iridoids and Cognition-Disorders

The amyloid plaques and neurofibrillary tangles found in the Alzheimer's disease (AD) brain arise as a result of self-assembly into fibrillar material of amyloid-β protein (Aβ) and hyperphosphorylated tau, respectively, through a pathological process starting with the appearance of aggregation nuclei and neurotoxic oligomers. Accordingly, the search of inhibitors of oligomer nucleation and growth is considered a promising target to prevent amyloid toxicity. In recent years, a number of dietary factors including antioxidants, vitamins, and polyphenols have been characterized for their ability to protect cells stressed by several factors including the presence of amyloid deposits as well as to inhibit amyloid self-assembly and cytotoxicity and some of them are currently in clinical trial. The present review summarizes the findings on the beneficial effects against neurodegeneration and other peripheral inflammatory and degenerative diseases of oleuropein aglycone (OLE), a natural phenol abundant in the extra virgin olive oil. The data presently available suggest that OLE could provide a protective and therapeutic effect against a number of pathologies, including AD as well as obesity, type 2 diabetes, non-alcoholic hepatitis, and other natural or experimentally-induced pathological conditions. Such a protection could result, at least in part, in a remarkable improvement of the pathological signs arising from stress conditions including oxidative stress, an excessive inflammatory response, and the presence of cytotoxic aggregated material. In particular, the recent data on the cellular and molecular correlates of OLE neuroprotection suggest it could also play a therapeutic role against AD.

Topics: Alzheimer Disease; Anti-Inflammatory Agents; Cognition Disorders; Humans; Inflammation; Iridoid Glucosides; Iridoids; Nerve Degeneration; Plaque, Amyloid

To investigate the effects and the mechanism of geniposide on the neuroinflammation occured in the neurodegeneration course of a chronic cerebral hypoperfusion rat model.. Permanent bilateral common carotid arteries occlusions was performed to induce gradient cognitive deficit in rats. The sham group was used as control group. Then 18 rats that met the Screening Criteria were randomly selected 8 weeks post surgery, and were randomly divided into three groups, the 2-VO rats with saline solution group (2-VO+saline group), 2-VO rats with 50 mg/kg per day geniposide group (2-VO+G50) and 2-VO rats with 100 mg/kg per day geniposide group (2-VO+G100). All intervention groups were daily administered with geniposide or saline for 4 weeks. The sham-operated rats were administrated with saline. Then the rats were tested for Morris water maze to evaluate the memory and learning ability. Rats were sacrificed to obtain cortex and hippocampus tissues for HE staining and to detect expression level of glial fibrillary acidic protein (GFAP), inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-κB), and the level of inflammatory factors tumor necrosis factor-α (TNF-α) and interleukin (IL)-6.. These findings demonstrated that geniposide significantly prevented cognition deterioration induced by chronic cerebral hypoperfusion in rats. Geniposide inhibited neuroinflammation occurred in the process of chronic cerebral ischemia probably via reducing iNOS and NF-κB expression and suppressing the release of inflammatory factor TNF-α and IL-6.

Topics: Animals; Anti-Inflammatory Agents; Brain Ischemia; Cognition Disorders; Disease Models, Animal; Hippocampus; Iridoids; Maze Learning; Random Allocation; Rats

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by memory deficits and cognitive decline. Amyloid-β (Aβ) deposition and cholinergic defect are widely thought to be the underlying mechanism of learning and memory impairment. Geniposide, which is the main active component of the traditional Chinese herbal Gardenia jasminoides Ellis, elicits neuroprotective effects by alleviating inflammation responses and oxidative damages. In this study, we investigated the protective effect of geniposide on levels of cholinergic markers, RAGE, RAGE-dependent signalling pathways and amyloid accumulation in the APPswe/PS1dE9 AD model mouse. Geniposide suppressed MAPK signaling over-activation mediated by Aβ-RAGE interaction, resulting in reduced Aβ accumulation and amelioration of cholinergic deficits in the cerebral hippocampus. Furthermore, geniposide inhibited the toxic effect of oligomeric Aβ

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloidosis; Animals; Brain; Cognition Disorders; Disease Models, Animal; Dose-Response Relationship, Drug; Iridoids; Male; MAP Kinase Signaling System; Memory Disorders; Mice, Inbred C57BL; Mice, Transgenic; Neurons; Neuroprotective Agents; Nootropic Agents; Peptide Fragments; Receptor for Advanced Glycation End Products

