Salivary biomarkers in Alzheimer´s disease / Biomarcadores salivales en la enfermedad de Alzheimer

The hypotheses currently considered the most likely causes of Alzheimer's disease (AD) are amyloid beta peptide deposition in the cerebral cortex and hyperphosphorylation of the Tau protein, with the consequent formation of neurofibrillary tangles. In clinical practice, although not accurate, AD diagnosis is based on the exclusion of other diseases, behavioural assessments and complementary examinations, such as imaging and blood tests. Advances in the field of biotechnology have created exciting prospects for the early detection of AD via biomarker assessment, which is considered a safer and more efficient procedure. Molecules recognised as biomarkers can be expressed in some body fluids, including cerebrospinal fluid, saliva and blood. The presence of amyloid beta peptide and Tau can be confirmed in saliva, which is also an easily and non-invasively collectable material with an accessible cost. The objective was evaluate the concentrations of the t-Tau protein and Ab42 peptide in the saliva of elderly individuals with and without dementia of the AD type Method: The objective of this case-control study, involving a total of 120 individuals, was to analyse whether a correlation exists between variations in the concentrations of the t-Tau and Ab42 biomarkers in the saliva of patients with confirmed AD and individuals in the inclusion group but without AD . We found that t-Tau expression in AD patients is significantly lower than that in individuals without AD, whereas the salivary concentration of Ab42 is higher in patients with AD but not significantly different from that of the group without AD. Conclusion: Thus, we demonstrate the feasibility of using salivary biomarkers as predictive markers for diagnosis of Alzheimer's disease.

Las hipótesis consideradas actualmente como las causas más probables de la enfermedad de Alzheimer (EA) son la deposición de péptido beta amiloide en la corteza cerebral y la hiperfosforilación de la proteína Tau, con la consiguiente formación de ovillos neurofibrilares. En la práctica clínica, aunque no es precisa, el diagnóstico de la EA se basa en la exclusión de otras enfermedades, evaluaciones de comportamiento y exámenes complementarios, como imágenes y análisis de sangre. Los avances en el campo de la biotecnología han creado interesantes perspectivas para la detección temprana de la EA a través de la evaluación de biomarcadores, que se considera un procedimiento más seguro y más eficiente. Las moléculas reconocidas como biomarcadores se pueden expresar en algunos fluidos corporales, incluidos el líquido cerebroespinal, la saliva y la sangre. La presencia del péptido beta amiloide (AB) y la proteína Tau (t-Tau) se puede confirmar en la saliva, que también es un material fácil y no invasivo de recolección con un costo accesible. El objetivo fue evaluar las concentraciones de la proteína t-Tau y el péptido Ab42 en la saliva de las personas de edad avanzada con y sin demencia del tipo de tipo EA. El estudio de casos y controles, se realizó en un total de 120 personas, para analizar si existe una correlación entre las variaciones en las concentraciones de los biomarcadores t-Tau y Ab42 en la saliva de pacientes con EA confirmada e individuos en el grupo de inclusión pero sin AD. Encontramos que la expresión de t-Tau en pacientes con EA es significativamente menor que en individuos sin EA, mientras que la concentración salival de Ab42 es mayor en pacientes con EA pero no significativamente diferente de la del grupo sin la enfermedad . Por lo tanto, se demuestra la viabilidad del uso de biomarcadores salivales como marcadores predictivos para el diagnóstico de la enfermedad de Alzheimer.

