Cu,Zn-Superoxide Dismutase has Minimal Effects Against Cuprizone-Induced Demyelination, Microglial Activation, and Neurogenesis Defects in the C57BL/6 Mouse Hippocampus.

Cuprizone causes consistent demyelination and oligodendrocyte damage in the mouse brain. Cu,Zn-superoxide dismutase 1 (SOD1) has neuroprotective potential against various neurological disorders, such as transient cerebral ischemia and traumatic brain injury. In this study, we investigated whether SOD1 has neuroprotective effects against cuprizone-induced demyelination and adult hippocampal neurogenesis in C57BL/6 mice, using the PEP-1-SOD1 fusion protein to facilitate the delivery of SOD1 protein into hippocampal neurons. Eight weeks feeding of cuprizone-supplemented (0.2%) diets caused a significant decrease in myelin basic protein (MBP) expression in the stratum lacunosum-moleculare of the CA1 region, the polymorphic layer of the dentate gyrus, and the corpus callosum, while ionized calcium-binding adapter molecule 1 (Iba-1)-immunoreactive microglia showed activated and phagocytic phenotypes. In addition, cuprizone treatment reduced proliferating cells and neuroblasts as shown using Ki67 and doublecortin immunostaining. Treatment with PEP-1-SOD1 to normal mice did not show any significant changes in MBP expression and Iba-1-immunoreactive microglia. However, Ki67-positive proliferating cells and doublecortin-immunoreactive neuroblasts were significantly decreased. Simultaneous treatment with PEP-1-SOD1 and cuprizone-supplemented diets did not ameliorate the MBP reduction in these regions, but mitigated the increase of Iba-1 immunoreactivity in the corpus callosum and alleviated the reduction of MBP in corpus callosum and proliferating cells, not neuroblasts, in the dentate gyrus. In conclusion, PEP-1-SOD1 treatment only has partial effects to reduce cuprizone-induced demyelination and microglial activation in the hippocampus and corpus callosum and has minimal effects on proliferating cells in the dentate gyrus.

Natural Products in the Prevention of Metabolic Diseases: Lessons Learned from the 20th KAST Frontier Scientists Workshop.

The incidence of metabolic and chronic diseases including cancer, obesity, inflammation-related diseases sharply increased in the 21st century. Major underlying causes for these diseases are inflammation and oxidative stress. Accordingly, natural products and their bioactive components are obvious therapeutic agents for these diseases, given their antioxidant and anti-inflammatory properties. Research in this area has been significantly expanded to include chemical identification of these compounds using advanced analytical techniques, determining their mechanism of action, food fortification and supplement development, and enhancing their bioavailability and bioactivity using nanotechnology. These timely topics were discussed at the 20th Frontier Scientists Workshop sponsored by the Korean Academy of Science and Technology, held at the University of Hawaii at Manoa on 23 November 2019. Scientists from South Korea and the U.S. shared their recent research under the overarching theme of Bioactive Compounds, Nanoparticles, and Disease Prevention. This review summarizes presentations at the workshop to provide current knowledge of the role of natural products in the prevention and treatment of metabolic diseases.

Gynura procumbens Root Extract Ameliorates Ischemia-Induced Neuronal Damage in the Hippocampal CA1 Region by Reducing Neuroinflammation.

Gynura procumbens has been used in Southeast Asia for the treatment of hypertension, hyperglycemia, and skin problems induced by ultraviolet irradiation. Although considerable studies have reported the biological properties of Gynura procumbens root extract (GPE-R), there are no studies on the effects of GPE-R in brain damages, for example following brain ischemia. In the present study, we screened the neuroprotective effects of GPE-R against ischemic damage and neuroinflammation in the hippocampus based on behavioral, morphological, and biological approaches. Gerbils received oral administration of GPE-R (30 and 300 mg/kg) every day for three weeks and 2 h after the last administration, ischemic surgery was done by occlusion of both common carotid arteries for 5 min. Administration of 300 mg/kg GPE-R significantly reduced ischemia-induced locomotor hyperactivity 1 day after ischemia. Significantly more NeuN-positive neurons were observed in the hippocampal CA1 regions of 300 mg/kg GPE-R-treated animals compared to those in the vehicle-treated group 4 days after ischemia. Administration of GPE-R significantly reduced levels of pro-inflammatory cytokines such as interleukin-1ß, -6, and tumor necrosis factor-α 6 h after ischemia/reperfusion. In addition, activated microglia were significantly decreased in the 300 mg/kg GPE-R-treated group four days after ischemia/reperfusion compared to the vehicle-treated group. These results suggest that GPE-R may be one of the possible agents to protect neurons from ischemic damage by reducing inflammatory responses.

