Evidence for the existence of facilitatory interactions between the dopamine D2 receptor and the oxytocin receptor in the amygdala of the rat. Relevance for anxiolytic actions

Introduction: The amygdala is a limbic region of high value for understanding anxiety and its treatment. Dopamine D2 receptors (D2Rs) and oxytocin receptors (OXTRs) have both been shown to participate in modulating anxiety involving effects in the amygdala. The goal is to understand if D2R-OXTR heterocomplexes exist in the central amygdala and if, through enhancing allosteric receptor-receptor interactions, may enhance anxiolytic actions. Methods: The methods used involve the shock-probe burying test, the in situ proximity ligation assay (PLA), image acquisition and analysis, and the BRET2 assay. Bilateral cannulas were introduced into the amygdala, and the effects of the coadministration of oxytocin and the D2R-like agonist quinpirole into the amygdala were studied. Results: The combination treatment enhanced the anxiolytic effects compared to the single treatment. The D2R/D3R antagonist raclopride blocked the effects of the combination treatment of oxytocin and the D2R agonist, although oxytocin is regarded as a distinct modulator of fear-mediating anxiolytic effects. In situ PLA results indicate the existence of D2R-OXTR heteroreceptor complexes and/or the co-location of OXTR and D2R within the same cell membrane nanodomains in the central amygdala. With BRET2, evidence is given for the existence of D2R-OXTR heteromers in HEK293 cells upon co-transfection. Discussion: The enhanced behavioral effects observed upon co-treatment with OXTR and D2R agonists may reflect the existence of improved positive receptor-receptor interactions in the putative D2R-OXTR heterocomplexes in certain neuronal populations of the basolateral and central amygdala. The D2R-OXTR heterocomplex, especially upon agonist co-activation in the central amygdala, may open a new pharmacological venue for the treatment of anxiety.

Perivascular phosphorylated TDP-43 inclusions are associated with Alzheimer's disease pathology and loss of CD146 and Aquaporin-4

The majority of patients with Alzheimer's disease (AD) exhibit aggregates of Trans-active response DNA binding protein 43 (TDP-43) in their hippocampus, which is associated with a more aggressive disease progression. The TDP-43 inclusions are commonly found in neurons, but also in astrocytes. The impact of the inclusions in astrocytes is less known. In the current study, we investigate the presence of phosphorylated TDP-43 (pTDP-43) inclusions in astrocytic endfeet and their potential association with blood-brain barrier (BBB) damage, glymphatic system dysfunction, and AD pathology. By staining postmortem hippocampal sections from AD patients and non-demented controls against TDP-43 and pTDP-43 together with the astrocytic markers glial fibrillary acidic protein (GFAP), astrocytic endfeet marker Aquaporin-4 (AQP4), and markers for BBB alterations (CD146) and leakiness (Immunoglobulin A), we demonstrate a close association between perivascular pTDP-43 or TDP-43 inclusions and GFAP or AQP4. These perivascular inclusions were more prominent in AD and correlated with the disease severity and loss of CD146 and AQP4. The findings indicate a relationship between pTDP-43 accumulation in astrocytic endfeet and BBB and glymphatic system dysfunction, which may contribute to the downstream pathological events seen in AD patients and the aggressive disease progression.

Molecular basis for different substrate-binding sites and chaperone functions of the BRICHOS domain

Proteins can misfold into fibrillar or amorphous aggregates and molecular chaperones act as crucial guardians against these undesirable processes. The BRICHOS chaperone domain, found in several otherwise unrelated proproteins that contain amyloidogenic regions, effectively inhibits amyloid formation and toxicity but can in some cases also prevent non-fibrillar, amorphous protein aggregation. Here, we elucidate the molecular basis behind the multifaceted chaperone activities of the BRICHOS domain from the Bri2 proprotein. High-confidence AlphaFold2 and RoseTTAFold predictions suggest that the intramolecular amyloidogenic region (Bri23) is part of the hydrophobic core of the proprotein, where it occupies the proposed amyloid binding site, explaining the markedly reduced ability of the proprotein to prevent an exogenous amyloidogenic peptide from aggregating. However, the BRICHOS-Bri23 complex maintains its ability to form large polydisperse oligomers that prevent amorphous protein aggregation. A cryo-EM-derived model of the Bri2 BRICHOS oligomer is compatible with surface-exposed hydrophobic motifs that get exposed and come together during oligomerization, explaining its effects against amorphous aggregation. These findings provide a molecular basis for the BRICHOS chaperone domain function, where distinct surfaces are employed against different forms of protein aggregation.

