Amyloid toxicity is enhanced after pharmacological or genetic invalidation of the σ 1 receptor

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Learning performances and vulnerability to amyloid toxicity in the butyrylcholinesterase knockout mouse

Butyrylcholinesterase (BChE) is an important enzyme for detoxication and metabolism of ester compounds.It also hydrolyzes the neurotransmitter acetylcholine (ACh) in pathological conditions and may play a role in Alzheimer’s disease (AD). We here compared the learning ability and vulnerability to AB toxicity in male and female BChE knockout (KO) mice and their 129 Sv wild-type (Wt) controls. Animals tested for place learning in the water-maze showed increased acquisition slopes and presence in the training quadrant during the probe test. An increased passive avoidance response was also observed for males. BChE KO mice therefore showed enhanced learning ability in spatial and non-spatial memory tests. Intracerebroventricular (ICV) injection of increasing doses of amyloid-B[25–35] (AB25–35) peptide oligomers resulted, in Wt mice, in learning and memory deficits, oxidative stress and decrease in ACh hippocampal content. In BChE KO mice, the AB25–35-induced deficit in place learning was attenuated in males and blocked in females. No change in lipid peroxidation or ACh levels was observed after AB25–35 treatment in male or female BChE KO mice. These data showed that the genetic invalidation of BChE inmice augmented learning capacities and lowered the vulnerability to AB toxicity

Learning performances and vulnerability to amyloid toxicity in acetylcholinesterase and butyrylcholinesterase knockout mice

Cholinergic neurons in the basal forebrain play a crucial role in plasticity, memory and vulnerability to neurodegenerative pathologies, such as Alzheimer's disease (AD). Like acetylcholinesterase (AChE), butyrylcholinesterase (BChE) hydrolyses the neurotransmitter acetylcholine ACh, contributing to choline generation and recycling. We here characterized the behavioral phenotypes of heterozygous AChE knockout (hetAChE KO) mice and homozygous BChE KO mice, focusing on memory functions and vulnerability to amyloid toxicity. First, AChE activity was significantly decreased in the hippocampus and cortex of male and female hetAChE KO mice, but BChE activity was preserved. hetAChE KO mice failed to show any difference in terms of locomotion, exploration and anxiety parameters in the open-field test. Animals were then tested for place learning in the water-maze using a ‘sustained acquisition’ protocol (three swim trials per day) or a ‘mild acquisition’ protocol (two swim trials per day) to locate an invisible platform in fixed position (reference memory procedure). Then, during 3 days, they were trained to locate the platform in a variable position (working memory procedure). Learning profiles and probe test performances were similar for hetAChE KO and wildtype mice. When mice were administered intracerebroventricularly (ICV) an oligomeric amyloid β25–35 peptide, generating AD-like toxicity, they failed to show learning deficits. The peptide also failed to generate oxidative stress in forebrain structures. Second, male and female BChE KO mice tested for place learning in the water-maze showed increased acquisition slopes and presence in the training quadrant during the probe test. An increased passive avoidance response was also observed for males. BChE KO mice therefore showed enhanced learning ability in spatial and non-spatial memory tests. In BChE KO mice, the Aβ25–35-induced deficit in place learning was attenuated in males and blocked in females. No changes in lipid peroxidation or ACh levels were observed after Aβ25–35 treatment in BChE KO mice. We conclude that, on the one hand, the increase in cholinergic tonus observed in hetAChE KO mice did not result in increased memory functions but allowed a significant prevention of the deleterious effects of amyloid toxicity. On the other hand, the genetic invalidation elimination of BChE in mice increased learning capacities and lowered the vulnerability to Aβ toxicity

An Intranasal Formulation of Erythropoietin (Neuro-EPO) Prevents Memory Deficits and Amyloid Toxicity in the APPSwe Transgenic Mouse Model of Alzheimer’s Disease

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Neuroprotection in non-transgenic and transgenic mouse models of Alzheimer's disease by positive modulation of σ1 receptors

International audienceThe sigma-1 (σ1) receptor is an endoplasmic reticulum (ER) chaperone protein, enriched in mitochondria-associated membranes. Its activation triggers physiological responses to ER stress and modulate Ca2+ mobilization in mitochondria. Small σ1 agonist molecules activate the protein and act behaviorally as antidepressant, anti-amnesic and neuroprotective agents. Recently, several chemically unrelated molecules were shown to be σ1 receptor positive modulators (PMs), with some of them a clear demonstration of their allostericity. We here examined whether a σ1 PM also shows neuroprotective potentials in pharmacological and genetic models of Alzheimer's disease (AD). For this aim, we describe (±)-2-(3-chlorophenyl)-3,3,5,5-tetramethyl-2-oxo-[1,4,2]-oxazaphosphinane (OZP002) as a novel σ1 PM. OZP002 does not bind σ1 sites but induces σ1 effects in vivo and boosts σ1 agonist activity. OZP002 was antidepressant in the forced swim test and its effect was blocked by the σ1 antagonist NE-100 or in σ1 receptor knockout mice. It potentiated the antidepressant effect of the σ1 agonist igmesine. In mice tested for Y-maze alternation or passive avoidance, OZP002 prevented scopolamine-induced learning deficits, in a NE-100 sensitive manner. Pre-administered IP before an ICV injection of amyloid Aβ25-35 peptide, a pharmacological model of Alzheimer's disease, OZP002 prevented the learning deficits induced by the peptide after one week in the Y-maze, passive avoidance and novel object tests. Biochemical analyses of the mouse hippocampi showed that OZP002 significantly decreased Aβ25-35-induced increases in reactive oxygen species, lipid peroxidation, and increases in Bax, TNFα and IL-6 levels. Immunohistochemically, OZP002 prevented Aβ25-35-induced reactive astrogliosis and microgliosis in the hippocampus. It also alleviated Aβ25-35-induced decreases in synaptophysin level and choline acetyltransferase activity. Moreover, chronically administered in APPswe mice during 2 months, OZP002 prevented learning deficits (in all tests plus place learning in the water-maze) and increased biochemical markers. This study shows that σ1 PM with high neuropotective potential can be identified, combining pharmacological efficacy, selectivity and therapeutic safety, and identifies a novel promising compound, OZP002

FAK activity in cancer-associated fibroblasts is a prognostic marker and a druggable key metastatic player in pancreatic cancer

International audienceCancer-associated fibroblasts (CAFs) are considered the most abundant type of stromal cells in pancreatic ductal adenocarcinoma (PDAC), playing a critical role in tumour progression and chemoresistance; however, a druggable target on CAFs has not yet been identified. Here we report that focal adhesion kinase (FAK) activity (evaluated based on 397 tyrosine phosphorylation level) in CAFs is highly increased compared to its activity in fibroblasts from healthy pancreas. Fibroblastic FAK activity is an independent prognostic marker for disease-free and overall survival of PDAC patients (cohort of 120 PDAC samples). Genetic inactivation of FAK within fibroblasts (FAK kinase-dead, KD) reduces fibrosis and immunosuppressive cell number within primary tumours and dramatically decreases tumour spread. FAK pharmacologic or genetic inactivation reduces fibroblast migration/invasion, decreases extracellular matrix (ECM) expression and deposition by CAFs, modifies ECM track generation and negatively impacts M2 macrophage polarization and migration. Thus, FAK activity within CAFs appears as an independent PDAC prognostic marker and a druggable driver of tumour cell invasion