iridoids and Memory-Disorders

Oleuropein, as an olive leaf extract antioxidant polyphenol, has been reported to be a free radical scavenger. This study was done to investigate the effects of oleuropein, against morphine-induced hippocampus neurotoxicity and memory impairment in rats. The Morris water maze (MWM) test was used to assess the effect of oleuropein (5, 15, and 30 mg/kg, i.p., co-administrated with morphine) on spatial learning and memory of male Wistar rats which were treated with morphine sulfate (45 mg/kg, s.c., 4 weeks). In order to evaluate the cleaved caspase-3, Bax, and Bcl2 protein expression (as biochemical markers of apoptosis) in CA1 area of hippocampus tissue, the western blot test was used. Also, to evaluate the oxidative stress status of hippocampus CA1 area tissue, the malondialdehyde (MDA) level, superoxide dismutase (SOD) activity, and glutathione peroxidase (GPx) activity were assessed. The data showed that oleuropein treatment (15 and 30 mg/kg) improves the spatial learning and memory impairments in morphine-treated animals. Also, oleuropein treatment decreased the apoptosis and oxidative stress levels in the hippocampus CA1 area of morphine-treated rats. Oleuropein can prevent the spatial learning and memory impairments in morphine-treated rats. Molecular mechanisms underlying the observed effects could be at least partially related to the inhibition of neuronal apoptosis and oxidative stress in the hippocampus CA1 area of morphine-treated rats.

Topics: Animals; Antioxidants; CA1 Region, Hippocampal; Glutathione Peroxidase; Iridoid Glucosides; Iridoids; Male; Maze Learning; Memory Disorders; Morphine; Neurotoxicity Syndromes; Oxidative Stress; Rats, Wistar; Spatial Learning; Superoxide Dismutase

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

Although the incidence rate of dementia is rapidly growing in the aged population, therapeutic and preventive reagents are still suboptimal. Various model systems are used for the development of such reagents in which scopolamine is one of the favorable pharmacological tools widely applied. Loganin is a major iridoid glycoside obtained from Corni fructus (Cornusofficinalis et Zucc) and demonstrated to have anti-inflammatory, anti-tumor and osteoporosis prevention effects. It has also been found to attenuate Aβ-induced inflammatory reactions and ameliorate memory deficits induced by scopolamine. However, there has been limited information available on how loganin affects learning and memory both electrophysiologically and behaviorally. To assess its effect on learning and memory, we investigated the influence of acute loganin administration on long-term potentiation (LTP) using organotypic cultured hippocampal tissues. In addition, we measured the effects of loganin on the behavior performance related to avoidance memory, short-term spatial navigation memory and long-term spatial learning and memory in the passive avoidance, Y-maze, and Morris water maze learning paradigms, respectively. Loganin dose-dependently increased the total activity of fEPSP after high frequency stimulation and attenuated scopolamine-induced blockade of fEPSP in the hippocampal CA1 area. In accordance with these findings, loganin behaviorally attenuated scopolamine-induced shortening of step-through latency in the passive avoidance test, reduced the percent alternation in the Y-maze, and increased memory retention in the Morris water maze test. These results indicate that loganin can effectively block cholinergic muscarinic receptor blockade -induced deterioration of LTP and memory related behavioral performance. Based on these findings, loganin may aid in the prevention and treatment of Alzheimer's disease and learning and memory-deficit disorders in the future.

Topics: Analysis of Variance; Animals; Avoidance Learning; Biophysics; Cholinergic Antagonists; Electric Stimulation; Hippocampus; In Vitro Techniques; Iridoids; Learning Disabilities; Long-Term Potentiation; Maze Learning; Memory Disorders; Patch-Clamp Techniques; Rats; Recovery of Function; Scopolamine

Intracerebral-ventricular (ICV) injection of streptozotocin (STZ) induces an insulin-resistant brain state that may underlie the neural pathogenesis of sporadic Alzheimer disease (AD). Our previous work showed that prior ICV treatment of glucagon-like peptide-1 (GLP-1) could prevent STZ-induced learning memory impairment and tau hyperphosphorylation in the rat brain. The Chinese herbal medicine geniposide is known to relieve symptoms of type 2 diabetes. Because geniposide is thought to act as a GLP-1 receptor agonist, we investigated the potential therapeutic effect of geniposide on STZ-induced AD model in rats. Our result showed that a single injection of geniposide (50 μM, 10 μL) to the lateral ventricle prevented STZ-induced spatial learning deficit by about 40% and reduced tau phosphorylation by about 30% with Morris water maze test and quantitative immunohistochemical analysis, respectively. It has been known that tau protein can be phosphorylated by glycogen synthase kinase-3 (GSK3) and STZ can increase the activity of GSK3β. Our result with Western blot analysis showed that central administration of geniposide resulted in an elevated expression of GSK3β(pS-9) but suppressed GSK3β(pY-216) indicating that geniposide reduced STZ-induced GSK3β hyperactivity. In addition, ultrastructure analysis showed that geniposide averted STZ-induced neural pathology, including paired helical filament (PHF)-like structures, accumulation of vesicles in synaptic terminal, abnormalities of endoplasmic reticulum (ER) and early stage of apoptosis. In summary, our study suggests that the water soluble and orally active monomer of Chinese herbal medicine geniposide may serve as a novel therapeutic agent for the treatment of sporadic AD.

