Relationship between β-amyloid protein 1-42, thyroid hormone levels and the risk of cognitive impairment after ischemic stroke

BACKGROUND Post-stroke cognitive impairment(PSCI)is not only a common consequence of stroke but also an important factor for adverse prognosis of patients.Biochemical indicators such as blood lipids and blood pressure are affected by many factors,and the ability of evaluating the progress of patients with PSCI is insufficient.Therefore,it is necessary to find sensitive markers for predicting the progress of patients and avoiding PSCI.Recent studies have shown thatβ-amyloid protein 1-42(Aβ1-42)and thyroid hormone levels are closely related to PSCI,which may be the influencing factors of PSCI,but there are few related studies.AIM To investigate the relationship between serum levels of Aβand thyroid hormones in acute stage and PSCI and its predicted value.METHODS A total of 195 patients with acute cerebral infarction confirmed from June 2016 to January 2018 were enrolled in this study.Baseline data and serological indicators were recorded to assess cognitive function of patients.All patients were followed up for 1 year.Their cognitive functions were evaluated within 1 wk,3 mo,6 mo and 1 yr after stroke.At the end of follow-up,the patients were divided into PSCI and non-PSCI according to Montreal cognitive assessment score,and the relationship between biochemical indexes and the progression of PSCI was explored.RESULTS Compared with patients with non-PSCI,the levels of Aβ1-42,triiodothyronine(T3)and free thyroxin were lower in the patients with PSCI.Repeated measures analysis of variance showed that the overall content of Aβ1-42 and T3 in PSCI was also lower than that of the non-PSCI patients.Further analysis revealed that Aβ1-42(r=0.348),T3(r=0.273)and free thyroxin(r=0.214)were positively correlated with disease progression(P<0.05),suggesting that these indicators have the potential to predict disease progression and outcome.Cox regression analysis showed that Aβ1-42 and T3 were important factors of PSCI.Then stratified analysis showed that the lower the Aβ1-42 and T3,the higher risk of PSCI in patients who were aged over 70,female and illiterate.CONCLUSION Aβ1-42 and T3 have the ability to predict the progression of PSCI,which is expected to be applied clinically to reduce the incidence of PSCI and improve the quality of life of patients.

Effect of Panax notoginseng saponins on the expression of beta-amyloid protein in the cortex of the parietal lobe and hippocampus, and spatial learning and memory in a mouse model of senile dementia

BACKGROUND： The pharmacological actions of Panax notoginseng saponins （PNS） lie in removing free radicals, anti-inflammation and anti-oxygenation. It can also improve memory and behavior in rat models of Alzheimer＇s disease. OBJECTIVE： Using the Morris water maze, immunohistochemistry, real-time PCR and RT-PCR, this study aimed to measure improvement in spatial learning, memory, expression of amyloid precursor protein （App） and β -amyloid （A β ）, to investigate the mechanism of action of PNS in the treatment of AD in the senescence accelerated mouse-prone 8 （SAMP8） and compare the effects with huperzine A. DESIGN, TIME AND SETTING： A completely randomized grouping design, controlled animal experiment was performed in the Center for Research ＆ Development of New Drugs, Guangxi Traditional Chinese Medical University from July 2005 to April 2007. MATERIALS： Sixty male SAMP8 mice, aged 3 months, purchased from Tianjin Chinese Traditional Medical University of China, were divided into four groups： PNS high-dosage group, PNS low-dosage group, huperzine A group and control group. PNS was provided by Weihe Pharmaceutical Co., Ltd. （batch No.： Z53021485, Yuxi, Yunan Province, China）. Huperzine A was provided by Zhenyuan Pharmaceutical Co., Ltd. （batch No.： 20040801, Zhejiang, China）. METHODS： The high-dosage group and low-dosage group were treated with 93.50 and 23.38 mg/kg PNS respectively per day and the huperzine A group was treated with 0.038 6 mg/kg huperzine A per day, all by intragastric administration, for 8 consecutive weeks. The same volume of double distilled water was given to the control group. MAIN OUTCOME MEASURES： After drug administration, learning and memory abilities were assessed by place navigation and spatial probe tests. The recording indices consisted of escape latency （time-to-platform）, and the percentage of swimming time spent in each quadrant. The number of A β 1-40, A β 1-42 and App immunopositive neurons in the brains of SAMP8 mice was analyzed by immunohistochemistry. The mRNA content ofApp, tau, acetylcholinesterase, and synaptophysin （Syp） was tested by real time PCR and RT-PCR. RESULTS： The PCR results show that PNS can downregulate the expression of the App gene and upregulate the expression of the Syp gene in the parietal cortex and hippocampus of SAMP8 mice. The therapeutic effects of the PNS high-dosage group were greater than those of the PNS low-dosage group and the huperzine A group （P 〈 0.05）. The results of the Morris water maze and immunohistochemistry indicated that PNS can improve the capacity for spatial learning and memory in SAMP8 mice, and reduce the content of A β 1-40, A β 1-42 and expression of App in the brains of SAMP8 mice. The therapeutic effects of the PNS high-dosage group were greater than that of the PNS low-dosage group and the huperzine A group （P 〈 0.05）. CONCLUSION： These results support the hypothesis that PNS plays a therapeutic and protective role on the pathological lesions and learning dysfunction of Alzheimer＇s disease. The therapeutic effects of PNS for Alzheimer＇s disease are possibly achieved through downregulating the expression of the App gene and upregulating the expression of the Syp gene. The therapeutic effects of PNS are dose-dependent and are greater than the effect of huperzine A.