The herbal medicine Tong Luo Jiu Nao (TLJN) contains geniposide (GP) and ginsenoside Rg1 at a molar ratio of 10:1. Rg1 is the major component of another herbal medicine, panax notoginseng saponin (PNS). TLJN has been shown to strengthen brain function in humans, and in animals it improves learning and memory. We have previously shown that TLJN reduces amyloidogenic processing in Alzheimer's disease (AD) mouse models. Together this suggests TLJN may be a potential treatment for patients with dementia. Because chronic damage of the central nervous system by formaldehyde (FA) has been presented as a risk factor for age-associated cognitive dysfunction, in the present study we investigated the protective effect of both TLJN and GP in neuron-like cells exposed to FA. FA-exposed murine N2a neuroblastoma cells were incubated with TLJN, its main ingredient GP, as well as PNS, to measure cell viability and morphology, the rate of apoptosis and expression of genes encoding Akt, FOXO3, Bcl2 and p53. The CCK-8 assay, cytoskeletal staining and flow cytometry were used to test cell viability, morphology and apoptosis, respectively. Fluorescent quantitative real-time PCR (qRT-PCR) was used to monitor changes in gene expression, and HPLC to determine the rate of FA clearance. Treatment of N2a cells with 0.09 mmol L(-1) FA for 24 h significantly reduced cell viability, changed cell morphology and promoted apoptosis. Both TLJN and GP conferred neuroprotection to FA-treated N2a cells, whereas PNS, which had to be used at lower concentrations because of its toxicity, did not. Our data demonstrate that TLJN can rescue neuronal damage caused by FA and that its main ingredient, GP, has a major role in this efficacy. This presents purified GP as a drug or lead compound for the treatment of AD.

Topics: Animals; Apoptosis; Cell Line, Tumor; Cell Survival; Central Nervous System; Chromatography, High Pressure Liquid; Cognition Disorders; Cytoskeleton; Dementia; Formaldehyde; Iridoids; Learning; Medicine, Chinese Traditional; Memory; Mice; Neuroblastoma; Plant Preparations; Real-Time Polymerase Chain Reaction

In this study, the neuroprotection of aucubin and its mechanism were evaluated in the rat model of diabetic encephalopathy. Diabetes mellitus (DM) rats were stratified by cognitive capability (CC), and assigned to four treatment groups for aucubin treatment (doses of 0, 1, 5 or 10 mg/kg aucubin), with a further two groups of non-DM rats ranked by CC as controls for aucubin (doses of 0 or 5 mg/kg aucubin). Neuroprotection was estimated by the indexes of behavior and histology. Behavioral testing was performed in a Y-maze. The surviving neurons in CA1-CA4 and subiculum (SC) of the hippocampus were counted under a microscope. In addition, the apoptotic neurons in the CA1 of the hippocampus were also examined by using TUNEL staining. In order to clarify the mechanism of aucubin's neuroprotection, the activities of endogenous antioxidants and nitric oxide synthase (NOS) together with the content of lipid peroxide in the hippocampus were assayed. The results proved that aucubin significantly reduced the content of lipid peroxide, regulated the activities of antioxidant enzymatic and decreased the activity of NOS. All these effects indicated that aucubin was a potential neuroprotective agent and its neuroprotective effects were achieved, at least in part, by promoting endogenous antioxidant enzymatic activities.

Topics: Animals; Antioxidants; Brain Diseases; Cognition Disorders; Diabetes Mellitus, Experimental; Glucosides; Hippocampus; Iridoid Glucosides; Iridoids; Lipid Peroxides; Male; Malondialdehyde; Neurons; Neuroprotective Agents; Nitric Oxide Synthase; Rats; Rats, Wistar

The neuroprotective effects of catalpol, an iridoid glycoside isolated from the fresh Rehmannia roots, on the senescent mice induced by D-galactose were assessed. The mice subcutaneously injected with catalpol (5 or 10 mg/kg, 2 weeks, from fifth week) showed significantly improved learning and memory ability in Morris water maze test compared with d-galactose treated mice (150 mg/kg, 6 weeks). We further investigated the mechanism involved in the neuroprotective effects of catalpol on the mice brain tissue. The results showed that catalpol increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), decreased the malondialdehyde (MDA) level, elevated the activities of Na+ -K+ ATPase and Ca2+ -Mg2+ ATPase on the cerebral cortex and hippocampus of d-galactose treated mouse. All the data suggested that catalpol had the potential to be a useful cognitive impairment treatment, and its beneficial effects may be partly mediated via enhancing endogenous antioxidant enzymatic activities and inhibiting free radical generation.

Topics: Aging; Animals; Brain Chemistry; Ca(2+) Mg(2+)-ATPase; Cerebral Cortex; Cognition Disorders; Female; Galactose; Glucosides; Glutathione Peroxidase; Indicators and Reagents; Iridoid Glucosides; Iridoids; Lipid Peroxidation; Male; Malondialdehyde; Maze Learning; Mice; Oxidative Stress; Plant Roots; Rehmannia; Sodium-Potassium-Exchanging ATPase; Superoxide Dismutase