Eugenol relieves the pathological manifestations of Alzheimer's disease in 5×FAD mice.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the accumulation of amyloid-ß (Aß) and excessive neuroinflammation, resulting in neuronal cell death and cognitive impairments. Eugenol, a phenylpropene, is the main component of Syzygium aromaticum L. (Myrtaceae) and has multiple therapeutic effects, including neuroprotective and anti-inflammatory effects, through multimodal mechanisms. PURPOSE: We aimed to investigate the effect of eugenol on AD pathologies using a 5× familiar AD (5×FAD) mouse model. METHODS: Eight-month-old 5×FAD and wild-type mice were administered with eugenol (10 or 30 mg/kg/day, p.o) for 2 months. Y-maze and Morris water maze tests were performed to assess the cognitive function of mice. After the behavioral test, molecular analysis was conducted to investigate the therapeutic mechanism of eugenol. RESULTS: Our findings indicate that eugenol treatment effectively mitigated cognitive impairments in 5×FAD mice. This beneficial effect was associated with a decrease in AD pathologies, including neuronal cell loss and Aß deposition. Specifically, eugenol inhibited necroptosis activation and increased microglial phagocytosis, which were the underlying mechanisms for the observed reductions in neuronal cell loss and Aß deposition, respectively. CONCLUSION: Overall, our data suggest that eugenol would be a potential therapeutic candidate for AD.

Aerial part of Houttuynia cordata reverses memory impairment by regulating amyloid beta accumulation and neuroinflammation in Alzheimer's disease model.

Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by amyloid-ß (Aß) deposition, accompanied by neuroinflammation and memory dysfunction. Houttuyniae Herba (aerial parts of Houttuynia cordata, also known as fish mint; HH), an herbal medicine traditionally used to treat fever, urinary disorders, and pus, is revealed to protect neurons from Aß toxicity and regulate cholinergic dysfunction in AD models. In this study, we aimed to investigate the effects of HH on excessive accumulation of Aß followed by neuroinflammation, synaptic degeneration, and memory impairment. Two-month-old 5xFAD transgenic mice were administered HH at 100 mg/kg for 4 months. We observed that HH treatment ameliorated memory impairment and reduced Aß deposits in the brains of the mice. HH directly inhibited Aß aggregation in vitro using the Thioflavin T assay and indirectly suppressed the amyloidogenic pathway by increasing alpha-secretase expression in the mice brain. In addition, HH exerted antineuroinflammatory effects by reducing of glial activation and p38 phosphorylation. Moreover, HH treatment increased the expression of synaptophysin, a presynaptic marker protein. Overall, HH alleviates memory impairment in AD by facilitating nonamyloidogenic pathway and inhibiting neuroinflammation. Therefore, we suggest that HH can be a promising herbal drug for patients with AD requiring multifaceted improvement.

A novel nutritional mixture, MBN, prevents memory impairment via inhibiting NLRP3 inflammasome formation in 5xFAD transgenic mice.

OBJECTIVES: Amyloid beta (Aß)-induced abnormal neuroinflammation is recognized as a major pathological factor of Alzheimer's disease (AD), which results in memory impairment. Inhibition of excessive neuroinflammation mediated by Aß is considered a promising strategy to ameliorate AD symptoms. To regulate the inflammatory response, nutritional and dietary supplements have been used for centuries. Based on this idea, we investigated whether MBN, a novel nutritional mixture including cassia bark, turmeric root, and ginkgo leaf, can prevent AD progression through neuroinflammatory regulation. METHODS: MBN (10, 30, or 100 µg/ml) and Aß1-42 monomer were incubated together, and the degree of Aß aggregation was measured using Thioflavin T assay. The effects of MBN on Aß pathology in vivo were evaluated by orally administering MBN (40 mg/kg/day for 16 weeks) to five familial AD (5xFAD) mice. RESULTS: We found that treatment with MBN inhibited Aß aggregation in vitro. Next, MBN treatment significantly inhibited the activation of microglia induced by aggregated Aß in 5xFAD mice. Caspase-1 activation, which plays an important role in the maturation of interleukin-1ß, was markedly reduced by MBN. We also found that oral administration of MBN in 5xFAD mice alleviated memory decline. Taken together, our findings demonstrate that MBN suppresses neuroinflammation by downregulating the caspase-1 expression, thereby ameliorating memory impairment in 5xFAD mice. DISCUSSION: Based on these results, we suggest that MBN may be a preventive and therapeutic supplement for AD through the regulation of neuroinflammation.