Biodegradable Ruthenium-Rhenium Complexes Containing Nanoamplifiers: Triggering ROS-Induced CO Release for Synergistic Cancer Treatment

The constrained effectiveness of photodynamic therapy (PDT) has impeded its widespread use in clinical practice. Urgent efforts are needed to address the shortcomings faced in photodynamic therapy, such as photosensitizer toxicity, short half-life, and limited action range of reactive oxygen species (ROS). In this study, a biodegradable copolymer nanoamplifier is reported that contains ruthenium complex (Ru-complex) as photosensitizer (PS) and rhenium complex (Re-complex) as carbon monoxide (CO)-release molecule (CORM). The well-designed nanoamplifier brings PS and CORM into close spatial proximity, significantly promotes the utilization of light-stimulated reactive oxygen species (ROS), and cascaded amplifying CO release, thus enabling an enhanced synergistic effect of PDT and gas therapy for cancer treatment. Moreover, owing to its intrinsic photodegradable nature, the nanoamplifier exhibits good tumor accumulation and penetration ability, and excellent biocompatibility in vivo. These findings suggest that the biodegradable cascaded nanoamplifiers pave the way for a synergistic and clinically viable integration of photodynamic and gas therapy.

Optimizing algal hydrogen photoproduction: a simplified and efficient protocol for anoxic induction in a semi-autotrophic approach

Green microalgae, such as Chlamydomonas reinhardtii, show great potential for producing green hydrogen using only water and sunlight, with no carbon emissions. However, sustainable hydrogen production requires addressing the hydrogenase sensitivity to oxygen and enhancing electron allocation to this enzyme. Previous methods for hydrogen photoproduction rely on a brief nitrogen flushing followed by a dark incubation phase to establish anoxia prior to exposure to high light. In this study, we present a straightforward protocol involving a mixotrophic growth phase followed by a semi-autotrophic hydrogen production phase. During the hydrogen production phase, extended nitrogen flushing induced anoxia in the liquid algae culture, even though oxygen was still present in the headspace. Anoxia was maintained under light at moderate intensity (120 μmol m-2 s-1) and a controlled temperature of 30°C, with an efficient mixing system. Throughout the hydrogen production phase, we monitored dissolved oxygen levels in the culture alongside traditional oxygen measurements in the headspace. Using our protocol with the pgr5 mutant of C. reinhardtii, we achieved a maximum specific rate of 72 μmol H₂ mg-1 Chl h-1 and an average rate of 30-35 μmol H₂ mg-1 Chl h-1 over 10 hours of illumination. Additional nitrogen flushing steps extended anoxia, resulting in a total hydrogen yield of 220 ± 20 mL L-1 over 48 hours of illumination. This performance is attributed to maintaining the redox balance of the plastoquinone pool and minimizing photodamage to the photosystem II complex. Our protocol offers a significant advancement for scalable and sustainable green hydrogen production.

Spatiotemporal Retention of Structural Color and Induced Stiffening in Crosslinked Hydroxypropyl Cellulose Beads

Hydroxypropyl cellulose (HPC) is known for its ability to form cholesteric liquid crystalline phases displaying vivid structural colors. However, these vibrant colors tend to fade over time when the material dries. This issue is a major bottleneck to finding practical applications for these materials. Here this problem is overcome by producing free-standing, millimeter-sized HPC structurally colored beads with spatiotemporal color retention, facilitated by a glutaraldehyde crosslinker. By leveraging the well-known chemically induced stabilization of cholesteric liquid crystalline phases, stable structural colors are achieved for at least three weeks. The presence of glutaraldehyde significantly increases the mechanical stiffness, with Young's modulus rising from 0.3± 0.1 GPa to 1.8± 0.2 GPa. This integrated approach of creating free-standing photonic HPC beads offers a strategy for developing robust and durable photonic HPC materials with enhanced stability, advancing photonic material applications with spatiotemporal color stability.

Commonly prescribed multi-medication therapies exert sex-specific effects on Alzheimer's disease pathology and metabolomic profiles in AppNL-G-F mice: Implications for personalized therapeutics in aging

INTRODUCTION

Polypharmacy is common among older adults and people with dementia. Multi-medication therapy poses risks of harm but also targets comorbidities and risk factors associated with dementia, offering therapeutic potential.

METHODS

We evaluated the effects of two polypharmacy regimens and monotherapies on male and female AppNL-G-F knock-in mice. We assessed functional, emotional, and cognitive outcomes;amyloid pathology; and serum metabolomics profiles.

RESULTS

A combination of metoprolol, simvastatin, aspirin, paracetamol, and citalopram improved memory, reduced amyloid burden and neuroinflammation, and modulated AD-associated metabolomic signatures in male mice, with negligible effects in female mice. Substituting two cardiovascular drugs impacted emotional domains but worsened memory, predominantly in female mice. In males, monotherapies could not explain the combination effects, suggesting drug synergy, whereas in female mice, certain monotherapy effects were lost when combined.

DISCUSSION

This study uncovers the sex-specific effects of polypharmacy in an AD model, identifying mechanisms and biomarkers that can guide gender-specific use of medicines in dementia prevention and management.

HIGHLIGHTS

Two polypharmacy combinations show sex-specific effects on AD pathology and serum metabolomic profiles. Metoprolol+simvastatin+aspirin+paracetamol+citalopram improves memory and amyloid pathology in male mice. Replacing metoprolol and simvastatin with enalapril and atorvastatin eliminates benefits in male mice and impairs memory in female mice. Selected monotherapies produce sex-specific effects but only partially explain the outcomes of the combinations. Metabolomic pathways in serum indicate possible mechanisms and biomarkers for evaluating the effectiveness and safety of personalized therapies in aging and dementia.