Key gene and protein changes in the beta-amyloid pathway following Longyanshen polysaccharides treatment in a mouse model of Alzheimer's disease

BACKGROUND： During onset and development of Alzheimer＇s disease, β-amyloid （Aβ） precursor protein （APP）, β-site amyloid precursor protein cleaving enzyme （BACE）, and β-amyloid are key genes and proteins in the Aβ pathway, and over-expression of these genes can lead to Aβ deposit/on in the brain. OBJECTIVE： To observe the influence of Longyanshen polysaccharides on expression of BACE, APP, and Aβ in the senescence-accelerated mouse prone/8 （SAMP8） brain, and to compare these effects with huperzine A treatment. DESIGN, TIME AND SETTING： A randomized, controlled, neurobiochemical experiment was performed at the Department of Pharmacology and Scientific Experimental Center of Guangxi Medical University from September 2005 to January 2008. MATERIALS： Longyanshen polysaccharfdes powder was extracted from the dried slices of the medicinal plant Longyanshen. The active component, Longyanshen polysaccharides, was provided by the Department of Pharmacology, Guangxi Medical University; huperzine A was purchased from Yuzhong Drug Manufactory, China. METHODS： Healthy SAMP8 mice were used to establish a model of Alzheimer＇s disease. A total of 50 SAMP8 mice were randomly assigned to 5 groups （n = 10）： SAMP8, huperzine A, low-, middle-, and high-dose polysaccharides. In addition, 10 senescence-accelerated mouse resistant 1 （SAMR1） mice were selected as normal controls. SAMP8 and SAMR1 mice were administered 30 mL/kg normal saline; the huperzine A group was administered 0.02 mg/kg huperzine A; the low-, middle-, and high-dose polysaccharides groups were respectively administered 45, 90, and 180 mg/kg Longyanshen polysaccharides. Each group was treated by intragastric administration, once per day, for 50 consecutive days. MAIN OUTCOME MEASURES： One hour after the final administration, immunohistochemical analysis was used to determine Aβ expression in the cortex and hippocampus of SAMP8 mice. Reverse-transcription polymerase chain reaction was used to determine mRNA levels of BACE and APP in SAMP8 brain tissue. RESULTS： Compared with the SAMR1 group, Aβ expression in the cerebral cortex and hippocampus, as well as expression of BACE, APP mRNA in the brain was significantly increased in the SAMP8 group （P 〈 0.05-0.01）. Compared with the SAMP8 group, Aβ expression, as well as BACE and APP mRNA expression, were significantly decreased in the cerebral cortex and hippocampus of huperzine A and low-, middle-, and high-dose polysaccharides groups （P 〈 0.05-0.01）. In particular, the effect of high-dose polysaccharides was the most significant （P 〈 0.05-0.01 ）. CONCLUSION： Longyanshen polysaccharides reduced or inhibited over-expression of BACE, APP, and Aβ in SAMP8 mice in a dose-dependent manner, and the effect was not worse than huperzine A.

Mutations of beta-amyloid precursor protein alter the consequence of Alzheimer's disease pathogenesis

Alzheimer's disease is pathologically defined by accumulation of extracellular amyloid-β(Aβ). Approximately 25 mutations in β-amyloid precursor protein(APP) are pathogenic and cause autosomal dominant Alzheimer's disease. To date, the mechanism underlying the effect of APP mutation on Aβ generation is unclear. Therefore, investigating the mechanism of APP mutation on Alzheimer's disease may help understanding of disease pathogenesis. Thus, APP mutations(A673T, A673 V, E682 K, E693 G, and E693Q) were transiently co-transfected into human embryonic kidney cells. Western blot assay was used to detect expression levels of APP, beta-secretase 1, and presenilin 1 in cells. Enzyme-linked immunosorbent assay was performed to determine Aβ_(1–40) and Aβ_(1–42) levels. Liquid chromatography-tandem mass chromatography was used to examine VVIAT, FLF, ITL, VIV, IAT, VIT, TVI, and VVIA peptide levels. Immunofluorescence staining was performed to measure APP and early endosome antigen 1 immunoreactivity. Our results show that the protective A673 T mutation decreases Aβ_(42)/Aβ_(40) rate by downregulating IAT and upregulating VVIA levels. Pathogenic A673 V, E682 K, and E693 Q mutations promote Aβ_(42)/Aβ_(40) rate by increasing levels of CTF99, Aβ_(42), Aβ_(40), and IAT, and decreasing VVIA levels. Pathogenic E693 G mutation shows no significant change in Aβ_(42)/Aβ_(40) ratio because of inhibition of γ-secretase activity. APP mutations can change location from the cell surface to early endosomes. Our findings confirm that certain APP mutations accelerate Aβ generation by affecting the long Aβ cleavage pathway and increasing Aβ_(42/40) rate, thereby resulting in Alzheimer's disease.

Beta-amyloid precursor protein cleavage enzyme-1 expression in adult rat retinal neurons in the early period after lead exposure

Previous studies have reported that non-human primates and rodents exposed to lead during brain development may become dependent on the deposition of pre-determined β-amyloid protein （Aβ）,and exhibit upregulation of β-site amyloid precursor protein expression in old age.However,further evidence is required to elucidate the precise relationship and molecular mechanisms underlying the effects of early lead exposure on excessive Aβ production in adult mammals.The present study investigated the effects of lead exposure on expression of β-amyloid precursor protein cleavage enzyme-1 （BACE-1） in the rat retina and the production of Aβ in early development,using the retina as a window for studying Alzheimer＇s disease.Adult rats were intraocularly injected with different doses of lead acetate （10μmol/L,100μmol/L,1 mmol/L,10 mmol/L and 100 mmol/L）.The results revealed that retinal lead concentration,BACE-1 and its cleavage products β-C-terminal fragment and retina Aβ1-40 were all significantly increased in almost all of the lead exposure groups 48 hours later in a dose-dependent manner.The only exception was the 10μmol/L group.The distribution of BACE-1 in the retina did not exhibit obvious changes,and no distinctive increase in the activation of retinal microglia was apparent.Similarly,retinal synaptophysin expression did not exhibit any clear changes.These data suggest that lead exposure can result in the upregulation of retinal neuron BACE-1 expression in the early period of development and further increase the overproduction of Aβ1-40 in the retina.Our results provided novel insight into the molecular mechanisms underlying environmentally-induced Alzheimer＇s disease.

