FK506-Binding Protein 12.6/1b, a Negative Regulator of [Ca2+], Rescues Memory and Restores Genomic Regulation in the Hippocampus of Aging Rats.

Hippocampal overexpression of FK506-binding protein 12.6/1b (FKBP1b), a negative regulator of ryanodine receptor Ca2+ release, reverses aging-induced memory impairment and neuronal Ca2+ dysregulation. Here, we tested the hypothesis that FKBP1b also can protect downstream transcriptional networks from aging-induced dysregulation. We gave hippocampal microinjections of FKBP1b-expressing viral vector to male rats at either 13 months of age (long-term, LT) or 19 months of age (short-term, ST) and tested memory performance in the Morris water maze at 21 months of age. Aged rats treated ST or LT with FKBP1b substantially outperformed age-matched vector controls and performed similarly to each other and young controls (YCs). Transcriptional profiling in the same animals identified 2342 genes with hippocampal expression that was upregulated/downregulated in aged controls (ACs) compared with YCs (the aging effect). Of these aging-dependent genes, 876 (37%) also showed altered expression in aged FKBP1b-treated rats compared with ACs, with FKBP1b restoring expression of essentially all such genes (872/876, 99.5%) in the direction opposite the aging effect and closer to levels in YCs. This inverse relationship between the aging and FKBP1b effects suggests that the aging effects arise from FKBP1b deficiency. Functional category analysis revealed that genes downregulated with aging and restored by FKBP1b were associated predominantly with diverse brain structure categories, including cytoskeleton, membrane channels, and extracellular region. Conversely, genes upregulated with aging but not restored by FKBP1b associated primarily with glial-neuroinflammatory, ribosomal, and lysosomal categories. Immunohistochemistry confirmed aging-induced rarefaction and FKBP1b-mediated restoration of neuronal microtubular structure. Therefore, a previously unrecognized genomic network modulating diverse brain structural processes is dysregulated by aging and restored by FKBP1b overexpression.SIGNIFICANCE STATEMENT Previously, we found that hippocampal overexpression of FK506-binding protein 12.6/1b (FKBP1b), a negative regulator of intracellular Ca2+ responses, reverses both aging-related Ca2+ dysregulation and cognitive impairment. Here, we tested whether hippocampal FKBP1b overexpression also counteracts aging changes in gene transcriptional networks. In addition to reducing memory deficits in aged rats, FKBP1b selectively counteracted aging-induced expression changes in 37% of aging-dependent genes, with cytoskeletal and extracellular structure categories highly associated with the FKBP1b-rescued genes. Our results indicate that, in parallel with cognitive processes, a novel transcriptional network coordinating brain structural organization is dysregulated with aging and restored by FKBP1b.

Allelic series of Huntington's disease knock-in mice reveals expression discorrelates.

Identifying molecular drivers of pathology provides potential therapeutic targets. Differentiating between drivers and coincidental molecular alterations presents a major challenge. Variation unrelated to pathology further complicates transcriptomic, proteomic and metabolomic studies which measure large numbers of individual molecules. To overcome these challenges towards the goal of determining drivers of Huntington's disease (HD), we generated an allelic series of HD knock-in mice with graded levels of phenotypic severity for comparison with molecular alterations. RNA-sequencing analysis of this series reveals high numbers of transcripts with level alterations that do not correlate with phenotypic severity. These discorrelated molecular changes are unlikely to be drivers of pathology allowing an exclusion-based strategy to provide a short list of driver candidates. Further analysis of the data shows that a majority of transcript level changes in HD knock-in mice involve alteration of the rate of mRNA processing and/or degradation rather than solely being due to alteration of transcription rate. The overall strategy described can be applied to assess the influence of any molecular change on pathology for diseases where different mutations cause graded phenotypic severity.

Blood-brain barrier penetration of an Aß-targeted, arginine-rich, d-enantiomeric peptide.

