Influence of the Melissa officinalis Leaf Extract on Long-Term Memory in Scopolamine Animal Model with Assessment of Mechanism of Action.
Ozarowski Marcin,Mikolajczak Przemyslaw L,Piasecka Anna,Kachlicki Piotr,Kujawski Radoslaw,Bogacz Anna,Bartkowiak-Wieczorek Joanna,Szulc Michal,Kaminska Ewa,Kujawska Malgorzata,Jodynis-Liebert Jadwiga,Gryszczynska Agnieszka,Opala Bogna,Lowicki Zdzislaw,Seremak-Mrozikiewicz Agnieszka,Czerny Boguslaw
Evidence-based complementary and alternative medicine : eCAM
Melissa officinalis (MO, English: lemon balm, Lamiaceae), one of the oldest and still most popular aromatic medicinal plants, is used in phytomedicine for the prevention and treatment of nervous disturbances. The aim of our study was to assess the effect of subchronic (28-fold) administration of a 50% ethanol extract of MO leaves (200 mg/kg, p.o.) compared with rosmarinic acid (RA, 10 mg/kg, p.o.) and huperzine A (HU, 0.5 mg/kg, p.o.) on behavioral and cognitive responses in scopolamine-induced rats. The results were linked with acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and beta-secretase (BACE-1) mRNA levels and AChE and BuChE activities in the hippocampus and frontal cortex of rats. In our study, MO and HU, but not RA, showed an improvement in long-term memory. The results were in line with mRNA levels, since MO produced a decrease of AChE mRNA level by 52% in the cortex and caused a strong significant inhibition of BACE1 mRNA transcription (64% in the frontal cortex; 50% in the hippocampus). However, the extract produced only an insignificant inhibition of AChE activity in the frontal cortex. The mechanisms of MO action are probably more complicated, since its role as a modulator of beta-secretase activity should be taken into consideration.
[Effect of exogenous hydrogen sulfide on BACE-1 enzyme expression and β-amyloid peptide metabolism in high-glucose primary neuronal culture].
Zhu Lijuan,Chen Xiaoshan,He Xuanli,Qi Yunwen,Yan Yong
Nan fang yi ke da xue xue bao = Journal of Southern Medical University
OBJECTIVE:To investigate the effects of exogenous hydrogen sulfide (H2S) on β-site APP cleaving enzyme 1 (BACE-1) and β-amyloid peptide (Aβ) metabolism in primary culture of neurons under high-glucose condition. METHODS:The cortical neurons in primary culture under normal and high glucose (60 mmol/L) conditions for 24 h were exposed to 25, 50 and 100 µmol/L NaHS. Aβ1-42 concentration in the cell culture was measured by ELISA, and BACE-1 mRNA and protein levels were detected by fluorescent quantitative real-time PCR and Western blotting, respectively. RESULTS:Compared with the neurons cultured in normal glucose, the neurons exposed to high glucose showed significantly increased Aβ1-42 concentration and BACE-1 mRNA and protein expressions (P<0.05). Exposure to 25, 50 and 100 µmol/L NaHS significantly decreased Aβ1-42 concentration and BACE-1 mRNA and protein expressions in the high-glucose cell culture (P<0.05). CONCLUSION:Neurons exposed to high glucose exhibit increased Aβ1-42 levels and BACE-1 mRNA and protein expressions, which can be concentration-dependently decreased by NaHS.
Transcriptional regulation of beta-secretase by p25/cdk5 leads to enhanced amyloidogenic processing.
Wen Yi,Yu W Haung,Maloney Bryan,Bailey Jason,Ma Junrong,Marié Isabelle,Maurin Thomas,Wang Lili,Figueroa Helen,Herman Mathieu,Krishnamurthy Pavan,Liu Li,Planel Emmanuel,Lau Lit-Fui,Lahiri Debomoy K,Duff Karen
Cyclin-dependent kinase 5 (cdk5) has been implicated in Alzheimer's disease (AD) pathogenesis. Here, we demonstrate that overexpression of p25, an activator of cdk5, led to increased levels of BACE1 mRNA and protein in vitro and in vivo. A p25/cdk5 responsive region containing multiple sites for signal transducer and activator of transcription (STAT1/3) was identified in the BACE1 promoter. STAT3 interacts with the BACE1 promoter, and p25-overexpressing mice had elevated levels of pSTAT3 and BACE1, whereas cdk5-deficient mice had reduced levels. Furthermore, mice with a targeted mutation in the STAT3 cdk5 responsive site had lower levels of BACE1. Increased BACE levels in p25 overexpressing mice correlated with enhanced amyloidogenic processing that could be reversed by a cdk5 inhibitor. These data demonstrate a pathway by which p25/cdk5 increases the amyloidogenic processing of APP through STAT3-mediated transcriptional control of BACE1 that could have implications for AD pathogenesis.
