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.

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.

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.

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.

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.

Caprospinol: discovery of a steroid drug candidate to treat Alzheimer's disease based on 22R-hydroxycholesterol structure and properties.

The overall ability of the brain to synthesise neuroactive steroids led us to the identification of compounds that would reproduce aspects of neurosteroid pharmacology. The rate-determining step in neurosteroid biosynthesis is the import of the substrate cholesterol into the mitochondria, where it is metabolised into pregnenolone via the intermediate 22R-hydroxycholesterol. The levels of translocator protein 18-kDa, mediating the import of cholesterol into mitochondria, correlated with increased pregnenolone formation and reduced levels of 22R-hydroxycholesterol in biopsies from Alzheimer's disease (AD), but not age-matched control, brains.

The naturally occurring steroid solasodine induces neurogenesis in vitro and in vivo.

In this study, we explored the capacity of the naturally occurring compound solasodine to promote neurogenesis in vitro and in vivo. Mouse embryonic teratocarcinoma P19 cells exposed to solasodine for 2 days followed by a 5-day washout differentiated into cholinergic neurons that expressed specific neuronal markers and displayed important axonal formation that continued growing even 30 days after treatment. In vivo, a 2-week infusion of solasodine into the left ventricle of the rat brain followed by a 3-week washout resulted in a significant increase in bromodeoxyuridine uptake by cells of the ependymal layer, subventricular zone, and cortex that co-localized with doublecortin immunostaining, demonstrating the proliferative and differentiating properties of solasodine on neuronal progenitors.

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-β peptide.

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

Background/aims: Impaired mitochondrial function has been described in Alzheimer's disease. We previously reported that, in neuronal cells, β-amyloid 1-42 (Aβ(1-42)) is targeted to mitochondria. We have also reported that, when incubated with isolated rat brain mitochondria, Aβ(1-42) inhibits complex IV, uncouples the mitochondrial respiratory chain, and promotes opening of the membrane permeability transition pore.

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.

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.

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.

Alzheimer's disease: effects of β-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). β-amyloid has been implicated in the pathogenesis of AD, and its accumulation may lead to degeneration of neuronal or non-neuronal cells.

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).

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.

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.

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.

Caprospinol reduces amyloid deposits and improves cognitive function in a rat model of Alzheimer's disease.

Alzheimer's disease (AD), the most prominent form of dementia in elderly, is a yet incurable degenerative neurological illness characterized by memory loss. Here, we used an AD rat model to investigate the in vivo efficacy of caprospinol, a disease-modifying steroid developed on the concept that reduced synthesis of 22R-hydroxycholesterol in the AD brain increases beta-amyloid neurotoxicity. Caprospinol treatment of diseased rats attenuated memory impairment, as assessed using Morris watermaze tests.

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.

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.

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.

Cutting-edge patents in Alzheimer's disease drug discovery: anticipation of potential future treatments.

Neurodegenerative disease broadly includes many different diseases, such as Alzheimer's, Parkinson's, amyotrophic lateral sclerosis, multiple sclerosis, Huntington's, dementias with Lewy bodies, post-traumatic brain injury, and stroke. Although few common physiopathological changes have been discovered among these conditions, the semiology (if known), the triggered molecular pathways that lead to the observed pathologies, and the symptomatology are essentially different. These differences entail that the treatments, both current and future, have disease-specific indications.

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.

22R-Hydroxycholesterol induces differentiation of human NT2 precursor (Ntera2/D1 teratocarcinoma) cells.

Recently, we have shown that 22R-hydroxycholesterol, a steroid intermediate in the pathway of pregnenolone formation from cholesterol, is present at lower levels in Alzheimer's disease (AD) hippocampus and frontal cortex tissue specimens than in age-matched controls, and that this substance protects against cell death induced by amyloid beta-peptide in both rat sympathetic nerve pheochromocytoma (PC12) and differentiated human Ntera2/D1 teratocarcinoma neurons. Herein we report that 22R-hydroxycholesterol inhibits the proliferation of human Ntera2/D1 teratocarcinoma precursor cells (NT2) and induces these cells to differentiate into "neuron-like" or "astrocyte-like" cells. 22R-Hydroxycholesterol-induced differentiation of NT2 cells is associated with increases in the expression of neurofilament protein NF200, the cytoskeletal proteins microtubule-associated protein type II (MAP2) a and MAP2b, glial fibrillary acidic protein (GFAP) and glial cell line-derived neurotrophic factor receptor-alpha 2 (GFRalpha2).