THE PROTECTIVE EFFECTS OF THE TOTAL SAPONIN OF DIPSACUS ASPEROIDES ON THE APOPTOSIS OF HIPPOCAMPAL NEURONS INDUCED BY β-AMYLOID PROTEIN

Objective To investigate the effects of the total saponin of Dipsacus asperoides (tSDA) and ginsenoside Rb1 (GRb1) on the apoptosis of primary cultured hippocampal neurons induced by β-amyloid protein (Aβ). Methods Primary cultured hippocampal neurons, the cultures were pretreated with tSDA and GRb1 on 10d for 24 hours respectively. Then the cultures were treated with 35 μmol·L -1 Aβ25-35 for 24 hours, observed the changing of survival rate of neurons and the apoptosis of neurons with biochemical analysis combining immunofluorescent cytochemical double-staining technique. Results Hippocampal neurons were treated with 35 μmol·L -1 Aβ for 24 hours, and survival rate of neurons downed to 52.6%. When neurons were pretreated by tSDA and GRb1, survival rate of neurons increased 11% to 15%. The findings of immunofluorescent cytochemical double-staining indicated that apoptotic neurons were obviously more than that of the blank group, reaching 43.9%.When neurons were pretreated by tSDA and GRb1, apoptotic neurons were downed to 16.6%, 10.8% respectively. Conclusion tSDA had the same effects as GRb1, protecting the neurons, antagonizing neurotoxicity of Aβ, increasing survival rate of neurons, and reducing apoptotic neurons induced by Aβ.

Dynamic changes of beta-amyloid protein deposition in hippocampus of female ovariectomized rats

BACKGROUND： To evaluate and summarize the effects of cerebral perfusion and vascular reserve on the treatment of SICAS. Recently, research on β-amyloid protein has focused on the regulatory effects of estrogen or phytoestrogen on its deposition. However, there have been only a few reports on dynamic changes of β -amyloid protein deposition in hippocampus of ovariectomized rats. OBJECTIVE： To measure β -amyloid protein deposition in the hippocampal formation of ovariectomized rats by using immunohistochemistry; to observe time-dependent dynamic changes. DESIGN： Randomized controlled animal study. SETTING： Third Xiangya Hospital of Central South University. MATERIALS： The experiment was carried out in the Central Laboratory of the Third Xiangya Hospital of Central South University from November 2005 to December 2006. Fifty healthy female Sprague Dawley （SD） rats, weighing （293 ± 10） g, were provided by the Animal Laboratory of Xiangya Medical College, Central South University. All rats had neither a childbearing history nor hepatic or renal disease, or skeletal deformity. β-amyloid protein immunohistochemical kit was provided by Wuhan Boster Company. The experiment was in accordance with animal ethics standards. METHODS： All rats were randomly divided into five groups, including normal control group （n = 10）, sham operation group （n = 10）, and ovariectomized group （n = 30）. After anesthesia in the ovariectomized group, the bilateral ovaries were separated and resected. The same volume of fat was resected in the sham operation group. Rats from the normal control group, however, did not receive any surgical treatments. Rats in the normal control group and sham operation group were sacrificed by anesthesia 7 weeks after surgery. Every ten rats from the ovariectomized group was respectively sacrificed at 7, 15, and 30 weeks after surgery. lmmunohistochemistry was used to detect β-amyloid protein deposition in hippocampal sections. Cell counting and gray value measurements served to record the dynamic changes in β-amyloid protein deposition. MAIN OUTCOME MEASURES： （1） Morphological changes. （2） Positive cell counts from β -amyloid protein stainings and gray value measurements. RESULTS： All 50 rats were involved in the final analysis. （1） Morphological changes. β -amyloid-positive cells were detected in the hippocampus of all rats. Biebrich scarlet stained neurites with a swollen cytoplasm. A few β -amyloid-positive cells were observed in all groups 7 weeks after surgery, and plasma and neurites were slightly stained. By 15 weeks after surgery, a number of β -amyloid-positive cells were observed in the ovariectomized group, and plasma and neurites were also slightly stained. By 30 weeks after surgery, however, many β-amyloid-positive cells were observed in the ovariectomized group. These cells were partially aggregated and darkly stained. （2） Positive cell counts and gray value of β-amyloid protein in hippocampus. At 7 weeks after surgery, cell counts and gray value measurements were not significantly different in the ovariectomized group compared to the sham operation group and normal control group （P 〉 0.05）. Cell counts and gray value measurements were higher in the ovariectomized group by 15 weeks compared to those by 7 weeks in the normal control group, sham operation group and ovariectomized group （P 〈 0.05）. At 30 weeks after surgery, cell counts and gray value measurements were higher in the ovariectomized group compared to the normal control group. In addition, there were significant differences between sham operation group and ovariectomized group, at 7 and 15 weeks after operation （P 〈 0.05-0.01 ）. Cell counts and gray value measurements increased in all groups over time. CONCLUSION： Extended estrogen deficiency in rats can increase β-amyloid protein deposition in the hippocampus and the deposition increases over time.