Biological brain age and resilience in cognitively unimpaired 70-year-old individuals

INTRODUCTION

This study investigated the associations of brain age gap (BAG)-a biological marker of brain resilience-with life exposures, neuroimaging measures, biological processes, and cognitive function.

METHODS

We derived BAG by subtracting predicted brain age from chronological age in 739 septuagenarians without dementia or neurological disorders. Robust linear regression models assessed BAG associations with life exposures, plasma inflammatory and metabolic biomarkers, magnetic resonance imaging, and cerebrospinal fluid biomarkers of neurodegeneration and vascular brain injury, and cognitive performance.

RESULTS

Greater BAG (older-looking brains) was associated with physical inactivity, diabetes, and stroke, while prediabetes was related to lower BAG, that is, younger-looking brains. Physical activity mitigated the link between obesity and BAG. Greater BAG was associated with greater small vessel disease burden, white-matter alterations, inflammation, high glucose, poorer vascular-related cognitive domains. Sex-specific associations were identified.

DISCUSSION

Vascular-related lifestyles and health shape brain appearance. Inflammation and insulin-related processes may be keys to understanding vascular cognitive disorders.

HIGHLIGHTS

BAG, reflecting deviations from CA, can indicate resilience. Diabetes, stroke, and low physical activity link to "older" brains (greater BAG). Physical activity yielded to "younger" brains in septuagenarians with obesity. High cerebrovascular burden, inflammation, and glucose associate with "older" brains. Sex differences were detected in all BAG-associated factors.

A Polymeric Two-in-One Electron Transport Layer and Transparent Electrode for Efficient Indoor All-Organic Solar Cells

Transparent electrodes (TEs) are vital in optoelectronic devices, enabling the interaction of light and charges. While indium tin oxide (ITO) has traditionally served as a benchmark TE, its high cost prompts the exploration of alternatives to optimize electrode characteristics and improve device efficiencies. Conducting polymers, which combine polymer advantages with metal-like conductivity, emerge as a promising solution for TEs. This work introduces a two-in-one electron transport layer (ETL) and TE based on films of polyethylenimine ethoxylated (PEIE)-modified poly(benzodifurandione) (PBFDO). These PEIE-modified PBFDO layers exhibit a unique combination of properties, including low sheet resistance (130 Ω sq-1), low work function (4.2 eV), and high optical transparency (>85% in the UV-vis-NIR range). In contrast to commonly used poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), the doping level of PBFDO remains unaffected by the PEIE treatment, as verified through UV-vis-NIR absorption and X-ray photoelectron spectroscopy measurements. When employed as a two-in-one ETL/TE in organic solar cells, the PEIE-modified PBFDO electrode exhibits performance comparable to conventional ITO electrodes. Moreover, this work demonstrates all-organic solar cells with record-high power conversion efficiencies of >15.1% under indoor lighting conditions. These findings hold promise for the development of fully printed, all-organic optoelectronic devices.

Reversible Metal-Mediated Molecular Switching of a Phosphaethene Polyaromatic Hydrocarbon

This experimental and theoretical study illustrates how phosphaalkenes, which are isolobal to alkenes, can utilize a variety of external triggers for molecular switching. The E/Z isomerization of a truxene-based phosphaalkene, i. e. TruxC=P-Mes* (Mes*=2,4,6-tris-t-butyl-benzene), is accomplished by irradiation, metal coordination, or deprotonation of the truxene core. The reversible and quantitative Z/E double bond isomerization by gold(I) coordination/decoordination of the phosphorous lone pair represents a novel fuelling strategy for molecular switches.

Brownian Motion Paving the Way for Molecular Translocation in Nanopores

Tracing fast nanopore-translocating analytes requires a high-frequency measurement system that warrants a temporal resolution better than 1 µs. This constraint may practically shift the challenge from increasing the sampling bandwidth to dealing with the rapidly growing noise with frequencies typically above 10 kHz, potentially making it still uncertain if all translocation events are unambiguously captured. Here, a numerical simulation model is presented as an alternative to discern translocation events with different experimental settings including pore dimension, bias voltage, the charge state of the analyte, salt concentration, and electrolyte viscosity. The model allows for simultaneous analysis of forces exerting on a large analyte cohort along their individual trajectories; these forces are responsible for the analyte movement leading eventually to the nanopore translocation. Through tracing the analyte trajectories, the Brownian force is found to dominate the analyte movement in electrolytes until the last moment at which the electroosmotic force determines the final translocation act. The mean dwell time of analytes mimicking streptavidin decreases from ≈6 to ≈1 µs with increasing the bias voltage from ±100 to ±500 mV. The simulated translocation events qualitatively agree with the experimental data with streptavidin. The simulation model is also helpful for the design of new solid-state nanopore sensors.