PCSK9 ablation attenuates Aß pathology, neuroinflammation and cognitive dysfunctions in 5XFAD mice.

BACKGROUND: Increasing evidence highlights the importance of novel players in Alzheimer's disease (AD) pathophysiology, including alterations of lipid metabolism and neuroinflammation. Indeed, a potential involvement of Proprotein convertase subtilisin/kexin type 9 (PCSK9) in AD has been recently postulated. Here, we first investigated the effects of PCSK9 on neuroinflammation in vitro. Then, we examined the impact of a genetic ablation of PCSK9 on cognitive performance in a severe mouse model of AD. Finally, in the same animals we evaluated the effect of PCSK9 loss on Aß pathology, neuroinflammation, and brain lipids. METHODS: For in vitro studies, U373 human astrocytoma cells were treated with Aß fibrils and human recombinant PCSK9. mRNA expression of the proinflammatory cytokines and inflammasome-related genes were evaluated by q-PCR, while MCP-1 secretion was measured by ELISA. For in vivo studies, the cognitive performance of a newly generated mouse line - obtained by crossing 5XFADHet with PCSK9KO mice - was tested by the Morris water maze test. After sacrifice, immunohistochemical analyses were performed to evaluate Aß plaque deposition, distribution and composition, BACE1 immunoreactivity, as well as microglia and astrocyte reactivity. Cholesterol and hydroxysterols levels in mouse brains were quantified by fluorometric and LC-MS/MS analyses, respectively. Statistical comparisons were performed according to one- or two-way ANOVA, two-way repeated measure ANOVA or Chi-square test. RESULTS: In vitro, PCSK9 significantly increased IL6, IL1B and TNFΑ mRNA levels in Aß fibrils-treated U373 cells, without influencing inflammasome gene expression, except for an increase in NLRC4 mRNA levels. In vivo, PCSK9 ablation in 5XFAD mice significantly improved the performance at the Morris water maze test; these changes were accompanied by a reduced corticohippocampal Aß burden without affecting plaque spatial/regional distribution and composition or global BACE1 expression. Furthermore, PCSK9 loss in 5XFAD mice induced decreased microgliosis and astrocyte reactivity in several brain regions. Conversely, knocking out PCSK9 had minimal impact on brain cholesterol and hydroxysterol levels. CONCLUSIONS: In vitro studies showed a pro-inflammatory effect of PCSK9. Consistently, in vivo data indicated a protective role of PCSK9 ablation against cognitive impairments, associated with improved Aß pathology and attenuated neuroinflammation in a severe mouse model of AD. PCSK9 may thus be considered a novel pharmacological target for the treatment of AD.

PCSK9 Affects Astrocyte Cholesterol Metabolism and Reduces Neuron Cholesterol Supplying In Vitro: Potential Implications in Alzheimer's Disease.

The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) involvement in Alzheimer's disease (AD) is poorly investigated. We evaluated the in vitro PCSK9 modulation of astrocyte cholesterol metabolism and neuronal cholesterol supplying, which is fundamental for neuronal functions. Moreover, we investigated PCSK9 neurotoxic effects. In human astrocytoma cells, PCSK9 reduced cholesterol content (−20%; p < 0.05), with a greater effect in presence of beta amyloid peptide (Aß) (−37%; p < 0.01). PCSK9 increased cholesterol synthesis and reduced the uptake of apoE-HDL-derived cholesterol (−36%; p < 0.0001), as well as the LDL receptor (LDLR) and the apoE receptor 2 (ApoER2) expression (−66% and −31%, respectively; p < 0.01). PCSK9 did not modulate ABCA1- and ABCG1-cholesterol efflux, ABCA1 levels, or membrane cholesterol. Conversely, ABCA1 expression and activity, as well as membrane cholesterol, were reduced by Aß (p < 0.05). In human neuronal cells, PCSK9 reduced apoE-HDL-derived cholesterol uptake (−41%; p < 0.001) and LDLR/apoER2 expression (p < 0.05). Reduced cholesterol internalization occurred also in PCSK9-overexpressing neurons exposed to an astrocyte-conditioned medium (−39%; p < 0.001). PCSK9 reduced neuronal cholesterol content overall (−29%; p < 0.05) and increased the Aß-induced neurotoxicity (p < 0.0001). Our data revealed an interfering effect of PCSK9, in cooperation with Aß, on brain cholesterol metabolism leading to neuronal cholesterol reduction, a potentially deleterious effect. PCSK9 also exerted a neurotoxic effect, and thus represents a potential pharmacological target in AD.