Pretreatment of Populus tomentiglandulosa protects hippocampal CA1 pyramidal neurons from ischemia-reperfusion injury in gerbils via increasing SODs expressions and maintaining BDNF and IGF-I expressions.

To examine the effects of Populus tomentiglandulosa (PT) extract on the expressions of antioxidant enzymes and neurotrophic factors in the cornu ammonis 1 (CA1) region of the hippocampus at 5 min after inducing transient global cerebral ischemia (TGCI) in gerbils, TGCI was induced by occlusion of common carotid arteries for 5 min. Before ischemic surgery, 200 mg·kg-1 PT extract was orally administrated once daily for 7 d. We performed neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B staining. Furthermore, we determined in situ production of superoxide anion radical, expression levels of SOD1 and SOD2 as antioxidant enzymes and brain-derived neurotrophic factor (BDNF) and insulin-like growth factor I (IGF-I) as neurotrophic factors. Pretreatment with 200 mg·kg-1 PT extract prevented neuronal death (loss). Furthermore, pretreatment with 200 mg·kg-1 PT extract significantly inhibited the production of superoxide anion radical, increased expressions of SODs and maintained expressions of BDNF and IGF-I. Such increased expressions of SODs were maintained in the neurons after IRI. In summary, pretreated PT extract can significantly increase levels of SODs and protect the neurons against TGCI, suggesting that PT can be a useful natural agent to protect against TGCI.

Leaf extracts from Dendropanax morbifera Léveille mitigate mercury-induced reduction of spatial memory, as well as cell proliferation, and neuroblast differentiation in rat dentate gyrus.

BACKGROUND: The brain is susceptible to methylmercury toxicity, which causes irreversible damage to neurons and glia and the leaf extract Dendropanax morbifera Léveille (DML) has various biological functions in the nervous system. In this study, we examined the effects of DML on mercury-induced proliferating cells and differentiated neuroblasts. METHODS: Dimethylmercury (5 µg/kg) and galantamine (5 mg/kg) was administered intraperitoneally and/or DML (100 mg/kg) was orally to 7-week-old rats every day for 36 days. One hour after the treatment, novel object recognition test was examined. In addition, spatial probe tests were conducted on the 6th day after 5 days of continuous training in the Morris swim maze. Thereafter, the rats were euthanized for immunohistochemical staining analysis with Ki67 and doublecortin and measurement for acetylcholinesterase (AChE) activity. RESULTS: Dimethylmercury-treated rats showed reduced discrimination index in novel object recognition test and took longer to find the platform than did control group. Compared with dimethylmercury treatment alone, supplementation with DML or galatamine significantly ameliorated the reduction of discrimination index and reduced the time spent to find the platform. In addition, the number of platform crossings was lower in the dimethylmercury-treated group than in controls, while the administration of DML or galantamine significantly increased the number of crossings than did dimethylmercury treatment alone. Proliferating cells and differentiated neuroblasts, assessed by Ki67 and doublecortin immunohistochemical staining was significantly decreased in the dimethylmercury treated group versus controls. Supplementation with DML or galantamine significantly increased the number of proliferating cells and differentiated neuroblasts in the dentate gyrus. In addition, treatment with dimethylmercury significantly increased AChE activity in hippocampal homogenates, while treatment with dimethylmercury+DML or dimethylmercury+galantamine significantly ameliorated this increase. CONCLUSIONS: These results suggest that DML may be a functional food that improves dimethylmercury-induced memory impairment and ameliorates dimethylmercury-induced reduction in proliferating cells and differentiated neuroblasts, and demonstrates corresponding activation of AChE activity in the dentate gyrus.

Improvement in neurogenesis and memory function by administration of Passiflora incarnata L. extract applied to sleep disorder in rodent models.

