Modeling Alzheimer's disease with non-transgenic rat models.

Alzheimer's disease (AD), for which there is no cure, is the most common form of dementia in the elderly. Despite tremendous efforts by the scientific community, the AD drug development pipeline remains extremely limited. Animal models of disease are a cornerstone of any drug development program and should be as relevant as possible to the disease, recapitulating the disease phenotype with high fidelity, to meaningfully contribute to the development of a successful therapeutic agent. Over the past two decades, transgenic models of AD based on the known genetic origins of familial AD have significantly contributed to our understanding of the molecular mechanisms involved in the onset and progression of the disease. These models were extensively used in AD drug development. The numerous reported failures of new treatments for AD in clinical trials indicate that the use of genetic models of AD may not represent the complete picture of AD in humans and that other types of animal models relevant to the sporadic form of the disease, which represents 95% of AD cases, should be developed. In this review, we will discuss the evolution of non-transgenic rat models of AD and how these models may open new avenues for drug development.

Control of hypercholesterolemia and atherosclerosis using the cholesterol recognition/interaction amino acid sequence of the translocator protein TSPO.

The translocator protein (18-kDa) TSPO is an ubiquitous high affinity cholesterol-binding protein reported to be present in the endothelial and smooth muscle cells of the blood vessels; its expression dramatically increased in macrophages found in atherosclerotic plaques. A domain in the carboxy-terminus of TSPO was identified and characterized as the cholesterol recognition/interaction amino acid consensus (CRAC). The ability of the CRAC domain to bind to cholesterol led us to hypothesize that this peptide could be used as an hypocholesterolemic, with potential anti-atherogenic properties, agent. We report herein the therapeutic benefit that resulted for the administration of the VLNYYVWR human CRAC sequence to guinea pigs fed with a high cholesterol diet and ApoE knock-out B6.129P2-Apoetm1Unc/J mice. CRAC treatment (3 and 30mg/kg once daily for 6 weeks) resulted in reduced circulating cholesterol levels in guinea pigs fed with 2% high cholesterol diet and ApoE knock-out B6.129P2-Apoetm1Unc/J mice. In high cholesterol fed guinea pigs, CRAC treatment administered once daily induced an increase in circulating HDL, decreased total, free and LDL cholesterol, and removed atheroma deposits in the aorta in a dose-dependent manner. The treatment also prevented the high cholesterol diet-induced increase in serum creatine kinase, total and isoforms, markers of neurological, cardiac and muscular damage. No toxicity was observed. Taken together these results support a role of TSPO in lipid homeostasis and atherosclerosis and indicate that CRAC may constitute a novel and safe treatment of hypercholesterolemia and atherosclerosis.

Identification of small-molecule inhibitors of the steroidogenic acute regulatory protein (STARD1) by structure-based design.

A homology model of the steroidogenic acute regulatory protein (STAR)-related lipid transfer (START) domain of STARD1 was built, and the cholesterol binding site was identified. Structure-based design studies were performed to identify small molecule inhibitors of the START domain. The lead compounds were selected based on cAMP-induced, but not 22R-hydroxycholesterol-supported, inhibition of steroid synthesis by 50% at 10 µM. The results obtained by molecular docking & dynamics show a good correlation between bioactivity, docking scores and calculated binding energies of ligand-protein complexes. The best active compounds will be optimized further and used to develop potential drugs to control excessive steroid formation.

A steroid isolated from the water mold Achlya heterosexualis induces neurogenesis in vitro and in vivo.

Using 22R-hydroxycholesterol as a sub-structure to screen natural compound databases, we identified a naturally occurring steroid (sc-7) with a 16-acetoxy-22R-hydroxycholesterol moiety, in which the hydroxyl groups in positions 3 and 22 are esterified by an acetoxy group and in which the carbon in position 26 carries a functional diacetylamino. sc-7 is an analog of the sex steroids dehydro-oogoniol and antheridiol, can be isolated from the water mold Achlya heterosexualis, and promoted neurogenesis in vitro and in vivo. Mouse embryonic teratocarcinoma P19 cells exposed to sc-7 for 2days followed by a 5-day wash-out differentiated into cholinergic neurons that expressed specific neuronal markers and displayed axonal formation. Axons continued growing up to 28days after treatment. In vivo, infusion of sc-7 for 2weeks into the left ventricle of the rat brain followed by a 3-week wash-out induced bromodeoxyuridine uptake by cells of the ependymal layer and subventricular zone that co-localized with doublecortin and glial fibrillary acidic protein immunostaining, demonstrating induction of proliferation and differentiation of neuronal progenitors. Migrating neuroblasts were also observed in the corpus callosum. Thus, under these experimental conditions, adult ependymal cells resumed proliferation and differentiation. Taken together, these results suggest that sc-7 is an interesting molecule for stimulating in situ neurogenesis from resident neuronal progenitors as part of neuron replacement therapy. sc-7 did not bind to nuclear steroid receptors and was not metabolized as a steroid, supporting our hypothesis that the neurogenic effect of sc-7 is not likely due to a steroid-like effect.

