The synergistic effects of heat shock protein 70 and ginsenoside Rg1 against tert-butyl hydroperoxide damage model in vitro

New insights into the role and mechanisms of ginsenoside Rg1 in the management of Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder in the elderly characterized by memory loss and cognitive dysfunction. The pathogenesis of AD is complex. One-targeted anti-AD drugs usually fail to delay AD progression. Traditional Chinese medicine records have documented the use of the roots of Panax ginseng (ginseng roots) and its prescriptions to treat dementia. Ginsenoside Rg1, the main ginsenoside component of ginseng roots, exhibits a certain therapeutic effect in the abovementioned diseases, suggesting its potential in the management of AD. Therefore, we combed the pathogenesis of AD and currently used anti-AD drugs, and reviewed the availability, pharmacokinetics, and pharmaceutic studies of ginsenoside Rg1. This review summarizes the therapeutic effects and mechanisms of ginsenoside Rg1 and its deglycosylated derivatives in AD in vivo and in vitro. The main mechanisms include improvement in Aβ and Tau pathologies, regulation of synaptic function and intestinal microflora, and reduction of inflammation, oxidative stress, and apoptosis. The underlying mechanisms mainly involve the regulation of PKC, MAPK, PI3K/Akt, CDK5, GSK-3β, BDNF/TrkB, PKA/CREB, FGF2/Akt, p21WAF1/CIP1, NF-κB, NLRP1, TLR3, and TLR4 signaling pathways. As the effects and underlying mechanisms of ginsenoside Rg1 on AD have not been systematically reviewed, we have provided a comprehensive review and shed light on the future directions in the utilization of ginsenoside Rg1 and ginseng roots as well as the development of anti-AD drugs.

Synergistic Antioxidant Effects of Araloside A and L-Ascorbic Acid on H2O2-Induced HEK293 Cells: Regulation of Cellular Antioxidant Status

Araloside A is a pentacyclic triterpenoid saponin, and L-ascorbic acid is a globally recognized antioxidant. In this study, coadministered araloside A and L-ascorbic acid were found to have a strong synergistic antioxidant effect, and correlations between cellular antioxidant indexes and free radical scavenging ability were found. Individual and combined pretreatment with araloside A and L-ascorbic acid increased both cell viability and antioxidant enzyme activity and inhibited the release of lactate dehydrogenase (LDH); the accumulation of malondialdehyde (MDA), lipid peroxidation (LPO) products, and H2O2; and the production of intracellular reactive oxygen species (ROS), protein carbonyls, and 8-hydroxy-2-deoxy guanosine (8-OHdG). Free radical scavenging ability was positively correlated with superoxide dismutase (SOD) and catalase (CAT) activity, the glutathione (GSH)/oxidized glutathione (GSSG) ratio, and total antioxidant capacity (T-AOC). Our study is the first investigation of araloside A and L-ascorbic acid coadministration for the treatment of diseases caused by oxidative stress. The synergistic antioxidant effects of araloside A and L-ascorbic acid support their potential as functional food ingredients for the elimination of oxidative stress-induced adverse reactions.

Heat Shock Protein 70 (HSP70) Induction: Chaperonotherapy for Neuroprotection after Brain Injury

The 70 kDa heat shock protein (HSP70) is a stress-inducible protein that has been shown to protect the brain from various nervous system injuries. It allows cells to withstand potentially lethal insults through its chaperone functions. Its chaperone properties can assist in protein folding and prevent protein aggregation following several of these insults. Although its neuroprotective properties have been largely attributed to its chaperone functions, HSP70 may interact directly with proteins involved in cell death and inflammatory pathways following injury. Through the use of mutant animal models, gene transfer, or heat stress, a number of studies have now reported positive outcomes of HSP70 induction. However, these approaches are not practical for clinical translation. Thus, pharmaceutical compounds that can induce HSP70, mostly by inhibiting HSP90, have been investigated as potential therapies to mitigate neurological disease and lead to neuroprotection. This review summarizes the neuroprotective mechanisms of HSP70 and discusses potential ways in which this endogenous therapeutic molecule could be practically induced by pharmacological means to ultimately improve neurological outcomes in acute neurological disease.

Lycopene protects against t-BHP-induced neuronal oxidative damage and apoptosis via activation of the PI3K/Akt pathway

Oxidative stress is a key factor of and closely implicated in the pathogenesis of Alzheimer's disease (AD). We herein used tert-butyl hydroperoxide (t-BHP) to induce oxidative stress and mimic oxidative neurotoxicity in vitro. Lycopene is a natural antioxidant that has a strong ability to eliminate free radicals and shows effective protection in some neurodegenerative disease models. However, the effect of lycopene on t-BHP-induced neuronal damage in primary mouse neurons is unknown. This study aimed to investigate the effects of lycopene on t-BHP-induced neuronal damage and the related mechanisms. We found that lycopene pretreatment effectively enhanced the cell viability, improved the neuron morphology, increased the GSH/GSSG level, restored the mitochondrial membrane potential (ΔΨm) and decreased reactive oxygen species generation. Furthermore, lycopene reduced the ratios of Bax:Bcl-2 and cleaved caspase-3:caspase-3 and the level of cytochrome C, increased the levels of synaptophysin (SYP) and postsynaptic density 95 (PSD95) and activated the PI3K/Akt pathway. In conclusion, lycopene attenuated oxidative stress and reduced t-BHP-induced cell apoptosis, and the mechanism is likely related to activation of the PI3K/Akt pathway. Therefore, lycopene is a potential agent for preventing oxidative stress-mediated AD.