Recently, there have been reports that chronic insomnia acts as an insult in the brain, causing memory loss through the production of ROS, inflammation, and, Alzheimer's disease if persistent. Insomnia remains the leading cause of sleep disturbance and as such has serious implications for public health. Patients with Alzheimer's disease are also known to suffer from severe sleep disturbance. Meanwhile, vitexin is a key ingredient in Passiflora incarnata L (passion flower, PF) extract, which is known to help with sleep. This medicinal plant has been used as a folk remedy for sedation, anxiety and sleep since centuries ago, but the standardization work has not been done and the extent of the effect has not been clearly demonstrated. For this reason, we tried to test the possibility that repeated administration of PF could improve the memory by promoting hippocampal neurogenesis at the DBA/2 mice known have inherited sleep disorders, as well as preventive effects of Alzheimer's disease. Here, we found that vitexin, which is the main bioactive component of ethanol extracts from leaves and fruits (ratio; 8:2) of PF, confirmed the improvement of neurogenesis (DCX) of DBA/2 mice repeated PF oral administration by immunohistochemistry (IHC) and western blot analysis. PF-treated group showed increased the neurotrophic factor (BDNF) in the hippocampus compared with that of vehicle-treated group, but the inflammation markers Iba-1 (microglial marker) and COX-2 were inconsistent between the groups. However, we found COX-2 signal is essential for hippocampal neurogenesis according to the additional IHC experiments using COX-2 inhibitor and pIkappaB have shown. In addition, although prescription sleeping pills have been reported to show significant changes in appetite and metabolic rate from time to time, no changes in the feeding behavior, body weight, metabolic rate and body composition of the animals were observed by administration of PF. Interestingly, we found that short-term oral administration of PF displayed improved memory according to the water maze test. Quantitative analysis of Tau protein, which is a marker of Alzheimer's disease, was performed in the SD rats and DBA/2 mice by repeated PF oral administration and pTau/Tau values were significantly decreased in PF-treated group than vehicle-treated group. In conclusion, our results suggest that PF lead high hippocampal neurogenesis in the animals even in inherited sleep-disturbed animals. The increased hippocampal neurogenesis functionally enhanced memory and learning functions by repeated PF oral administration. These results identify PF as a potential therapy for enhancing memory functions and prevention of Alzheimer's disease through actions on the hippocampus.

Methionine-Choline Deprivation Impairs Adult Hippocampal Neurogenesis in C57BL/6 Mice.

Methionine and choline, which are essential nutrients for mammalian animals, are important for cell composition, as metabolic factors, and for the synthesis of other biochemical compounds for cell metabolism. Methionine and choline, which are methyl group donors, play key roles in the homocysteine cycle and neuronal development and maintenance. In this study, we investigated the effects of methionine and choline deficiency on adult hippocampal neurogenesis and neural stem cell (NSC) lineage in the adult stage. For this study, we divided C57BL/6 mice into three groups as follows: normal chow (NC)-fed, methionine choline sufficient (MCS) diet-fed, and methionine choline deficient (MCD) diet-fed mice. The mice were fed the NC, MCS, and MCD diets for 4 weeks from the age of 8 weeks. MCD diet-fed mice showed significantly decreased proliferation and differentiation of NSCs when compared with the NC diet-fed or MCS diet-fed mice. In addition, the survival of newly generated neurons was critically impaired in the MCD diet-fed mice. We confirmed a decrease in the proliferation and differentiation of NSCs after 4 weeks of MCD diet administration, compared with that in NC- and MCS diet-fed mice. MCD diet critically impaired NSCs survival and survival of neurons during the 4 weeks. The number of phosphorylated cyclic AMP response element binding (pCREB) protein immunoreactive nuclei was decreased in the MCD diet-fed mice compared with that in the NC- or MCS diet-fed group. These results suggest that suitable levels of methionine and choline are essential for the maintenance of hippocampal neurogenesis in mice and affect NSC proliferation and differentiation through phosphorylation of CREB.

Metabolomics Analysis of the Lipid-Regulating Effect of Allium hookeri in a Hamster Model of High-Fat Diet-Induced Hyperlipidemia by UPLC/ESI-Q-TOF Mass Spectrometry.