Sex, the underestimated potential determining factor in brain tissue repair strategy.

Neural stem cells (NSCs) hold a lot of potential for the development of brain repair strategies. However, difficulties in clinical translation suggest that improving the "know how" demands that we improve our fundamental knowledge on mechanisms that regulate NSC transplantation outcome. In this article, we will focus on recent works conducted in our laboratory and by others supporting the fact that the sex of NSCs (the donor) may be a determining factor in the outcome of NSCs grafts. In particular, we will discuss the intrinsic sexual dimorphism recently reported in NSCs showing a differential expression of estrogen receptor alpha and beta as well as aromatase and how it affected NSCs transplantation outcome. An emphasis will be put on the importance of taking such sexual dimorphism into consideration for the design of future brain repair strategies.

A lead study on oxidative stress-mediated dehydroepiandrosterone formation in serum: the biochemical basis for a diagnosis of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive, yet irreversible, neurodegenerative disease for which there are limited means for its ante-mortem diagnosis. We previously identified a brain- and cell-specific oxidative stress-mediated mechanism for dehydroepiandrosterone (DHEA) biosynthesis present in rat, bovine, and human brain, independent of the cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17) enzyme activity found in the periphery. This alternative pathway is induced by pro-oxidant agents, such as Fe2+ and amyloid-ß peptide. Using brain tissue specimens from control and AD patients we subsequently provided evidence that DHEA is formed in the AD brain by the oxidative stress-mediated metabolism of an unidentified precursor, thus depleting the levels of the precursor present in the blood stream. Here, we tested for the presence of this DHEA precursor in human serum using a simple Fe2+-based reaction and determined the amounts of DHEA formed. A total of 86 subjects were included in this study: 19 male and 20 female AD patients; 18 male and 22 female age-matched controls; and 4 men and 3 women with mild cognitive impairment. Serum oxidation resulted in a dramatic increase of DHEA level in control patients, whereas only a moderate or no increase was observed in the AD patients. The DHEA variation after oxidation correlated with the patients' cognitive and mental status. These results suggest that the comparison of DHEA levels in patient serum before and after oxidation could provide a useful tool to diagnose AD.

Further evidence on mitochondrial targeting of ß-amyloid and specificity of ß-amyloid-induced mitotoxicity in neurons.

BACKGROUND/AIMS: Impaired mitochondrial function has been described in Alzheimer's disease. We previously reported that, in neuronal cells, ß-amyloid 1-42 (Aß(1-42)) is targeted to mitochondria. We have also reported that, when incubated with isolated rat brain mitochondria, Aß(1-42) inhibits complex IV, uncouples the mitochondrial respiratory chain, and promotes opening of the membrane permeability transition pore. Here, we further analyzed the targeting and mitotoxicity of Aß(1-42). METHODS AND RESULTS: Immunoelectron microscopy revealed that the mitochondrial targeting of Aß(1-42) was concentration- and time-dependent. Incubation of human neuroblastoma cells with Aß(1-42) increased the release of adenylate kinase, a mitochondrial enzyme released after membrane permeability transition pore opening. However, it failed to trigger DNA fragmentation and apoptosis, suggesting that the ability of this peptide to uncouple the respiratory chain underlies its mitotoxicity and cytotoxicity. Aß(1-42) targeting to mitochondria was blocked by caprospinol, a steroid derivative shown to protect neuronal cells against Aß(1-42)-induced neurotoxicity. Further experiments revealed that the mitotoxic effect of Aß(1-42) is specific to its primary amino acid sequence and suggested that it may be also related to its tertiary structure. Importantly, the mitotoxic effect of Aß(1-42) was not restricted to brain cells, indicating that it is not cell- or tissue-specific. CONCLUSION: Taken together, these results suggest that extracellular Aß(1-42) targets neuronal mitochondria to exert its toxic effects.

