Modification of GSK3β/β-catenin signaling on saikosaponins-d-induced inhibition of neural progenitor cell proliferation and adult neurogenesis.

Saikosaponins-d (SSd) is a major bioactive compound isolated from Radix Bupleuri, an herb widely used in traditional Chinese medicine. Emerging studies demonstrate that SSd adversely affects adult neurogenesis and impairs learning and memory. However, the molecular mechanisms remain to be determined. The current study investigated the potential regulatory of GSK3β/β-catenin signaling on SSd-induced neurotoxicity. We demonstrated that SSd exposure inhibited the cell viability and proliferation of primary neuronal stem/progenitor cells (NPCs) from hippocampus in a concentration-dependent manner. Significantly, SSd exposure induced activation of GSK3β and reduced the cellular β-catenin in NPCs. Treatment with SB216763, a specific inhibitor for GSK3β activation, we showed that inactivation GSK3β improved the β-catenin signaling by inhibiting degradation complex comprising Axin and APC and attenuated SSd-induced toxicity in NPCs. In addition, administration of SB216763 ameliorated SSd-induced inhibition of NPCs proliferation and enhanced radial glial cells in the hippocampus of mice. Moreover, inactivation GSK3β promoted dendritic arborization and the survival of newborn neurons together with alleviated the impairment of SSd-induced cognitive function in mice. Overall, these data demonstrated that the significant inhibitory effects of SSd on NPCs proliferation and adult neurogenesis via GSK3β/β-catenin signaling pathway. Our results contribute to a better understanding of the molecular mechanisms of SSd-induced neurotoxicity.
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