Progression Of Alzheimer's Disease Pathology Research Articles

CCR5 deficiency induces astrocyte activation, Aβ deposit and impaired memory function

Activation of astrocytes has been known to be associated with amyloid-beta (Aβ) deposit and production of pro-inflammatory cytokines and chemokines that lead to neuronal cell death in the pathogenesis of Alzheimer disease (AD). In the present study, we investigated whether the absence of CC chemokine receptor 5 (CCR5) results in activation of astrocytes, Aβ deposit and memory dysfunction in CCR5 knock (CCR5 −/−) out mice. We found that long-term and spatial memory functions were impaired in CCR5 −/− mice. There was a significant increased expression of glial fibrillary acidic protein (GFAP) in the brain of CCR5 −/− mice as compared with that of wild type of CCR5 (CCR5 +/+) mice. The expression of CCR5 was observed in CCR5 +/+ astrocytes, but was reduced in the CCR5 −/− astrocytes even though the expression of GFAP was much higher. Paralleling with the activation of astorcytes, the Aβ 1−42 level was higher in the brains of CCR5 −/− mice than that of CCR5 +/+ mice. Expression of β-secretase (BACE1) and its product C99 was significantly elevated in CCR5 −/− mice. The activation of CC chemokine receptor 2 (CCR2) causes activation of astrocytes that leads to Aβ deposit and memory dysfunction in CCR5 −/− mice. In CCR5 −/− mice, CCR2 expression was high and co-localized with GFAP. These findings suggest that the absence of CCR5 increases expression of CCR2, which leads to the activation of astrocytes causing Aβ deposit, and thereby impairs memory function. These results suggest that CCR5 may be a critical suppressor of the development and progression of AD pathology.

Microglial Dysfunction and Defective β-Amyloid Clearance Pathways in Aging Alzheimer's Disease Mice

Early microglial accumulation in Alzheimer's disease (AD) delays disease progression by promoting clearance of beta-amyloid (Abeta) before formation of senile plaques. However, persistent Abeta accumulation despite increasing microglial numbers suggests that the ability of microglia to clear Abeta may decrease with age and progression of AD pathology. To determine the effects of aging and Abeta deposition on microglial ability to clear Abeta, we used quantitative PCR to analyze gene expression in freshly isolated adult microglia from 1.5-, 3-, 8-, and 14-month-old transgenic PS1-APP mice, an established mouse model of AD, and from their nontransgenic littermates. We found that microglia from old PS1-APP mice, but not from younger mice, have a twofold to fivefold decrease in expression of the Abeta-binding scavenger receptors scavenger receptor A (SRA), CD36, and RAGE (receptor for advanced-glycosylation endproducts), and the Abeta-degrading enzymes insulysin, neprilysin, and MMP9, compared with their littermate controls. In contrast, PS1-APP microglia had a 2.5-fold increase in the proinflammatory cytokines IL-1beta (interleukin-1beta) and tumor necrosis factor alpha (TNFalpha), suggesting that there is an inverse correlation between cytokine production and Abeta clearance. In support of this possibility, we found that incubation of cultured N9 mouse microglia with TNFalpha decreased the expression of SRA and CD36 and reduced Abeta uptake. Our data indicate that, although early microglial recruitment promotes Abeta clearance and is neuroprotective in AD, as disease progresses, proinflammatory cytokines produced in response to Abeta deposition downregulate genes involved in Abeta clearance and promote Abeta accumulation, therefore contributing to neurodegeneration. Antiinflammatory therapy for AD should take this dichotomous microglial role into consideration.

P-076: Estrogen receptor-selective ligands regulate ApoE expression and neurogenesis in 3xTgAD mouse hippocampus