Novel androstenetriol interacts with the mitochondrial translocator protein and controls steroidogenesis.

Steroid hormones are metabolically derived from multiple enzymatic transformations of cholesterol. The controlling step in steroid hormone biogenesis is the delivery of cholesterol from intracellular stores to the cytochrome P450 enzyme CYP11A1 in the mitochondrial matrix. The 18-kDa translocator protein (TSPO) plays an integral part in this mitochondrial cholesterol transport. Consistent with its role in intracellular cholesterol movement, TSPO possesses a cholesterol recognition/interaction amino acid consensus (CRAC) motif that has been demonstrated to bind cholesterol. To further investigate the TSPO CRAC motif, we performed molecular modeling studies and identified a novel ligand, 3,17,19-androsten-5-triol (19-Atriol) that inhibits cholesterol binding at the CRAC motif. 19-Atriol could bind a synthetic CRAC peptide and rapidly inhibited hormonally induced steroidogenesis in MA-10 mouse Leydig tumor cells and constitutive steroidogenesis in R2C rat Leydig tumor cells at low micromolar concentrations. Inhibition at these concentrations was not due to toxicity or inhibition of the CYP11A1 enzyme and was reversed upon removal of the compound. In addition, 19-Atriol was an even more potent inhibitor of PK 11195-stimulated steroidogenesis, with activity in the high nanomolar range. This was accomplished without affecting PK 11195 binding or basal steroidogenesis. Finally, 19-Atriol inhibited mitochondrial import and processing of the steroidogenic acute regulatory protein without any effect on TSPO protein levels. In conclusion, we have identified a novel androstenetriol that can interact with the CRAC domain of TSPO, can control hormonal and constitutive steroidogenesis, and may prove to be a useful tool in the therapeutic control of diseases of excessive steroid formation.

Alzheimer's disease: effects of ß-amyloid on mitochondria.

The impairment of the respiratory chain or defects in the detoxification system can decrease electron transfer efficiency, reduce ATP production, and increase reactive oxygen species (ROS) production by mitochondria. Accumulation of ROS results in oxidative stress, a hallmark of neurodegenerative diseases such as Alzheimer's disease (AD). ß-amyloid has been implicated in the pathogenesis of AD, and its accumulation may lead to degeneration of neuronal or non-neuronal cells. There is evidence that ß-amyloid interacts with mitochondria but little is known concerning the significance of this interaction in the physiopathology of AD. This review explores possible mechanisms of ß-amyloid-induced mitochondrial toxicity.

Oxidative Stress-Mediated Brain Dehydroepiandrosterone (DHEA) Formation in Alzheimer's Disease Diagnosis.

Neurosteroids are steroids made by brain cells independently of peripheral steroidogenic sources. The biosynthesis of most neurosteroids is mediated by proteins and enzymes similar to those identified in the steroidogenic pathway of adrenal and gonadal cells. Dehydroepiandrosterone (DHEA) is a major neurosteroid identified in the brain. Over the years we have reported that, unlike other neurosteroids, DHEA biosynthesis in rat, bovine, and human brain is mediated by an oxidative stress-mediated mechanism, independent of the cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17A1) enzyme activity found in the periphery. This alternative pathway is induced by pro-oxidant agents, such as Fe(2+) and ß-amyloid peptide. Neurosteroids are involved in many aspects of brain function, and as such, are involved in various neuropathologies, including Alzheimer's disease (AD). AD is a progressive, yet irreversible neurodegenerative disease for which there are limited means for ante-mortem diagnosis. Using brain tissue specimens from control and AD patients, we provided evidence that DHEA is formed in the AD brain by the oxidative stress-mediated metabolism of an unidentified precursor, thus depleting levels of the precursor in the blood stream. We tested for the presence of this DHEA precursor in human serum using a Fe(2+)-based reaction and determined the amounts of DHEA formed. Fe(2+) treatment of the serum resulted in a dramatic increase in DHEA levels in control patients, whereas only a moderate or no increase was observed in AD patients. The DHEA variation after oxidation correlated with the patients' cognitive and mental status. In this review, we present the cumulative evidence for oxidative stress as a natural regulator of DHEA formation and the use of this concept to develop a blood-based diagnostic tool for neurodegenerative diseases linked to oxidative stress, such as AD.

Age and sex differences in neural stem cell transplantation: a descriptive study in rats.