Nonsteroidal anti-inflammatory drugs repress beta-secretase gene promoter activity by the activation of PPARgamma.
Sastre Magdalena,Dewachter Ilse,Rossner Steffen,Bogdanovic Nenad,Rosen Evan,Borghgraef Peter,Evert Bernd O,Dumitrescu-Ozimek Lucia,Thal Dietmar R,Landreth Gary,Walter Jochen,Klockgether Thomas,van Leuven Fred,Heneka Michael T
Proceedings of the National Academy of Sciences of the United States of America
Epidemiological evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the risk for Alzheimer's disease (AD). Certain NSAIDs can activate the peroxisome proliferator-activated receptor-gamma (PPARgamma), which is a nuclear transcriptional regulator. Here we show that PPARgamma depletion potentiates beta-secretase [beta-site amyloid precursor protein cleaving enzyme (BACE1)] mRNA levels by increasing BACE1 gene promoter activity. Conversely, overexpression of PPARgamma, as well as NSAIDs and PPARgamma activators, reduced BACE1 gene promoter activity. These results suggested that PPARgamma could be a repressor of BACE1. We then identified a PPARgamma responsive element (PPRE) in the BACE1 gene promoter. Mutagenesis of the PPRE abolished the binding of PPARgamma to the PPRE and increased BACE1 gene promoter activity. Furthermore, proinflammatory cytokines decreased PPARgamma gene transcription, and this effect was supressed by NSAIDs. We also demonstrate that in vivo treatment with PPARgamma agonists increased PPARgamma and reduced BACE1 mRNA and intracellular beta-amyloid levels. Interestingly, brain extracts from AD patients showed decreased PPARgamma expression and binding to PPRE in the BACE1 gene promoter. Our data strongly support a major role of PPARgamma in the modulation of amyloid-beta generation by inflammation and suggest that the protective mechanism of NSAIDs in AD involves activation of PPARgamma and decreased BACE1 gene transcription.
The effects of chronic copper exposure on the amyloid protein metabolisim associated genes' expression in chronic cerebral hypoperfused rats.
Mao Xuexuan,Ye Jiantao,Zhou Shiyou,Pi Rongbiao,Dou Juan,Zang Linquan,Chen Xiaohong,Chao Xiaojuan,Li Wenming,Liu Mengfei,Liu Peiqing
The pathogens of Alzheimer's disease (AD) are still unclear, while accumulating evidences have indicated that both genetic and environmental factors are involved in the pathogenesis of AD. Recent studies suggest that AD is primarily a vascular disorder and copper (Cu) may play an important role in AD pathology. However, the consequences of chronic Cu exposure at the presence of other AD risk factors remain to be clarified. To investigate the effects of chronic Cu intake on cerebral hypoperfusion-induced AD pathology, Sprague-Dawley rats suffered bilateral common carotid artery occlusion (2VO) were administrated with 250 ppm copper-containing water or not. Morris water maze test showed that Cu exposure for 3 months exacerbated cognitive impairment induced by 2VO. Elevated amyloid precursor protein (APP) and beta-site APP-cleaving enzyme 1 (BACE1) expression in mRNA and protein levels were also observed in brain of Cu-exposed rats suffered 2VO. In contrast, these Cu-exacerbated changes were ameliorated after Cu was withdrawn from drinking water. In summary, our findings demonstrate that chronic Cu exposure might exacerbate AD pathology in 2VO rats.
Experimental traumatic brain injury in rats stimulates the expression, production and activity of Alzheimer's disease beta-secretase (BACE-1).