The β-amyloid protein induces S100β expression in rat hippocampus through a mechanism that involves IL-1

Objective To explore the effect of β-amyloid protein (Aβ) on S100β expression in rat hippocampus and its mechanisms. Methods At 7 days after bilateral stereotaxis injection of different dose of fibrillar Aβ 25-35 and interluekin-1 receptor antagonist (IL-1ra) into the rat CA1 region, the learning and memory abilities of rats were tested with passive avoidance task. Amyloid deposition was detected by using Congo red staining technique. Nissl staining and immunohistochemical techniques were used to analyze the number of neurons, and GFAP and the S100β expression in hippocampal CA1 region , respectively. Results After fibrillar Aβ injection, the step-through latency of rats was significantly shortened compared to that of the control group. The GFAP positive astrocytes were found surrounding amyloid deposition. Neuronal loss occurred in the pyramidal cell layer of CA1 region. The number of S100β positive cells in Aβ-treated group was significantly increased compared with that in the control group. After IL-1ra injection, the number of S100β positive cells was significantly decreased. Conclusion Intrahippocampal injection of Aβ 25-35 could cause similar pathologic changes of Alzheimer’s disease. Aβ 25-35 was capable of up-regulating S100β expression in a dose-dependent manner. The injection of IL-1ra could attenuate the effect of Aβ on S100β expression.

BACE1 inhibitors:A promising therapeutic approach for the management of Alzheimer’s disease

Alzheimer’s disease is a neurological disorder marked by the accumulation of amyloid beta(Aβ)aggregates,resulting from mutations in the amyloid precursor protein.The enzymeβ-secretase,also known asβ-site amyloid precursor protein cleaving enzyme 1(BACE1),plays a crucial role in generating Aβpeptides.With no targeted therapy available for Alzheimer’s disease,inhibiting BACE1 aspartic protease has emerged as a primary treatment target.Since 1999,compounds demonstrating potential binding to the BACE1 receptor have advanced to human trials.Structural optimization of synthetically derived compounds,coupled with computational approaches,has offered valuable insights for developing highly selective leads with drug-like properties.This review highlights pivotal studies on the design and development of BACE1 inhibitors as anti-Alzheimer’s disease agents.It summarizes computational methods employed in facilitating drug discovery for potential BACE1 inhibitors and provides an update on their clinical status,indicating future directions for novel BACE1 inhibitors.The promising clinical results of Elenbecestat(E-2609)catalyze the development of effective,selective BACE1 inhibitors in the future.

Impact of Sub-chronic Aluminium-maltolate Exposure on Catabolism of Amyloid Precursor Protein in Rats

Objective To investigate the impact of sub-chronic Aluminium-maltolate [Al（mal）s] exposure on the catabolism of amyloid precursor protein （APP） in rats. Methods Forty adult male Sprague-Dawley （SD） rats were randomly divided into five groups： the control group, the maltolate group （7.56 mg/kg BW）, and the Al（mal）s groups （0.27, 0.54, and 1.08 mg/kg BW, respectively）. Control rats were administered with 0.9% normal saline through intraperitoneal （i.p.） injection. Maltolate and Al（mal）s were administered to the rats also through i.p. injections. Administration was conducted daily for two months. Rat neural behavior was examined using open field tests （OFT）. And the protein expressions and their mRNAs transcription related with APP catabolism were studied using enzyme-linked immunosorbent assay （ELISA） and real-time polymerase chain reaction （RT-PCR）. Results The expressions of APP, 13-site APP cleaving enzyme 1 （BACEI） and presenilin-1 （PSi） proteins and their mRNAs transcription increased gradually with the increase of Al（mal）3 doses （P〈0.05）. The enzyme activity of BACEI in the 0.54 and 1.08 mg/kg Al（mal）s groups increased significantly （P〈0.05）. The expression of 8-amyloid protein （AS） 1-40 gradually decreased while the protein expression of A81-42 increased gradually with the increase of Al（mal）s doses （P〈0.05）. Conclusion Result from our study suggested that one of the possible mechanisms that Al（mal）s can cause neurotoxicity is that Al（mal）s can increase the generation of A81-42 by facilitating the expressions of APP, β-, and γ-secretase.

Improving cognitive impairment by Tongxinluo via inhibiting expression of beta-secretase 1/beta-amyloid peptide in experimental vascular dementia