Artemisiae Iwayomogii Herba inhibits lipopolysaccharide-induced neuroinflammation by regulating NF-κB and MAPK signaling pathways.

BACKGROUND: Neuroinflammation plays a major role in the development of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. The regulation of microglia is an efficient therapeutic approach to controlling neuroinflammation. PURPOSE: In this study, we aimed to determine whether Artemisiae Iwayomogii Herba (AIH), which is herbal medicine traditionally used for inflammation-related disorders, controls neuroinflammatory responses by regulating the microglia-mediated signaling pathway. METHODS: BV-2 microglial cells were treated with AIH and lipopolysaccharides (LPS), then various pro-inflammatory mediators were analyzed using griess reaction, quantitative reverse-transcription polymerase chain reaction, or western blotting. C57BL/6 J mice were orally administered by AIH for 17 days and intraperitoneally injected with LPS for the last 14 days. The brains were collected and the microglial activation and nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing 3 (NLRP3) expression in the cortex and hippocampus were analyzed using immunohistochemistry or western blotting. RESULTS: In BV-2 microglial cells, we found that AIH inhibited nitric oxide (NO) production induced by LPS. AIH also suppressed the expressions of pro-inflammatory mediators, including inducible NO synthase, cyclooxygenase-2, tumor necrosis factor-α, and interleukin-6. The study also revealed that the effects of AIH are related to the regulation of the nuclear factor kappa B (NF-κB) and the mitogen-activated protein kinase (MAPK) signaling pathway. Additionally, we found that AIH prevented the formation of NLRP3 inflammasomes. Consistent with the results of in vitro studies on the brains of LPS-injected mice, we observed that AIH suppressed microglial activation and NLRP3 expression. CONCLUSION: Taken together, these results suggest that AIH attenuates neuroinflammation by regulating the NF-κB and MAPK pathways, and it may be used for treating neurological diseases.

Trans-Cinnamaldehyde Alleviates Amyloid-Beta Pathogenesis via the SIRT1-PGC1α-PPARγ Pathway in 5XFAD Transgenic Mice.

Abnormal amyloid-ß (Aß) accumulation is the most significant feature of Alzheimer's disease (AD). Among the several secretases involved in the generation of Aß, ß-secretase (BACE1) is the first rate-limiting enzyme in Aß production that can be utilized to prevent the development of Aß-related pathologies. Cinnamon extract, used in traditional medicine, was shown to inhibit the aggregation of tau protein and Aß aggregation. However, the effect of trans-cinnamaldehyde (TCA), the main component of cinnamon, on Aß deposition is unknown. Five-month-old 5XFAD mice were treated with TCA for eight weeks. Seven-month-old 5XFAD mice were evaluated for cognitive and spatial memory function. Brain samples collected at the conclusion of the treatment were assessed by immunofluorescence and biochemical analyses. Additional in vivo experiments were conducted to elucidate the mechanisms underlying the effect of TCA in the role of Aß deposition. TCA treatment led to improvements in cognitive impairment and reduced Aß deposition in the brains of 5XFAD mice. Interestingly, the levels of BACE1 were decreased, whereas the mRNA and protein levels of three well-known regulators of BACE1, silent information regulator 1 (SIRT1), peroxisome proliferator-activated receptor γ (PPARγ) coactivator 1α (PGC1α), and PPARγ, were increased in TCA-treated 5XFAD mice. TCA led to an improvement in AD pathology by reducing BACE1 levels through the activation of the SIRT1-PGC1α-PPARγ pathway, suggesting that TCA might be a useful therapeutic approach in AD.

Picrorhiza kurroa Prevents Memory Deficits by Inhibiting NLRP3 Inflammasome Activation and BACE1 Expression in 5xFAD Mice.