Hyperlipidemia is a risk factor for atherosclerotic cardiovascular disease and is a major public health concern. Allium hookeri (AH) is an Allium species containing high levels of bioactive organosulfur compounds such as methiin and cycloalliin. AH exerts hypolipidemic effects in animals fed a high-fat diet. However, there exists little information on the mechanisms underlying these effects. To address this issue, we used a metabolomic approach based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry to identify factors mediating the lipid-lowering effects of AH. Principal component and partial least-squares discriminant analyses of serum metabolome profiles revealed 25 metabolites as potential biomarkers for the effects of AH on lipid levels. These compounds were predominantly phospholipids, including phosphatidylcholines (PCs), lysoPCs, and lysophosphatidylethanolamines. Glycerophospholipid metabolism was identified as a significantly enriched pathway. These results provide mechanistic insight into the antihyperlipidemic effects of AH and evidence for its efficacy as a therapeutic agent.

Glehnia littoralis Extract Promotes Neurogenesis in the Hippocampal Dentate Gyrus of the Adult Mouse through Increasing Expressions of Brain-Derived Neurotrophic Factor and Tropomyosin-Related Kinase B.

BACKGROUND: Glehnia littoralis has been used for traditional Asian medicine, which has diverse therapeutic activities. However, studies regarding neurogenic effects of G. littoralis have not yet been considered. Therefore, in this study, we examined effects of G. littoralis extract on cell proliferation, neuroblast differentiation, and the maturation of newborn neurons in the hippocampus of adult mice. METHODS: A total of 39 male ICR mice (12 weeks old) were randomly assigned to vehicle-treated and 100 and 200 mg/kg G. littoralis extract-treated groups (n = 13 in each group). Vehicle and G. littoralis extract were orally administrated for 28 days. To examine neurogenic effects of G. littoralis extract, we performed immunohistochemistry for 5-bromo-2-deoxyuridine (BrdU, an indicator for cell proliferation) and doublecortin (DCX, an immature neuronal marker) and double immunofluorescence staining for BrdU and neuronal nuclear antigen (NeuN, a mature neuronal marker). In addition, we examined expressional changes of brain-derived neurotrophic factor (BDNF) and its major receptor tropomyosin-related kinase B (TrkB) using Western blotting analysis. RESULTS: Treatment with 200 mg/kg, not 100 mg/kg, significantly increased number of BrdU-immunoreactive (+) and DCX+ cells (48.0 ± 3.1 and 72.0 ± 3.8 cells/section, respectively) in the subgranular zone (SGZ) of the dentate gyrus (DG) and BrdU+/NeuN+ cells (17.0 ± 1.5 cells/section) in the granule cell layer as well as in the SGZ. In addition, protein levels of BDNF and TrkB (about 232% and 244% of the vehicle-treated group, respectively) were significantly increased in the DG of the mice treated with 200 mg/kg of G. littoralis extract. CONCLUSION: G. littoralis extract promots cell proliferation, neuroblast differentiation, and neuronal maturation in the hippocampal DG, and neurogenic effects might be closely related to increases of BDNF and TrkB proteins by G. littoralis extract treatment.

Bacopa monnieri extract improves novel object recognition, cell proliferation, neuroblast differentiation, brain-derived neurotrophic factor, and phosphorylation of cAMP response element-binding protein in the dentate gyrus.

Bacopa monnieri is a medicinal plant with a long history of use in Ayurveda, especially in the treatment of poor memory and cognitive deficits. In the present study, we hypothesized that Bacopa monnieri extract (BME) can improve memory via increased cell proliferation and neuroblast differentiation in the dentate gyrus. BME was administered to 7-week-old mice once a day for 4 weeks and a novel object recognition memory test was performed. Thereafter, the mice were euthanized followed by immunohistochemistry analysis for Ki67, doublecortin (DCX), and phosphorylated cAMP response element-binding protein (CREB), and western blot analysis of brain-derived neurotrophic factor (BDNF). BME-treated mice showed moderate increases in the exploration of new objects when compared with that of familiar objects, leading to a significant higher discrimination index compared with vehicle-treated mice. Ki67 and DCX immunohistochemistry showed a facilitation of cell proliferation and neuroblast differentiation following the administration of BME in the dentate gyrus. In addition, administration of BME significantly elevated the BDNF protein expression in the hippocampal dentate gyrus, and increased CREB phosphorylation in the dentate gyrus. These data suggest that BME improves novel object recognition by increasing the cell proliferation and neuroblast differentiation in the dentate gyrus, and this may be closely related to elevated levels of BDNF and CREB phosphorylation in the dentate gyrus.