The single amino acid substitutions of apolipoprotein E (ApoE) drive late-onset Alzheimer's disease (AD) in opposite directions. ApoE2 and ApoE3 are protectors from AD progression, but ApoE4 is a major risk factor for AD progression. Population-based investigations indicated that the ApoE4 allele is a major risk factor for ∼50% of AD cases in the United States. Recent data indicated that ectopic expression of ApoE4 increased Amyloid β (Aβ) deposition and burden, while expression of ApoE2/3 markedly reduced the AD pathology progression in DPAPP mouse hippocampus by intracerebral administration of lentiviral vectors expressing the three common human ApoE isoforms. The above data strongly support the idea that regulation of the levels of ApoE in human subjects is a powerful AD-prevention stratagem. We recently demonstrated that ApoE expression could be differentially regulated by estrogen receptor selective ligands in rat hippocampal neurons in vitro and in vivo. This study investigated the impact of ER-selective ligands on ApoE expression and neurogenesis in 3xTgAD mouse SGZ. Methods: ApoE expression, neurogenesis and AD progression in LaFerla 3xTgAD and non-Tg mouse were measured by Western blot, IHC and unbiased stereology. 1) ER-selective ligands differentially regulated ApoE expression in mouse and rat hippocampus; 2) 17β-estradiol reduced Aβ burden in 3xTgAD mouse hippocampus; 3) 17β-estradiol and propyl pyrazole triol (PPT, an ERα-selective ligand which increases ApoE expression) reversed the neurogenic deficits, while diarylpropionitrile (DPN, an ERβ ligand which reduces ApoE expression) had no effect on neurogenesis in the SGZ of 3xTgAD mouse. This study suggests, when ERα- and ERβ-selective ligands are applied to ApoE2/3 and ApoE4 allelic carriers, respectively, that the ERα-specific ligand will reduce AD pathology and enhance neurogenesis in ApoE3/AD carriers, while the ERβ-specific ligand will reduce AD pathology and increase neurogenesis in ApoE4/AD carriers.

Human Cytokine Response toex vivoAmyloid-β Stimulation is Mediated by Genetic Factors

AbstractThrough its ability to induce the enhanced release and production of cytokines, amyloid-β is responsible for the chronic inflammatory response that contributes to Alzheimer's disease (AD). Determining whether the response of monocytes to amyloid-β stimulation is under genetic control may help understand the basis of why some people are more prone to develop neuronal degeneration than others. In the current study we investigated the heritability of the cytokine (IL-10, IL-6, IL-1β, IL-1ra, TNF-[.alpha]) production capacity upon ex vivo stimulation with amyloid-β in whole blood samples of 222 twins and 85 singleton siblings from 139 extended twin families. It was found that individual differences in amyloid-β-induced cytokine production capacity are to a large extent of genetic origin, with heritability estimates ranging from 55% (IL-1β) to 68% (IL-6). We conclude that genes influencing amyloid-β-induced cytokine response may provide clues to the progression of AD pathology.

Human Cytokine Response to <I>ex vivo</I> Amyloid-β Stimulation is Mediated by Genetic Factors

Through its ability to induce the enhanced release and production of cytokines, amyloid-beta is responsible for the chronic inflammatory response that contributes to Alzheimer's disease (AD). Determining whether the response of monocytes to amyloid-beta stimulation is under genetic control may help understand the basis of why some people are more prone to develop neuronal degeneration than others. In the current study we investigated the heritability of the cytokine (IL-10, IL-6, IL-1beta, IL-1ra, TNF-alpha) production capacity upon ex vivo stimulation with amyloid-beta in whole blood samples of 222 twins and 85 singleton siblings from 139 extended twin families. It was found that individual differences in amyloid-beta induced cytokine production capacity are to a large extent of genetic origin, with heritability estimates ranging from 55% (IL-1beta) to 68% (IL-6). We conclude that genes influencing amyloid-beta-induced cytokine response may provide clues to the progression of AD pathology.

Exclusive association and simultaneous appearance of congophilic plaques and AT8-positive dystrophic neurites in Tg2576 mice suggest a mechanism of senile plaque formation and progression of neuritic dystrophy in Alzheimer's disease.

Progression of neuritic dystrophy is a histological hallmark of Alzheimer's disease (AD) in addition to amyloid deposition and neurofibrillary tangle formation. Dystrophic neurites (DNs) are abnormal neurites, and are closely associated with amyloid deposits. To clarify the process of DN formation, we immunohistochemically investigated phosphorylated tau (AT8 and Ser396)-positive DNs and plaques in Tg2576 mice overexpressing human beta-amyloid precursor protein (APP) with the Swedish type mutation (K670N/M671L). AT8-positive DNs were exclusively associated with the Congo red-positive plaques examined, and all Abeta(1-40)-positive plaques appeared to be associated with AT8-positive DNs, whereas there were no AT8-positive DNs with Abeta(1-42)-positive/Abeta(1-40)-negative plaques. Since we have previously shown that Abeta(1-42)-positive plaque precede Abeta(1-40) deposition, the appearance of congophilic structures is also late. Quantitative analyses were performed on AT8-positive DNs that were associated with congophilic plaques in the cerebral cortex and hippocampus (more than 1,000 plaques). The number of congophilic plaques increased dramatically with age. The area of DNs in the cerebral cortex and hippocampus increased 120- and 60-fold from 11-13 to 20.5 months of age, respectively. Interestingly, the mean ratio of DN area to congophilic plaque area in every plaque was unchanged, approximately 10%, through the ages examined. The mean plaque size was stable with age in both the cortex and hippocampus. These data suggest that the formation of AT8-positive DNs is simultaneous with Congo red-positive plaque development, and that the event may be closely related in the pathological progression of AD.