The application of small peptides targeting amyloid beta (Aß) is one of many drug development strategies for the treatment of Alzheimer's disease (AD). We have previously identified several peptides consisting solely of D-enantiomeric amino acid residues obtained from mirror-image phage display selection, which bind to Aß in different assembly states and eliminate toxic Aß aggregates. Some of these D-peptides show both diagnostic and therapeutic potential in vitro and in vivo. Here we have analysed the similarity of the arginine-rich D-peptide D3 to the arginine-rich motif (ARM) of the human immunodeficiency virus type 1 transactivator of transcription (HIV-Tat) protein, and examined its in vivo blood-brain barrier (BBB) permeability using wild type mice and transgenic mouse models of Alzheimer's disease. We are able to demonstrate that D3 rapidly enters the brain where it can be found associated with amyloid plaques suggesting a direct penetration of BBB.

Altered phosphorylation, electrophysiology, and behavior on attenuation of PDE4B action in hippocampus.

BACKGROUND: PDE4 cyclic nucleotide phosphodiesterases regulate 3', 5' cAMP abundance in the CNS and thereby regulate PKA activity and phosphorylation of CREB, which has been implicated in learning and memory, depression and other functions. The PDE4 isoform PDE4B1 also interacts with the DISC1 protein, implicated in neural development and behavioral disorders. The cellular functions of PDE4B1 have been investigated extensively, but its function(s) in the intact organism remained unexplored. RESULTS: To specifically disrupt PDE4B1, we developed mice that express a PDE4B1-D564A transgene in the hippocampus and forebrain. The transgenic mice showed enhanced phosphorylation of CREB and ERK1/2 in hippocampus. Hippocampal neurogenesis was increased in the transgenic mice. Hippocampal electrophysiological studies showed increased baseline synaptic transmission and enhanced LTP in male transgenic mice. Behaviorally, male transgenic mice showed increased activity in prolonged open field testing, but neither male nor female transgenic mice showed detectable anxiety-like behavior or antidepressant effects in the elevated plus-maze, tail-suspension or forced-swim tests. Neither sex showed any significant differences in associative fear conditioning or showed any demonstrable abnormalities in pre-pulse inhibition. CONCLUSIONS: These data support the use of an isoform-selective approach to the study of PDE4B1 function in the CNS and suggest a probable role of PDE4B1 in synaptic plasticity and behavior. They also provide additional rationale and a refined approach to the development of small-molecule PDE4B1-selective inhibitors, which have potential functions in disorders of cognition, memory, mood and affect.

Vitamin A and retinoic acid combination attenuates neonatal hyperoxia-induced neurobehavioral impairment in adult mice.

Preterm infants exposed to supra-physiological levels of oxygen often have poor executive and memory function associated with reductions in hippocampal volume later in life. We recently showed that adult mice exposed to neonatal hyperoxia have deficits in spatial navigation and increased exploratory behavior associated with hippocampal shrinkage. Retinoids attenuate hyperoxia-induced lung injury in animal models and reduce neonatal chronic lung disease in preterm infants. We hypothesized that retinoid (combination of Vitamin A+Retinoic Acid [VARA]) administration in mice during neonatal hyperoxia would attenuate oxygen-induced cognitive impairment when assessed in adult life. C57BL/6 mouse pups were exposed to hyperoxia (85% oxygen) or air (21% oxygen), in combination with VARA or canola oil (Vehicle) from postnatal day 2 to 14 and then returned to air. Neurobehavioral (Morris water maze, open field and zero maze tests), structural assessments (MRI and histology), and hippocampal protein measurements were performed. Neonatal hyperoxia resulted in spatial navigation deficits and increased exploratory behavior and accompanied by hippocampal shrinkage in adults, all of which were attenuated by VARA administration. During hyperoxia, VARA increased hippocampal phosphorylated and total mammalian target of rapamycin, and synaptophysin levels to a greater extent in hyperoxia compared to normoxia. In conclusion, VARA attenuated neonatal hyperoxia-induced neurobehavioral impairment and associated reductions in hippocampal volume in adult mice, possibly by increasing mTOR signaling and synaptic density. These novel data suggest that retinoids may be neuroprotective in extremely preterm infants at high risk of impairment, and may potentially be effective in other models of oxidant stress as well.