PURPOSE: The purpose of this study was to determine whether neural stem cell (NSC) sexual dimorphism previously demonstrated in vitro translates in vivo in NSC transplantation experiments and constitutes a defining factor of the transplantation outcome. METHODS: NSCs isolated from the subventricular zone of 2-day-old or 20-month-old male and female rats were grown as neurospheres prior to being transplanted in the striatum of 2-day-old or 20-month-old male and female recipient animals. The outcome of the transplantation and the NSC differentiation status were analyzed 8 weeks later by assessing the expression of the markers doublecortin (DCX) for neuroblasts, glial fibrillary acidic protein (GFAP) for astrocytes, nestin for stem cells, and choline acetyltransferase (ChAT) for neuronal cholinergic phenotype by immunofluorescence. RESULTS: No NSCs were detected in the brain of rat pups 8 weeks after transplantation. However, the endogenous neurogenesis was dramatically increased in a sex-dependent manner. These data suggest that the transplanted NSCs may have triggered endogenous neurogenesis by the intermediate growth factors they may have produced or the production they may have induced. However, NSCs transplanted into the striatum of adult rats were detectable at week 8. NSC survival was dependent on the sex and age of the donor and the recipient. Some of the transplanted cells were found to express DCX, GFAP, and ChAT, supporting an ongoing differentiation process toward astroglial and neuronal cholinergic phenotypes. CONCLUSION: The outcome of the NSC transplantation was highly dependent on the sex and age of the combination donor/recipient. Data generated from our work may allow us in the future to answer the question "What NSCs and for whom?" and consequently lead to the optimization of the grafting process and improvement of the clinical prognosis.

Dimethyl-carbamic acid 2,3-Bis-Dimethylcarbamoyloxy-6-(4-Ethyl-Piperazine-1-Carbonyl)-phenyl ester: a novel multi-target therapeutic approach to neuroprotection.

We report herein the synthesis and biological evaluation of dimethyl-carbamic acid 2,3-bis-dimethylcarbamoyloxy-6-(4-ethyl-piperazine-1-carbonyl)-phenyl ester (SP-04), a new drug candidate that is designed to offer a multi-target therapeutic neuroprotective approach as a treatment for Alzheimer's disease (AD). SP-04 inhibits acetylcholinesterase (AchE) activity both in vitro and in vivo, and induces a dose-dependent increase in Ach levels. SP-04 releases the metabolite 4-(4-ethyl-piperazin-1-yl)-1-(2,3,4-trihydroxy-phenyl)-butan-1-one (SP-04m). Both SP-04 and SP-04m are s1-receptor antagonists supporting their interest in relieving symptoms related to psychosis, a non-cognitive condition often associated with AD. SP-04m displays important antioxidant properties and both SP-04 and SP-04m offers neuroprotection against Ab42 toxicity in various neuronal cell lines. In addition, both SP-04 and SP-04m protect neuronal cells and rat brain mitochondria exposed to various mitochondrial respiratory chain complex toxins. Taken together these data suggest that the SP-04 multi-targeting approach might offer a novel therapeutic strategy for the treatment of AD.

Amyloidosis and neurodegenerative diseases: current treatments and new pharmacological options.

Most neurodegenerative diseases share several clinical, genetic and pathophysiological features, and an irreversible evolution as well. They are characterized by an endogenous production of abnormal proteins called amyloid proteins (AP), which are not hydrosoluble, form depots, and are only partly cleared by autophagy and the ubiquitin-protease system. Despite their different structures, they are probably generated by a common pathological pathway, a misfolding process. This hypothesis suggests a common pharmacological approach, which can consist of either the blockade of the misfolding process, the elimination of AP or both. The currently validated treatments are mostly palliative ones, trying to supplant the function of destroyed neurons. New trends involve the regulation of the cerebral cholesterol metabolism and the preservation of neuron mitochondrial functions. Special attention is given to already marketed drugs used for other indications, which are also able to act on neurodegeneration.

Aging differentially affects male and female neural stem cell neurogenic properties.