Early Abeta accumulation and progressive synaptic loss, gliosis, and tangle formation in AD brain.

Pathologic changes in the Alzheimer disease (AD) brain occur in a hierarchical neuroanatomical pattern affecting cortical, subcortical, and limbic regions. To define the time course of pathologic and biochemical changes-amyloid deposition, amyloid beta-peptide (Abeta) accumulation, neurofibrillary tangle (NFT) formation, synaptic loss, and gliosis-within the temporal association cortex of AD cases of varying disease duration, relative to control brains. Stereologic assessments of amyloid burden and tangle density as well as ELISA-based measurements of Abeta, synaptophysin, and glial fibrillary acidic protein (GFAP) were performed in the superior temporal sulcus from a cohort of 83 AD and 26 nondemented control brains. Relative to control cases, AD brains were characterized by accumulation of NFT and amyloid plaques, increase of tris- and formic acid-extractable Abeta species, reduced levels of synaptophysin, and elevated levels of GFAP. In AD cases, the duration of dementia correlated with the degree of tangle formation, gliosis, and synaptic loss but not with any Abeta measures. Accumulation of Abeta, measured both neuropathologically and biochemically, was markedly increased in AD brains independent of disease duration, even in cases of short duration. These data support distinct processes in the initiation and progression of AD pathology within the temporal cortex: Deposition of Abeta reaches a "ceiling" early in the disease process, whereas NFT formation, synaptic loss, and gliosis continue throughout the course of the illness.

17β-Estradiol Reduces Plasma Aβ40 for HRT-Naïve Postmenopausal Women With Alzheimer Disease: A Preliminary Study

OBJECTIVE One mechanism to support the potentially beneficial effects of estrogen in the brain for postmenopausal women potentially involves the hormone's ability to favorably alter the processing of amyloid-precursor protein (APP), believed to play an important role in the pathobiology of Alzheimer disease (AD). The authors evaluated the effects of estrogen administration on plasma concentration of one by-product of APP processing, Aβ40, for postmenopausal women with AD. METHODS In a placebo-controlled, double blind, parallel-group design study, 20 women were randomized to receive either 0.10 mg/day of transdermal 17β-estradiol or a placebo for 8 weeks and were retrospectively evaluated as to whether basal levels of Aβ40 were affected by pre-study use of hormone replacement therapy (HRT). Blood samples were collected and cognitive tests were administered at baseline; at Weeks 3, 5, and 8 during treatment; and again 8 weeks after treatment termination. RESULTS For the group as a whole, plasma Aβ40 was not reliably reduced in response to short-term estradiol administration. For HRT-naïve subjects, baseline Aβ40 concentrations were higher than those of previous HRT users, and controlled estradiol administration significantly reduced plasma Aβ40 by the end of the 8-week treatment period. CONCLUSIONS These results provide preliminary clinical evidence to support an effect of estradiol on Aβ-processing for AD women who are HRT-naïve. This finding suggests that the hormone may serve as an Aβ-lowering agent for HRT-naïve AD women, which may, in turn, have ultimate ramifications for the progression of AD pathology. One mechanism to support the potentially beneficial effects of estrogen in the brain for postmenopausal women potentially involves the hormone's ability to favorably alter the processing of amyloid-precursor protein (APP), believed to play an important role in the pathobiology of Alzheimer disease (AD). The authors evaluated the effects of estrogen administration on plasma concentration of one by-product of APP processing, Aβ40, for postmenopausal women with AD. In a placebo-controlled, double blind, parallel-group design study, 20 women were randomized to receive either 0.10 mg/day of transdermal 17β-estradiol or a placebo for 8 weeks and were retrospectively evaluated as to whether basal levels of Aβ40 were affected by pre-study use of hormone replacement therapy (HRT). Blood samples were collected and cognitive tests were administered at baseline; at Weeks 3, 5, and 8 during treatment; and again 8 weeks after treatment termination. For the group as a whole, plasma Aβ40 was not reliably reduced in response to short-term estradiol administration. For HRT-naïve subjects, baseline Aβ40 concentrations were higher than those of previous HRT users, and controlled estradiol administration significantly reduced plasma Aβ40 by the end of the 8-week treatment period. These results provide preliminary clinical evidence to support an effect of estradiol on Aβ-processing for AD women who are HRT-naïve. This finding suggests that the hormone may serve as an Aβ-lowering agent for HRT-naïve AD women, which may, in turn, have ultimate ramifications for the progression of AD pathology.