Blasko I,Beer R,Bigl M,Apelt J,Franz G,Rudzki D,Ransmayr G,Kampfl A,Schliebs R
Journal of neural transmission (Vienna, Austria : 1996)
Traumatic brain injury (TBI) is a risk factor for the development of Alzheimer's disease (AD). After a traumatic brain injury depositions of amyloid beta (Abeta) in the brain parenchyma were found. In this study we investigated the expression pattern of beta-secretase (BACE-1) in ipsi- or contralateral hippocampus and cortex following controlled cortical TBI in rats. BACE-1 mRNA levels, estimated by real time RT-PCR, were elevated 24 h post injury, and persisting up to 72 h, in the ipsi- and contralateral hippocampus and cerebral cortex as compared to the sham-treated animals (p<0.01). The TBI-induced changes in BACE-1 mRNA are due to enhanced hippocampal and cortical expression of BACE-1 mRNA in neurons and reactive astrocytes as revealed by in situ hybridization. The alterations in hippocampal BACE-1 mRNA levels are accompanied by corresponding increases in BACE-1 protein levels in ipsi- and contralateral hippocampus and ipsilateral cortex as demonstrated by Western blot analysis. In contrast, in the contralateral cortex only a weak increase of traumatically induced BACE-1 protein production was found. The activity of BACE-1 as measured by the formation of the cleavage product of amyloid beta precursor protein, transiently increased up to 48 h after injury, but returned to basal level 7 days post injury. This study demonstrates that the beta-secretase is stimulated following TBI and may suggest a mechanism for the temporal increase of Abeta levels observed in patients with brain trauma.
Molecular events during the induction of neurodegeneration and memory loss in estrogen-deficient rats.
Anukulthanakorn Kanya,Malaivijitnond Suchinda,Kitahashi Takashi,Jaroenporn Sukanya,Parhar Ishwar
General and comparative endocrinology
This study aims to delineate the relationship among estrogen deficiency, neurodegeneration, and cognitive impairment of ovariectomized rats. Female Sprague-Dawley rats were ovariectomized and euthanized after 1-4 month periods (M(0)-M(4) groups). Blood samples were collected for the determination of serum levels of 17β-estradiol (E(2)), luteinizing hormone (LH), and follicle stimulating hormone (FSH). Five consecutive days before the euthanization, cognitive performance of the rats was examined by Morris water maze test. After euthanization, the hippocampus was collected, and expression of the genes associated with amyloid plaques (App, Adam10 and Bace1) and neurofibrillary tangles (Tau4 and Tau3) were examined by real-time PCR. Serum E(2) levels were declined following 2 weeks of ovariectomy. Conversely, serum FSH and LH levels were profoundly increased by 2 weeks of ovariectomy for approximately 4 and 22 times, respectively. Cognitive impairments, indicated by the longer latency and distance, were observed only in the M(3) and M(4) groups. The Tau4 mRNA levels were significantly increased as early as 1 month after ovariectomy (in the M(1) group; P<0.05), and tended to be increased further with the advancing time. Similarly, the Tau3 mRNA levels were increased by ovariectomy, but with the highest level in the M(1) group, and decreased thereafter. The mRNA levels of App, Adam10 and Bace1 were increased by ovariectomy, but significant differences were observed only in the M(4) group. These results indicate that estrogen deficiency can induce a sequence of events that results in the production of neurofibrillary tangles, amyloid deposition, and spatial memory deficit in rats.
The role of Toll-like receptor 4 on inflammation and Aβ formation in cortex astrocytes.
Gong Chang-Yin,Zhou Ai-Ling,Mao Jia-Hui,Hu Ya-E,Geng Jin-Song
Sheng li xue bao : [Acta physiologica Sinica]
To investigate the role and possible molecular mechanism of astrocytes in inflammation and amyloid β-protein (Aβ) formation, in this research, by using LPS to stimulate cultured rat astrocytes in vitro with or without anti-Toll-like receptor 4 (TLR4) antibody pretreatment, we first detected the TLR4, TNF-α, IL-1β, β-amyloid precursor protein (β-APP) and β-site APP clearing enzyme 1 (BACE1) mRNA with real-time PCR, and TLR4, NF-κB/P65 protein in cultured astrocytes by Western blot, and then further probed the translocation of NF-κB/P65 using immunofluorescence and the contents of TNF-α, IL-1β and Aβ in culture supernatant through ELISA. We found that all of these indexes increased at different degrees after LPS-stimulation. However, if pretreatment with anti- TLR4 antibody, such stimulating effects of LPS on the nuclear translocation of NF-κB/P65 and TNF-α, IL-1β, Aβ contents in astrocytic culture supernatant were reduced significantly or disappeared in comparison with the group with only LPS-administration. Our results suggest that TLR4 in astrocytes might play an important role in the inflammation and Aβ formation through the TLR4/NF-κB signaling pathway, thus providing new knowledge and understanding of the inflammatory hypothesis of AD pathogenesis.
Chronological Molecular Changes in Neuronal Communication in Androgen-Deficient Rats.