BACKGROUND： Tongxinluo has been clinically proven to be effective in improving memory and cognitive function in patients with post-stroke vascular dementia. Is the mechanism related to the deposition of beta-amyloid peptide （A β ） in hippocampus？ OBJECTIVE： To observe the effect of Tongxinluo on cognitive impairment in a mouse model with vascular dementia and the changes of A β deposition and β -secretase 1 （BACE1） expression. DESIGN： Randomized controlled study. SETTING： State Key Laboratory of Pharmaceutical Biotechnology of Nanjing University and Affiliated Drum Tower Hospital of Nanjing University Medical School. MATERIALS： The experiment was carried out in the State Key Laboratory of Pharmaceutical Biotechnology of Nanjing University and Affiliated Drum Tower Hospital of Nanjing University Medical School from March 2006 to January 2007. A total of 36 healthy Kunming mice, 18 of each gender, were chosen. The study was conducted in accordance with the National Regulations of Experimental Animal Administration, and all animal experiments were approved by the Committee of Experimental Animal Administration of Nanjing University. Tongxinluo was provided by Shijiazhuang Yiling Pharmaceutical Co., Ltd. METHODS： All mice were randomly divided into 6 groups, including naive control （n=6）, sham-operated control （n=6） and experimental groups treated with different doses of Tongxinluo （0.2, 0.4, and 0.6 g/kg/d; n=6 for each group） or vehicle （n=6）. Five groups were subjected to bilateral common carotid arteries （2-VO） occlusion to produce a vascular dementia model （no occlusion was performed in sham-operated group）. The mice in the Tongxinluo treatment groups were intragastricly administered daily with a Tongxinluo suspension （40 g/L in distilled water） at doses of 0.2, 0.4 or 0.6 g/kg/d from day 1 to day 30 post-surgery. The animals in vehicle, sham-operated and naive groups were administered an equal volume of distilled water. MAIN OUTCOME MEASURES： ①Escape latency time determined in all groups of mice before and after 2-VO occlusion by Morris water maze. ②Changes in BACEI mRNA expression in the hippocampi of mice among the six groups by RT-PCR assay, and BACEI and A β protein expression in the hippocampi of mice by Western blot. RESULTS： All 36 mice were involved in the final analysis.① No difference was detected in escape latency time to a hidden platform among all groups in water maze test before surgery （P 〉 0.05） At 30 days after 2-VO occlusion, the vehicle animals exhibited a significantly longer latency in finding the hidden platform compared to that of sham-operated and naive animals （P 〈 0.01）. The prolonged escape latency was significantly reduced by oral administration of 0.4 g or 0.6 kg/day （P 〈 0.01, P 〈 0.05）. BACEI mRNA and protein expression in vehicle animals were much higher than in sham-operated and naive animals （P 〈 0.01）. The ischemia-induced increases in BACE1 mRNA and protein level were attenuated by all three doses of Tongxinluo treatment （P 〈 0.01）, and the 0.4 g/kg/d treatment was the most effective. A β protein expression in vehicle animals after 2-VO occlusion were much higher than in sham-operated and naive animals （P 〈 0.01）. 2-VO occlusion-induced A β generation was significantly attenuated by all doses of Tongxinluo treatment, with the most effective dose being 0.4 g/kg/d （P 〈 0.01）. CONCLUSION： BACE1 mRNA levels and protein levels of BACEI and A β are reduced in the hippocampi of vascular dementia model mice by all three doses of Tongxinluo treatment, with the most effective dose being 0.4 g/kg/d. The results suggest that inhibition of post-ischemia BACEI expression and A β generation in brain might underlie Tongxinluo＇s effects in improving cognitive impairment.

Effects of Ginsenoside Rg1 on nuclear factor-kappa B activity in beta amyloid protein-treated neural cells

BACKGROUND： Modern pharmacological studies have shown that Ginsenoside Rgl is one of the active components of ginseng that promote intelligence in the nervous system. Ginsenoside Rgl can improve memory and learning in mouse models of β-amyloid protein （Aβ）-induced dementia. OBJECTIVE： To investigate whether effects of Ginsenoside Rgl against Aβ are associated with activity of nuclear factor-kappa B （NF-κB）. DESIGN, TIME AND SETTING： The randomized performed at the DME Center, Institute of Clinica controlled, cell biological experiment was Pharmacology, Guangzhou University of Chinese Medicine, China from July 2005 to May 2006. MATERIALS： Beta-amyloid fragment 25-35 （Aβ25-35） was supplied by the Neural Biochemical Laboratory, Xuanwu Hospital, Capital Medical University, China. Ginsenoside Rgl was obtained from National Institute for the Control of Pharmaceutical and Biological Products, China. Rabbit anti-rat NF-κB p65 antibody was purchased from Santa Cruz Biotechnology, USA. METHODS： Hippocampal neurons and cortical astrocytes of neonatal Sprague Dawley rats were harvested and treated with various concentrations （0, 5, 10, 20, and 40 μmol/L） of Aβ for 6, 12, and 24 hours to establish cellular models of Alzheimer＇s disease. Cellular models were pretreated with various concentrations of Ginsenoside Rgl （1,2, 4, 8, and 16 μmol/L）. According to cell morphology and activity, the following conditions were selected： 40 μmol/L Aβ for 24 hours, as well as 2, 4, and 8 μmol/L Ginsenoside Rg1. NF-κB activity was observed using immunofluorescence and cytochemical staining. MAIN OUTCOME MEASURES： Morphology and viability of hippocampal neurons and cortical astrocytes, and activities of NF-κB were measured. RESULTS： Hippocampal neuron activity was significantly greater in the normal and 2 and 4 μmol/L Ginsenoside Rgl groups compared with the model group （P 〈 0.05）. Astrocyte activity was significantly greater in the normal, 1,2, 4, 8, and 16 μmol/L Ginsenoside Rgl groups compared with the model group （P 〈 0.05）. NF-κB activity of hippocampal neurons was significantly greater in the normal, 2, 4, and 8 μmol/L Ginsenoside Rgl groups compared with the model group （P 〈 0.01）. NF-κB activity of astrocytes was significantly less in the normal, 2, 4, and 8 μmol/L Ginsenoside Rgl groups compared with the model group （P 〈 0.01 or P 〈 0.05）. No significant difference in NF-κB activity was determined between the 2 μmol/L Ginsenoside Rgl and normal groups （P 〉 0.05）. CONCLUSION： Ginsenoside Rgl protected neural cells by upregulating NF-κB activity in neurons and downregulating NF-κB activity in astrocytes. Ginsenoside Rgl （2 μmol/L） maintained cell activity and NF-κB activity at normal levels.