Effect of hydrogen sulfide on aβ25-35 -induced autophagy in mouse neuro-2a cells / 第二军医大学学报

Objective To investigate thêoeffect of exogenous hydrogen sulfide on Aβ25-35-induced autophagy in mouse Neuro-2a cells and the underlying mechanism. Methods The Neuro-2a cells were randomly divided into control group. Aβ25-35 treatment group. Aβ25-35 + NaHS group. Aβ25-35 n3-MA (3-methyl adenine) group. NaHS group and Aβ25-35 + NaHS + LY294002 group. In Aβ25-35+ NaHS group and Aβ25-35 +3-MA group. NaHS and 3-MA were used for pretreatment for 2 h. which was followed by 24 h co-incubation with Aβ5-35; in Aβ25-35 + NaHS+LY294002 group. after pretreatment with NaHS. LY294002 was administered for 0. 5 h before Aβ25-35 was given. MTT assay was used to detect the viability of Neuro-2a cells. The expression of the autophagy related proteins including Beclin-1. LC3 and P62was measured by Western blotting analysis. Immunofluorescence was used to detect the expression and distribution of LC3. The formation ofautophagosomes was determined by transmission electron microscopy (TEM). Results (1) Compared with control group. Aβ25-35 group had significantly declined cell viability (P<0. 05). significantly increased expression of Beclin-1 and LC3H and decreased P62 expression (P<0. 05). accompanied by increased autophagsomes under fluorescencemicroscope and electron microscope. (2) Compared with Aβ25-35 group. the cell viability was significantly increased in Aβ25-35 + 3-MA and Aβ25-35 +NaHS groups (P< 0. 05). and expression of Beclin-1 and LC3H was decreased and expression of P62 was increased (P<0. 05). accompanied by reduced autophagosomes. (3) The expression of p-Akt and p-mTOR in Aβ25-35 +NaHS group was significantly higher than that in Aβ25-35 group (P<0. 05); however. the expression of p-Akt and p-mTOR was significantly reduced after given the specific PI3K/Akt pathway inhibitor LY294002 compared with Aβ25-35 +NaHS group (P<0. 05). Conclusion The exogenous H2S can protect against Aβ25-35 -induced cytotoxicity. which is probably related to the activation of PI3K/Akt/mTOR pathways and the inhibition of Aβ25-35 -induced cell autophagy.

Neuroprotective effect of renin angiotensin system blockers on experimentally induced Alzheimer’s disease in rats.

Background: Alzheimer’s disease (AD) is a major world-wide health problem. Much evidence points to a link between hypertension and AD. However, the exact effects of different antihypertensive drugs on AD need to be more assessed. The aim was to evaluate and compare the possible effects of perindopril, and candesartan on cognitive impairment, oxidative stress markers, and brain concentrations of amyloid beta-peptide (Aβ-P) in a rat model of induced dementia. Methods: Thirty-two adult male Wistar rats were distributed among 4 groups; (1) normal controls; (2) rats with dementia induced by intracerebroventricular administration of streptozotocin (ICV-STZ) and received no treatment; (3) ICV-STZ rats treated orally with perindopril for 3 weeks; and (4) ICV-STZ rats treated orally with candesartan for 3 weeks. The assessed parameters were spatial memory by Morris Water Maze test, brain tissue level of total antioxidant capacity (TAC), reduced glutathione (GSH), lipid peroxidation product (malondialdehyde [MDA]), and Aβ-P. Results: Both perindopril and candesartan attenuated STZ-induced memory impairment, caused a significant increase in TAC and GSH levels, reduced MDA levels, whereas only candesartan significantly reduced Aβ-P levels. Conclusions: This study reports that candesartan and perindopril can reverse the free radical induced damages and resultant memory defects, and may suggest candesartan as worthy drugs for prevention of Aβ-P deposition in this animal model of AD.

Prolonged oral administration of Gastrodia elata extract improves spatial learning and memory of scopolamine-treated rats / 한국실험동물학회지

Gastrodia elata (GE) is traditionally used for treatment of various disorders including neurodegenerative diseases such as Alzheimer's disease. To investigate the neuroprotective effect of GE, amyloid-beta peptide (Abeta)-treated PC12 cells were cultured with GE aqueous extract. In vitro assay demonstrated that 50 microM of pre-aggregated Abeta was lethal to about a half portion of PC12 cells and that Abeta aggregate-induced cell death was significantly decreased with GE treatment at < or =10 mg/mL in a dose-dependent manner. To further examine in vivo cognitive-improving effects, an artificial amnesic animal model, scopolamine-injected Sprague-Dawley rats, were orally administered the extract for 6 weeks followed by behavioral tests (the passive avoidance test and Morris water maze test). The results showed that an acute treatment with scopolamine (1 mg/kg of body weight) effectively induced memory impairment in normal rats and that the learning and memory capability of scopolamine-treated rats improved after prolonged administration of GE extract (50, 250 and 500 mg/kg of body weight for 6 weeks). These findings suggest that a GE regimen may potentially ameliorate learning and memory deficits and/or cognitive impairments caused by neuronal cell death.