Topics: Alzheimer Disease; Animals; Antibiotics, Antineoplastic; Apoptosis; Disease Models, Animal; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hippocampus; Iridoids; Male; Maze Learning; Memory Disorders; Microscopy, Electron, Transmission; Phosphorylation; Rats; Rats, Sprague-Dawley; Signal Transduction; Streptozocin; tau Proteins; Vacuoles

Oxidative stress and mitochondrial dysfunction appear early and contribute to the disease progression in Alzheimer's disease (AD), which can be detected extensively in AD patients brains as well as in transgenic AD mice brains. Thus, treatments that result in attenuation of oxidative stress and mitochondrial dysfunction may hold potential for AD treatment. Geniposide, a pharmacologically active component purified from gardenia fruit, exhibits anti-oxidative, antiinflammatory and other important therapeutic properties. However, whether geniposide has any protective effect on oxidative stress and mitochondrial dysfunction in AD transgenic mouse model has not yet been reported. Here, we demonstrate that intragastric administration of geniposide significantly reduces oxidative stress and mitochondrial dysfunction in addition to improving learning and memory in APP/PS1 mice. Geniposide exerts protective effects on mitochondrial dysfunction in APP/PS1 mice through suppressing the mitochondrial oxidative damage and increasing the mitochondrial membrane potential and activity of cytochrome c oxidase. These studies indicate that geniposide may attenuate memory deficits through the suppression of mitochondrial oxidative stress. Thus, geniposide may be a potential therapeutic reagent for halting and preventing AD progress.

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Brain; Disease Models, Animal; Electron Transport Complex IV; Humans; Iridoids; Male; Malondialdehyde; Maze Learning; Membrane Potential, Mitochondrial; Memory Disorders; Mice, Inbred C57BL; Mice, Transgenic; Mitochondria; Nootropic Agents; Oxidative Stress; Presenilin-1; Random Allocation; Reactive Oxygen Species

The claimed beneficial effects of the Mediterranean diet include prevention of several age-related dysfunctions including neurodegenerative diseases and Alzheimer-like pathology. These effects have been related to the protection against cognitive decline associated with aging and disease by a number of polyphenols found in red wine and extra virgin olive oil. The double transgenic TgCRND8 mice (overexpressing the Swedish and Indiana mutations in the human amyloid precursor protein), aged 1.5 and 4, and age-matched wild type control mice were used to examine in vivo the effects of 8 weeks dietary supplementation of oleuropein aglycone (50 mg/kg of diet), the main polyphenol found in extra virgin olive oil. We report here that dietary supplementation of oleuropein aglycone strongly improves the cognitive performance of young/middle-aged TgCRND8 mice, a model of amyloid-ß deposition, respect to age-matched littermates with un-supplemented diet. Immunofluorescence analysis of cerebral tissue in oleuropein aglycone-fed transgenic mice showed remarkably reduced ß-amyloid levels and plaque deposits, which appeared less compact and "fluffy"; moreover, microglia migration to the plaques for phagocytosis and a remarkable reduction of the astrocyte reaction were evident. Finally, oleuropein aglycone-fed mice brain displayed an astonishingly intense autophagic reaction, as shown by the increase of autophagic markers expression and of lysosomal activity. Data obtained with cultured cells confirmed the latter evidence, suggesting mTOR regulation by oleuropein aglycone. Our results support, and provide mechanistic insights into, the beneficial effects against Alzheimer-associated neurodegeneration of a polyphenol enriched in the extra virgin olive oil, a major component of the Mediterranean diet.