Differential Effects of Low- and High-dose Zinc Supplementation on Synaptic Plasticity and Neurogenesis in the Hippocampus of Control and High-fat Diet-fed Mice.

In the present study, we investigated the concentration-dependent effect of zinc (Zn) supplementation on the adult hippocampus in a high-fat diet (HFD)-fed obese mouse model. Four-weeks after HFD- and control diet (CD)-feeding, mice were provided with low (15 ppm) or high (60 ppm) doses of Zn in their drinking water for additional 4 more weeks along with their respective diets. Compared to the CD-fed mice, HFD-feeding elicited the reduction of neurogenic markers such as nestin, Ki67, doublecortin (DCX), and 5-bromo-2'-deoxyuridine (BrdU) in the dentate gyrus. Additionally, HFD-feeding reduced the levels of synaptic markers (synaptophysin and N-methyl-D-aspartate receptor) and brain-derived neurotrophic factor (BDNF), while lipid peroxidation was significantly increased in the hippocampus of HFD-fed mice. Against detrimental effects of high-dose Zn, low-dose Zn supplementation in CD-fed mice did not yield any remarkable changes in these parameters. Interestingly, administration of low doses of Zn to HFD-induced obese mice prominently ameliorated HFD-induced changes in neurogenic, synaptic plasticity markers and BDNF levels as well as lipid peroxidation in the hippocampus. In contrast, high-dose Zn supplementation in HFD-fed mice exacerbated the reduction of markers for neurogenesis and synaptic plasticity as well as BDNF levels, but not 4-HNE levels, in the hippocampus. These results suggest that low-dose Zn supplementation in obese mice could reverse the HFD-induced reduction in neurogenic and synaptic marker proteins in the hippocampus by reducing lipid peroxidation and improving BDNF expression, while high-dose Zn supplementation exacerbates the reduction of neurogenesis by affecting synaptic markers and BDNF levels in the hippocampus.

Pretreated Glehnia littoralis Extract Prevents Neuronal Death Following Transient Global Cerebral Ischemia through Increases of Superoxide Dismutase 1 and Brain-derived Neurotrophic Factor Expressions in the Gerbil Hippocampal Cornu Ammonis 1 Area.

BACKGROUND: Glehnia littoralis, as a traditional herbal medicine to heal various health ailments in East Asia, displays various therapeutic properties including antioxidant effects. However, neuroprotective effects of G. littoralis against cerebral ischemic insults have not yet been addressed. Therefore, in this study, we first examined its neuroprotective effects in the hippocampus using a gerbil model of transient global cerebral ischemia (TGCI). METHODS: Gerbils were subjected to TGCI for 5 min. G. littoralis extract (GLE; 100 and 200 mg/kg) was administrated orally once daily for 7 days before ischemic surgery. Neuroprotection was examined by neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B histofluorescence staining. Gliosis was observed by immunohistochemistry for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1. For neuroprotective mechanisms, immunohistochemistry for superoxide dismutase (SOD) 1 and brain-derived neurotrophic factor (BDNF) was done. RESULTS: Pretreatment with 200 mg/kg of GLE protected pyramidal neurons in the cornu ammonis 1 (CA1) area from ischemic insult area (F = 29.770, P < 0.05) and significantly inhibited activations of astrocytes (F = 22.959, P < 0.05) and microglia (F = 44.135, P < 0.05) in the ischemic CA1 area. In addition, pretreatment with GLE significantly increased expressions of SOD1 (F = 28.561, P < 0.05) and BDNF (F = 55.298, P < 0.05) in CA1 pyramidal neurons of the sham- and ischemia-operated groups. CONCLUSIONS: Our findings indicate that pretreatment with GLE can protect neurons from ischemic insults, and we suggest that its neuroprotective mechanism may be closely associated with increases of SOD1 and BDNF expressions as well as attenuation of glial activation.

