Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive impairment. The main hypotheses about the pathogenesis of AD include the hypothesis of β-amyloid protein, the hypothesis of abnormal phosphorylation of Tau protein, and the hypothesis of neuroinflammation. In recent years, environmental pollutants have been considered as an important factor in causing neurological dysfunction. Common environmental pollutants include heavy metals, pesticides, polychlorinated biphenyls, microplastics, and air pollutants, all of which have been proven to have neurotoxicity. In this review, we not only discussed epidemiological and animal experimental studies that link environmental pollution with AD, but also summarized the mechanisms of action of relevant toxins, providing insights for studying the interrelationships between environmental pollutants and AD.
Animals ; Alzheimer Disease/chemically induced* ; Environmental Pollutants/toxicity* ; Neurodegenerative Diseases ; Plastics ; Amyloid beta-Peptides/metabolism*

Amyloid beta-Peptides ; toxicity ; Animals ; Drugs, Chinese Herbal ; pharmacology ; Estradiol ; pharmacology ; PC12 Cells ; Peptide Fragments ; toxicity ; Rats

Amyloid β-protein(Aβ) deposition in the brain is directly responsible for neuronal mitochondrial damage of Alzheimer's disease(AD) patients. Mitophagy, which removes damaged mitochondria, is a vital mode of neuron protection. Ginsenoside Rg_1(Rg_1), with neuroprotective effect, has displayed promising potential for AD treatment. However, the mechanism underlying the neuroprotective effect of Rg_1 has not been fully elucidated. The present study investigated the effects of ginsenoside Rg_(1 )on the autophagy of PC12 cells injured by Aβ_(25-35) to gain insight into the neuroprotective mechanism of Rg_1. The autophagy inducer rapamycin and the autophagy inhi-bitor chloroquine were used to verify the correlation between the neuroprotective effect of Rg_1 and autophagy. The results showed that Rg_1 enhanced the viability and increased the mitochondrial membrane potential of Aβ-injured PC12 cells, while these changes were blocked by chloroquine. Furthermore, Rg_(1 )treatment increased the LC3Ⅱ/Ⅰ protein ratio, promoted the depletion of p62 protein, up-regulated the protein levels of PINK1 and parkin, and reduced the amount of autophagy adaptor OPTN, which indicated the enhancement of autophagy. After the silencing of PINK1, a key regulatory site of mitophagy, Rg_1 could not increase the expression of PINK1 and parkin or the amount of NDP52, whereas it can still increase the LC3Ⅱ/Ⅰ protein ratio and promote the depletion of OPTN protein which indicated the enhancement of autophagy. Collectively, the results of this study imply that Rg_1 can promote autophagy of PC12 cells injured by Aβ, and may reduce Aβ-induced mitochondrial damage by promoting PINK1-dependent mitophagy, which may be one of the key mechanisms of its neuroprotective effect.
Amyloid beta-Peptides/toxicity* ; Animals ; Ginsenosides/pharmacology* ; Humans ; Mitophagy/physiology* ; PC12 Cells ; Protein Kinases/metabolism* ; Rats ; Ubiquitin-Protein Ligases/metabolism*

OBJECTIVETo examine the protective effect of ecdysterone (ECR) against beta-amyloid peptide fragment(25-35) (Abeta(25-35))-induced PC12 cells cytotoxicity, and to further explore its mechanism.

METHODSExperimental PC12 cells were divided into the Abeta group (treated by Abeta(25-35) 100 micromol/L), the blank group (untreated), the positive control group (treated by Vit E 100 micromol/L after induction) and the ECR treated groups (treated by ECR with different concentrations of 1, 50 and 100 micromol/L). The damaged and survival condition of PC12 cells in various groups was monitored by lactate dehydrogenase (LDH) release and MTT assay. The content of malondialdehyde (MDA) was measured by fluorometric assay to indicate the lipid peroxidation. And the antioxidant enzymes activities in PC12 cells, including superoxide dismutases (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), were detected respectively.