Reversal of Aging-Related Neuronal Ca2+ Dysregulation and Cognitive Impairment by Delivery of a Transgene Encoding FK506-Binding Protein 12.6/1b to the Hippocampus.

Brain Ca2+ regulatory processes are altered during aging, disrupting neuronal, and cognitive functions. In hippocampal pyramidal neurons, the Ca2+ -dependent slow afterhyperpolarization (sAHP) exhibits an increase with aging, which correlates with memory impairment. The increased sAHP results from elevated L-type Ca2+ channel activity and ryanodine receptor (RyR)-mediated Ca2+ release, but underlying molecular mechanisms are poorly understood. Previously, we found that expression of the gene encoding FK506-binding protein 12.6/1b (FKBP1b), a small immunophilin that stabilizes RyR-mediated Ca2+ release in cardiomyocytes, declines in hippocampus of aged rats and Alzheimer's disease subjects. Additionally, knockdown/disruption of hippocampal FKBP1b in young rats augments neuronal Ca2+ responses. Here, we test the hypothesis that declining FKBP1b underlies aging-related hippocampal Ca2+ dysregulation. Using microinjection of adeno-associated viral vector bearing a transgene encoding FKBP1b into the hippocampus of aged male rats, we assessed the critical prediction that overexpressing FKBP1b should reverse Ca2+ -mediated manifestations of brain aging. Immunohistochemistry and qRT-PCR confirmed hippocampal FKBP1b overexpression 4-6 weeks after injection. Compared to aged vector controls, aged rats overexpressing FKBP1b showed dramatic enhancement of spatial memory, which correlated with marked reduction of sAHP magnitude. Furthermore, simultaneous electrophysiological recording and Ca2+ imaging in hippocampal neurons revealed that the sAHP reduction was associated with a decrease in parallel RyR-mediated Ca2+ transients. Thus, hippocampal FKBP1b overexpression reversed key aspects of Ca2+ dysregulation and cognitive impairment in aging rats, supporting the novel hypothesis that declining FKBP1b is a molecular mechanism underlying aging-related Ca2+ dysregulation and unhealthy brain aging and pointing to FKBP1b as a potential therapeutic target. SIGNIFICANCE STATEMENT: This paper reports critical tests of a novel hypothesis that proposes a molecular mechanism of unhealthy brain aging and possibly, Alzheimer's disease. For more than 30 years, evidence has been accumulating that brain aging is associated with dysregulation of calcium in neurons. Recently, we found that FK506-binding protein 12.6/1b (FKBP1b), a small protein that regulates calcium, declines with aging in the hippocampus, a brain region important for memory. Here we used gene therapy approaches and found that raising FKBP1b reversed calcium dysregulation and memory impairment in aging rats, allowing them to perform a memory task as well as young rats. These studies identify a potential molecular mechanism of brain aging and may also have implications for treatment of Alzheimer's disease.

Observational research rigour alone does not justify causal inference.

BACKGROUND: Differing opinions exist on whether associations obtained in observational studies can be reliable indicators of a causal effect if the observational study is sufficiently well controlled and executed. MATERIALS AND METHODS: To test this, we conducted two animal observational studies that were rigorously controlled and executed beyond what is achieved in studies of humans. In study 1, we randomized 332 genetically identical C57BL/6J mice into three diet groups with differing food energy allotments and recorded individual self-selected daily energy intake and lifespan. In study 2, 60 male mice (CD1) were paired and divided into two groups for a 2-week feeding regimen. We evaluated the association between weight gain and food consumption. Within each pair, one animal was randomly assigned to an S group in which the animals had free access to food. The second paired animal (R group) was provided exactly the same diet that their S partner ate the day before. RESULTS: In study 1, across all three groups, we found a significant negative effect of energy intake on lifespan. However, we found a positive association between food intake and lifespan among the ad libitum feeding group: 29·99 (95% CI: 8·2-51·7) days per daily kcal. In study 2, we found a significant (P = 0·003) group (randomized vs. self-selected)-by-food consumption interaction effect on weight gain. CONCLUSION: At least in nutrition research, associations derived from observational studies may not be reliable indicators of causal effects, even with the most rigorous study designs achievable.

