Biology subjects

Lourenco, M. V.

Publications and source records attributed to Lourenco, M. V..

7 recordsLinked to original sources

bioRxiv2024

Genetic reduction of the translational repressors FMRP and 4E-BP2 preserves memory in mouse models of Alzheimer's disease

Alzheimers disease (AD) is characterized by progressive memory decline. Converging evidence indicates that hippocampal mRNA translation (protein synthesis) is defective in AD. Here, we show that genetic reduction of the translational repressors, Fragile X messenger ribonucleoprotein (FMRP) or eukaryotic initiation factor 4E (eIF4E)-binding protein 2 (4E-BP2), prevented the attenuation of hippocampal protein synthesis and memory impairment induced by AD-linked amyloid-{beta} oligomers (A{beta}Os) in mice. Moreover, genetic reduction of 4E-BP2 rescued memory deficits in aged APPswe/PS1dE9 (APP/PS1) transgenic mouse model of AD. Our findings demonstrate that strategies targeting repressors of mRNA translation correct hippocampal protein synthesis and memory deficits in AD models. Results suggest that modulating pathways controlling brain mRNA translation may confer memory benefits in AD.

neuroscience↗

bioRxiv2023

Effects of sex and gestational exercise on pain perception, BDNF and irisin levels in an animal model of ADHD

Abnormal cognitive and sensorial properties have been reported in patients with psychiatric and neurodevelopmental conditions, such as attention deficit hyperactivity disorder (ADHD). ADHD patients exhibit impaired dopaminergic signaling and plasticity in brain areas related to cognitive and sensory processing. The spontaneous hypertensive rat (SHR), in comparison to the Wistar Kyoto rat (WKY), is the most used genetic animal model to study ADHD. Brain neurotrophic factor (BDNF), critical for midbrain and hippocampal dopaminergic neuron survival and differentiation, is reduced in both ADHD subjects and SHR. Physical exercise (e.g. swimming) promotes neuroplasticity and improves cognition by increasing BDNF and irisin. Here we investigate the effects of gestational swimming on sensorial and behavioral phenotypes, striatal dopaminergic parameters, and hippocampal FNDC5/irisin and BDNF levels observed in WKY and SHR. Gestational swimming improved nociceptive reflex impairment in SHR rats and increased hippocampal BDNF levels in a sex-dependent manner in adolescent offspring. Sex differences were observed in hippocampal FNDC5/irisin levels, with females presenting lower levels than males. Our results contribute to the notion that swimming during pregnancy is a promising alternative to improve ADHD phenotypes in the offspring. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/551984v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1737c93org.highwire.dtl.DTLVardef@f7bb8aorg.highwire.dtl.DTLVardef@3999f0org.highwire.dtl.DTLVardef@1a981a2_HPS_FORMAT_FIGEXP M_FIG C_FIG

animal behavior and cognition↗

bioRxiv2023

Stimulation of mRNA translation rescues hippocampal synaptic plasticity and memory in mouse models of Alzheimer's disease

Impaired synaptic plasticity and progressive memory deficits are major hallmarks of Alzheimers disease (AD). Hippocampal mRNA translation, required for memory consolidation, is defective in AD. Here, we show that systemic treatment with (2R,6R)- hydroxynorketamine (HNK), an active metabolite of the antidepressant ketamine, prevented deficits in hippocampal mRNA translation, long-term potentiation (LTP) and memory induced by AD-linked amyloid-{beta} oligomers (A{beta}Os) in mice. HNK activated hippocampal extracellular signal-regulated kinase 1/2 (ERK1/2), mechanistic target of rapamycin (mTOR), and p70S6 kinase 1 (S6K1)/ribosomal protein S6 (S6), which promote protein synthesis and synaptic plasticity. Stimulation of S6 phosphorylation by HNK was mTORC1-dependent, while rescue of hippocampal LTP and memory in HNK-treated A{beta}O-infused mice was ERK1/2-dependent and, partially, mTORC1- dependent. Remarkably, treatment with HNK corrected LTP and memory deficits in aged APP/PS1 mice. Transcriptomic analysis further showed that HNK rescued signaling pathways that are aberrant in APP/PS1 mice, including inflammatory and hormonal responses, and programmed cell death. Taken together, our findings demonstrate that HNK induces signaling and transcriptional responses that correct deficits in hippocampal synaptic plasticity and memory in AD mouse models. These results raise the prospect that HNK could serve as a therapeutic to prevent or reverse memory decline in AD.