One of the most significant pathologies of Alzheimer's disease (AD), an irreversible and progressive neurodegenerative disease that causes cognitive impairment, is the neuroinflammation facilitating the accumulation of amyloid-ß (Aß) peptide. Hence, the inhibition of abnormal neuroinflammatory response is considered a promising therapeutic approach for AD. Picrorhiza kurroa Bentham, Scrophulariae (PK) is a medicinal herb that has been traditionally used for the treatment of various diseases, including inflammation. This study aims to report the significance of PK treatment in markedly improving spatial learning memory and dramatically decreasing Aß levels in Tg6799 mice, also known 5xFAD mice, which have five familial AD (FAD) mutations. Remarkably, these effects correlated with reversal of disease-related microglial neuroinflammation, as evidenced by shifting microglia phenotypes from the inflammatory form to the anti-inflammatory form and inhibiting the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3 inflammasome activity. Moreover, PK administration induced silent information regulator type1/peroxisome proliferator-activated receptor-γ signaling, resulting in a decrease of ß-secretase 1 (BACE1) expression, which involved in Aß production. Overall, this study suggests that PK exhibits a neuroprotective effect by inducing alternative activation of microglia and downregulating the BACE1 expression, thereby ameliorating the disease pathophysiology and reversing the cognitive decline related to Aß deposition in AD mice.

Cuscutae Japonicae Semen Ameliorates Memory Dysfunction by Rescuing Synaptic Damage in Alzheimer's Disease Models.

Alzheimer's disease (AD) is the most common type of dementia in the elderly. It is characterized by the accumulation of amyloid-beta (Aß) and progressive cognitive impairment. To alleviate the symptoms of AD, functional foods and nutrients have been used for centuries. In this study, we investigated whether Cuscutae Japonicae Semen (CJS), a medicinal food traditionally used in East Asia, has effects on memory improvement and synapse protection in AD. We orally administered CJS to 5x familiar AD (5xFAD) transgenic mice and performed the Morris water maze test. The results showed that CJS treatment ameliorated the decline of memory function. Then, we demonstrated that CJS attenuated the degeneration of pre- and post-synaptic proteins in the hippocampi of 5xFAD mice. To demonstrate the effects of CJS in vitro, we treated Aß in primary neuronal culture with CJS and observed that CJS rescued the loss of functional synapses. The protective effects of CJS on the synapse were due to the inhibition of activated caspase-3 expression. Additionally, CJS inhibited the phosphorylation of glycogen synthase kinase-3ß and tau proteins, which contribute to synaptic dysfunction. Taken together, our results suggest that CJS is efficient in alleviating memory loss by rescuing caspase-3-mediated synaptic damage in AD treatment.

Anti-neuroinflammatory effect of Iresine celosia on lipopolysaccharide-stimulated microglial cells and mouse.

Abnormal inflammatory response in the central nervous system plays a critical role in various neurological disorders such as Parkinson's disease, Alzheimer's disease and Huntington's disease. Therefore, modulation of abnormal neuroinflammation is thought to be a promising therapeutic strategy for these diseases. Based on this idea, we focused on finding a potential candidate material that would regulate excessive neuroinflammation. Iresine celosia has long been used as a traditional Mexican medicine to treat fever and oral disorders. In the present study, we evaluated the anti-neuroinflammatory effects of Iresine celosia extract (ICE) in lipopolysaccharide (LPS)-stimulated BV2 microglia cells and mice models. In BV2 microglia cells, ICE markedly inhibited production of nitric oxide and proinflammatory cytokines such as tumor necrosis factor-α, interleukin-1ß, and interleukin-6 without causing cytotoxicity. ICE also ameliorated translocation of nuclear factor-κB from cytosol to nucleus by LPS. Moreover, ICE attenuated behavioral disturbances by inhibiting activation of microglia and astrocytes in LPS-treated mice. Collectively, these data indicate that ICE is a potential therapeutic agent for treating inflammation-related diseases.

Peucedani Japonici Radix ameliorates lipopolysaccharide-induced neuroinflammation by regulating microglial responses.