Neuronal maturation in the hippocampal dentate gyrus via chronic oral administration of Artemisa annua extract is independent of cyclooxygenase 2 signaling pathway in diet-induced obesity mouse model.

Recently, we reported that Artemisia annua (AA) has anti-adipogenic properties in vitro and in vivo. Reduction of adipogenesis by AA treatment may dampen systemic inflammation and protect neurons from cytokine-induced damage. Therefore, the present study was undertaken to assess whether AA increases neuronal maturation by reducing inflammatory responses, such as those mediated by cyclooxygenase 2 (COX-2). Mice were fed normal chow or a high-fat diet with or without chronic daily oral administration of AA extract (0.2 g/10 mL/kg) for 4 weeks; then, changes in their hippocampal dentate gyri were measured via immunohistochemistry/immunofluorescence staining for bromodexoxyuridine, doublecortin, and neuronal nuclei, markers of neuronal maturation, and quantitative western blotting for COX-2 and Iba-1, in order to assess correlations between systemic inflammation (interleukin-6) and food type. Additionally, we tested the effect of AA in an Alzheimer's disease model of Caenorhabditis elegans and uncovered a potential benefit. The results show that chronic AA dosing significantly increases neuronal maturation, particularly in the high-fat diet group. This effect was seen in the absence of any changes in COX-2 levels in mice given the same type of food, pointing to the possibility of alternate anti-inflammatory pathways in the stimulation of neurogenesis and neuro-maturation in a background of obesity.

Dendropanax morbifera Léveille extract ameliorates cadmium-induced impairment in memory and hippocampal neurogenesis in rats.

BACKGROUND: Cadmium leads to learning and memory impairment. Dendropanax morbifera Léveille stem extract (DMS) reduces cadmium-induced oxidative stress in the hippocampus. We investigated the effects of DMS on cadmium-induced impairments in memory in rats. METHODS: Cadmium (2 mg/kg), with or without DMS (100 mg/kg), was orally administered to 7-week-old Sprague-Dawley rats for 28 days. Galantamine (5 mg/kg), an acetylcholinesterase inhibitor, was intraperitoneally administered as a positive control. A novel-object recognition test was conducted 2 h after the final administration. Cell proliferation and neuroblast differentiation were assessed by immunohistochemistry for Ki67 and doublecortin, respectively. Acetylcholinesterase activity in the synaptosomes of the hippocampus was also measured based on the formation of 5,5'-dithio-bis-acid nitrobenzoic acid. RESULTS: An increase in the preferential exploration time of new objects was observed in both vehicle-treated and cadmium-treated rats. In addition, DMS administration increased cell proliferation and neuroblast differentiation in the dentate gyrus of vehicle-treated and cadmium-treated rats. Acetylcholinesterase activity in the hippocampal synaptosomes was also significantly higher in the DMS-treated group than in the vehicle-treated group. The effect of DMS on cadmium-induced memory impairment and cell proliferation in the hippocampus was comparable to that of galantamine. CONCLUSIONS: These results suggest that DMS ameliorates cadmium-induced memory impairment via increase in cell proliferation, neuroblast differentiation, and acetylcholinesterase activity in the hippocampus. The consumption of DMS may reduce cadmium-induced neurotoxicity in animals or humans.

Essential oils from two Allium species exert effects on cell proliferation and neuroblast differentiation in the mouse dentate gyrus by modulating brain-derived neurotrophic factor and acetylcholinesterase.

BACKGROUND: In the present study, we investigated the effects of oil products from two Allium species: Allium sativum (garlic) and Allium hookeri (Chinese chives) on cell proliferation and neuroblast differentiation in the mouse dentate gyrus. METHODS: Using corn oil as a vehicle, the essential oil from garlic (10 ml/kg), or Chinese chives (10 ml/kg) was administered orally to 9-week-old mice once a day for 3 weeks. One hour following the last treatment, a novel object recognition test was conducted and the animals were killed 2 h after the test. RESULTS: In comparison to the vehicle-treated group, garlic essential oil (GO) treatment resulted in significantly increased exploration time and discrimination index during the novel object recognition test, while Chinese chives essential oil (CO) reduced the exploration time and discrimination index in the same test. In addition, the number of Ki67-immunoreactive proliferating cells and doublecortin-immunoreactive neuroblasts significantly increased in the dentate gyrus of GO-treated animals. However, administration of CO significantly decreased cell proliferation and neuroblast differentiation. Administration of GO significantly increased brain-derived neurotrophic factor (BDNF) levels and decreased acetylcholinesterase (AChE) activity in the hippocampal homogenates. In contrast, administration of CO decreased BDNF protein levels and had no significant effect on AChE activity, compared to that in the vehicle-treated group. CONCLUSIONS: These results suggest that GO significantly improves novel object recognition as well as increases cell proliferation and neuroblast differentiation, by modulating hippocampal BDNF protein levels and AChE activity, while CO impairs novel object recognition and decreases cell proliferation and neuroblast differentiation, by reducing BDNF protein levels in the hippocampus.