Phytomedicines as potential inhibitors of β amyloid aggregation: significance to Alzheimer's disease / 中国天然药物

Throughout the history of drug development, plants have been an important source for the discovery of novel therapeutically active compounds for many diseases. The ethnopharmacological approach has provided several leads to identify potential new drugs from plant sources, including those for memory disorders. For the treatment of Alzheimer's disease the drug discovery focus shifted from cholinesterase inhibitors, to other targets primarily based on two key neuropathological hallmarks, namely the hyperphosphorylation of the tau protein resulting in the formation of neurofibrillary tangles (NFTs), and the increased formation and aggregation of amyloid-beta peptide (Aβ) derived from amyloid precursor protein (APP). The present article aims to provide a comprehensive literature survey of plants and their constituents that have been tested for Aβ aggregation, thus possibly relieving several features of Alzheimer's disease (AD).

Effect of exercise training on amyloid-beta peptide and β-secretase in the hippocampus of the rats with vascular dementia / 中华行为医学与脑科学杂志

ObjectiveTo study the effect of exercise training on β-amyloid polypeptide (Aβ) and β-secretase(BACE) in the hippocampus of the rats with vascular dementia (VD).Methods 30 Sprague-Dawley (SD) rats were carried out to an exercise group (n =10 ),a model group (n =10 ),and a sham-operation group ( n =10 ).VD rat models were made by the ligation of bilateral common carotid arteries.Morris water maze test were carried out 4 weeks after the operation to assess the ability in learning and memory of the rats and Aβ and β-secretase (BACE)expression was detected in the hippocampus of the rats using immunohistochemical techniques.ResultsIn the Morris water maze test,the model group showed reduction in the learning and memorizing ability,with obvious longer escape latencies ( ( 101.34 ± 19.67 ) s,(95.42 ± 23.89 ) s,( 89.39 ± 22.67 ) s,( 90.12 ± 19.77 ) s,respective-ly) than that of sham-operation group ( ( 62.13 ± 11.38 ) s,( 24.84 ± 13.69 ) s,( 16.98 ± 12.51 )s,( 11.41 ± 8.93 ) s,correspond-dingly) (P ＜ 0.05 ),and the exercise group was improved in the learning and memorizing ability ( corresponding to ( 80.15 ± 21.56 ) s,( 51.24 ± 20.91 ) s,( 43.78 ± 22.36) s,( 45.67 ± 20.87 ) s ),compared with the model group(P＜0.05).The grey values of Aβ in the hippocampus of the rats for the exercise group was ( 130.12 ± 19.01 ),( 116.77 ± 23.67 ) for the model group and ( 148.44 ± 17.67 ) for the sham-operation group(P＜ 0.05).The grey values of BACE in the hippocampus of the ratsfor the exercise group were( 131.21± 25.25 ),( 120.53± 10.21 ) for the model group(P＜ 0.05 ) and ( 162.38 ± 28.11 ) for the sham-operation group (P ＜ 0.05).ConclusionExercise training can lower the expression of BACE and Aβ in the hippocampus of rats with VD,therefore improving the learning and memory ability of rats with VD.