PURPOSE: Neural stem cell transplantation as a brain repair strategy is a very promising technology. However, despite many attempts, the clinical success remains very deceiving. Despite clear evidence that sexual dimorphism rules many aspects of human biology, the occurrence of a sex difference in neural stem cell biology is largely understudied. Herein, we propose to determine whether gender is a dimension that drives the fate of neural stem cells through aging. Should it occur, we believe that neural stem cell sexual dimorphism and its variation during aging should be taken into account to refine clinical approaches of brain repair strategies. METHODS: Neural stem cells were isolated from the subventricular zone of three- and 20-month-old male and female Long-Evans rats. Expression of the estrogen receptors, ERα and ERß, progesterone receptor, androgen receptor, and glucocorticoid receptor was analyzed and quantified by Western blotting on undifferentiated neural stem cells. A second set of neural stem cells was treated with retinoic acid to trigger differentiation, and the expression of neuronal, astroglial, and oligodendroglial markers was determined using Western blotting. CONCLUSION: We provided in vitro evidence that the fate of neural stem cells is affected by sex and aging. Indeed, young male neural stem cells mainly expressed markers of neuronal and oligodendroglial fate, whereas young female neural stem cells underwent differentiation towards an astroglial phenotype. Aging resulted in a lessened capacity to express neuron and astrocyte markers. Undifferentiated neural stem cells displayed sexual dimorphism in the expression of steroid receptors, in particular ERα and ERß, and the expression level of several steroid receptors increased during aging. Such sexual dimorphism might explain, at least in part, the sex difference in neural fate we observed in young and old neural stem cells. These results suggest that sex and aging are two factors to be taken into consideration for future neural stem cell transplantation protocols in brain repair strategies.

Neural stem cell sex dimorphism in aromatase (CYP19) expression: a basis for differential neural fate.

PURPOSE: Neural stem cell (NSC) transplantation and pharmacologic activation of endogenous neurogenesis are two approaches that trigger a great deal of interest as brain repair strategies. However, the success rate of clinical attempts using stem cells to restore neurologic functions altered either after traumatic brain injury or as a consequence of neurodegenerative disease remains rather disappointing. This suggests that factors affecting the fate of grafted NSCs are largely understudied and remain to be characterized. We recently reported that aging differentially affects the neurogenic properties of male and female NSCs. Although the sex steroids androgens and estrogens participate in the regulation of neurogenesis, to our knowledge, research on how gender-based differences affect the capacity of NSCs to differentiate and condition their neural fate is lacking. In the present study, we explored further the role of cell sex as a determining factor of the neural fate followed by differentiating NSCs and its relationship with a potential differential expression of aromatase (CYP19), the testosterone-metabolizing enzyme. RESULTS: Using NSCs isolated from the subventricular zone of three-month-old male and female Long-Evans rats and maintained as neurospheres, we showed that differentiation triggered by retinoic acid resulted in a neural phenotype that depends on cell sex. Differentiated male NSCs mainly expressed markers of neuronal fate, including ßIII-tubulin, microtubule associated protein 2, growth-associated protein 43, and doublecortin. In contrast, female NSCs essentially expressed the astrocyte marker glial fibrillary acidic protein. Quantification of the expression of aromatase showed a very low level of expression in undifferentiated female NSCs, whereas aromatase expression in male NSCs was 14-fold greater than the female level. CONCLUSION: Our results confirm our previous data that the neural phenotype acquired by differentiating NSCs largely depends on cell sex, and that differential expression of aromatase in undifferentiated NSCs might contribute to this sex-based dimorphism. Although still preliminary, our discovery may have clinical application in the development of future brain repair strategies.

Identification of a benzamide derivative that inhibits stress-induced adrenal corticosteroid synthesis.

Elevated serum glucocorticoid levels contribute to the progression of many diseases, including depression, Alzheimer's disease, hypertension, and acquired immunodeficiency syndrome. Here we show that the benzamide derivative N-[2-(4-cyclopropanecarbonyl-3-methyl-piperazin-1-yl)-1-(tert-butyl-1H-indol-3-yl-methyl)-2-oxo-ethyl]-4-nitrobenzamide (SP-10) inhibits dibutyryl cyclic AMP (dbcAMP)-induced corticosteroid synthesis in a dose-dependent manner in Y-1 adrenal cortical mouse tumor cells, without affecting basal steroid synthesis and reduced stress-induced corticosterone increases in rats without affecting the physiological levels of the steroid in blood. SP-10 did not affect cholesterol transport and metabolism by the mitochondria but was unexpectedly found to increase 3-hydroxy-3-methylglutaryl-coenzyme A, low density lipoprotein receptor, and scavenger receptor class B type I (SR-BI) expression. However, it also markedly reduced dbcAMP-induced NBD-cholesterol uptake, suggesting that this is a compensatory mechanism aimed at maintaining cholesterol levels. SP-10 also induced a redistribution of filamentous (F-) and monomeric (G-) actin, leading to decreased actin levels in the submembrane cytoskeleton suggesting that SP-10-induced changes in actin distribution might prevent the formation of microvilli-cellular structures required for SRBI-mediated cholesterol uptake in adrenal cells.