Effect of Bak Foong Pills on the expression of β-amyloid in rat retina with optic nerve transection

AIM:To investigate the effect of Bak Foong Pills(BFP) on the expression of β-amyloid(Aβ) in rats retina with optic nerve transaction,and its roles and possible mechanisms in protecting optic nerve damage.· METHODS:Seventy-two healthy,Sprague-Dawley,adult rats were randomly assigned to three groups:negative control group(control group),optic nerve transection group(model group) and BFP treatment group(BFP group,100μg/mL) followed by establishing optic nerve transection model.The expression of Aβ was measured at 48 hours by Western-blotting.Moreover,the expressions of Bcl-2,Bax and Caspase-3 mRNA were evaluated at 48 hours by reverse transcriptase polymerase chain reaction(RT-PCR).RESULTS:There were significant differences among the control,model and BFP groups in the expression of Aβ(all P <0.01).Aβ expression was significantly higher in the model and BFP groups than that in the control group(P < 0.01),with a more significant reduction in the BFP group than that in the model group(P <0.01).Moreover,there were also significant differences among the three groups in the expressions of Bcl-2/Bax(Bcl-2:anti-apoptotic;Bax:proapoptotic) and Caspase-3 mRNA(proapoptotic)(all P<0.01).Bcl-2/Bax ratio was significantly lower and Caspase-3 mRNA expression was significantly higher in the model and BFP groups than those in the control group(P <0.01),with a significant growing of Bcl-2/Bax and reduction of Caspase-3 in the BFP group than those in the model group(P<0.01).· CONCLUSION:BFP can down-regulate Aβ expression in retina and may inhibit apoptosis and protect optic nerve by enhancing Bcl-2/Bax ratio and inhibiting Caspase-3 pathway.

Effects of Yishendaluo decoction on axonal degeneration,inflammatory reaction,and neurological function in a mouse model of experimental autoimmune encephalomyelitis

BACKGROUND： Yishendaluo decoction reduces production of inflammatory mediators, relieves damage due to inflammatory reactions, and improves neural functions during experimental autoimmune encephalomyelitis. OBJECTIVE： To investigate the effects of Yishendaluo decoction on a mouse model of experimental autoimmune encephalomyelitis. DESIGN, TIME AND SETTING： The randomized, controlled, neuropathological, and molecular biological animal study was performed at the Key Laboratory of Chinese Internal Medicine, Ministry of Education, Dongzhimen Hospital of Beijing University of Chinese Medicine and Center for Neuroinformatics, General Hospital of Chinese PLA from 2005 to 2006. MATERIALS： Yishendaluo decoction pieces consisting of prepared rehmannia root, colla comus cervi, cape jasmine fruit, and grassleaf sweetflag rhizome were purchased from the Dongzhimen Hospital of Beijing University of Chinese Medicine. Rabbit anti-mouse β-amyloid precursor protein and p38 polyclonal antibody （Zhongshan Goldenbridge Biotechnology, China）, as well interferon-y and interleukin-4 ELISA kit （Boster, China）, were used in this study. METHODS： A total of 96 healthy, female, SJL/J mice, aged 8 12 weeks, were equally and randomly assigned to normal, model, hormone, and Chinese medicine groups. A total of 0.2 mL antigen preparation, supplemented with 150 μg PLP 139-151 and 400 μg H37RA, was subcutaneously injected into the upper abdomen of mice from the model, hormone, and Chinese medicine groups. Mouse models of experimental autoimmune encephalomyelitis were established by intravenous injection of 0.1 mL Bordetella pertussis solution containing 0.6 × 10^6 Bordetella pertussis at days 1 and 3. Mice from the model, Chinese medicine, and hormone groups were respectively subjected to 0.2 mL saline, 2 g/kg Yishendaluo decoction, and 0.078 mg/kg prednisone acetate, once daily for 14 consecutive days. Mice from the normal group were left intact. MAIN OUTCOME MEASURES： Pathological changes were observed using hematoxylin-eosin staining and Luxol fast blue staining. Expression of β-amyloid precursor protein and p38 protein was determined by immunohistochemistry. Levels of interferon-y and interleukin-4 were detected by ELISA. Behavioral changes were assessed in mice according to scores of neurological function. RESULTS： A few inflammatory cell infiltration, nerve fiber breakage and slight demyelination were detected in the central nervous system of mice from the Chinese medicine and hormone groups compared with the model group. Expression of β-amyloid precursor protein and p38 protein was significantly diminished in the central nervous system of mice from the Chinese medicine and hormone groups compared with the model group （P 〈 0.05 or P 〈 0.01）, and the decrease was greatest in the Chinese medicine group. The decrease in mouse weight was not significant, and neurological function scores were less in the Chinese medicine and hormone groups compared with the model group （P 〈 0.05 or P 〈 0.01）. Interferon-y levels were significantly reduced （P 〈 0.01）, and interleukin-4 levels were significantly increased （P 〈 0.01） in the brains of the Chinese medicine and hormone groups, compared with the model group. CONCLUSION： Yishendaluo decoction improved neurological function in mice with experimental autoimmune encephalomyelitis by downregulating β-amyloid precursor protein expression, resistingaxonal degeneration, and relieving inflammatory reaction. The anti-inflammatory mechanism was regulated by inhibition of the p38 mitogen-activated protein kinase signal pathway.