Novel peptide-conjugated nanomedicines for brain targeting: In vivo evidence.

Central nervous system (CNS) compartments remain one of the most difficult districts for drug delivery. This is due to the presence of the blood-brain barrier (BBB) that hampers 90% of drug passage, dramatically requiring non-invasive treatment strategies. Here, for the first time, the use of opioid-derived deltorphin-derivative peptides to drive biodegradable and biocompatible polymeric (i.e. poly-lactide-co-glycolide, PLGA) nanomedicines delivery across the BBB was described. Opioid-derived peptides were covalently conjugated to furnish activated polymers which were further used for fluorescently tagged nanoformulations. Beyond reporting production, formulation methodology and full physico-chemical characterization, in vivo tests generated clear proof of BBB crossing and CNS targeting by engineered nanomedicines opening the research to further applications of drug delivery and targeting in CNS disease models.

Heterosynaptic GABAergic plasticity bidirectionally driven by the activity of pre- and postsynaptic NMDA receptors.

Dynamic changes of the strength of inhibitory synapses play a crucial role in processing neural information and in balancing network activity. Here, we report that the efficacy of GABAergic connections between Golgi cells and granule cells in the cerebellum is persistently altered by the activity of glutamatergic synapses. This form of plasticity is heterosynaptic and is expressed as an increase (long-term potentiation, LTPGABA) or a decrease (long-term depression, LTDGABA) of neurotransmitter release. LTPGABA is induced by postsynaptic NMDA receptor activation, leading to calcium increase and retrograde diffusion of nitric oxide, whereas LTDGABA depends on presynaptic NMDA receptor opening. The sign of plasticity is determined by the activation state of target granule and Golgi cells during the induction processes. By controlling the timing of spikes emitted by granule cells, this form of bidirectional plasticity provides a dynamic control of the granular layer encoding capacity.

In vivo study of the role of α6-containing nicotinic acetylcholine receptor in retinal function using subtype-specific RDP-MII(E11R) toxin.

Although α6-contaning (α6*) nicotinic acetylcholine receptors (nAChRs) are densely expressed in the visual system, their role is not well known. We have characterized a family of toxins that are antagonists for α6ß2* receptors and used one of these [RDP-MII(E11R)] to localize α6* nAChRs and investigate their impact on retinal function in adult Long-Evans rats. The α6*nAChRs in retinal tissue were localized using either a fluorescently tagged [RDP-MII(E11R)] or anti-α6-specific antibodies and found to be predominantly at the level of the ganglion cell layer. After intraocular injection of RDP-MII(E11R) in one eye and vehicle or inactive MII in contralateral eyes as controls, we recorded flash electroretinograms (F-ERGs), pattern ERGs (P-ERGs), and cortical visual-evoked potential (VEPs). There was no significant difference in F-ERG between the RDP-MII(E11R)-treated and control eyes. In contrast, P-ERG response amplitude was significantly reduced in the RDP-MII(E11R)-injected eye. Blocking α6* nAChRs at retinal level also decreased the VEP amplitude recorded in the visual cortex contralateral to the injected eye. Because both the cortical and inner retina output were affected by RDP-MII(E11R), whereas photoreceptor output was preserved, we conclude that the reduced visual response was due to an alteration in the function of α6* nAChRs present in the ganglion cell layer.-Barloscio, D., Cerri, E., Domenici, L., Longhi, R., Dallanoce, C., Moretti, M., Vilella, A., Zoli, M., Gotti, C., and Origlia, N. In vivo study of the role of α6-containing nicotinic acetylcholine receptor in retinal function using subtype-specific RDP-MII(E11R) toxin.

LPS-induced histone H3 phospho(Ser10)-acetylation(Lys14) regulates neuronal and microglial neuroinflammatory response.