The effects of rehabilitation training on amyloid-beta peptide and insulin-degrading enzyme levels in the hippocampus of rats with vascular dementia / 中华物理医学与康复杂志

Objective To investigate the effects of rehabilitation training on hippocampal amyloid-beta peptide (Aβ) and insulin-degrading enzyme (IDE) levels in vascular dementia (VD).Methods Thirty female Sprague-Dawley rats were randomly assigned to a rehabilitation group (n =10),a model group (n =10) or a sham-operation group (n =10).An experimental VD model was established in the rats of the first 2 groups by bilateral common carotid artery permanent ligation.The rats in the rehabilitation group then received 1 h of rehabilitation training daily.Learning and memory were assessed at 4 weeks aftet the operation.Immunohistochemical staining was used to detect Aβ and IDE expression in the hippocampus dentate gyrus (DG) area.Results The rats in the rehabilitation group showed significantly better learning ability compared with the model group.The expression of Aβ in the rehabilitation group was significantly less than in the model group.The expression of IDE in the rehabilitation group was significantly greater Conclusion Rehabilitation can accelerate the recovery of learning and memory in VD,at least in rats The mechanism is possibly related to decreased accumulation of Aβ in the hippocampus due to up-regulation of the expression of IDE.

Effect of nerve growth factor delivering intranasally on β-amyloid deposition after traumatic brain injury in rats / 中华神经科杂志

Objective To study the effect of intranasal nerve growth factor (NGF) on the expression of amyloid-β,peptide (Aβ) in the central nervous system in rats with traumatic brain injury (TBI).Methods Eighty rats were randomly divided into sham(n =26),control(n =27) and treatment group (n =27 ).They were subjected to the modified Feeney' s weight-drop model.The treatment group was treated with NGF administered by nasal route,and the control group was given phosphate-buffered saline (PBS).Beam walking and Morris water maze test were performed in the three groups.The concentration of Aβ40 and Aβ42 in the injured ipsilateral hippocampus was elevated by ELISA measurement.Immunohistochemistry was used to detect the amyloid precursor protein (APP) positive cells near the region of injury in the hippocampus in rats after TBI.Results NGF group traversed the beam significantly quicker (s) than control group ( 19.00 + 6.99 vs 27.33 ± 7.39 respectively,F2,15 =12.87,P =0.028 ).Morris water maze performance revealed that mean time of latency in the NGF group was significant shorter than vehicle group,and significant memory retention in NGF group as evidenced by a greater percentage of the 60 s allotted time spent in the target quadrant (45.82％ ± 11.15％ vs 33.99％ ± 3.46％,F2,15 =6.814,P=0.037),as well as the number crossing of the former site of the removed platform in NGF group was significant more than control group (8.60 ±2.73 vs 3.60 ±2.06,F2,15 =5.346,P =0.04).The Aβ42 level in control group was increased significantly higher than NGF group as indicated by ELISA measurements.While the Aβ40 level did not have similar shown.Immunohistochemical staining showed that APP level had significant differences among three groups ( F2,15 =8.672,P =0.003).The APP level in NGF group did not alter with control group.Conclusion Intranasal administration of NGF can regulate Aβ42 overproduction,improve the motor and cognitive function after brain injury in rats.

GD3 Accumulation in Cell Surface Lipid Rafts Prior to Mitochondrial Targeting Contributes to Amyloid-beta-induced Apoptosis

Neuronal apoptosis induced by amyloid beta-peptide (A beta) plays an important role in the pathophysiology of Alzheimer's disease (AD). However, the molecular mechanism underlying A beta-induced apoptosis remains undetermined. The disialoganglioside GD3 involves ceramide-, Fas- and TNF-alpha-mediated apoptosis in lymphoid cells and hepatocytes. Although the implication of GD3 has been suggested, the precise role of GD3 in A beta-induced apoptosis is still unclear. Here, we investsigated the changes of GD3 metabolism and characterized the distribution and trafficking of GD3 during A beta-induced apoptosis using human brain-derived TE671 cells. Extracellular A beta induced apoptosis in a mitochondrial-dependent manner. GD3 level was negligible in the basal condition. However, in response to extracellular A beta, both the expression of GD3 synthase mRNA and the intracellular GD3 level were dramatically increased. Neosynthesized GD3 rapidly accumulated in cell surface lipid microdomains, and was then translocated to mitochondria to execute the apoptosis. Disruption of membrane lipid microdomains with methyl-beta-cyclodextrin significantly prevented both GD3 accumulation in cell surface and A beta-induced apoptosis. Our data suggest that rapidly accumulated GD3 in plasma membrane lipid microdomains prior to mitochondrial translocation is one of the key events in A beta-induced apoptosis.