Neuroinflammation is an inflammatory process within the central nervous system that is mediated by microglial activation, which releases pro-inflammatory mediators leading to neurodegeneration. In this study, we investigated the effects of Peucedani Japonici Radix (PJR), a medicinal herb traditionally used in East Asia to treat neuroinflammation both in vitro and in vivo. First, we examined the effects of PJR on pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. The results showed that PJR suppressed the LPS-induced increase of several inflammatory factors, such as nitric oxide, inducible nitric oxide synthase, cyclooxygenase-2, prostaglandin E2, interleukin-1ß, and tumor necrosis factor-α. We also revealed that PJR inhibited the nuclear factor kappa B (NF-κB) pathway, which is the upstream modulator of inflammatory processes. Furthermore, to confirm the regulatory effects of PJR on microglia in vivo, we measured the number of ionized calcium-binding adapter molecule 1-positive cells in mouse brains and found that PJR treatment reduced microglial activation. Taken together, these results suggest that PJR inhibits microglia-mediated neuroinflammation through the modulation of NF-κB signaling and has the therapeutic potential to prevent inflammation-related neurodegenerative diseases.

Butterbur Leaves Attenuate Memory Impairment and Neuronal Cell Damage in Amyloid Beta-Induced Alzheimer's Disease Models.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease, and is characterized by the accumulation of amyloid beta (Aß) as a pathological hallmark. Aß plays a central role in neuronal degeneration and synaptic dysfunction through the generation of excessive oxidative stress. In the present study, we explored whether leaves of Petasites japonicus (Siebold & Zucc.) Maxim. (PL), called butterbur and traditionally used in folk medicine, show neuroprotective action against Aß25⁻35 plaque neurotoxicity in vitro and in vivo. We found that PL protected Aß25⁻35 plaque-induced neuronal cell death and intracellular reactive oxygen species generation in HT22 cells by elevating expression levels of phosphorylated cyclic AMP response element-binding protein, heme oxygenase-1, and NAD(P)H quinine dehydrogenase 1. These neuroprotective effects of PL were also observed in Aß25⁻35 plaque-injected AD mouse models. Moreover, administration of PL diminished Aß25⁻35 plaque-induced synaptic dysfunction and memory impairment in mice. These findings lead us to suggest that PL can protect neurons against Aß25⁻35 plaque-induced neurotoxicity and thus may be a potential candidate to regulate the progression of AD.

Effects of Rhei Undulati Rhizoma on lipopolysaccharide-induced neuroinflammation in vitro and in vivo.

Neuroinflammation plays a critical role in the pathogenesis of degenerative brain diseases such as Alzheimer's disease and Parkinson's disease. Microglia are the major components of the brain immune system that regulate inflammatory processes. Activated microglia release pro-inflammatory factors and cytokines, resulting in neuronal cell death. We focused on inhibiting the activation of microglia from a stimulus as a strategy to search for neuroprotective drugs. Rhei Undulati Rhizoma (RUR) is traditionally used to treat various inflammatory disorders. In this study, we investigated whether RUR modulates inflammatory processes in lipopolysaccharide (LPS)-stimulated BV2 microglia cells and the mouse brain. RUR exerted anti-neuroinflammatory effects by inhibiting the production of nitric oxide and reactive oxygen species induced by LPS via the downregulation of transcription factors such as inducible nitric oxide synthase and cyclooxygenase-2 (COX-2) without causing cytotoxicity. RUR also regulated mitogen-activated protein kinase pathway by inhibiting phosphorylation of p38 and c-Jun N-terminal kinases and translocation of nuclear factor kappa B. Moreover, RUR attenuated LPS-induced glial activation and COX-2 expression in the substantia nigra and hippocampus of the mouse brain. These results indicate that RUR is a potential candidate to treat neurodegenerative diseases by regulating neuroinflammation.

Dangguijakyak-san ameliorates memory deficits in ovariectomized mice by upregulating hippocampal estrogen synthesis.