Translocator protein (18 kDa) TSPO: an emerging therapeutic target in neurotrauma.

Traumatic brain injury (TBI) induces physical, cognitive, and psychosocial deficits that affect millions of patients. TBI activates numerous cellular mechanisms and molecular cascades that produce detrimental outcomes, including neuronal death and loss of function. The mitochondrion is one of the major targets of TBI, as seen by increased mitochondrial activity in activated and proliferating microglia (due to high energy requirements and/or calcium overload) as well as increased reactive oxygen species, changes in mitochondrial permeability transition, release of cytochrome c, caspase activation, reduced ATP levels, and cell death in neurons. Translocator protein (TSPO) is an 18-kDa outer mitochondrial membrane protein that interacts with the mitochondria permeability transition pore and binds with high affinity to cholesterol and various classes of drug ligands, including some benzodiazepines such as 4'-chlorodiazepam (Ro5-4864). Although TSPO levels in the brain are low, they are increased after brain injury and inflammation. This finding has led to the proposed use of TSPO expression as a marker of brain injury and repair. TSPO drug ligands have been shown to participate in the control of mitochondrial respiration and function, mitochondrial steroid and neurosteroid formation, as well as apoptosis. This review and commentary will outline our current knowledge of the benefits of targeting TSPO for TBI treatment and the mechanisms underlying the neuroprotective effects of TSPO drug ligands in neurotrauma.

Caprospinol: moving from a neuroactive steroid to a neurotropic drug.

In search of new drugs for Alzheimer's disease, we departed from the classic concepts and investigated the ability of normal and Alzheimer's disease brain to convert cholesterol to steroids, otherwise known as neurosteroids. We identified 22R-hydroxycholesterol to be present in much lower levels in the hippocampus and frontal cortex of Alzheimer's disease than in tissue from age-matched controls. 22R-hydroxycholesterol was shown to protect against beta-amyloid (A beta(42))-induced neurotoxicity and block the formation of A beta oligomers. In search of a 22R-hydroxycholesterol stable analog, we identified the naturally occurring heterospirostenol, (22R,25R)-20 alpha-spirost-5-en-3beta-yl hexanoate (caprospinol). The mechanism of action underlying the neuroprotective properties of caprospinol involves, first, the ability of the compound to bind A beta(42) and, second, its interaction with components of the mitochondria respiratory chain. Samaritan Pharmaceuticals is developing caprospinol as a disease-modifying drug for the treatment of Alzheimer's disease. Samaritan Pharmaceuticals filed for an Investigational New Drug application with the FDA in 2006. The pharmacokinetic and pharmacodynamic parts of the application were found satisfactory, and the FDA has requested that additional information is submitted in support of caprospinol's safety prior to initiating the Phase I clinical study.

A neuronal microtubule-interacting agent, NAPVSIPQ, reduces tau pathology and enhances cognitive function in a mouse model of Alzheimer's disease.

Neurofibrillary tangles composed of aggregated, hyperphosphorylated tau in an abnormal conformation represent one of the major pathological hallmarks of Alzheimer's disease (AD) and other tauopathies. However, recent data suggest that the pathogenic processes leading to cognitive impairment occur before the formation of classic tangles. In the earliest stages of tauopathy, tau detaches from microtubules and accumulates in the cytosol of the somatodendritic compartment of cells. Either as a cause or an effect, tau becomes hyperphosphorylated and aggregates into paired helical filaments that comprise the tangles. To assess whether an agent that modulates microtubule function can inhibit the pathogenic process and prevent cognitive deficits in a transgenic mouse model with AD-relevant tau pathology, we administered the neuronal tubulin-preferring agent, NAPVSIPQ (NAP). Three months of treatment with NAP at an early-to-moderate stage of tauopathy reduced the levels of hyperphosphorylated soluble and insoluble tau. A 6-month course of treatment improved cognitive function. Although nonspecific tubulin-interacting agents commonly used for cancer therapy are associated with adverse effects due to their anti-mitotic activity, no adverse effects were found after 6 months of exposure to NAP. Our results suggest that neuronal microtubule interacting agents such as NAP may be useful therapeutic agents for the treatment or prevention of tauopathies.