A1 Receptor-mediated Protection against Amyloid Beta-induced Injury in Human Neuroglioma Cells

Adenosine has been reported to provide cytoprotection in the central nervous systems as well as myocardium by activating cell surface adenosine receptors. However, the exact target and mechanism of its action still remain controversial. The present study was performed to examine whether adenosine has a protective effect against Abeta-induced injury in neuroglial cells. The astrocyte-derived human neuroglioma cell line, A172 cells, and Abeta25~35 were employed to produce an experimental Abeta-induced glial cell injury model. Adenosine significantly prevented Abeta-induced apoptotic cell death. Studies using various nucleotide receptor agonists and antagonists suggested that the protection was mediated by A1 receptors. Adenosine attenuated Abeta-induced impairment in mitochondrial functional integrity as estimated by cellular ATP level and MTT reduction ability. In addition, adenosine prevented Abeta-induced mitochondrial permeability transition, release of cytochrome c into cytosol and subsequent activation of caspase-9. The protective effect of adenosine disappeared when cells were pretreated with 5-hydroxydecanoate, a selective blocker of the mitochondrial ATP-sensitive K+ channel. In conclusion, therefore we suggest that adenosine exerts protective effect against Abeta-induced cell death of A172 cells, and that the underlying mechanism of the protection may be attributed to preservation of mitochondrial functional integrity through opening of the mitochondrial ATP-sensitive K+ channels.

Inhibition of Amyloid beta Peptide-induced Neuronal Cytotoxicity by EGCG / 체질인류학회지

This study is aimed to investigate the signal transduction pathway of amyloid beta peptide (Abeta)-induced neuronal toxicity and the inhibitory effects of epigallocatechin gallate (EGCG), one of the major constituents of green-tea and the potent anti-oxidant, on the nerve cell damage in PC12 cells. Cellular toxicity was estimated by MTT assay and observation of morphological changes in PC12 cells. By using the methods such as measurement of Reactive Oxygen Species (ROS), western blot and RT-PCR, the underlying mechanisms and signal transduction pathway of Abeta- induced neurotoxicity and the inhibitory effects of EGCG were examined. Abeta-induced cellular toxicity was found in a dose dependent manner. This is confirmed by morphological observations of cultured cells such as findings of cell death similar to apoptosis. Abeta-induced neurotoxicity was effectively inhibited by EGCG pretreatment. Moreover, EGCG reduced ROS as same potent as he NAC (N-acetyl cystein), the ROS scavenger. Among the several process of signal transduction for cell death, a intracytoplasmic cytochrome c, the protein associated with the mitochondria- dependent pathway, was increased from 12 hours after Abeta treatment and the increased cytochrome c by Abeta was blocked by EGCG. Expression levels of Bax/Bcl-2 in relation to intracytoplasmic release of cytochrome c were examined by RT-PCR. Abeta up-regulated Bax expression but did not affect Bcl-2 expression. EGCG was found to block the effect of Abeta-induced Bax increase. From these results, it is speculated that Abeta-induced neuronal toxicity may be assumed to be affected by ROS and the mitochondria-dependent pathway of cell death as well. EGCG, besides having the role of anti-oxidant, is found to have a protective effect against Abeta-induced neurotoxicity through the inhibition of the expression of the protein associated with the mitochondria-dependent cell death pathway.

