NEP1-40 Regulates the Development of Hippocampal Neural Stem Cells in Schizophrenic Mice.

Abstract

Objective: Schizophrenia is a complex neuropsychiatric disorder characterized by cognitive, affective, and behavioral abnormalities. Existing treatments have yielded limited effects on improving cognitive function. Recent studies have identified the abnormal differentiation of hippocampal neural stem cells (NSCs), neuronal loss, and dysregulated proliferation of astrocytes as significant pathological mechanisms contributing to the symptoms of schizophrenia. Impaired hippocampal neurogenesis may lead to emotional and cognitive deficits and biases in learning and memory, indicating that NSC differentiation is critical. NEP1-40, a Nogo-A receptor inhibitor, has shown promise for nerve protection and repair promotion. However, the effects of NEP1-40 on stem cell differentiation, the reduction in neuronal apoptosis, and the amelioration of schizophrenia-like behaviors have not been adequately investigated. This study examined the influence of NEP1-40 on NSC differentiation, hippocampal neuronal apoptosis, and proliferation in adolescent mice, along with its potential to enhance cognitive and behavioral outcomes in MK-801-induced schizophrenia mouse models.

Methods: In in vivo experiments, a schizophrenia mouse model was successfully established. Subsequently, behavioral tests were conducted, followed by Western blotting (WB) and immunofluorescence (IF) analyses. In in vitro settings, NSCs were cultured and transfected. Flow cytometry, along with WB and IF assays, was employed to evaluate the effects of NEP1-40.

Results: Schizophrenia-like behaviors in mice were significantly improved with the overexpression of NEP1-40. Compared with the model group, the NEP1-40 treatment group presented increased expression of a neuronal marker (Tuj1), reduced expression of an astroglial marker (GFAP), and decreased hippocampal neuronal apoptosis. NSC differentiation was assessed by quantifying the number of BrdU-positive cells coexpressing Tuj1 and GFAP in the hippocampal dentate gyrus. NEP1-40 treatment led to an increase in BrdU/Tuj1-positive cells and a reduction in BrdU/GFAP-positive cells. In cellular studies, NEP1-40 overexpression similarly increased the number of Tuj1-positive cells, reduced the number of GFAP-positive cells, decreased the degree of neuronal apoptosis, and promoted neuronal proliferation.

Conclusion: These findings demonstrated the neurogenic effects of NEP1-40 on NSCs and their potential to mitigate schizophrenia-like behaviors in vivo.