Epigenetic modifications of DNA and histone proteins are emerging as fundamental mechanisms by which neural cells adapt their transcriptional response to environmental cues, such as, immune stimuli or stress. In particular, histone H3 phospho(Ser10)-acetylation(Lys14) (H3S10phK14ac) has been linked to activation of specific gene expression. The purpose of this study was to investigate the role of H3S10phK14ac in a neuroinflammatory condition. Adult male rats received a intraperitoneal injection of lipopolysaccharide (LPS) (830 µg/Kg/i.p., n = 6) or vehicle (saline 1 mL/kg/i.p., n = 6) and were sacrificed 2 or 6 h later. We showed marked region- and time-specific increases in H3S10phK14ac in the hypothalamus and hippocampus, two principal target regions of LPS. These changes were accompanied by a marked transcriptional activation of interleukin (IL) 1ß, IL-6, Tumour Necrosis Factor (TNF) α, the inducible nitric oxide synthase (iNOS) and the immediate early gene c-Fos. By means of chromatin immunoprecipitation, we demonstrated an increased region- and time-specific association of H3S10phK14ac with the promoters of IL-6, c-Fos and iNOS genes, suggesting that part of the LPS-induced transcriptional activation of these genes is regulated by H3S10phK14ac. Finally, by means of multiple immunofluorescence approach, we showed that increased H3S10phK14ac is cell type-specific, being neurons and reactive microglia, the principal histological types involved in this response. Present data point to H3S10phK14ac as a principal epigenetic regulator of neural cell response to systemic LPS and underline the importance of distinct time-, region- and cell-specific epigenetic mechanisms that regulate gene transcription to understand the mechanistic complexity of neuroinflammatory response to immune challenges.

Activity and circadian rhythm influence synaptic Shank3 protein levels in mice.

Various recent studies revealed that the proteins of the Shank family act as major scaffold organizing elements in the post-synaptic density of excitatory synapses and that their expression level is able to influence synapse formation, maturation and ultimately brain plasticity. An imbalance in Shank3 protein levels has been associated with a variety of neuropsychological and neurodegenerative disorders including autism spectrum disorders and Phelan-McDermid syndrome. Given that sleep disorders and low melatonin levels are frequently observed in autism spectrum disorders, and that circadian rhythms may be able to modulate Shank3 signaling and thereby synaptic function, here, we performed in vivo studies on CBA mice using protein biochemistry to investigate the synaptic expression levels of Shank3α during the day in different brain regions. Our results show that synaptic Shank3 protein concentrations exhibit minor oscillations during the day in hippocampal and striatal brain regions that correlate with changes in serum melatonin levels. Furthermore, as circadian rhythms are tightly connected to activity levels in mice, we increased physical activity using running wheels. The expression of Shank3α increases rapidly by induced activity in thalamus and cortex, but decreases in striatum, superimposing the circadian rhythms of different brain regions. We conclude that synaptic Shank3 proteins build highly dynamic platforms that are modulated by the light:dark cycles but even more so driven by activity. Using wild-type CBA mice, we show that Shank3 is a highly dynamic and activity-regulated protein at synapses. In the hippocampus, changes in synaptic Shank3 levels are influenced by circadian rhythm/melatonin concentration, while running activity increases and decreases levels of Shank3 in the cortex and striatum respectively.

Astrocyte-targeted production of IL-10 induces changes in microglial reactivity and reduces motor neuron death after facial nerve axotomy.

Interleukin-10 (IL-10) is a cytokine that plays a crucial role in regulating the inflammatory response and immune reactions. In the central nervous system (CNS), IL-10 is mainly produced by astrocytes and microglia and it is upregulated after various insults, such as experimental autoimmune encephalomyelitis, middle cerebral artery occlusion, excitotoxicity and traumatic brain injury. To better understand the effects of IL-10 in the normal and injured CNS, we generated transgenic mice (termed GFAP-IL-10Tg) that expressed the murine IL-10 gene under the transcriptional control of the glial fibrillary acidic protein (GFAP) promoter. Previous studies demonstrated marked changes in the microglial phenotype in these mice under basal conditions. The objective of the present study was to investigate the effects of local astrocyte-targeted IL-10 production on glial activation, neuronal degeneration and leukocyte recruitment after axotomy. GFAP-IL-10Tg mice had marked changes in the phenotype of activated microglial cells, as well as in the number of microglial clusters and in microglial cell density. These microglial changes are accompanied by a twofold increase in lymphocyte infiltration in GFAP-IL-10Tg mice and around twofold decrease in neuronal cell death at 21 dpi. Altogether, our findings suggested that astrocyte-targeted production of IL-10 impacted the microglial response and lymphocyte recruitment and culminated in a beneficial effect on neuronal survival.