Memory-enhancing and brain protein expression-stimulating effects of novel calcium antagonist in Alzheimer's disease transgenic female mice.

The prevalence of Alzheimer's disease (AD) is higher in females than in males, and causes more severe cognitive, memory and behavioral impairments. Previously, in male transgenic (Tg) APPSweDI mice, we reported that the novel lipophilic 1,4-dihydropyridine (DHP) derivative AP-12 crossed the blood-brain barrier, blocked neuronal and vascular calcium channels, changed brain protein expression and improved behavior. In this study, we used female Tg APPSweDI mice to assess the effects of AP-12 on behavior, and brain protein expression, with a particular focus on those of the GABAergic system. The results showed that in female Tg mice, similar to male Tg mice, AP-12 improved spatial learning/memory performance in the water maze test and demonstrated anxiolytic effect in the elevated zero maze (after single administration of AP-12) and elevated plus maze (after chronic injections of AP-12). In addition, we demonstrated upregulated expression of glutamate decarboxylase 67 (GAD67) and vesicular GABA transporter (VGAT) in the cingulate cortex and hippocampus, pointing to the role of the GABAergic system as one of the neural networks dysregulated in AD. In both female and male mice, AP-12 did not change the expression of hippocampal Homer-1, a protein which is involved in synaptic plasticity. However, in cingulate cortex, the staining density of Homer-1 was significantly increased in female mice. Further, female mice (similar to male mice) did not show changes in brain AChE expression and in the amyloid beta load in the hippocampus and cingulate cortex. In conclusion, the memory enhancing, anxiolytic and protein expression effects of AP-12 did not show sex specificity in APPSweDI mice. Considering the ability of AP-12 to block brain calcium channels and improve memory by enhancing the GABAergic and synaptic plasticity processes, AP-12 is a promising compound which merits further pre-clinical studies to investigate its usefulness in the treatment of AD.

Mildronate improves cognition and reduces amyloid-ß pathology in transgenic Alzheimer's disease mice.

Mildronate, a carnitine congener drug, previously has been shown to provide neuroprotection in an azidothymidine-induced mouse model of neurotoxicity and in a Parkinson's disease rat model. The aim of this study was to investigate the effects of mildronate treatment on cognition and pathology in Alzheimer's disease (AD) model mice (APP(SweDI)). Mildronate was administered i.p. daily at 50 or 100 mg/kg for 28 days. At the end of treatment, the animals were behaviorally and cognitively tested, and brains were assessed for AD-related pathology, inflammation, synaptic markers, and acetylcholinesterase (AChE). The data show that mildronate treatment significantly improved animal performance in water maze and social recognition tests, lowered amyloid-ß deposition in the hippocampus, increased expression of the microglia marker Iba-1, and decreased AChE staining, although it did not alter expression of proteins involved in synaptic plasticity (GAP-43, synaptophysin, and GAD67). Taken together, these findings indicate mildronate's ability to improve cognition and reduce amyloid-ß pathology in a mouse model of AD and its possible therapeutic utility as a disease-modifying drug in AD patients.

Neurodevelopmental impairment following neonatal hyperoxia in the mouse.

Extremely premature infants are often exposed to supra-physiologic concentrations of oxygen, and frequently have hypoxemic episodes. These preterm infants are at high risk (~40%) for neurodevelopmental impairment (NDI) even in the absence of obvious intracranial pathology such as intraventricular hemorrhage or periventricular leukomalacia. The etiology for NDI has not been determined, and there are no animal models to simulate neurodevelopmental outcomes of prematurity. Our objectives were to develop and characterize a mouse model to determine long-term effects of chronic hypoxia or hyperoxia exposure on neurodevelopment. Newborn C57BL/6 mice were exposed to hypoxia (12% O(2)) or hyperoxia (85% O(2)) from postnatal days 1 to 14 and then returned to air. At 12-14 weeks of age, neurobehavioral assessment (Water Maze test, Novel Object Recognition test, Open Field test, Elevated Plus Maze, and Rotarod test) was performed, followed by MRI and brain histology. Neurobehavioral testing revealed that hyperoxia-exposed mice did poorly on the water maze and novel object recognition tests compared to air-exposed mice. MRI demonstrated smaller hippocampi in hyperoxia- and hypoxia-exposed mice with a greater reduction in hyperoxia-exposed mice, including a smaller cerebellum in hyperoxia-exposed mice. Brain histology showed reduced CA1 and CA3 and increased dentate gyral width in hippocampus. In conclusion, neonatal hyperoxia in mice leads to abnormal neurobehavior, primarily deficits in spatial and recognition memory, associated with smaller hippocampal sizes, similar to findings in ex-preterm infants. This animal model may be useful to determine mechanisms underlying developmental programming of NDI in preterm infants, and for evaluation of therapeutic strategies.

