Sigma-1 receptor positive allosteric modulator promotes neuronal survival and improves cognitive deficits in AD mice via sigma-1 receptor/ERK pathway

The sigma-1 receptor is an important new therapeutic drug target for Alzheimer’s disease (AD). Here, we reported that SOMCL-668, a novel selective and potent sigma-1 receptor allosteric modulator, is neuroprotective in AD both in vitro and in vivo. SOMCL-668 promoted PC12 cells against Aβ-induced intracellular reactive oxygen species (ROS) accumulation, mitochondrial membrane potential hyperpolarization and neuronal apoptosis. Similar results were obtained in SH-SY5Y and primary cortical culture neurons. The mechanistic study showed that SOMCL-668 stimulated the phosphorylation of ERK and CREB, while pharmacological inhibition or knockout of ERK via CRISPR-Cas9 attenuated its protective effects. Further studies with the sigma-1 receptor agonists/antagonists and knockout of sigma-1 receptor via CRISPR-Cas9 indicated that the sigma-1 receptor is essential for the effect of SOMCL-668. In 3xTg-AD mice, SOMCL-668 improved the learning and memory deficits, inhibited neuronal apoptosis and oxidative stress, reduced Aβ deposition and tau protein phosphorylation via ERK/CREB pathway. Moreover, pretreatment with sigma-1 receptor antagonist BD1047 blocked the effect of SOMCL-668. These results demonstrated that SOMCL-668 provides neuroprotection in AD and its effect is mediated by the sigma-1 receptor/ERK/CREB pathway. Our findings support that SOMCL-668 can be utilized as a potential drug for the prevention and treatment of Alzheimer’s disease.