Alterations in microglial phenotype and hippocampal neuronal function in transgenic mice with astrocyte-targeted production of interleukin-10.

Interleukin-10 (IL-10) is a cytokine classically linked with anti-inflammatory and protective functions in the central nervous system (CNS) in different neurodegenerative and neuroinflammatory conditions. In order to study the specific role of local CNS produced IL-10, we have created a new transgenic mouse line with astrocyte-targeted production of IL-10 (GFAP-IL10Tg). In the present study, the effects of local CNS IL-10 production on microglia, astrocytes and neuronal connectivity under basal conditions were investigated using immunohistochemistry, molecular biology techniques, electrophysiology and behavioural studies. Our results showed that, in GFAP-IL10Tg animals, microglia displayed an increase in density and a specific activated phenotype characterised by morphological changes in specific areas of the brain including the hippocampus, cortex and cerebellum that correlated with the level of transgene expressed IL-10 mRNA. Distinctively, in the hippocampus, microglial cells adopted an elongated morphology following the same direction as the dendrites of pyramidal neurons. Moreover, this IL-10-induced microglial phenotype showed increased expression of certain molecules including Iba1, CD11b, CD16/32 and F4/80 markers, "de novo" expression of CD150 and no detectable levels of either CD206 or MHCII. To evaluate whether this specific activated microglial phenotype was associated with changes in neuronal activity, the electrophysiological properties of pyramidal neurons of the hippocampus (CA3-CA1) were analysed in vivo. We found a lower excitability of the CA3-CA1 synapses and absence of long-term potentiation (LTP) in GFAP-IL10Tg mice. This study is the first description of a transgenic mouse with astrocyte-targeted production of the cytokine IL-10. The findings indicate that IL-10 induces a specific activated microglial phenotype concomitant with changes in hippocampal LTP responses. This transgenic animal will be a very useful tool to study IL-10 functions in the CNS, not only under basal conditions, but also after different experimental lesions or induced diseases.

Identification of 4-amino-2-Pyridones as new potent PCSK9 inhibitors: From phenotypic hit discovery to in vivo tolerability.

Among the strategies to overcome the underperformance of statins in cardiovascular diseases (CVDs), the development of drugs targeting the Proprotein Convertase Subtilisin-like Kexin type 9 (PCSK9) is considered one of the most promising. However, only anti-PCSK9 biological drugs have been approved to date, and orally available small-molecules for the treatment of hypercholesterolemic conditions are still missing on the market. In the present work, we describe the application of a phenotypic approach to the identification and optimization of 4-amino-2-pyridone derivatives as a new chemotype with anti-PCSK9 activity. Starting from an in-house collection of compounds, functional assays on HepG2 cells followed by a chemistry-driven hit optimization campaign, led to the potent anti-PCSK9 candidate 5c. This compound, at 5 µM, totally blocked PCSK9 secretion from HepG2 cells, significantly increased LDL receptor (LDLR) expression, and acted cooperatively with simvastatin by reducing its induction of PCSK9 expression. Finally, compound 5c also proved to be well tolerated in C57BL/6J mice at the tested concentration (40 mg/kg) with no sign of toxicity or behavior modifications.

Evidence for a protective effect of the loss of α4-containing nicotinic acetylcholine receptors on Aß-related neuropathology in Tg2576 mice.