The effect of a pharmaceutical ghrelin agonist on lifespan in C57BL/6J male mice: A controlled experiment.

Interventions for animal lifespan extension like caloric restriction (CR) have identified physiologic and biochemical pathways related to hunger and energy-sensing status as possible contributors, but mechanisms have not been fully elucidated. Prior studies using ghrelin agonists show greater food intake but no effect on lifespan in rodent models. This experiment in male C57BL/6J mice tested the influence of ghrelin agonism for perceived hunger, in the absence of CR, on longevity. Mice aged 4 weeks were allowed to acclimate for 2 weeks prior to being assigned (N = 60/group). Prior to lights off daily (12:12 cycle), animals were fed a ghrelin agonist pill (LY444711; Eli Lilly) or a placebo control (Ctrl) until death. Treatment (GhrAg) animals were pair-fed daily based on the group mean food intake consumed by Ctrl (ad libitum feeding) the prior week. Results indicate an increased lifespan effect (log-rank p = 0.0032) for GhrAg versus placebo Ctrl, which weighed significantly more than GhrAg (adjusted for baseline weight). Further studies are needed to determine the full scope of effects of this ghrelin agonist, either directly via increased ghrelin receptor signaling or indirectly via other hypothalamic, systemic, or tissue-specific mechanisms.

Disrupting function of FK506-binding protein 1b/12.6 induces the Ca²+-dysregulation aging phenotype in hippocampal neurons.

With aging, multiple Ca(2+)-associated electrophysiological processes exhibit increased magnitude in hippocampal pyramidal neurons, including the Ca(2+)-dependent slow afterhyperpolarization (sAHP), L-type voltage-gated Ca(2+) channel (L-VGCC) activity, Ca(2+)-induced Ca(2+) release (CICR) from ryanodine receptors (RyRs), and Ca(2+) transients. This pattern of Ca(2+) dysregulation correlates with reduced neuronal excitability/plasticity and impaired learning/memory and has been proposed to contribute to unhealthy brain aging and Alzheimer's disease. However, little is known about the underlying molecular mechanisms. In cardiomyocytes, FK506-binding protein 1b/12.6 (FKBP1b) binds and stabilizes RyR2 in the closed state, inhibiting RyR-mediated Ca(2+) release. Moreover, we recently found that hippocampal Fkbp1b expression is downregulated, whereas Ryr2 and Frap1/Mtor (mammalian target of rapamycin) expression is upregulated with aging in rats. Here, we tested the hypothesis that disrupting FKBP1b function also destabilizes Ca(2+) homeostasis in hippocampal neurons and is sufficient to induce the aging phenotype of Ca(2+) dysregulation in young animals. Selective knockdown of Fkbp1b with interfering RNA in vitro (96 h) enhanced voltage-gated Ca(2+) current in cultured neurons, whereas in vivo Fkbp1b knockdown by microinjection of viral vector (3-4 weeks) dramatically increased the sAHP in hippocampal slice neurons from young-adult rats. Rapamycin, which displaces FKBP1b from RyRs in myocytes, similarly enhanced VGCC current and the sAHP and also increased CICR. Moreover, FKBP1b knockdown in vivo was associated with upregulation of RyR2 and mTOR protein expression. Thus, disruption of FKBP1b recapitulated much of the Ca(2+)-dysregulation aging phenotype in young rat hippocampus, supporting a novel hypothesis that declining FKBP function plays a major role in unhealthy brain aging.