Function of beta-amyloid in cholesterol transport: a lead to neurotoxicity.

Amyloid beta-peptide (Abeta), Abeta precursor protein (APP), apolipoprotein E (apoE), and elevated cholesterol levels have been linked to Alzheimer's disease (AD) pathology. High cholesterol levels increase APP and apoE expression in human NT2 neuron progenitor cells. A cholesterol-rich environment also induces processing of APP, leading to the formation of Abeta and Abeta peptide fragments. Using a novel method, we determined that 1) cholesterol binds to Abeta at alpha-secretase cleavage site; 2) Abeta17-40 rather than Abeta1-40 prevents cholesterol from binding to apoE; 3) Abeta1-40 inhibits cholesterol from binding to low-density lipoprotein (LDL), leading to decrease cholesterol influx and intracellular cholesterol levels; 4) the binding of cholesterol to apoE or LDL was abolished completely in presence of Abeta1-42. Increased extracellular free cholesterol levels are toxic to neurons; this toxicity is prevented by specific lipoproteins, such as high-density lipoproteins, which maintain their ability to bind cholesterol in the presence of Abeta. We propose that one of the physiological functions of Abeta and APP is to control cholesterol transport. AD is associated with increased Abeta production. High cholesterol levels also lead to overproduction of Abeta. Abeta blocks cholesterol trafficking and changes cholesterol homeostasis leading to neurodegeneration and the onset and/or progression of AD pathology.

Novel excitatory actions of galanin on rat cholinergic basal forebrain neurons: implications for its role in Alzheimer's disease.

Galanin, a 29-amino-acid neuropeptide, is generally viewed as an inhibitory neuromodulator in a variety of central systems. Galanin expression is upregulated in the cholinergic basal forebrain nuclei in Alzheimer's disease (AD) and is postulated to play an important role in memory and cognitive function. In this study, application of galanin to acutely dissociated rat neurons from the basal forebrain nucleus diagonal band of Broca (DBB), caused a decrease in whole cell voltage-activated currents in a majority of cells. Galanin reduces a suite of potassium currents, including calcium-activated potassium (I(C)), the delayed rectifier (I(K)), and transient outward potassium (I(A)) conductances, but not calcium or sodium currents. Under current-clamp conditions, application of galanin evoked an increase in excitability and a loss of accommodation in cholinergic DBB neurons. Using single-cell RT-PCR technique, we determined that galanin actions were specific to cholinergic, but not GABAergic DBB neurons The notion that galanin plays a deleterious role in AD is based, in part, on galanin hyperinnervation of cholinergic cells in the basal forebrain of AD patients, its ability to depress acetylcholine release and its inhibitory actions at other CNS sites. However, our results suggest that by virtue of its excitatory actions on cholinergic neurons, galanin may in fact play a compensatory role by augmenting the release of acetylcholine from remaining cholinergic basal forebrain neurons. This action might serve to delay the progression of AD pathology linked to a reduction in central cholinergic tone.

Receptor-G-protein signalling in Alzheimer's disease.