RESULTSAfter PC12 cells were treated with Abeta(25-35) (100 micromol/L) for 24 hrs, they revealed a great decrease in MTT absorbance and activity of antioxidant enzymes, including SOD, CAT and GSH-Px as well as a significant increase of LDH activity and MDA content in PC12 cells (P < 0.01). When the cells was pretreated with 1-100 micromol/L ECR for 24 hrs before Abeta(25-35) treatment, the above-mentioned cytotoxic effect of Abeta(25-35) could be significantly attenuated dose-dependently, for ECR 50 micromol/L, P < 0.05 and for ECR 100 micromol/L, P < 0.01. Moreover, ECR also showed significant inhibition on the Abeta(25-35) induced decrease of SOD and GSH-Px activity, but not on that of CAT.

CONCLUSIONECR could protect PC12 cells from cytotoxicity of Abeta(25-35), and the protective mechanism might be related to the increase of SOD and GSH-Px activities and the decrease of MDA resulting from the ECR-pretreatment.

Amyloid beta-Peptides ; toxicity ; Animals ; Catalase ; analysis ; Ecdysterone ; pharmacology ; Glutathione Peroxidase ; analysis ; L-Lactate Dehydrogenase ; analysis ; Malondialdehyde ; analysis ; PC12 Cells ; Peptide Fragments ; toxicity ; Rats

OBJECTIVETo compare the toxicity of mechanism beta amyloid peptide (Abeta) 25-35 and 31-35 to cultured rat cortical neurons.

METHODSThe primary rat cerebral cortical neurons of rat were cultured 48 hours and randomly divided into control, Abeta25-35 (25 micromol/L)and Abeta31-35 (25 micromol/L) treated groups. After twenty four hours culturing, the cells were collected MTT assay was performed to measure the viability of cultured neurons. The mitochondrial membrane potential was determined to investigate the alteration of mitochondrial structure and function of neurons by laser scanning confocal microscope. The DNA damage of neurons was measured by single cell gel electrophoresis. The expressions of Bcl-2, Bax and p53 gene were measured by reverse transcriptase polymerase chain reaction (RT-PCR). Each experiment was repeated three times.

RESULTSThe absorbance (0.746 +/- 0.071, 0.811 +/- 0.083) and fluorescence intensity (3.050 +/- 0.240, 2.806 +/- 0.203) of neurons in Abeta25-35 and 31-35 treated group were significantly lower (t(A) were 4.023 and 5.401, t(fluorescence intensity) were 9.524 and 7.589 respectively, P < 0.01) than those in control group (1.038 +/- 0.125 and 4.280 +/- 0.358 respectively). The percentage of comet cells (59.0%, 48.5%) and tail length (57.3 +/- 4.7, 54.2 +/- 6.8) microm in Abeta25-35 and 31-35 treated group were significantly higher (chi(2)(comet cell) were 99.397 and 137.071, t(tail length) were 19.058 and 29.173 respectively, P < 0.01) than those in control group (4.5% and (5.2 +/- 1.1) microm respectively). Compared with control group (Bax/Bcl-2 ratio 0.2090 +/- 0.0991, p53/beta-actin ratio 1.6560 +/- 0.0853), the Bax/Bcl-2 ratio (t value were 2.429 and 2.356 respectively, P < 0.05) and expressions of p53 (t value were 2.366 and 2.503 respectively, P < 0.05) gene were significantly increased (P < 0.05) in Abeta25-35 (Bax/Bcl-2 ratio 1.2774 +/- 0.0762, p53/beta-actin ratio 2.0284 +/- 0.2223) and Abeta31-35 (Bax/Bcl-2 ratio 1.0330 +/- 0.0683, p53/beta-actin ratio 1.9505 +/- 0.2725) treated group.

CONCLUSIONSNeurotoxicity-induced by Abeta31-35 in cortical neurons is similar to that induced by Abeta25-35, which is possibly related to its direct neurotoxic and apoptotic effects to neurons.

