Scm-198 Ameliorates Cognitive Deficits, Promotes Neuronal Survival And Enhances Creb/Bdnf/Trkb Signaling Without Affecting A Beta Burden In A Beta Pp/Ps1 Mice

SCM-198 is an alkaloid found only in Herba leonuri and it has been reported to possess considerable neuroprotective effects in animal models of ischemic stroke, Parkinson's disease and Alzheimer's disease (AD). In this study, we demonstrated for the first time that 3-month oral SCM-198 treatment could significantly improve both recognition and spatial memory, inhibit microgliosis and promote neuronal survival in amyloic protein precursor and presenilin-1(APP/PS1) double-transgenic mice without affecting amyloid-beta (A) burden. In addition, decreases in cAMP-response element-binding protein (CREB) phosphorylation, brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) phosphorylation were attenuated by SCM-198 both in vivo and in primary cortical neurons, which could be blocked by protein kinase A (PKA) inhibitors, suggesting the involvement of upstream PKA in enhancing the BDNF/TrkB/CREB signaling by SCM-198. Our results indicate that SCM-198, a drug that could promote neuronal survival and enhance BDNF/TrkB/CREB signaling, has beneficial effects on behavioral and biochemical alterations without affecting A burden in APP/PS1 mice and might become a potential drug candidate for AD treatment in the future.