Zerumbone promotes proliferation of endogenous neural stem cells in vascular dementia by regulating Notch signalling

Introduction
Present investigation determines the effect of zerumbone on the proliferation of stem cells in vascular dementia (VD) rats.

Material and methods
Vascular dementia was induced by cerebral ischemia and reperfusion through non-invasive clamp. Rats were treated with zerumbone 50 mg/kg and 100 mg/kg intraperitoneally 30 min for four weeks after the surgery. Cognitive functions are determined by the Morris water maze (MWM) test and neurological function score in VD rats. Moreover mediators of inflammation and parameters of oxidative stress were estimated in the brain tissue homogenate of ischemia-induced vascular dementia rats. The expression of proteins and mRNA expressions were determined by western blot assay and RT-PCR methods. Moreover histopathological changes were observed by H&E staining on the brain tissue of vascular dementia rats.

Results
There was a significant reduction in the cognitive function and neurological score in the zerumbone-treated group compared to the VD group of rats. Data of the study reveal that treatment with zerumbone attenuates the altered level of cytokines and markers of oxidative stress parameters in the brain tissue of VD rats. The expression of NICD, Hes-1 and Nestin proteins was significantly (p < 0.01) reduced in the brain tissue of the zerumbone-treated group compared to the VD group of rats. There was a significant reduction in the mRNA expression of Notch-1 and Hes-1 in the brain tissue of the zerumbone-treated group compared to the VD group of rats.

Conclusions
This study concludes that treatment with zerumbone protects the neuronal injury and ameliorates the cognitive function by stimulating the proliferation of endogenous neural stem cells. Moreover proliferation of neural stem cells was stimulated in zerumbone-treated rats by regulating the Notch signalling.