Introduction: Loss of cholinergic neurons as well as α4ß2* (* = containing) nicotinic acetylcholine receptors (nAChRs) is a prominent feature of Alzheimer's disease (AD). Specifically, amyloid ß (Aß), the principal pathogenic factor of AD, is a high affinity ligand for nAChRs. Yet, the pathophysiological role of nAChRs in AD is not well established. Methods: In the present study, we have investigated the effects of the loss of α4* nAChRs on the histological alterations of the Tg2576 mouse model of AD (APPswe) crossing hemizygous APPswe mice with mice carrying the genetic inactivation of α4 nAChR subunit (α4KO). Results: A global decrease in Aß plaque load was observed in the forebrain of APPswe/α4KO mice in comparison with APPswe mice, that was particularly marked in neocortex of 15 month-old mice. At the same age, several alterations in synaptophysin immunoreactivity were observed in cortico-hippocampal regions of APPswe mice that were partially counteracted by α4KO. The analysis of the immunoreactivity of specific astroglia (glial fibrillary acidic protein, GFAP) and microglia (ionized calcium-binding adapter molecule, Iba1) markers showed an increase in the number as well as in the area occupied by these cells in APPswe mice that were partially counteracted by α4KO. Conclusion: Overall, the present histological study points to a detrimental role of α4* nAChRs that may be specific for Aß-related neuropathology.

Hydroxypropyl-ß-Cyclodextrin Depletes Membrane Cholesterol and Inhibits SARS-CoV-2 Entry into HEK293T-ACEhi Cells.

Vaccination has drastically decreased mortality due to coronavirus disease 19 (COVID-19), but not the rate of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Alternative strategies such as inhibition of virus entry by interference with angiotensin-I-converting enzyme 2 (ACE2) receptors could be warranted. Cyclodextrins (CDs) are cyclic oligosaccharides that are able to deplete cholesterol from membrane lipid rafts, causing ACE2 receptors to relocate to areas devoid of lipid rafts. To explore the possibility of reducing SARS-CoV-2 entry, we tested hydroxypropyl-ß-cyclodextrin (HPßCD) in a HEK293T-ACE2hi cell line stably overexpressing human ACE2 and Spike-pseudotyped SARS-CoV-2 lentiviral particles. We showed that HPßCD is not toxic to the cells at concentrations up to 5 mM, and that this concentration had no significant effect on cell cycle parameters in any experimental condition tested. Exposure of HEK293T-ACEhi cells to concentrations of HPßCD starting from 2.5 mM to 10 mM showed a concentration-dependent reduction of approximately 50% of the membrane cholesterol content. In addition, incubation of HEK293T-ACEhi cells with HIV-S-CoV-2 pseudotyped particles in the presence of increasing concentrations of HPßCD (from 0.1 to 10 mM) displayed a concentration-dependent effect on SARS-CoV-2 entry efficiency. Significant effects were detected at concentrations at least one order of magnitude lower than the lowest concentration showing toxic effects. These data indicate that HPßCD is a candidate for use as a SARS-CoV-2 prophylactic agent.

MicroRNA-218 instructs proper assembly of hippocampal networks.

The assembly of the mammalian brain is orchestrated by temporally coordinated waves of gene expression. Post-transcriptional regulation by microRNAs (miRNAs) is a key aspect of this program. Indeed, deletion of neuron-enriched miRNAs induces strong developmental phenotypes, and miRNA levels are altered in patients with neurodevelopmental disorders. However, the mechanisms used by miRNAs to instruct brain development remain largely unexplored. Here, we identified miR-218 as a critical regulator of hippocampal assembly. MiR-218 is highly expressed in the hippocampus and enriched in both excitatory principal neurons (PNs) and GABAergic inhibitory interneurons (INs). Early life inhibition of miR-218 results in an adult brain with a predisposition to seizures. Changes in gene expression in the absence of miR-218 suggest that network assembly is impaired. Indeed, we find that miR-218 inhibition results in the disruption of early depolarizing GABAergic signaling, structural defects in dendritic spines, and altered intrinsic membrane excitability. Conditional knockout of Mir218-2 in INs, but not PNs, is sufficient to recapitulate long-term instability. Finally, de-repressing Kif21b and Syt13, two miR-218 targets, phenocopies the effects on early synchronous network activity induced by miR-218 inhibition. Taken together, the data suggest that miR-218 orchestrates formative events in PNs and INs to produce stable networks.

Melanocortin receptor agonist NDP-α-MSH improves cognitive deficits and microgliosis but not amyloidosis in advanced stages of AD progression in 5XFAD and 3xTg mice.

