Sigma-1 receptor knockout impairs neurogenesis in dentate gyrus of adult hippocampus via down-regulation of nmda receptors

Abstract

Summary: Aims: This study investigated the influence of sigma-1 receptor (σ1R) deficiency on adult neurogenesis. Methods: We employed 8-week-old male σ1R knockout (σ1R-/-) mice to examine the proliferation and differentiation of progenitor cells, and the survival and neurite growth of newborn neurons in hippocampal dentate gyrus (DG). Results: In comparison with wild-type (WT) littermates, the numbers of 24-h-old BrdU+ cells and Ki67+ cells in σ1R-/- mice increased, while the number of 28-day-old BrdU+ cells decreased without changes in proportion of BrdU+/NeuN+ cells and BrdU+/GFAP+ cells. The neurite density of newborn neurons was slightly reduced in σ1R-/- mice. In DG granular cells, N-methyl-d-aspartate (NMDA)-activated current (INMDA) and phosphorylation of NMDA receptor (NMDAr) NR2B were reduced in σ1R-/- mice without the alteration of NR2B expression and membrane properties compared to WT mice. The NR2B antagonist abolished the difference in INMDA between σ1R-/- mice and WT mice. The application of NMDAr agonist in σ1R-/- mice prevented the over-proliferation of cells and reduction in newborn neurons, but it had no effects on the hypoplastic neurite. The administration of NMDAr antagonist in WT mice enhanced the cell proliferation and depressed the survival of newborn neurons. Conclusion: The σ1R deficiency impairs neurogenesis in DG through down-regulation of NMDArs. © 2013 John Wiley & Sons Ltd.