Amyloid beta-Peptides ; toxicity ; Animals ; Apoptosis ; drug effects ; Cells, Cultured ; Cerebral Cortex ; cytology ; Neurons ; drug effects ; Peptide Fragments ; toxicity ; Rats ; Rats, Wistar

OBJECTIVETo explore the biological activity of recombinant human single-chain antibody against amyloid beta peptide in vitro.

METHODSHuman single-chain antibody against amyloid beta peptide was obtained from recombinant bacteria. The antigen-binding activity of this antibody was measured by enzyme-linked immunosorbent assay (ELISA) and competitive ELISA. Human neuroblastoma SH-SY5Y cells were used as cell models to test the protective role of human single-chain antibody against amyloid beta peptide.

RESULTSRecombinant human single-chain antibody was mainly located in the insoluble inclusion bodies of bacteria. The antibody was dissolved by urea and purified by metal affinity chromatography as active form to bind synthetic amyloid beta peptide 40 or amyloid beta peptide 42. The improvement of the survival rates of human neuroblastoma cells was significantly superior in amyloid peptide 42 plus equimolar antibody group than in amyloid peptide 42 group (P < 0.05), and was significantly superior in the amyloid peptide 40 plus equimolar antibody group than in amyloid peptide 40 group (P < 0.01).

CONCLUSIONThe recombinant human single-chain antibody against beta amyloid peptide 40 from E. coli can partially inhibit the neurotoxicity effect of amyloid beta peptide in vitro.

Amyloid beta-Peptides ; immunology ; metabolism ; toxicity ; Cell Line, Tumor ; Cell Survival ; drug effects ; Humans ; Peptide Fragments ; metabolism ; toxicity ; Protein Binding ; Recombinant Proteins ; pharmacology ; Single-Chain Antibodies ; pharmacology

OBJECTIVETo investigate the effect of berberine on expressions of tumor necrosis factor alpha (TNF-alpha) and receptor type I (TNFR1) in Abeta25-35-induced inflammatory reaction in SH-SYSY cell lines.

METHODThe 5 micromol . L-1 Abeta25-35 was used to treat SH-SY5Y cells for 24 hours, in order to establish the Alzheimer's disease (AD) model. Before modeling, berberine was given for pretreatment for 2 hours. The experiment included the normal control group, the AD model group, and indometacin low dose and high dose groups. Spectrophotometry was adopted to detect the activity of LDH. Meanwhile, the level of TNF-alpha was determined by ELISA, and the expression of TNFR1 genes was detected by RT-PCR.

RESULTCompared with the normal control group, the AD cell model group showed significant increase in LDH, TNF-alpha, and TNFR1 gene and protein expressions in the culture media. After intervention with berberine, the activity of LDH and TNF-alpha reduced in cell supernatant. The intervention with berberine could down-regulate TNFR1 gene and protein expressions, particularly 1, 10 x 10(-6) mol . L-l berberine showed a more notable effect in regulating TNFR1.

CONCLUSIONBerberine has the protective effect in Abeta-induced inflammatory injury in SH-SY5Y cells. Its mechanism may be related to the expression of its anti inflammatory factor TNF-alpha and its type I receptor TNFR1. Specifically, its regulation to TNFR1 shows dose dependence.

Amyloid beta-Peptides ; toxicity ; Berberine ; pharmacology ; Cell Line ; Humans ; Inflammation ; chemically induced ; metabolism ; Peptide Fragments ; toxicity ; Receptors, Interleukin-1 Type I ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo investigate the protective effects of cerebrospinal fluid (CSF)-containing Jiawei Wuzi Yanzong formula (CSF-C) on beta-amyloid protein-induced injury of hippocampal neurons.