Fainanta Taratorn,Jaroenporn Sukanya,Wititsuwankul Patteera,Malaivijitnond Suchinda
Journal of molecular neuroscience : MN
We investigated the early onset of molecular changes in the hippocampus of orchidectomy (ODX)-induced androgen-deficient rats. Transcript levels of the genes associated with loss of synaptic plasticity (Bdnf, Syn, GluN1, α7-nAChR, and M-mAChR), formation of neurofibrillary tangles (Tau4 and Tau3), and amyloid plaques (App, Adam10, and Bace1), in the hippocampus of rats at 0, 1, 3, 6, and 9 days after ODX (D, D, D, D and D, respectively) were determined. Primarily, the sudden loss of androgen, as confirmed by the decreased serum testosterone levels and accessory sex organ weights, induced a chronological reduction in Syn (at D), and increase in GluN1 (at D), α7-nAChR, and M-mAChR (at D) and a decrease in Bdnf (at D) transcript levels. Tau4 and Tau3 mRNA levels were increased at D and D, respectively. No changes in App, Adam10, and Bace1 mRNA levels were detected within the 9-day study period. To confirm those changes were caused by androgen deprivation and not increasing age, the mRNA expression levels of those genes in 9-day orchidectomized rats (ODX-D) were compared with age-matched intact rats. All changes of mRNA expression levels of the ODX-D rats were aligned with the D rats, except for GluN1 that was decreased in the ODX-D rats. Moreover, the total and phosphorylated tau protein levels were increased in the ODX-D rats. These results denote that androgen deficiency induces the early onset of neurodegeneration, while the loss of synaptic plasticity together with the formation of neurofibrillary tangles could be used as markers for neurodegenerative prediction.
Cerebroprotective effects of ibuprofen on diabetic encephalopathy in rats.
Liu Yao-Wu,Zhu Xia,Zhang Liang,Lu Qian,Zhang Fan,Guo Hao,Yin Xiao-Xing
Pharmacology, biochemistry, and behavior
OBJECTIVE:Diabetic encephalopathy is characterised by cognitive impairment, neurochemical and structural abnormalities. The aim of the study was to investigate the effects of ibuprofen on diabetic encephalopathy and potential mechanisms. RESEARCH DESIGN AND METHOD:Diabetes was induced through a single intraperitoneal injection of streptozotocin (60 mg/kg). Diabetic rats were treated with ibuprofen (40 mg/kg) by gavage for 8 weeks. Cognitive performances were evaluated using Morris water maze. The temporal cortex and hippocampus were obtained to evaluate the levels of advanced glycation endproducts (AGEs) and their receptor (RAGE), the activity, protein expression, and mRNA levels of β-amyloid precursor protein cleaving enzyme 1 (BACE1), the protein and mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ), and the protein expression of cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS). Blood was obtained for the evaluation of interleukin 1β level. RESULTS:Chronic ibuprofen treatment significantly prevented the decline in learning and memory ability of diabetic rats and loss of neurons in the CA1 and CA3 areas of the hippocampus. Moreover, ibuprofen treatment markedly reduced the activity, protein, and mRNA levels of BACE1, AGE level, protein expression of RAGE, COX-2, and iNOS in the brain, and interleukin 1β level in serum, while increasing the protein and mRNA expression of PPARγ in the brain of diabetic rats. However, ibuprofen had no effects on the hyperglycaemia and the body weight of diabetic rats. CONCLUSION:These findings demonstrated that ibuprofen markedly ameliorated diabetic encephalopathy, potentially reflecting the down-regulation of BACE1, the suppression of the AGE/RAGE axis, and the anti-inflammation in diabetic rat brain.
The role of intestinal endotoxemia in a rat model of aluminum neurotoxicity.
Wang Feng,Guo Rui-Xia,Li Wen-Xing,Yu Bao-Feng,Han Bai,Liu Li-Xin,Han De-Wu
Molecular medicine reports
The present study aimed to investigate the effects of intestinal endotoxemia (IETM) in a rat model of aluminum neurotoxicity established by D-galactose and aluminum trichloride (AlCl3). Adult Wistar rats were administered D‑galactose and AlCl3 to create the aluminum neurotoxicity model. The learning and memory abilities of the rats were subsequently observed using a Morris water maze test and the serum levels of lipopolysaccharide (LPS), tumor necrosis factor (TNF)‑α, interleukin (IL)‑1, diamine oxidase (DAO), glutamine (Gln) and glutaminase were measured. The expression of S‑100β in the serum was detected using an enzyme‑linked immunosorbent assay. The expression levels of the amyloid β‑protein (Aβ) precursor (APP), presenilin 1 (PS1), β‑site APP‑cleaving enzyme (BACE), zona occludens protein (ZO)‑1 and Aβ 1‑40 in the brain of rats were detected via reverse‑transcription polymerase chain reaction, western blotting and immunohistochemistry. The levels of LPS, TNF‑α, IL‑1, DAO, Gln and S‑100β in serum and the mRNA and protein expression levels of APP, PS1, BACE and Aβ1‑40 in the brain were markedly increased in the model rats compared with controls. The level of glutaminase in the serum and the expression of ZO‑1 in the brain were decreased in the model rats compared with controls. IETM was present in the rat model of aluminum neurotoxicity established by D‑galactose and AlCl3 and may be important in the development of this neurotoxicity.