Relationship between post-operative cognitive dysfunction and regional cerebral oxygen saturation and β-amyloid protein

Objective： To investigate the relationship between post-operative cognitive dysfunction（POCD） and regional cerebral oxygen saturation（rSO2） and β-amyloid protein（Aβ） in patients undergoing laparoscopic pancreaticoduodenectomy. Methods： Fifty patients undergoing elective laparoscopic pancreaticoduodenectomy received five groups of neuropsychological tests 1 d pre-operatively and 7 d post-operatively, with continuous monitoring of rSO2 intra-operatively. Before anesthesia induction（t0）, at the beginning of laparoscopy（t1）, and at the time of pneumoperitoneum 120 min（t2）, pneumoperitoneum 240 min（t3）, pneumoperitoneum 480 min（t4）, the end of pneumoperitoneum（t5）, and 24 h after surgery, jugular venous blood was drawn respectively for the measurement of Aβ by enzyme-linked immunosorbent assay（ELISA）. Results： Twenty-one cases of the fifty patients suffered from POCD after operation. We found that the maximum percentage drop in rSO2（rSO2, %max） was significantly higher in the POCD group than in the non-POCD group. The rSO2, %max value of over 10.2% might be a potential predictor of neurocognitive injury for those patients. In the POCD group, the plasma Aβ levels after 24 h were significantly higher than those of pre-operative values（P〈0.01）. After 24 h, levels of plasma Aβ in the POCD group were significantly higher than those in the non-POCD group（P〈0.01）. Conclusions： The development of POCD in patients undergoing laparoscopic pancreaticoduodenectomy is associated with alterations of rSO2 and Aβ. Monitoring of rSO2 might be useful in the prediction of POCD, and Aβ might be used as a sensitive biochemical marker to predict the occurrence of POCD.

Platelets and Alzheimer's disease:Potential of APP as a biomarker

Platelets are the first peripheral source of amyloid precursor protein(APP). They possess the proteolytic machinery to produce Aβ and fragments similar to those produced in neurons, and thus offer an ex-vivo model to study APP processing and changes associated with Alzheimer's disease(AD). Platelet process APP mostly through the α-secretase pathway to release soluble APP(s APP). They produce small amounts of Aβ, predominantly Aβ40 over Aβ42. s APP and Aβ are stored inα-granules and are released upon platelet activation by thrombin and collagen, and agents inducing platelet degranulation. A small proportion of full-length APP is present at the platelet surface and this increases by 3-fold upon platelet activation. Immunoblotting of platelet lysates detects APP as isoforms of 130 kD a and106-110 kD a. The ratio of these of APP isoforms is significantly lower in patients with AD and mild cognitive impairment(MCI) than in healthy controls. This ratio follows a decrease that parallels cognitive decline andcan predict conversion from MCI to AD. Alterations in the levels of α-secretase ADAM10 and in the enzymatic activities of α- and β-secretase observed in platelets of patients with AD are consistent with increased processing through the amyloidogenic pathway. β-APP cleaving enzyme activity is increased by 24% in platelet membranes of patients with MCI and by 17% in those with AD. Reports of changes in platelet APP expression with MCI and AD have been promising so far and merit further investigation as the search for blood biomarkers in AD, in particular at the prodromal stage, remains a priority and a challenge.

Effect of Huannao Yicong Prescription (还脑益聪方) Extract onβ-Amyloid Precursor Protein Metabolic Signal Transduction-Related Protein in Brain Tissue of Dementia Model Transgenic Mouse

Objective： To observe the effect of Huannao Yicong Prescription （还脑益聪方, HNYC, a Chinese medical compound） extract on β-amyloid precursor protein （APP） metabolic signal transductionrelated protein kinase C （PKC）, tyrosine amyloid protein kinase （TrKA）, and glycogen synthase kinase-3 （GSK-3） in brain tissue of transgenic mouse dementia model induced by APP. Methods： Sixty dementia model transgenic 3-month-old mice induced by APP695V7171 were randomly allocated in four groups： the model group （A）, the Donepezil （0.65×10^-3 g.kg-1.d-1）-treated group （B）, and the two HNYC-treated groups （C and D） with high dosage （2.8 g.kg^-1.d^-1） and low dosage （1.4 g.kg^-1.d^-1） of HNYC extract, respectively, 15 mice in each group. Besides, a normal control group was set up with 15 C57BL/6J mice with the same age and genetic background as the model mice. The drugs for treatment were administered once a day by dissolving in equal-volume distilled water through gastric infusion, continued for 6 months, to mice in group A and to normal control group equal-volume distilled water was administered instead. Spatial learning and memory capacity of mice were observed by Morris water maze; their one-time escape response memory capacity was tested by diving platform; and changes of PKC, TrkA, and GSK-3 levels in hippocampus and cortex of brain were detected by Western blotting. Results： HNYC extract showed significant effects on increasing the time of model mice for swimming through the flat roof and the swimming time and path in the fourth quadrant （P〈0.05 or P〈0.01）. Diving platform test showed that the latent times in Groups B and C were longer than that in Group A significantly （P〈0.05 and P〈0.01）. Compared with the normal control group, PKC and TrkA protein expression levels in hippocampus and cortex of model mice＇s brain lowered significantly （P〈0.01）, while GSK-3 protein expression increased significantly （P〈0.01）; compared with Group A （the model group）, hippocampal and cortical levels of PKC protein expression in the intervened groups （B-D） as well as those of TrkA in Group C were higher （P〈0.01 or P〈0.05）, while hippocampal levels of GSK-3 in intervened groups were lower （P〈0.01）. Conclusion： HNYC extract could obviously increase the protein expressions of PKC and TrkA and decrease the expression of GSK-3 protein in brain tissue of transgenetic mice model of dementia, and regulate APP metabolic signal transduction path, and thus to suppress the production of A β, which is one of the dominant mechanisms for improving learning/memory capacity of dementia model animals.