Valerenic Acid Protects Against Physical and Psychological Stress by Reducing the Turnover of Serotonin and Norepinephrine in Mouse Hippocampus-Amygdala Region.

In a previous study, we demonstrated that a Valeriana officinalis extract could attenuate increases in serum corticosterone levels in a mouse model of physical and psychological stress. In addition, our results showed that the extract could modulate serotonin (5-HT) and norepinephrine (NE) turnover in the hippocampus and amygdala region. In this study, we intended to investigate the effects of valerenic acid (VA), the main component of V. officinalis extract, on corticosterone levels in serum in normal mice and monoamine turnover in hippocampus-amygdala homogenates in a mouse model of physical and psychological stress. To determine the minimum dose of VA for antianxiety effect, eight-week-old ICR mice were orally administered VA (0.2, 0.5, and 1.0 mg/kg/0.3 mL) once daily for 3 weeks to probe for immobility time and serum corticosterone levels. At a VA dose of 0.5 and 1.0 mg/kg, animals showed a decrease in the duration of immobility time and serum corticosterone levels. To confirm the antianxiety effect of VA, eight-week-old ICR mice received VA at a dose of 0.5 mg/kg, orally, once daily for 3 weeks, before being subjected to physical or psychological stress for 3 days, in a specially designed communication box, followed by estimation of levels of monoamines and their metabolites in the hippocampus-amygdala region. In conclusion, VA administration at 0.5 mg/kg can mitigate the physical and psychological stress response by decreasing the turnover of 5-HT to 5-hydroxyindoleacetic acid and NE to 3-methoxy-4-hydroxyphenylethyleneglycol sulfate in the hippocampus and amygdala.

Antioxidant effects of Dendropanax morbifera Léveille extract in the hippocampus of mercury-exposed rats.

BACKGROUND: Dendropanax morbifera Léveille has been employed for the treatment of infectious diseases using folk medicine. In this study, we evaluated the antioxidant effects of a leaf extract of Dendropanax morbifera Léveille in the hippocampus of mercury-exposed rats. METHODS: Seven-week-old Sprague-Dawley rats received a daily intraperitoneal injection of 5 µg/kg dimethylmercury and/or oral Dendropanax morbifera Léveille leaf extract (100 mg/kg) for 4 weeks. Animals were sacrificed 2 h after the last dimethylmercury and/or leaf extract treatment. Mercury levels were measured in homogenates of hippocampal tissue, a brain region that is vulnerable to mercury toxicity. In addition, we measured reactive oxygen species production, lipid peroxidation levels, and antioxidant levels in these hippocampal homogenates. RESULTS: Treatment with Dendropanax morbifera Léveille leaf extract significantly reduced mercury levels in hippocampal homogenates and attenuated the dimethylmercury-induced increase in the production of reactive oxygen species and formation of malondialdehyde. In addition, this leaf extract treatment significantly reversed the dimethylmercury-induced reduction in the hippocampal activities of Cu, Zn-superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase. CONCLUSION: These results suggest that a leaf extract of Dendropanax morbifera Léveille had strong antioxidant effects in the hippocampus of mercury-exposed rats.

Valeriana officinalis Extracts Ameliorate Neuronal Damage by Suppressing Lipid Peroxidation in the Gerbil Hippocampus Following Transient Cerebral Ischemia.