Widespread Doublecortin Expression in the Cerebral Cortex of the Octodon degus.

It has been demonstrated that in adulthood rodents show newly born neurons in the subgranular layer (SGL) of the dentate gyrus (DG), and in the subventricular zone (SVZ). The neurons generated in the SVZ migrate through the rostral migratory stream (RMS) to the olfactory bulb. One of the markers of newly generated neurons is doublecortin (DCX). The degu similarly shows significant numbers of DCX-labeled neurons in the SGL, SVZ, and RMS. Further, most of the nuclei of these DCX-expressing neurons are also labeled by proliferating nuclear antigen (PCNA) and Ki67. Finally, whereas in rats and mice DCX-labeled neurons are predominantly present in the SGL and SVZ, with only a few DCX neurons present in piriform cortex, the degu also shows significant numbers of DCX expressing neurons in areas outside of SVZ, DG, and PC. Many areas of neocortex in degu demonstrate DCX-labeled neurons in layer II, and most of these neurons are found in the limbic cortices. The DCX-labeled cells do not stain with NeuN, indicating they are immature neurons.

Hippocampal and cognitive aging across the lifespan: a bioenergetic shift precedes and increased cholesterol trafficking parallels memory impairment.

Multiple hippocampal processes and cognitive functions change with aging or Alzheimer's disease, but the potential triggers of these aging cascades are not well understood. Here, we quantified hippocampal expression profiles and behavior across the adult lifespan to identify early aging changes and changes that coincide with subsequent onset of cognitive impairment. Well powered microarray analyses (N = 49 arrays), immunohistochemistry, and Morris spatial maze learning were used to study male F344 rats at five age points. Genes that changed with aging (by ANOVA) were assigned to one of four onset age ranges based on template pattern matching; functional pathways represented by these genes were identified statistically (Gene Ontology). In the earliest onset age range (3-6 months old), upregulation began for genes in lipid/protein catabolic and lysosomal pathways, indicating a shift in metabolic substrates, whereas downregulation began for lipid synthesis, GTP/ATP-dependent signaling, and neural development genes. By 6-9 months of age, upregulation of immune/inflammatory cytokines was pronounced. Cognitive impairment first appeared in the midlife range (9-12 months) and coincided and correlated primarily with midlife upregulation of genes associated with cholesterol trafficking (apolipoprotein E), myelinogenic, and proteolytic/major histocompatibility complex antigen-presenting pathways. Immunolabeling revealed that cholesterol trafficking proteins were substantially increased in astrocytes and that myelination increased with aging. Together, our data suggest a novel sequential model in which an early-adult metabolic shift, favoring lipid/ketone body oxidation, triggers inflammatory degradation of myelin and resultant excess cholesterol that, by midlife, activates cholesterol transport from astrocytes to remyelinating oligodendrocytes. These processes may damage structure and compete with neuronal pathways for bioenergetic resources, thereby impairing cognitive function.

Pulmonary angiogenesis in a rat model of hepatopulmonary syndrome.

BACKGROUND & AIMS: Hepatopulmonary syndrome (HPS), defined as intrapulmonary vasodilation, occurs in 10%-30% of cirrhotics and increases mortality. In a rat model of HPS induced by common bile duct ligation (CBDL), but not thioacetamide (TAA)-induced nonbiliary cirrhosis, lung capillary density increases, monocytes accumulate in the microvasculature, and signaling factors in the angiogenesis pathway (Akt and endothelial nitric oxide synthase [eNOS]) are activated. Pentoxifylline (PTX) directly decreases lung endothelial Akt and eNOS activation, blocks intravascular monocyte accumulation, and improves experimental HPS; we evaluated whether pulmonary angiogenesis develops in this model. METHODS: TAA- and PTX-treated animals were evaluated following CBDL. Lung angiogenesis was assessed by quantifying factor VIII-positive microvessels and levels of von Willebrand factor (vWf), vascular endothelial cadherin (VE-cadherin), and proliferating cell nuclear antigen (PCNA). Angiogenic factors including phospho-Akt, phospho-eNOS, vascular endothelial growth factor (VEGF)-A, and phospho-VEGF receptor-2 (p-VEGFR-2) were compared and monocyte accumulation was assessed. RESULTS: Following CBDL, but not TAA exposure, rats developed HPS that was temporally correlated with increased numbers of lung microvessel; increased levels of vWf, VE-cadherin and PCNA; and activation of Akt and eNOS. Angiogenesis was accompanied by increased pulmonary VEGF-A and p-VEGFR-2 levels, with VEGF-A staining in accumulated intravascular monocytes and alveolar endothelial cells. Following CBDL, PTX-treated rats had reduced numbers of microvessels, reduced lung monocyte accumulation, downregulation of pulmonary angiogenic factors, and reduced symptoms of HPS. CONCLUSIONS: A specific increase in pulmonary angiogenesis occurs as experimental HPS develops, accompanied by activation of VEGF-A-associated angiogenic pathways. PTX decreases the angiogenesis, reduces the symptoms of HPS, and downregulates VEGF-A mediated pathways.