The Secretion from Neural Stem Cells Pretreated with Lycopene Protects against tert-Butyl Hydroperoxide-Induced Neuron Oxidative Damage

Neural stem cells (NSCs) hold great potential for the treatment of Alzheimer's disease (AD) through both cellular replacement and their secretion of trophic factors. Lycopene is a potent β-carotenoid antioxidant that has been shown to ameliorate oxidative damage in previous studies. However, it is unclear if lycopene can interact with NSCs to induce the secretion of growth factors, and whether pretreatment with lycopene will allow NSCs to secrete enough trophic factors to reduce oxidative damage to neurons. We pretreated cultured NSCs with lycopene, then applied the lycopene-treated-NSC-conditioned media (Ly-NSC-CM) to primary neuronal cultures exposed to tert-butyl hydroperoxide (t-BHP) to induce oxidative damage. We found that lycopene promoted the secretion of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) from NSCs. In addition, Ly-NSC-CM attenuated oxidative stress and reduced t-BHP-induced cell apoptosis. We found an antiapoptotic effect related to inhibited expression of Bax/Bcl-2, cytochrome C, and cleaved caspase-3. Moreover, Ly-NSC-CM increased the levels of synaptic proteins, including synaptophysin (SYP) and postsynaptic density 95 (PSD-95), and activated the PI3K/Akt pathway in cultured neurons. Collectively, these data indicate that Ly-NSC-CM could protect neurons from t-BHP-induced oxidative damage.

HMG-CoA Reductase Inhibitors Relieve Endoplasmic Reticulum Stress by Autophagy Inhibition in Rats With Permanent Brain Ischemia

Exploring and expanding the indications of common clinical drugs, such as statins, is important to improve the prognosis of patients with permanent cerebral infarction. It has been suggested that reversing the defects in cellular autophagy and ER stress with statin therapy may be a potential treatment option for reducing ischemic damage. Male Sprague-Dawley rats underwent permanent middle cerebral artery occlusion (PMCAO) by electrocoagulation surgery. Atorvastatin (ATV, 10 mg/kg/day) or vehicle was administered intraperitoneally. Rats were divided into the vehicle-treated (SHAM), ATV pretreatment for MCAO (AMCAO), and 3-methyladenine (3MA) combined with ATV pretreatment (3MAMCAO) groups. Magnetic resonance imaging, as well as immunohistochemical and Western blot assessments, were performed 24 h after MCAO. Each ATV-treated group demonstrated significant reductions in infarct volume compared with that in the vehicle-treated group at 24 h after MCAO, which was associated with autophagy reduction and ER stress attenuation in neurons and neovascularization. Next, Western blotting was used to detect the levels of the autophagy-related proteins LC3B and P62 and of ER stress pathway proteins. However, 3MA significantly partially inhibited the ER stress pathway via limiting the autophagic flux in the AMCAO group. In conclusion, our results imply that the neuroprotective function of ATV depends on autophagic activity to diminish ER stress-related cell apoptosis in rats with PMCAO and suggest that compounds that inhibit autophagic activity might reduce the neuroprotective effect of ATV after brain ischemia.

Ginsenoside Rg1 relieves tert-Butyl hydroperoxide-induced cell impairment in mouse microglial BV2 cells

Microglial activation plays an important role in neurodegenerative diseases associated with oxidative stress. tert-Butyl hydroperoxide (t-BHP), an analog of hydroperoxide, mimics the oxidative damage to microglial cells. It has been reported that ginsenoside Rg1 (G-Rg1), an active ingredient of Panax ginseng, has anti-stress and anti-inflammatory properties. The present study aims to investigate the ability of G-Rg1 to decrease the t-BHP-mediated cell damage of BV2 microglial cells. We performed flow cytometry assays to facilitate the detection of reactive oxygen species as well as Western blotting analyses and immunofluorescence assays using specific antibodies, such as antibodies against phospho-mitogen-activated protein kinases (p-MAPKs), phospho-nuclear factor-κB (p-NF-κB), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X (Bax), Caspase-3, autophagy marker light chain 3 (LC3), and Becline-1. We found that treatment with 50 μM G-Rg1 protected microglial cells against oxidative damage induced by 10 μM t-BHP.