BACKGROUND: Dangguijakyak-san (DJS) is an herbal formulation that has been clinically applicable for treating postmenopausal symptoms and neurological disorders. It is reported that hippocampal estrogen attenuates memory impairment via neuroprotection and synaptogenesis. However, the effect of DJS on hippocampal estrogen synthesis remains unknown. In this study, we explored the effect of DJS and its neuroprotective mechanism against memory impairment in ovariectomized (OVX) mice, with respect to hippocampal estrogen stimulation. METHODS: Cell cultures were prepared from the hippocampi of 18-day-old embryos from timed pregnant Sprague-Dawley rats. The hippocampi were dissected, collected, dissociated, and plated in 60-mm dishes. The cells were treated with DJS for 48 h and the supernatant was collected to determine estrogen levels. Female ICR mice (8-weeks-old) were housed for 1 week and ovariectomy was performed to remove the influence of ovary-synthesized estrogens. Following a 2-week post-surgical recovery period, the mice were administrated with DJS (50 and 100 mg/kg/day, p.o.) or 17ß-estradiol (200 µg/kg/day, i.p.) once daily for 21 days. Hippocampal and serum estrogen levels were determined using enzyme-linked immunosorbent assay kit. Memory behavioral tests, western blot, and immunohistochemical analyses were performed to evaluate the neuroprotective effects of DJS in this model. RESULTS: DJS treatment promoted estrogen synthesis in primary hippocampal cells and the hippocampus of OVX mice, resulting in the amelioration of OVX-induced memory impairment. Hippocampal estrogen stimulated by DJS treatment contributed to the activation of cAMP response element-binding protein and synaptic protein in OVX mice. CONCLUSION: DJS may attenuate memory deficits in postmenopausal women via hippocampal estrogen synthesis.

White Ginseng Protects Mouse Hippocampal Cells Against Amyloid-Beta Oligomer Toxicity.

Amyloid-beta oligomer (AßO) is a soluble oligomer form of the Aß peptide and the most potent amyloid-beta form that induces neuronal damage in Alzheimer's disease. We investigated the effect of dried white ginseng extract (WGE) on neuronal cell damage and memory impairment in intrahippocampal AßO (10 µM)-injected mice. Mice were treated with WGE (100 and 500 mg/kg/day, p.o.) for 12 days after surgery. WGE improved memory impairment by inhibiting hippocampal cell death caused by AßO. In addition, AßO-injected mice treated with WGE showed restoration of reduced synaptophysin and choline acetyltransferase intensity and lower levels of ionized calcium-binding adaptor molecule 1 in the hippocampus compared with those of vehicle-treated controls. These results suggest that WGE reverses memory impairment in Alzheimer's disease by attenuating neuronal damage and neuroinflammation in the AßO-injected mouse hippocampus. Copyright © 2017 John Wiley & Sons, Ltd.

An experimental study on providing a scientific evidence for seven-time alcohol-steaming of Rhei Rhizoma when clinically used.

BACKGROUND: Rhei Rhizoma (RR) has been widely used as laxative and processed to alter its therapeutic actions or reduce its side effects. In this study, we evaluated experimentally the clinical application guideline that RR should be alcohol-steamed seven times before being used in elderly patients, as described in Dongeuibogam, the most famous book on Korean traditional medicine. METHODS: Unprocessed RR (RR-U) was soaked in rice wine, steamed and then fully dried (RR-P1). The process was repeated four (RR-P4) or seven times (RR-P7). Reversed-phase high-performance liquid chromatography was used to determine the RR-U, RR-P1, RR-P4 and RR-P7 (RRs) constituents. To evaluate the effect of RRs on liver toxicity, human hepatoma cells (HepG2) were treated with RRs at 100 µg/mL for 4 h and then cell viabilities were measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. To confirm the effects in vivo, 5-week-old male Sprague-Dawley rats were treated with RRs at 3 g/kg/day for 21 days. Body weight and serum biochemical parameters were measured and liver histology was assessed. RESULTS: The levels of sennosides decreased in processed RRs in an iteration-dependent manner, while the emodin level was unaffected. In HepG2 cells, cell viability was reduced with RR-U, while the toxicity decreased according to the number of processing cycles. The changes in body weight, relative liver weight and liver enzymes of RR-U-treated rats were reduced in processed RRs-treated rats. Histopathological analysis indicated swelling and cholestasis improved following seven times alcohol-steaming cycles. CONCLUSIONS: These results provide experimental evidence that RR-P7 almost completely reduces RR hepatotoxicity.