Based on radioligand binding studies, it has long been assumed that the neurochemical pathology of Alzheimer's disease (AD) does not involve widespread changes in post-synaptic neurotransmitter function. However, more recent studies suggest that receptor function in AD may be compromised due to disrupted post-receptor signal transduction, in particular that mediated by the G-protein regulated phosphoinositide hydrolysis and adenylate cyclase (AC) pathways. The phosphoinositide hydrolysis pathway has been shown to be altered at a number of levels in AD post-mortem brains, including impaired agonist and G-protein regulation of phospholipase C, decreased protein kinase C (PKC) levels and activity, and a reduced number of receptor sites for the second messenger, Ins(1,4,5)P3. Of these, loss of Ins(1,4,5)P3 receptors and PKC in the entorhinal cortex and hippocampus correlates with AD-related neurofibrillary changes, as staged according to Braak's protocol. Disregulation of the phosphoinositide hydrolysis pathway may therefore have consequences for the progression of AD pathology. In contrast to the extensive pattern of disruption seen with the phosphoinositide hydrolysis pathway, changes to AC signalling in AD appear more circumscribed. Disruptions include a lesion at the level of Gs-protein stimulation of AC and, at least in the hippocampus, reduced enzyme activities in response to forskolin stimulation. Of these, the latter change has been shown to precede neurofibrillary changes. Apart from a loss of calcium/calmodulin sensitive AC isoforms, other components of this signalling pathway, including G-protein levels, Gi-protein mediated inhibition and protein kinase A levels and activity, remain relatively preserved in the disorder.

Receptor – G-protein signalling in Alzheimer's disease

Based on radioligand binding studies, it has long been assumed that the neurochemical pathology of Alzheimer's disease (AD) does not involve widespread changes in post-synaptic neurotransmitter function. However, more recent studies suggest that receptor function in AD may be compromised due to disrupted post-receptor signal transduction, in particular that mediated by the G-protein regulated phosphoinositide hydrolysis and adenylate cyclase (AC) pathways. The phosphoinositide hydrolysis pathway has been shown to be altered at a number of levels in AD post-mortem brains, including impaired agonist and G-protein regulation of phospholipase C, decreased protein kinase C (PKC) levels and activity, and a reduced number of receptor sites for the second messenger, Ins(1,4,5)P3. Of these, loss of Ins(1,4,5)P3 receptors and PKC in the entorhinal cortex and hippocampus correlates with AD-related neurofibrillary changes, as staged according to Braak's protocol. Disregulation of the phosphoinositide hydrolysis pathway may therefore have consequences for the progression of AD pathology. In contrast to the extensive pattern of disruption seen with the phosphoinositide hydrolysis pathway, changes to AC signalling in AD appear more circumscribed. Disruptions include a lesion at the level of Gs-protein stimulation of AC and, at least in the hippocampus, reduced enzyme activities in response to forskolin stimulation. Of these, the latter change has been shown to precede neurofibrillary changes. Apart from a loss of calcium/calmodulin sensitive AC isoforms, other components of this signalling pathway, including G-protein levels, Gi-protein mediated inhibition and protein kinase A levels and activity, remain relatively preserved in the disorder.

Quantitative autoradiography of [ [formula omitted]]forskolin binding sites in post-mortem brain staged for Alzheimer's disease neurofibrillary changes and amyloid deposits

Adenylyl cyclase (AC) signal transduction has been shown to be affected in Alzheimer's disease (AD). Deficits have been described in different components of the system, from the receptor to the effector level. [ 3 H ]forskolin is a diterpene that binds with high affinity to AC. In the present report, we used autoradiography to study [ 3 H ]forskolin binding to sections of entorhinal cortex and hippocampus from 23 cases staged for AD pathology according to Braak and Braak [Acta Neuropathol. 82 (1991) 239–259]. This protocol defines six stages according to neurofibrillary changes, which start in the entorhinal region (stages I–II), spread to the hippocampus (stages III–IV) and finally to the isocortical areas (stages V–VI). The amyloid classification includes three stages in which the basal isocortex is first affected (stage A), followed by other isocortical association areas (stage B) and finally the primary isocortical areas (stage C). We also studied the effects of the GTP-analogue Gpp[NH]p on binding, in order to detect changes in G-protein–AC coupling. We used two different concentrations of Gpp[NH]p, that were previously reported to inhibit and stimulate [ 3 H ]forskolin binding via G i and G s, respectively. Results showed that [ 3 H ]forskolin binding declined significantly with staging for neurofibrillary changes only in the entorhinal region ( P<0.05, ANOVA). In addition, the decrease in [ 3 H ]forskolin binding observed in the presence of 1 μM Gpp[NH]p diminished significantly with staging in the entorhinal region ( P<0.05, ANOVA). No significant changes were seen with amyloid staging, with the exception of the CA1 subfield of the hippocampus, where [ 3 H ]forskolin binding in the absence of Gpp[NH]p was significantly decreased at stage B compared with all other stages ( P<0.05, ANOVA). In conclusion, our results showed a very limited decrease in [ 3 H ]forskolin binding with the progression of AD pathology, suggesting that the AC levels may be largely preserved in the disease. The specific change in the effect of a low concentration of Gpp[NH]p on the binding could indicate the loss of Ca 2+/calmodulin-sensitive AC isoforms in AD.