Topics: Amyloid beta-Protein Precursor; Animals; Autophagy; Brain; Cell Line; Cognition; Dietary Supplements; Female; Humans; Iridoid Glucosides; Iridoids; Male; Memory Disorders; Mice; Mice, Transgenic; Mutation; Olive Oil; Plant Oils; Polyphenols; Pyrans; TOR Serine-Threonine Kinases

Optimized-SopungSunkiwon (OSS) is a multi-herbal formula that contains six medicinal herbs from SopungSunkiwon, a traditional medicine used for neurodegenerative disorders. In this study, we investigated the anti-amnesic effects of OSS in a dementia model. Acetylcholinesterase (AChE) inhibition assay was performed to investigate the cholinergic antagonistic effect of OSS. In addition, a step-through passive-avoidance test was performed with scopolamine-induced memory impairment in mice, and immunohistochemistry was analyzed to investigate synaptic formation with synaptic proteins. OSS inhibited AChE activity, resulting in significant improvement of memory functions. In the passive-avoidance test, the latency time of OSS-treated mice was significantly longer than that of either the control or scopolamine-treated group. In the immunohistochemical analysis, synaptic proteins such as synaptophysin and PSD-95 were significantly increased in OSS-treated mice. These results demonstrate that OSS may affect impairment and enhancement of memory and increase synaptophysin and PSD-95 facilitating acetylcholine release and synaptic growth.

Topics: Acetylcholinesterase; Animals; Anthraquinones; Avoidance Learning; Brain; Carotenoids; Chromatography, High Pressure Liquid; Immunohistochemistry; Iridoids; Male; Maze Learning; Medicine, Korean Traditional; Memory; Memory Disorders; Mice; Mice, Inbred ICR; Neuroprotective Agents; Phytotherapy; Plant Extracts; Plants, Medicinal; Senna Extract; Sennosides

Loganin is an iridoid glycoside found in the Flos lonicerae, Fruit cornus, and Strychonos nux vomica. We investigated the effect of loganin on learning and memory impairments induced by scopolamine (0.5mg/kg, i.p.), a muscarinic antagonist, using the Y-maze, passive avoidance, and the Morris water maze tests in mice. In the Y-maze test, loganin (40 mg/kg, p.o.) significantly improved the scopolamine-induced memory impairment. In addition, loganin (20 and 40 mg/kg, p.o.) significantly reversed scopolamine-induced impairments measured by the passive avoidance and the Morris water maze tests. A day after the last trial session of the Morris water maze test (probe trial session), loganin (20 and 40 mg/kg) dose-dependently increased the latency time in the target quadrant. Furthermore, loganin significantly inhibited acetylcholinesterase activity in the hippocampus and frontal cortex. Loganin may have anti-amnesic activity that may hold significant therapeutic value in alleviating certain memory impairments observed in Alzheimer's disease.

Topics: Acetylcholinesterase; Animals; Behavior, Animal; Iridoids; Learning; Male; Maze Learning; Memory Disorders; Mice; Muscarinic Antagonists; Neuroprotective Agents; Scopolamine

The neuroprotective effects of catalpol, an iridoid glycoside isolated from the fresh rehmannia roots, on the behavior and brain energy metabolism in senescent mice induced by d-galactose were assessed. Except control group, mice were subcutaneously injected with d-galactose (150 mg/kg body weight) for 6 weeks. From the fifth week, drug group mice were treated with catalpol (2.5, 5, 10 mg/kg body weight) and piracetam (300 mg/kg body weight) for the last 2 weeks. Behavioral changes including open field test and passive avoidance were examined after drug administration. To determine the brain damage, pathological alterations were measured by hematoxylin and eosin (HE) staining. The activities of lactate dehydrogenase (LDH), glutathione S-transferase (GSH-ST), glutamine synthetase (GS), creatine kinase (CK) in brain cortex and hippocampus were determined using different biochemical methods. Consistent with the cognition deficits, the activities of GSH-ST, GS and CK decreased while the activity of LDH increased in aging mice brain. Administration of catalpol for 2-weeks not only ameliorated cognition deficit, but also reversed the biochemical markers mentioned above and reduced the histological lesions in mouse brain. These results suggest that catalpol has protective effects on memory damage and energy metabolism failure in aging model mice and is worth testing for further preclinical study aimed for senescence or neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD).

Topics: Aging; Animals; Avoidance Learning; Brain; Brain Chemistry; Cerebral Cortex; Cognition; Creatine Kinase; Energy Metabolism; Female; Galactose; Glucosides; Glutathione; Glutathione Transferase; Hippocampus; Indicators and Reagents; Iridoid Glucosides; Iridoids; L-Lactate Dehydrogenase; Male; Memory Disorders; Mice; Motor Activity; Plant Roots; Rehmannia