Improvement of the cholinergic function by melatonin in amnesic rats induced by amyloid β-peptide 25-35 / 中国药理学通报

AIM: To investigate whether melatonin improve the learning and memory dysfunction in the amnesic rats induced by amyloid β-peptide 25-35 (Aβ25-35) via cholinergic nervous system or not. METHODS: The amnesic model in adult rats was induced by injection of Aβ25-35 into hippocampus; Morris water maze was used to determine the effects of Aβ25-35 and melatonin on the learning and memory. The activity of the choline acetyltransferase and acetylcholinesterase were determined by immunohistochemistry and spectrophotometry respectively. RESULTS: Injection of Aβ25-35 20 μginto the adult rats hippocampus induced learning and memory dysfunction, and a decrease in the number of ChAT-immunoreactive neurons in hippocampus. Melatonin (0.1, 1, and 10 mg·kg-1, ig X 10 d) improved the Aβ25-35-treated rats cognitive function and increased the number of ChAT-immunoreactive neurons in hippocampus. CONCLUSION: Improvement of the cholinergic dysfunction by melatonin in adult rats induced by amyloid β-peptide 25-35 may be via cholinergic nervous system.

CDK4-pRB-E2F1 pathway may mediate A?_(1-40)-induced apoptosis in rat cortical neurons / 中国病理生理杂志

AIM: To study the possible molecular mechanism of beta-amyloid peptide_ 1-40 -induced apoptosis in rat cortical neurons. METHODS: 40 mg/L beta-amyloid peptide_ 1-40 (A?_ 1-40 ) was used to induce apoptosis in cultured rat cortical neurons. The level of CDK4, phosphorylated pRB were detected by flow cytometry and immunoblotting; RT-PCR was used to examine the mRNA expression of E2F1 while fluorescent spectrofluorometer was used to measure caspase-3 activity. All of the above study was designed to observe whether the level of CDK4, phosphorylated pRB and E2F1 mRNA expression could be affected by A?_ 1-40 . RESULTS: (1)The level of CDK4, phosphorylated pRB increased markedly 2-4 hours after treatment with A?_ 1-40 , and caspase-3 activity elevated remarkably 12-24 hours after treatment with A?_ 1-40 ; (2) E2F1 mRNA expression was upregulated 3 hours after incubation with A?_ 1-40 . CONCLUSION: A?_ 1-40 may induce apoptosis in rat cortical neurons in a manner dependent on CDK4-pRB-E2F1 pathway.

Improvement of the cholinergic function by melatonin in amnesic rats induced by amyloid ?-peptide 25～35 / 中国药理学通报

AIM To investigate whether melatonin improve the learning and memory dysfunction in the amnesic rats induced by amyloid ? peptide 25～35 (A? 25～35 ) via cholinergic nervous system or not.Methods The amnesic model in adult rats was induced by injection of A? 25～35 into hippocampus; Morris water maze was used to determine the effects of A? 25～35 and melatonin on the learning and memory. The activity of the choline acetyltransferase and acetylcholinesterase were determined by immunohistochemistry and spectrophotometry respectively. RESULTS Injection of A? 25～35 20 ?ginto the adult rats hippocampus induced learning and memory dysfunction, and a decrease in the number of ChAT immunoreactive neurons in hippocampus. Melatonin (0 1, 1, and 10 mg?kg -1 , ig?10 d) improved the A? 25～35 treated rats cognitive function and increased the number of ChAT immunoreactive neurons in hippocampus. CONCLUSION Improvement of the cholinergic dysfunction by melatonin in adult rats induced by amyloid ? peptide 25～35 may be via cholinergic nervous system.

EXPRESSION OF MAPK AND NMDAR IN THE HIPPOCAMPUS OF ALZHEIMER RAT / 解剖学报

Objective To investigate the changes of expression of N-methyl-D-aspartate receptor(NMDAR)and mitogen activated protein kinase(MAPK)in Alzheimer disease(AD)rat model. Methods AD rat model was established by injection of amyloid-beta protein 1-40 1?l(10 g/L)into hippocampus of rat.NMDAR-mRNA and MAPK protein were immunostained by in situ hybradization histochemistry and immunohistochemistry respectively.Learning and memory ability,LTP were determined by Morris water maze and electrophysiological methods respectively. Results The escape latent was prolongated in Alzheimer rats two weeks after injection of A? than in control rats and in rats before the injection of A?(P