The phenylpropionamide extract of hemp (Cannabis sativa L.) seed improves learning memory ability and survival rate by attenuating microglia activation? and reducing amyloid deposition via the SIRT1-AMAD10 pathway in APP/PS1 mice

Abstract

Background: Fructus cannabis (Hemp seed), the dried and mature fruit of Cannabis sativa L., was reported to have effects against Alzheimer's disease (AD) in different experimental models. However, either chemical composition or the action of mechanisms was not clear. Our previous work isolated and identified diverse phenylpropionamides such as cannabisin A-F, caffeoyltyramine and feryroyltyramine from hemp seed, which showed antioxidant and anti-neuroinflammatory activity in cells models. Purpose: To study the anti-AD effect and mechanism of the total phenylpropionamides (TPA) extract from hemp seed using APPswe/PS1dE9 mice model. Methods: TPA extract was prepared via extraction and column chromatography techniques, then analyzed and measured using HPLC, HPLC-MS and Folin-Ciocalteu method. The extract was administered by gavage to APPswe/PS1dE9 mice. The learning memory ability of mice were examined using new object recognition test and Morris water maze. Hematoxylin and Eosin staining was used to observe the morphology of neuronal cells in the hippocampal region of brain tissue; ELISA was used to measure the content of IL-1β, TNF-а, IL-6, superoxide dismutase (SOD), malondialdehyde (MDA) in the brain tissue; the deposition of Aβ protein was measured by immunohistochemistry and Western blotting; the activation of microglia was measured by immunofluorescence. The expression of APP, PS1, SIRT1, and ADAM10 proteins was measured by Western blotting. Results: Folin-Ciocalteu method showed the total phenylpropionamide content was 238.03 μg caffeic acid equivalent /mg TPA. HPLC and HPLC-MS analysis showed the contents of N-trans-caffeoyltyramine, cannabisin A and B were 20.16 μg/mg, 32.16 μg/mg and 214.35 μg/mg, respectively, in TPA extract. TPA treatment significantly increased the survival rate of APP/PS1 mice, improved the learning and memory ability, reversed the neural cell damage in the hippocampal region, and reduced Aβ deposition and activated microglia in brain tissue. Meanwhile, the administration decreased the neuroinflammatory factors TNF-α, IL-6, IL-1β expression, increased antioxidant enzyme SOD activity, and attenuated MDA expression. Western blotting showed that TPA administration increased SIRT1 and ADAM10 protein expression and decreased APP and PS1 protein expression. Conclusion: TPA improved learning memory capacity, increased survival, attenuated neuroinflammation, oxidative stress, microglia activation and hippocampal apoptosis, and reduced amyloid deposition via the SIRT1-ADAM10 pathway in APP/PS1 mice.