Change of cholinergic transmission and memory deficiency induced by injection of β-amyloid protein into NBM of rats

The change of cholinergic transmission of p-amyloid protein (P-AP) treated rats was studied by intracerebral microdialysis sampling combined with HPLC analysis. β-AP1-40 was injected into nucleus basalis magnocellularis (NBM). Passive avoidance response test (step-down test) and delayed alternation task were used for memory testing. The impairment of memory after injection of β-AP1-40 into NBM exhibited mainly the deficiency of short-term working memory. One week after injection of β-AP1-40 the release of acetylcholine (ACh) from frontal cortex of freely-moving rats decreased significantly, and the response of cholinergic nerve ending to the action of high [K+] solution was rather weak. In control animals the percentage of increase of ACh-release during behavioral performance was 57%, while in β-AP1-40-treated rats it was 34%. The temporary increase of the ACh-release of the rat put into a new place was also significantly diminished in β-AP1-40 -treated rats. The results show that the injection of β-AP1-40 into NBM impairs the cholinergic transmission in frontal cortex, and the impairment of cholinergic transmission may be the main cause of the deficit of working memory.

Physalin B reduce secretion of Aβ by inhibiting phosphorylation of STAT3 via down-regulated expression of β-secretase and γ-secretase

OBJECTIVE Extracellular amyloid-β(Aβ) plaques are one of the major pathological hallmarks of Alzheimer disease(AD). Therefore, decreasing Aβ levels is one strategyfor preventing the etiology of AD. Aβ peptides are generated from the cleavage of amyloid precursor protein(APP) by the β-secretase(BACE1) and γ-secretase(PS1). Inhibition of these secretases represents an obvious logical strategy to inhibit the generation of Aβ. In addition, signal transducer and activator of transcription 3(STAT3) is known to regulate many genes, and to significantly affect Aβ generation by controlling BACE1 and PS1 expression. Physalin B(PB), one of the major active steroidal constituents of solanaceaephysalis plants, possesses a wide variety of biological activities. PB down-regulates BACE1 and PS1 expression while it is unclear whether PB can regulate Aβ in N2 a/APPswe cells, and if so, whether it is by inhibiting the phosphorylation of STAT3. METHODS N2 a/APPswe cells were treated with PB in different concentrations for 24 h.(1) We used CCK8 method to detect the effects of different concentrations of PB on cell viability, and selected the best concentration for drug treatment to the cells.(2)The contents of Aβ40 and Aβ42 were determined by ELISA.(3) Western blotting was used to detect the expression levels of p-STAT3 and APP metabolism-related proteins, including APP, CTFα, CTFβ, BACE1,PS1, ADAM10 and so on.(4) RT-PCR was performed to detected the m RNA expression of BACE1 and PS1.(5) β-secretase activity Fluorometric assay kit was used to analyzed β-secretase activity.(6) In order to further explore the underlying mechanisms, N2 a/APPswe cells were pre-treated with 100 μmol·L-1 S3 I-201(a STAT3 inhibitor,can effectively prevent STAT3 phosphorylation) for 30 min and then treated with 3 μmol·L-1 PB incubated for 24 h. Then we evaluated the level of expression of STAT3 and p-STAT3 by Western blotting. RESULTS(1) CCK8 experiment results illustrated that PB did not show cytotoxicity at the applied concentration when cells were treated with PB(0, 0.3, 1 and 3 μmol·L-1). So, we used these concentrations in the following experiment.(2) ELISA results showed, compared to the control group, the contents of Aβ40 and Aβ42 decreased with the increasing of PB concentration.(3)According to Western blotting results, PB significant down-regulated the expression of BACE1, PS1, APP, CTFβ and p-STAT3 compared to the control group.(4) RT-PCR results indicated that PB can reduced the m RNA expression of BACE1 and PS1 effectively.(5) It turns out that PB can significantly inhibit BACE1 activity tested by BACE1 activity Fluorometric assay kit.(6) S3 I-201 had a similar manner to significantly inhibited STAT3 phosphorylation with PB through Western blotting. Moreover, co-treated with S3 I-201 and PB inhibited STAT3 phosphorylation much more than treatment with S3 I-201 alone. CONCLUSION These findings indicate that PB can effectively inhibit the expression of BACE1 and PS1 to reduce Aβ secretion by inhibiting the phosphorylation of STAT3.

Set up Alzheimer＇s Disease Cell Apoptosis Model with PC-12 Cell Induced by Aβ25-35

Objective: To prepare an apoptosis cell model of Alzheimer Disease (AD) by PC-12 cells treated with β-amyloid protein (Aβ). Methods: PC-12 cells were incubated with different concentrations of Aβ25-35 for different duration in vitro. The cell viability was detected by MTT assay. Morphological features of apoptosis were analyzed, with Hoechst 33258/ Propidium iodide dual staining, The level of intracellular free calcium ([Ca2+]i) was calculated by Fura-2/AM fluorescence ratio imaging. Results: ① The viability of PC-12 cells was significantly decreased in proportion to concentration of Aβ25-35 and duration of exposure to Aβ25-35. ② The apoptotic cells appeared in a time and concentration-dependent manner, and the maximal apoptosis happened at 48 h after exposure to 20 μmol/L of Aβ25-35 and 36 h to 30 μmol/L, Cell death reached the peak at 12-24 h later than the apoptotic peak. (3) [Ca2+]i of PC-12 cells was increased in proportion to duration of exposure to the same concentration of Aβ25-35. The time of the highest increase rate of [Ca2+]i was about 12 h earlier than that of apoptosis. Conclusion: An AD cell model using the PC-12 cells induced with Aβ25-35 displays a series of changes related to apoptosis, which may be related to elevation of [Ca2+]i.