As a medicinal plant, the roots of Valeriana officinalis have been used as a sedative and tranquilizer. In the present study, we evaluated the neuroprotective effects of valerian root extracts (VE) on the hippocampal CA1 region of gerbils after 5 min of transient cerebral ischemia. Gerbils were administered VE orally once a day for 3 weeks, subjected to ischemia/reperfusion injury, and continued on VE for 3 weeks. The administration of 100 mg/kg VE (VE100 group) significantly reduced the ischemia-induced spontaneous motor hyperactivity 1 day after ischemia/reperfusion. Four days after ischemia/reperfusion, animals treated with VE showed abundant cresyl violet-positive neurons in the hippocampal CA1 region when compared to the vehicle or 25 mg/kg VE-treated groups. In addition, the VE treatment markedly decreased microglial activation in the hippocampal CA1 region 4 days after ischemia. Compared to the other groups, the VE100 group showed the lowest level of lipid peroxidation during the first 24 h after ischemia/reperfusion. In summary, the findings in this study suggest that pretreatment with VE has protective effects against ischemic injury in the hippocampal pyramidal neurons by decreasing microglial activation and lipid peroxidation.

Electroacupuncture at the Zusanli and Baihui acupoints ameliorates type-2 diabetes-induced reductions in proliferating cells and differentiated neuroblasts in the hippocampal dentate gyrus with increasing brain-derived neurotrophic factor levels.

In the current study, we investigated whether electroacupuncture (EA) can inhibit pathological reductions in neurogenesis. Zucker diabetic fatty (ZDF) rats at 7 weeks of age were anesthetized with zoletil, and sham-acupuncture or EA at the Zusanli (ST36) and Baihui (GV20) acupoints was administered once a day for 5 weeks. In the ZDF group that received sham-EA (ZDF-Sham group), the blood glucose level was significantly increased together with age as compared to the control littermates [Zucker lean control (ZLC) rat]. In contrast, proliferating cells and differentiated neuroblasts were significantly decreased in the ZDF-Sham group compared to the ZLC group. Although EA treatment decreased blood glucose levels, this was not statistically significant when compared to blood glucose levels changes in the ZDF-Sham group. However, proliferating cells and differentiated neuroblasts were significantly increased with EA in ZDF rats as compared to those in the ZDF-Sham group. Brain-derived neurotrophic factor (BDNF) levels were significantly decreased in hippocampal homogenates of ZDF-Sham group compared to those in the ZLC group. The EA treatment significantly increased the BDNF levels compared to those in the ZDF-Sham group, and BDNF levels in this group were similar to those in the ZLC group. These results suggest that EA at ST36 and GV20 can ameliorate the reductions in proliferating cells and differentiated neuroblasts in the dentate gyrus induced by type-2 diabetes without significantly reducing blood glucose levels with increasing BDNF levels.

Valeriana officinalis root extract suppresses physical stress by electric shock and psychological stress by nociceptive stimulation-evoked responses by decreasing the ratio of monoamine neurotransmitters to their metabolites.

BACKGROUND: In this study, we investigate the effects of valerian root extracts (VE) on physical and psychological stress responses by utilizing a communication box. METHODS: Eight-week-old ICR mice received oral administration of VE (100 mg/kg/0.5 ml) or equal volume of distilled water in every day for 3 weeks prior to being subjected to physical or psychological stress for 3 days, which are induced by communication box developed for physical electric shock and psychological stress by nociceptive stimulation-evoked responses. The stress condition was assessed by forced swimming test and serum corticosterone levels. In addition, norepinephrine (NE), serotonin (5-HT), and their metabolites such as 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4) and 5-hydroxyindoleacetic acid (5-HIAA) were measured in the hippocampus and amygdala at 1 h after final stress condition, respectively. RESULTS: Immobility time and corticosterone levels were significantly increased in both the physical and psychological stress groups compared to the control group. The administration of VE significantly reduced these parameters in both the physical and psychological stress groups. In addition, compared to the control group, physical and psychological stress groups showed significantly increased levels of MHPG-SO4 and 5-HIAA in the hippocampus and amygdala, respectively. The administration of VE significantly suppressed the increase of MHPG-SO4 and 5-HIAA in the two stress groups. CONCLUSION: These results suggest that VE can suppress physical and psychological stress responses by modulating the changes in 5-HT and NE turnover in the hippocampus and amygdala.