Introduction: Alzheimer's disease (AD) is the most frequent cause of dementia and still lacks effective therapy. Clinical signs of AD include low levels of endogenous melanocortins (MCs) and previous studies have shown that treatment with MC analogs induces neuroprotection in the early stages of AD. Methods: We investigated the neuroprotective role of MCs in two transgenic mouse models of severe AD using 5 and 7 month-old (mo) 5XFAD mice and 9 and 12 mo 3xTg mice. These mice were subjected to a chronic stimulation of MC receptors (MCRs) with MC analogue Nle4-D-Phe7-α-melanocyte stimulating hormone (NDP-α-MSH, 340 µg/kg, i.p.). Mouse behavior and ex-vivo histological and biochemical analyses were performed after 50 days of treatment. Results: Our analysis demonstrated an improvement in cognitive abilities of AD mice at late stage of AD progression. We also showed that these protective effects are associated with decreased levels of hyperphosphorylated Tau but not with Aß burden, that was unaffected in the hippocampus and in the cortex of AD mice. In addition, an age-dependent NDP effect on glial reactivity was observed only in 3xTg mice whereas a global downregulation of p38 mitogen-activated protein kinase was selectively observed in 7 mo 5XFAD and 14 mo 3xTg mice. Conclusion: Our results suggest that MCR stimulation by NDP-α-MSH could represent a promising therapeutic strategy in managing cognitive decline also at late stage of AD, whereas the effects on neuroinflammation may be restricted to specific stages of AD progression.

Bioresorbable Nanostructured Chemical Sensor for Monitoring of pH Level In Vivo.

Here, the authors report on the manufacturing and in vivo assessment of a bioresorbable nanostructured pH sensor. The sensor consists of a micrometer-thick porous silica membrane conformably coated layer-by-layer with a nanometer-thick multilayer stack of two polyelectrolytes labeled with a pH-insensitive fluorophore. The sensor fluorescence changes linearly with the pH value in the range 4 to 7.5 upon swelling/shrinking of the polymer multilayer and enables performing real-time measurements of the pH level with high stability, reproducibility, and accuracy, over 100 h of continuous operation. In vivo studies carried out implanting the sensor in the subcutis on the back of mice confirm real-time monitoring of the local pH level through skin. Full degradation of the pH sensor occurs in one week from implant in the animal model, and its biocompatibility after 2 months is confirmed by histological and fluorescence analyses. The proposed approach can be extended to the detection of other (bio)markers in vivo by engineering the functionality of one (at least) of the polyelectrolytes with suitable receptors, thus paving the way to implantable bioresorbable chemical sensors.

A regional and cellular analysis of the early intracellular and extracellular accumulation of Aß in the brain of 5XFAD mice.

Intracellular Aß (iAß) expression, extracellular Aß (eAß) plaque formation and microglial reactivity are characteristic neuropathological events of Alzheimer's disease (AD) and have been detected in several transgenic mouse models of this disease. In this work we decided to investigate the early (2-7 months of age) development of these phenomena at both regional and cellular levels in 5XFAD mice, a severe transgenic mouse model of AD. We demonstrated that 1) Aß pathology develops in many but not all brain regions, 2) iAß is transient and almost always followed by eAß in grey matter regions, and the respective levels are roughly proportional, and 3) in about 1/3 of the grey matter regions with Aß pathology and in several white matter regions, eAß plaques can appear where no iAß-positive structures were detected. We also showed that male and female mice share a similar regional and cellular pattern of Aß pathology development that is more prominent in females. Early iAß is associated to the activation of microglia, while subsequent formation of eAß plaques is associated with markedly increased density of microglial cells that acquire a characteristic clustered phenotype. Present analysis is relevant to set a reference for pathophysiological studies and to define specific targets for the test of therapeutic interventions in this widely used AD transgenic model.

Dorsal and ventral striatal neuronal subpopulations differentially disrupt male mouse copulatory behavior.