METHODSPrimary hippocampal neurons were isolated and cultured for 7 days in vitro. CSF-C was prepared by cerebrospinal fluid extracted from SD rats fed continuously with various components of Jiawei Wuzi Yanzong formula (total formula, total flavonoids or total polysaccharides) respectively. The viability, morphological change, apoptotic rate and apoptosis-related proteins (caspase-3, PARP, Bcl-2, Bcl-XL, JNK1/2 and p38 MAPK) of neurons were detected in different groups: the untreated normal group, the Abeta(25-35)-treated group, and the CSF-C protected groups (co-acted by CSF-C and 20 micromol/L of Abeta(25-35)), respectively.

RESULTSCSF-C showed significant neuro-protective effect, and the protection of CSF-C contained total flavonoids or total polysaccharides was significantly greater than that contained total formula (P < 0.05 or P < 0.01). Moreover, the effects of CSF-C contained various components on apoptosis-related proteins were different.

CONCLUSIONSome flavonoid and polysaccharide components in Jiawei Wuzi Yanzong formula can pass through the blood brain barrier and protect neurons from beta-amyloid protein-induced neuron injury to some extents.

Amyloid beta-Peptides ; toxicity ; Animals ; Drugs, Chinese Herbal ; pharmacology ; Female ; Hippocampus ; pathology ; Male ; Neurons ; pathology ; Neuroprotective Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley

AIMTo observe the relationship between amyloid beta-protein (Abeta) and oxidative stress and the protective role of pituitary adenylate cyclase activating polypeptide (PACAP, PACAP-27) against damage induced by oxidative stress (H2O2) in neurem-2a cells.

METHODSWith cultured neuro-2a cells the cell survival and apoptosis were measured by MTT assay, Hoechest33258 staining, DNA ladder and the percentage of small DNA fragment.

RESULTSConcentration-dependent toxicity was induced with H2O2 treatment for 24 h. The neurotoxicity of H2O2 was increased by about 10 times with cotreatment neurons with amyloid beta-protein fragment 25-35 (Abeta(25-35)). While decrease the percentage of small DNA fragmentation the cell survival was increased with co-treatment with PACAP-27(which were added to the culture everyday). The effect of PACAP was not reversed with antagonist of PACAP receptor, PACAP(6-27).

CONCLUSIONAbeta and H2O2 can promote each other's neurotoxicity. Cultured neurons were protected by PACAP27 from the neurotoxicity of H2O2 but not through the activation of PACAP-27 receptor.

Amyloid beta-Peptides ; toxicity ; Apoptosis ; Cell Survival ; Cells, Cultured ; Humans ; Hydrogen Peroxide ; pharmacology ; Neurons ; cytology ; drug effects ; Oxidative Stress ; Pituitary Adenylate Cyclase-Activating Polypeptide ; pharmacology

MTT analysis and intracellular calcium measurement by using confocal laser scanning microscopy were used to study the possible mechanism of protective effect of pituitary adenylate cyclase activating polypeptide 27 (PACAP27) from beta amyloid protein (Abeta)-induced neurotoxicity. The results showed that treatment with PACAP (less than 0.1 micromol/L) increased the survival and reproductive ability of neuro-2a cells and protected the neuro-2a cells from being injured by Abeta. The protective effect of PACAP27 was reversed by the competitive PACAP receptor antagonist PACAP6-27. An increase in intracellular calcium was observed when the cells were challenged with Abeta and PACAP. But the calcium increase induced by Abeta kept stable for a long time while PACAP caused a transient rise in intracellular calcium. The intracellular calcium increase induced by Abeta was blocked by pretreatment with PACAP for 10 min. It is suggested that the neuroprotective effect of PACAP against neuronal damage induced by Abeta may result from its role in inhibiting the sustained rise in intracellular calcium.
Amyloid beta-Peptides ; antagonists & inhibitors ; toxicity ; Calcium ; metabolism ; Calcium Channels ; metabolism ; Cell Line, Tumor ; Humans ; Neuroblastoma ; pathology ; Neuroprotective Agents ; pharmacology ; Pituitary Adenylate Cyclase-Activating Polypeptide ; pharmacology