Combination of docosahexaenoic acid and Ginko biloba extract improves cognitive function and hippocampal tissue damages in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases characterized by a progressive loss of memory and other cognitive functions among elder people. Nowadays, natural antioxidants have been used to recover the quality of life for those with AD. In this study, we investigated, for the first time, the combined effect of docosahexaenoic acid (DHA) and Ginkgo bilobastandardized extract (EGb761) on AD mice. AD was induced in adult male albino mice with AlCl₃ (20 mg/kg b.w, i.g.) and D-galactose (D-gal; 120 mg/kg, i.p.) for 90 days. 30 days after induction, mice were treated with DHA (200 mg/kg b.w., i.g.) and EGb761 (200 mg/kg b.w., i.g.) for two months. Our data revealed that the dual treatment of DHA and EGb761 significantly improved cognitive memory and spatial learning abilities in AD-induced mice. The drug treatments preserved the hippocampal CA3 architecture and restored neuronal ultrastructural alterations. Expression of protein phosphatase 2A (PP2A), the most implicated protein phosphatase in AD neurodegeneration, was highly upregulated in the CA3 hippocampus of AD mice treated with DHA and EGb761. Intriguingly, TNF-α expression was significantly reduced in the same group. In conclusion, our findings proved that the combined effect of DHA and EGb761 tended to be potent against the neurodegenerative effect of AlCl₃ and D-gal. The applied treatment enhanced neuronal survival and cognitive functions via upregulation of PP2A and restoration of TNF-α expression.

Golgi-Cox impregnation combined with fluorescence staining of amyloid plaques reveals local spine loss in an Alzheimer mouse model

BACKGROUND

Spine loss is a hallmark of Alzheimer´s and other neurodegenerative diseases, and testing candidate therapeutic drugs needs quantitative analysis of dendritic spine densities. Golgi-Cox impregnation of neurons is a classical method to visualize dendritic spines in diseased brains. Importantly, at early disease stages spine loss occurs locally in the vicinity of amyloid plaques, and concomitant fluorescence labeling of amyloid plaques is required to detect local spine damage.

NEW METHOD

Because Golgi-Cox impregnation is done on unsectioned brains, whereas fluorescence staining is performed on sectioned material, the combination is technically challenging. We have now developed a novel combination of Golgi-Cox impregnation with methoxy-X04 fluorescence labeling of plaques that is performed on unsectioned brains.

RESULTS

We used this new combination method to quantify dendritic spine densities in mouse hippocampal CA1 pyramidal neurons. Comparison of neurons from wildtype and APP/PS1 mice revealed local spine loss in the vicinity of amyloid plaques in both male and female APP/PS1 mice.

COMPARISON WITH EXISTING METHOD

Golgi-Cox impregnation of neurons combined with methoxy-X04 staining of amyloid plaques is a highly reliable, easy-to-use method for permanent visualization of spines as compared to the technically more sophisticated and less stable fluorescence imaging of spines.

CONCLUSION

Our novel combination method will be highly useful for testing potential therapeutic drugs in Alzheimer mouse models.