Progression of Regional Neuropathology in Alzheimer Disease and Normal Elderly: Findings from the Nun Study

Although diffuse plaques in the neocortex may represent an early stage in the evolution of neuritic plaques, plaques in the striatum and cerebellum retain their predominantly diffuse nature in Alzheimer disease (AD), regardless of disease duration. We had the opportunity to explore the progression of these regional features by using autopsy brain specimens from 15 cognitively normal and five AD subjects, all Catholic sisters enrolled in the Nun Study, a longitudinal study on aging and AD. Neuropathologic changes were assessed in the temporal cortex, striatum, and cerebellum without knowledge of clinical status. We found diffuse plaques in the striatum in six (40%) and cerebellar plaques in none of the brains from the non-demented subjects. Striatal plaques were present in all five and cerebellar plaques in four of the five AD cases. In the 20 cases overall, the presence of striatal plaques generally paralleled the occurrence of neuritic plaques in neocortex and correlated with lower scores on several neuropsychologic tests assessing memory. Our findings suggest that striatal diffuse plaques occur relatively early in the progression of AD pathology and coincide with neocortical pathology and cognitive changes. Thus, it is unlikely that temporal factors alone account for regional differences in progression of AD neuropathology.

Astrocyte-apolipoprotein E associations in senile plaques in Alzheimer disease and vascular lesions: a regional immunohistochemical study.

While apolipoprotein E (ApoE) and beta-amyloid (A beta) co-localize in senile plaques in cortex and cerebellum in Alzheimer disease (AD), the A beta-positive, predominantly diffuse plaques in the striatum do not exhibit ApoE immunoreactivity regardless of disease duration. As astrocytes are a major source of ApoE in the brain, we investigated potential regional differences in the ability of astrocytes to produce ApoE that might affect A beta processing and the progression of AD pathology. Using antibodies to ApoE, glial fibrillary acidic protein (GFAP), and A beta, we compared the pattern of immunoreactivity in senile plaques in AD autopsy tissue with that of reactive astrocytes surrounding subacute and old infarcts in both AD and non-AD cases. We found GFAP and ApoE immunoreactivity, but not A beta label in cell bodies and processes of reactive astrocytes in zones of infarction within cerebral cortex, striatum, and cerebellum, indicating that astrocytes are capable of upregulating ApoE within these 3 regions. In contrast, while astrocytes surrounded many neocortical neuritic plaques in AD, these GFAP-positive cells failed to label with ApoE; instead. ApoE label within plaques paralleled that of A beta. As expected, neither the ApoE-negative diffuse plaques of the striatum nor the ApoE-immunopositive diffuse plaques of the cerebellum were clearly associated with GFAP-immunoreactive astrocytes. The apparent absence of ApoE label in cortical plaque-associated astrocytes may signify a regulatory mechanism affecting ApoE synthesis and secretion, influenced by binding of ApoE to fibrillar amyloid within the plaques, neuritic changes, or other factors.

Evaluation of DCL mercury-free chloride reagent of hitachi analyzers

Alzheimer's disease (AD) is characterized by the accumulation of the β-amyloid peptide (Aβ), which is generated from sequential cleavages of the amyloid precursor protein (APP) by β-secretase (BACE1) and γ-secretase. Fatty acid alterations in AD brains have recently received substantial attention. Because increased very long chain fatty acid (VLCFA) levels in AD brains imply that peroxisomal β-oxidation dysfunction may be associated with AD pathogenesis, we investigated the effects of impaired peroxisomal β-oxidation on Aβ generation in vivo and in vitro using thioridazine, a selective peroxisomal β-oxidation inhibitor. Under the experimental conditions, thioridazine caused VLCFA accumulation and increases in Aβ40 content, APP immunoreactivity and APP751+770 mRNA expressions in the rat cerebral cortex. A correlation analysis showed that the Aβ40 levels were positively correlated with the cortex C24:0 and C26:0 levels. Additionally, the primary cerebral cortex neurons treated with this compound showed increases in APP751+770 mRNA, APP protein, BACE1 mRNA and protein, and secreted Aβ40 levels. This work supports an emerging viewpoint that impaired peroxisomal function may play an important role in the progression of AD pathology.