Subchronic administration of auranofin reduced amyloid-ß plaque pathology in a transgenic APPNL-G-F/NL-G-F mouse model.

Alzheimer's disease (AD) is the most common cause of dementia. Neuropathological processes, including the accumulation of amyloid-ß (Aß) plaques and neurofibrillary tangles, and neuroinflammation, lead to cognitive impairment at middle and eventually later stages of AD progression. Over the last decade, focused efforts have explored repurposed drug approaches for AD pathophysiological mechanisms. Recently, auranofin, an anti-inflammatory drug, was shown to have therapeutic potential in a number of diseases in addition to rheumatoid arthritis. Surprisingly, no data regarding the effects of auranofin on cognitive deficits in AD mice or the influence of auranofin on Aß pathology and neuroinflammatory processes are available. In the present study, we used 14-month-old transgenic male APPNL-G-F/NL-G-F mice to assess the effects of subchronic administration of auranofin at low doses (1 and 5 mg/kg, intraperitoneal) on spatial memory, Aß pathology and the expression of cortical and hippocampal proteins (glial fibrillary acidic protein (GFAP), ionized calcium binding adaptor molecule-1 (Iba-1)) and proteins related to synaptic plasticity (glutamic acid decarboxylase 67 (GAD67), homer proteins homologue-1 (Homer-1)). The data demonstrated that auranofin significantly decreased Aß deposition in the hippocampus and the number of Aß plaques in the cingulate cortex, but it did not have memory-enhancing effects or induce changes in the expression of the studied proteins. Our current results highlight the importance of considering further pre-clinical research to investigate the possible beneficial effects of auranofin on the other pathological aspects of AD.

Oral apolipoprotein A-I mimetic peptide improves cognitive function and reduces amyloid burden in a mouse model of Alzheimer's disease.

Recent evidence indicates that inflammation may significantly contribute to the pathogenesis of Alzheimer's disease (AD). Since the apo A-I mimetic peptide D-4F has been shown to inhibit atherosclerotic lesion formation and regress already existing lesions (in the presence of pravastatin) and the peptide also decreases brain arteriole inflammation, we undertook a study to evaluate the efficacy of oral D-4F co-administered with pravastatin on cognitive function and amyloid beta (A beta) burden in the hippocampus of APPSwe-PS1 Delta E9 mice. Three groups of male mice were administered D-4F and pravastatin, Scrambled D-4F (ScD-4F, a control peptide) and pravastatin in drinking water, while drinking water alone served as control. The escape latency in the Morris Water Maze test was significantly shorter for the D-4F+statin administered animals compared to the other two groups. While the hippocampal region of the brain was covered with 4.2+/-0.5 and 3.8+/-0.6% of A beta load in the control and ScD-4F+statin administered groups, in the D-4F+statin administered group A beta load was only 1.6+/-0.1%. Furthermore, there was a significant decrease in the number of activated microglia (p<0.05 vs the other two groups) and activated astrocytes (p<0.05 vs control) upon oral D-4F+statin treatment. Inflammatory markers TNFalpha and IL-1 beta levels were decreased significantly in the D-4F+statin group compared to the other two groups (for IL-1 beta p<0.01 vs the other two groups and for TNF-alpha p<0.001 vs control) and the expression of MCP-1 were also less in D-4F+statin administered group compared to the other two groups. These results suggest that the apo A-I mimetic peptide inhibits amyloid beta deposition and improves cognitive function via exerting anti-inflammatory properties in the brain.

