Lychee Seed Saponins Improve Cognitive Function and Prevent Neuronal Injury via Inhibiting Neuronal Apoptosis in a Rat Model of Alzheimer’s Disease

Abstract

Lychee seed is a traditional Chinese medicine and possesses many activities, including hypoglycemia, liver protection, antioxidation, antivirus, and antitumor. However, its effect on neuroprotection is still unclear. The present study investigated the effects of lychee seed saponins (LSS) on neuroprotection and associated mechanisms. We established a rat model of Alzheimer’s disease (AD) by injecting Aβ25–35 into the lateral ventricle of rats and evaluated the effect of LSS on spatial learning and memory ability via the Morris water maze. Neuronal apoptosis was analyzed by hematoxylin and eosin stain and terminal deoxynucleotidyl transferase (Tdt)-mediated dUTP nick-end labeling analysis, and mRNA expression of caspase-3 and protein expressions of Bax and Bcl-2 by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The results showed that LSS remarkably improved cognitive function and alleviated neuronal injury by inhibiting apoptosis in the hippocampus of AD rats. Furthermore, the mRNA expression of caspase-3 and the protein expression of Bax were downregulated, while the protein expression of Bcl-2 and the ratio of Bcl-2/Bax were increased by LSS. We demonstrate that LSS significantly improves cognitive function and prevent neuronal injury in the AD rats via regulation of the apoptosis pathway. Therefore, LSS may be developed as a nutritional supplement and sold as a drug for AD prevention and/or treatment.

Inhibitory Effect of Lychee Seed Saponins on Apoptosis Induced by Aβ25-35 through Regulation of the Apoptotic and NF-κB Pathways in PC12 Cells

“…Our previous studies have found that LSS can decrease the formation of Aβ and mitochondrial cytochrome C release, thereby inhibiting neuronal apoptosis in the brain of AD rats [51]. In the present study, we found that the anti-apoptotic effect of LSS in PC12 cells treated with Aβ 25-35 may be associated with mitochondrial membrane function and the NF-κB signaling pathway.…”

<p>Transferrin-Modified Osthole PEGylated Liposomes Travel the Blood-Brain Barrier and Mitigate Alzheimer’s Disease-Related Pathology in APP/PS-1 Mice</p>

“…BAD can increase mitochondrial permeability, release pro-apoptotic factors and CytC, and bind to Bcl-2 family proteins to form dimers, which trigger caspase signaling and cleave pro-caspase-3 into its active forms, resulting in neuronal apoptosis. 47 There is increasing evidence that oxidative stress and neuroinflammation play an important role in the mechanisms associated with Aβ-induced neurotoxicity in AD. 48 Aggregated Aβ may induce oxidative stress by causing mitochondrial dysfunction, which induces the release of reactive oxygen species (ROS), reduces antioxidant levels, such as those of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), etc., and increases oxidant levels, such as those of malondialdehyde (MDA).…”

The seed of Litchi chinensis fraction ameliorates hippocampal neuronal injury in an Aβ25-35-induced Alzheimer’s disease rat model via the AKT/GSK-3β pathway

“…In the current study, the AD animal model was established per our previously described method (Ma et al 2013;Wang et al 2017). In brief, normal male SD rats were first stereotaxically injected with 10 lg aggregated Ab 25-35 in the lateral ventricle at accurate positions based on the dorsoventral (DV), mediolateral (ML) and anteroposterior (AP) coordinates (respectively -2.8 mm, -2.2 mm and -3.0 mm), to locate the CA1 subregion of their hippocampus (Facchinetti et al 2018).…”

“…The seeds of Litchi chinensis contain remarkable amounts of phenolic compounds such as protocatechuic acid, protocatechuic aldehyde, procyanidin D, (-)-epicatechin, cinnamtannin B1, procyanidin A1, rutin and phlorizin (Man et al 2016(Man et al , 2017. In addition, it also contains glycosides such as litchioside D, taxifolin 4 0 -O-b-D-glucopyranoside and kaempferol 7-O-neohesperidoside (Xu et al 2011;Wang et al 2017). Other categories such as organic acids, flavonoids, amino acids, fatty acids and sugar, are also fundamental chemical components of Litchi chinensis seeds (Guo and Pan 2006;Zhang and Zhang 2015).…”

“…The aqueous extracts of the seed can improve learning and memory in mice (Ye et al 2013). Recently, we reported that Litchi chinensis seed fraction (SLF) improved cognitive function by inhibiting neuronal apoptosis in rats (Wang et al 2017). However, it remains unclear whether SLF can prevent hippocampal neuronal injury via the AKT/GSK-3b signalling pathway.…”