neuroscience↗

bioRxiv2023

Gestational physical exercise prevents early-life behavioral impairments and normalizes dopamine D2 receptor expression in the frontal cortex in the offspring of a rat model of attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is characterized by inattention, hyperactivity and impulsivity, and develops most frequently during childhood and adolescence. Spontaneously hypertensive rats (SHR) are the most used experimental model for the study of ADHD. SHR exhibit behavioral impairments that recapitulate phenotypes observed in individuals with ADHD. SHR further develop dopaminergic hypofunction in frontostriatal circuits and an imbalance in dopamine and norepinephrine systems. Maternal physical exercise (e.g., swimming) during pregnancy has been shown to promote angiogenesis, neurogenesis, learning, and memory in the offspring of control rats. We investigated the impact of gestational swimming on behavioral and dopaminergic parameters in childhood (1-2 weeks of age) and adolescent (4-5 weeks of age) SHR and Wistar Kyoto rats (WKY), used as a control. Maternal gestational swimming resulted in a reversal of neurodevelopmental impairments in behavior, assessed by the righting reflex and olfactory recognition tests, in the offspring. Furthermore, during adolescence, SHRs from exercised dams exhibited reduced novelty seeking, an important behavioral trait in this developmental period. Finally, SHRs exhibited increased expression of dopamine transporter (DAT) and D2 receptors (D2R) in the frontal cortex. D2R expression was normalized in the frontal cortex of adolescent SHRs whose mothers were exercised. Results suggest that physical exercise during pregnancy could be an effective preventative strategy against ADHD-associated behavioral and neurochemical phenotypes in the offspring. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/550350v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1a3ca8corg.highwire.dtl.DTLVardef@46d319org.highwire.dtl.DTLVardef@1cd1eddorg.highwire.dtl.DTLVardef@1a54431_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

The unfolded protein response transcription factor XBP1s ameliorates Alzheimer`s disease by improving synaptic function and proteostasis

Alteration in the buffering capacity of the proteostasis network is an emerging feature of Alzheimers disease (AD), highlighting the occurrence of endoplasmic reticulum (ER) stress. The unfolded protein response (UPR) is the main adaptive pathway to cope with protein folding stress at the ER. Inositol requiring enzyme-1 (IRE1) is an ER-located kinase and endoribonuclease that operates as a central ER stress sensor, enabling the establishment of adaptive and repair programs through the control of the expression of the transcription factor X-Box binding protein 1 (XBP1). A polymorphism in the XBP1 promoter has been suggested as a risk factor for AD. To artificially enforce the adaptive capacity of the UPR in the AD brain, we developed strategies to express the active form of XBP1 in neurons using preclinical models. Overexpression of an active form of XBP1 in the nervous system using transgenic mice significantly reduced the load of amyloid deposits in the cerebral cortex and hippocampus and preserved synaptic and cognitive function. Moreover, local delivery of XBP1 into the hippocampus of an AD mice using adeno-associated vectors improved long-term potentiation, memory performance, and dendritic spine density. Quantitative proteomics of the hippocampus revealed that XBP1 expression corrects a large proportion of the alterations observed in the 5xFAD model, restoring the levels of several synaptic proteins and factors involved in actin cytoskeleton regulation and axonal growth. Our results illustrate the therapeutic potential of targeting UPR-dependent gene expression programs as a strategy to ameliorate AD features and sustain synaptic function.

animal behavior and cognition↗

bioRxiv2021

Age-linked suppression of lipoxin A4 mediates cognitive deficits in mice and humans

Age increases the risk for cognitive impairment and is the single major risk factor for Alzheimers disease (AD), the most prevalent form of dementia in the elderly. The pathophysiological processes triggered by aging that render the brain vulnerable to dementia involve, at least in part, changes in inflammatory mediators. Here we show that lipoxin A4 (LXA4), a lipid mediator of inflammation resolution known to stimulate endocannabinoid signaling in the brain, is reduced in the aging central nervous system. We demonstrate that genetic suppression of 5-lipoxygenase (5-LOX), the enzyme mediating LXA4 synthesis, promotes learning impairment in mice. Conversely, administration of exogenous LXA4 attenuated cytokine production and memory loss induced by inflammation in mice. We further show that cerebrospinal fluid LXA4 is reduced in patients with dementia and positively associates with memory performance, brain-derived neurotrophic factor (BDNF), and AD-linked amyloid-. Our findings suggest that reduced LXA4 levels may lead to vulnerability to age-related cognitive disorders and that promoting LXA4 signaling may comprise an effective strategy to prevent early cognitive decline in AD.

neuroscience↗

bioRxiv2020

Correction of eIF2-dependent defects in brain protein synthesis, synaptic plasticity, and memory in mouse models of Alzheimer's disease

Neuronal protein synthesis is essential for long-term memory consolidation. Conversely, dysregulation of protein synthesis has been implicated in a number of neurodegenerative disorders, including Alzheimers disease (AD). Several types of cellular stress trigger the activation of protein kinases that converge on the phosphorylation of eukaryotic translation initiation factor 2 (eIF2-P). This leads to attenuation of cap-dependent mRNA translation, a component of the integrated stress response (ISR). We show that AD brains exhibit increased eIF2-P and reduced eIF2B, key components of the eIF2 translation initiation complex. We further demonstrate that attenuating the ISR with the small molecule compound ISRIB (ISR Inhibitor) rescues hippocampal protein synthesis and corrects impaired synaptic plasticity and memory in mouse models of AD. Our findings suggest that attenuating eIF2-P-mediated translational inhibition may comprise an effective approach to alleviate cognitive decline in AD.

neuroscience↗