Hippocampal expression analyses reveal selective association of immediate-early, neuroenergetic, and myelinogenic pathways with cognitive impairment in aged rats.

Although expression of some genes is known to change during neuronal activity or plasticity, the overall relationship of gene expression changes to memory or memory disorders is not well understood. Here, we combined extensive statistical microarray analyses with behavioral testing to comprehensively identify genes and pathways associated with aging and cognitive dysfunction. Aged rats were separated into cognitively unimpaired (AU) or impaired (AI) groups based on their Morris water maze performance relative to young-adult (Y) animals. Hippocampal gene expression was assessed in Y, AU, and AI on the fifth (last) day of maze training (5T) or 21 d posttraining (21PT) and in nontrained animals (eight groups total, one array per animal; n = 78 arrays). ANOVA and linear contrasts identified genes that differed from Y generally with aging (differed in both AU and AI) or selectively, with cognitive status (differed only in AI or AU). Altered pathways/processes were identified by overrepresentation analyses of changed genes. With general aging, there was downregulation of axonal growth, cytoskeletal assembly/transport, signaling, and lipogenic/uptake pathways, concomitant with upregulation in immune/inflammatory, lysosomal, lipid/protein degradation, cholesterol transport, transforming growth factor, and cAMP signaling pathways, primarily independent of training condition. Selectively, in AI, there was downregulation at 5T of immediate-early gene, Wnt (wingless integration site), insulin, and G-protein signaling, lipogenesis, and glucose utilization pathways, whereas Notch2 (oligodendrocyte development) and myelination pathways were upregulated, particularly at 21PT. In AU, receptor/signal transduction genes were upregulated, perhaps as compensatory responses. Immunohistochemistry confirmed and extended selected microarray results. Together, the findings suggest a new model, in which deficient neuroenergetics leads to downregulated neuronal signaling and increased glial activation, resulting in aging-related cognitive dysfunction.

Aging-Related Calcium Dysregulation in Rat Entorhinal Neurons Homologous with the Human Entorhinal Neurons in which Alzheimer's Disease Neurofibrillary Tangles First Appear.

Aging is the leading risk factor for idiopathic Alzheimer's disease (AD), indicating that normal aging processes promote AD and likely are present in the neurons in which AD pathogenesis originates. In AD, neurofibrillary tangles (NFTs) appear first in entorhinal cortex, implying that aging processes in entorhinal neurons promote NFT pathogenesis. Using electrophysiology and immunohistochemistry, we find pronounced aging-related Ca2 + dysregulation in rat entorhinal neurons homologous with the human neurons in which NFTs originate. Considering that humans recapitulate many aspects of animal brain aging, these results support the hypothesis that aging-related Ca2 + dysregulation occurs in human entorhinal neurons and promotes NFT pathogenesis.

Inhibition of amyloid Aß aggregation by high pressures or specific d-enantiomeric peptides.

Pressure can shift the polymer-monomer equilibrium of Aß, increasing pressure first leads to a release of Aß-monomers, surprisingly at pressures higher than 180 MPa repolymerization is induced. By high pressure NMR spectroscopy, differences of partial molar volumes ΔV0 and compressibility factors Δß' of polymerization were determined at different temperatures. The d-enantiomeric peptides RD2 and RD2D3 bind to monomeric Aß with affinities substantially higher than those determined for fibril formation. By reducing the Aß concentration below the critical concentration for polymerization they inhibit the formation of toxic oligomers. Chemical shift perturbation allows the identification of the binding sites. The d-peptides are candidates for drugs preventing Alzheimer's disease. We show that RD2D3 has a positive effect on the cognitive behaviour of transgenic (APPSwDI) mice prone to Alzheimer's disease. The heterodimer complexes have a smaller Stokes radius than Aß alone indicating the recognition of a more compact conformation of Aß identified by high pressure NMR before.