The specific role of the striatum, especially its dorsolateral (DLS) and dorsomedial (DMS) parts, in male copulatory behavior is still debated. In order to clarify their contribution to male sexual behavior, we specifically ablated the major striatal neuronal subpopulations, direct and indirect medium spiny neurons (dMSNs and iMSNs) in DMS or DLS, and dMSNs, iMSNs and cholinergic interneurons in nucleus accumbens (NAc), The main results of this study can be summarized as follows: In DMS, dMSN ablation causes a reduction in the percent of mice that mount a receptive female, and a complex alteration in the parameters of the copulatory performance, that is largely opposite to the alterations induced by iMSN ablation. In DLS, dMSN ablation causes a widespread alteration in the copulatory behavior parameters, that tends to disappear at repetition of the test; iMSN ablation induces minor copulatory behavior alterations that are complementary to those observed after dMSN ablation. In NAc, dMSN ablation causes a marked reduction in the percent of mice that mount a receptive female and a disruption of copulatory behavior, while iMSN ablation induces minor copulatory behavior alterations that are opposite to those observed with dMSN ablation, and cholinergic neuron ablation induces a selective decrease in mount latency. Overall, present data point to a complex region and cell-specific contribution to copulatory behavior of the different neuronal subpopulations of both dorsal and ventral striatum, with a prominent role of the dMSNs of the different subregions.

S100B dysregulation during brain development affects synaptic SHANK protein networks via alteration of zinc homeostasis.

Autism Spectrum Disorders (ASD) are caused by a combination of genetic predisposition and nongenetic factors. Among the nongenetic factors, maternal immune system activation and zinc deficiency have been proposed. Intriguingly, as a genetic factor, copy-number variations in S100B, a pro-inflammatory damage-associated molecular pattern (DAMP), have been associated with ASD, and increased serum S100B has been found in ASD. Interestingly, it has been shown that increased S100B levels affect zinc homeostasis in vitro. Thus, here, we investigated the influence of increased S100B levels in vitro and in vivo during pregnancy in mice regarding zinc availability, the zinc-sensitive SHANK protein networks associated with ASD, and behavioral outcomes. We observed that S100B affects the synaptic SHANK2 and SHANK3 levels in a zinc-dependent manner, especially early in neuronal development. Animals exposed to high S100B levels in utero similarly show reduced levels of free zinc and SHANK2 in the brain. On the behavioral level, these mice display hyperactivity, increased stereotypic and abnormal social behaviors, and cognitive impairment. Pro-inflammatory factors and zinc-signaling alterations converge on the synaptic level revealing a common pathomechanism that may mechanistically explain a large share of ASD cases.

Identification of a Thyroid Hormone Derivative as a Pleiotropic Agent for the Treatment of Alzheimer's Disease.

The identification of effective pharmacological tools for Alzheimer's disease (AD) represents one of the main challenges for therapeutic discovery. Due to the variety of pathological processes associated with AD, a promising route for pharmacological intervention involves the development of new chemical entities that can restore cellular homeostasis. To investigate this strategy, we designed and synthetized SG2, a compound related to the thyroid hormone thyroxine, that shares a pleiotropic activity with its endogenous parent compound, including autophagic flux promotion, neuroprotection, and metabolic reprogramming. We demonstrate herein that SG2 acts in a pleiotropic manner to induce recovery in a C. elegans model of AD based on the overexpression of Aß42 and improves learning abilities in the 5XFAD mouse model of AD. Further, in vitro ADME-Tox profiling and toxicological studies in zebrafish confirmed the low toxicity of this compound, which represents a chemical starting point for AD drug development.

PLGA-PEG-ANG-2 Nanoparticles for Blood-Brain Barrier Crossing: Proof-of-Concept Study.

The treatment of diseases that affect the central nervous system (CNS) represents a great research challenge due to the restriction imposed by the blood-brain barrier (BBB) to allow the passage of drugs into the brain. However, the use of modified nanomedicines engineered with different ligands that can be recognized by receptors expressed in the BBB offers a favorable alternative for this purpose. In this work, a BBB-penetrating peptide, angiopep-2 (Ang-2), was conjugated to poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles through pre- and post-formulation strategies. Then, their ability to cross the BBB was qualitatively assessed on an animal model. Proof-of-concept studies with fluorescent and confocal microscopy studies highlighted that the brain-targeted PLGA nanoparticles were able to cross the BBB and accumulated in neuronal cells, thus showing a promising brain drug delivery system.