Expression of amyloid-associated miRNAs in both the forebrain cortex and hippocampus of middle-aged rat.
Che Hui,Sun Li-Hua,Guo Fei,Niu Hui-Fang,Su Xiao-Lin,Bao Ya-Nan,Fu Zidong Donna,Liu Huai-Lei,Hou Xu,Yang Bao-Feng,Ai Jing
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology
BACKGROUND:Aging is associated with the gradual cognitive decline and shows the typical senile plaque formation in the brain, which results from the aggregation of beta amyloid (Aβ) peptide following the abnormal proteolytic processing of amyloid precursor protein (APP) by β-secretase (BACE1) and γ-secretase. Accumulating evidence indicates that several microRNAs (miRNAs) are involved in the Alzheimer's disease (AD) by regulating the expression of APP and BACE1 proteins. However, the cognitive ability and the expression profile of the APP- and BACE1-associated miRNAs in the middle-aged population are largely unknown. METHODS:The learning and memory ability in rats were determined by Morris Water Maze test. The protein levels of APP and BACE1 were detected by western blotting. The quantitative polymerase chain reaction was used to identify the miRNAs levels in forebrain cortex and the hippocampus. RESULTS:Middle-aged rats have declined learning ability without changes in the memory ability, and increased APP and BACE1 protein expression in the forebrain cortex. Computational analysis using Targetscan and Pictar databases reveals that totally 4 predicted miRNAs have conserved binding site with APP, namely miR-106b, -17-5p, -153, -101. All of them showed decreased expression in both the forebrain cortex and hippocampus. Among the 10 predicted miRNAs targeting BACE1, different expression profiles were identified in the forebrain cortex (decreased: miR-9, -19a, -135a, -15b, -16, -195, -29c, -214; increased: miR-124; no change: miR-141) and the hippocampus (decreased: miR-9, -15b, -16, -195, -29c, -124; increased: miR-19a, -135a, -214, -141) in the middle-aged rats compared with the young rats. CONCLUSION:Our results provided the first evidence that middle-aged rats have begun displaying cognitive disability with abnormal expression of APP- and BACE1-related miRNAs in the hippocampus and forebrain cortex.
Expression of APP, BACE1, AChE and ChAT in an AD model in rats and the effect of donepezil hydrochloride treatment.
Li Qiang,Chen Min,Liu Hongmin,Yang Liqun,Yang Guiying
Molecular medicine reports
The aim of this study was to investigate the pathological changes in a rat model of Alzheimer's disease (AD) and the effect of donepezil hydrochloride (HCl) treatment. The rat model of AD was established by the bilateral injection of amyloid β₁₋₄₀ (Aβ₁₋₄₀) into the hippocampus. Changes in spatial learning and memory functions were examined using the Morris water maze test and changes in catalase (CAT) and glutathione peroxidase (GSH-Px) activities were determined using chemical colorimetry. Moreover, the changes in acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) expression were analyzed using immunohistochemical staining. The mRNA expression levels of the amyloid precursor protein (APP) and β-secreted enzyme 1 (BACE1) were evaluated using RT-PCR. The effects of donepezil HCl on the aforementioned indices were also observed. The rat memories of the platform quadrants in the blank, sham and donepezil HCl groups were improved compared with those of the rats in the model group. The ratio of swim distance in the fourth platform quadrant (l₄) to the total swim distance (l total) for the model group rats (l₄/l total) was significantly decreased compared with that for the blank and sham group rats. Following donepezil HCl treatment, the ratio of l₄/l total significantly increased. AD modeling caused a significant decrease in the CAT and GSH-Px activities in the brain tissues of the rats. The CAT and GSH-Px activities in the AD model rats significantly increased following donepezil HCl treatment. Moreover, donepezil HCl treatment significantly decreased the AChE, APP and BACE1 mRNA expression levels and increased the ChAT expression levels. Therefore, donepezil HCl was able to significantly decrease learning and memory damage in a rat model of AD.