) and can modulate numerous voltage- and ligand-gated ion channels. One of these channels is the N-methyl-D-aspartate receptor (NMDAR), and σ-1R ligands are able to enhance the potentiation of NMDARs, but the mechanism involved remains poorly understood. Using various biochemical techniques, we show that 90 min following an i.p. injection of σ-1R agonists ((+)-SKF 10,047 (SKF), (+)- Pentazocine (PTZ), or PRE-084 (PRE), there is an increase in the expression of GluN2- containing NMDARs in the rat hippocampus. These results suggest that σ-1R activation is able to enhance NMDAR function by modulating protein expression levels both in the cytosol and on the cell surface. This suggests that σ-1Rs could be excellent therapeutic targets for many neurological disorders, and for the development of novel antipsychotics.