Assessment and Validation of Globodera pallida as a Novel In Vivo Model for Studying Alzheimer's Disease

Neuroprotective effect of nose-to-brain delivery of Asiatic acid in solid lipid nanoparticles and its mechanisms against memory dysfunction induced by Amyloid Beta1-42 in mice

BACKGROUND

Amyloid-β1-42 (Aβ1-42) plays an essential role in the development of the early stage of Alzheimer's disease (AD). Asiatic acid (AA), an active compound in Centella asiatica L, exhibit neuroprotective properties in previous studies. Due to its low bioavailability, the nose-to-brain delivery technique was used to enhance AA penetration in the brain. In this study, AA was also loaded in solid lipid nanoparticles (SLNs) as a strategy to increase its absorption in the nasal cavity.

METHODS

Memory impairment was induced via direct intracerebroventricular injection of Aβ1-42 oligomer into mouse brain. The neuroprotective effect and potential underlying mechanisms were investigated using several memory behavioral examinations and molecular techniques.

RESULTS

The intranasal administration of AA in SLNs attenuated learning and memory impairment induced by Aβ1-42 in Morris water maze and novel object recognition tests. AA significantly inhibited tau hyperphosphorylation of pTau-S396 and pTau-T231 and prevented astrocyte reactivity and microglial activation in the hippocampus of Aβ1-42-treated mice. It is also decreased the high levels of IL-1β, TNF-α, and malondialdehyde (MDA) in mouse brain.

CONCLUSIONS

These results suggested that nose-to-brain delivery of AA in SLNs could be a promising strategy to treat the early stage of AD.

Ethnomedicinal Plants with Protective Effects against Beta-Amyloid Peptide (Aβ)1-42 Indicate Therapeutic Potential in a New In Vivo Model of Alzheimer's Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with unmet medical need. This investigation consisted of testing a range of ethanolic ethnomedicinal plant extracts (n = 18) traditionally used in the treatment of disorders such as anxiety, delirium, and memory loss. They were then screened for in vitro inhibitory activity against acetylcholinesterase (AChE), butylcholinesterase (BuChE), beta-secretase 1/beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), and antioxidant activities. Plants with potent activities were further characterised using a recently developed in vivo model of AD, Globodera pallida. The ability of phytoextracts to protect this organism against amyloid-beta Aβ (1-42) exposure was assessed by measuring chemosensing, survival rate, production of reactive oxygen species (ROS), and antioxidant responses. Extracts (n = 5) from Juglans regia (leaves), Ellettaria cardamomum (seeds), Cinnamomum zeylanicum (bark), Salvia officinalis (leaves/flowers), and Hypericum perforatum (flowers) exerted concentration-dependent inhibitory activities against AChE and BuChE. Three of these plant extracts (i.e., J. regia, E. cardamomum, and S. officinalis) possessed strong concentration-dependent inhibitory activity against BACE1. Furthermore, the five selected medicinal plant extracts not only enhanced significantly (p < 0.05) the nematode’s chemosensing, survival rate, and antioxidant responses (i.e., anti-ROS production, mitochondrial reductase activity, oxidized glutathione (GSSG) to reduced glutathione (GSH) ratio), but also greatly restored (p < 0.05) in a concentration-dependent manner the Aβ (1-42)-induced deleterious changes in these same parameters. In brief, this investigation highlights plant extracts with strong anti-AD activities which could be trialled as novel therapeutic supplements or undergo further biodiscovery research.