Impact of Two Neuronal Sigma-1 Receptor Modulators, PRE084 and DMT, on Neurogenesis and Neuroinflammation in an Aβ1–42-Injected, Wild-Type Mouse Model of AD

Alzheimer's disease (AD), the most common form of dementia, involves cognitive decline. Two sigma-1 receptor (S1R) agonists, dimethyltryptamine (DMT) and PRE084, were tested in a mouse model of AD induced by amyloid-beta (Aβ). DMT, which also binds strongly to serotonin receptors, reduced neurogenesis, likely due to its mixed receptor activity. In contrast, the highly selective S1R agonist PRE084 increased hippocampal cell proliferation and differentiation. Both DMT and PRE084 significantly reduced astrogliosis (a marker of neuroinflammation) caused by Aβ, but neither affected microglial activation. The findings suggest that selective S1R agonists like PRE084 may be promising therapeutic agents for AD, though further research is needed.

Study at a glance

Abstract

Alzheimer’s disease (AD) is the most common form of dementia characterized by cognitive dysfunctions. Pharmacological interventions to slow the progression of AD are intensively studied. A potential direction targets neuronal sigma-1 receptors (S1Rs). S1R ligands are recognized as promising therapeutic agents that may alleviate symptom severity of AD, possibly via preventing amyloid-β-(Aβ-) induced neurotoxicity on the endoplasmic reticulum stress-associated pathways. Furthermore, S1Rs may also modulate adult neurogenesis, and the impairment of this process is reported to be associated with AD. We aimed to investigate the effects of two S1R agonists, dimethyltryptamine (DMT) and PRE084, in an Aβ-induced in vivo mouse model characterizing neurogenic and anti-neuroinflammatory symptoms of AD, and the modulatory effects of S1R agonists were analyzed by immunohistochemical methods and western blotting. DMT, binding moderately to S1R but with high affinity to 5-HT receptors, negatively influenced neurogenesis, possibly as a result of activating both receptors differently. In contrast, the highly selective S1R agonist PRE084 stimulated hippocampal cell proliferation and differentiation. Regarding neuroinflammation, DMT and PRE084 significantly reduced Aβ1–42-induced astrogliosis, but neither had remarkable effects on microglial activation. In summary, the highly selective S1R agonist PRE084 may be a promising therapeutic agent for AD. Further studies are required to clarify the multifaceted neurogenic and anti-neuroinflammatory roles of these agonists.