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.

Quantifying CO-release from a photo-CORM using 19F NMR: An investigation into light-induced CO delivery.

Carbon monoxide (CO) is an innate signaling molecule that can regulate immune responses and interact with crucial elements of the circadian clock. Moreover, pharmacologically, CO has been substantiated for its therapeutic advantages in animal models of diverse pathological conditions. Given that an excessive level of CO can be toxic, it is imperative to quantify the necessary amount for therapeutic use accurately. However, estimating gaseous CO is notably challenging. Therefore, novel techniques are essential to quantify CO in therapeutic applications and overcome this obstacle precisely. The classical Myoglobin (Mb) assay technique has been extensively used to determine the amount of CO-release from CO-releasing molecules (CORMs) within therapeutic contexts. Nevertheless, specific challenges arise when applying the Mb assay to evaluate CORMs featuring innovative molecular architectures. Here, we report a fluorinated photo-CORM (CORM-FBS) for the photo-induced CO-release. We employed the 19F NMR spectroscopy approach to monitor the release of CO as well as quantitative evaluation of CO release. This new 19F NMR approach opens immense opportunities for researchers to develop reliable techniques for identifying molecular structures, quantitative studies of drug metabolism, and monitoring the reaction process.

GABA co-released from striatal dopamine axons dampens phasic dopamine release through autoregulatory GABAA receptors.

Striatal dopamine axons co-release dopamine and gamma-aminobutyric acid (GABA), using GABA provided by uptake via GABA transporter-1 (GAT1). Functions of GABA co-release are poorly understood. We asked whether co-released GABA autoinhibits dopamine release via axonal GABA type A receptors (GABAARs), complementing established inhibition by dopamine acting at axonal D2 autoreceptors. We show that dopamine axons express α3-GABAAR subunits in mouse striatum. Enhanced dopamine release evoked by single-pulse optical stimulation in striatal slices with GABAAR antagonism confirms that an endogenous GABA tone limits dopamine release. Strikingly, an additional inhibitory component is seen when multiple pulses are used to mimic phasic axonal activity, revealing the role of GABAAR-mediated autoinhibition of dopamine release. This autoregulation is lost in conditional GAT1-knockout mice lacking GABA co-release. Given the faster kinetics of ionotropic GABAARs than G-protein-coupled D2 autoreceptors, our data reveal a mechanism whereby co-released GABA acts as a first responder to dampen phasic-to-tonic dopamine signaling.

RSS and ROS Sequentially Activated Carbon Monoxide Release for Boosting NIR Imaging-Guided On-Demand Photodynamic Therapy.

Carbon monoxide shows great therapeutic potential in anti-cancer. In particular, the construction of multifunctional CO delivery systems can promote the precise delivery of CO and achieve ideal therapeutic effects, but there are still great challenges in design. In this work, a RSS and ROS sequentially activated CO delivery system is developed for boosting NIR imaging-guided on-demand photodynamic therapy. This designed system is composed of a CO releaser (BOD-CO) and a photosensitizer (BOD-I). BOD-CO can be specifically activated by hydrogen sulfide with simultaneous release of CO donor and NIR fluorescence that can identify H2S-rich tumors and guide light therapy, also depleting H2S in the process. Moreover, BOD-I generates 1O2 under long-wavelength light irradiation, enabling both PDT and precise local release of CO via a photooxidation mechanism. Such sequential activation of CO release by RSS and ROS ensured the safety and controllability of CO delivery, and effectively avoided leakage during delivery. Importantly, cytotoxicity and in vivo studies reveal that the release of CO combined with the depletion of endogenous H2S amplified PDT, achieving ideal anticancer results. It is believed that such theranostic nanoplatform can provide a novel strategy for the precise CO delivery and combined therapy involved in gas therapy and PDT.

Alterations in neurotransmitter co-release in Parkinson's disease.

Parkinson's disease is a neurological disorder characterized by degeneration of midbrain dopamine neurons, which results in numerous adaptations in basal ganglia circuits. Research over the past twenty-five years has identified that midbrain dopamine neurons of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) co-release multiple other transmitters including glutamate and GABA, in addition to their canonical transmitter, dopamine. This review summarizes previous work characterizing neurotransmitter co-release from dopamine neurons, work examining potential changes in co-release dynamics that result in animal models of Parkinson's disease, and future opportunities for determining how dysfunction in co-release may contribute to circuit dysfunction in Parkinson's disease.

UBR-1 ubiquitin ligase regulates the balance between GABAergic and glutamatergic signaling.

Excitation/inhibition (E/I) balance is carefully maintained by the nervous system. The neurotransmitter GABA has been reported to be co-released with its sole precursor, the neurotransmitter glutamate. The genetic and circuitry mechanisms to establish the balance between GABAergic and glutamatergic signaling have not been fully elucidated. Caenorhabditis elegans DVB is an excitatory GABAergic motoneuron that drives the expulsion step in the defecation motor program. We show here that in addition to UNC-47, the vesicular GABA transporter, DVB also expresses EAT-4, a vesicular glutamate transporter. UBR-1, a conserved ubiquitin ligase, regulates DVB activity by suppressing a bidirectional inhibitory glutamate signaling. Loss of UBR-1 impairs DVB Ca2+ activity and expulsion frequency. These impairments are fully compensated by the knockdown of EAT-4 in DVB. Further, glutamate-gated chloride channels GLC-3 and GLC-2/4 receive DVB's glutamate signals to inhibit DVB and enteric muscle activity, respectively. These results implicate an intrinsic cellular mechanism that promotes the inherent asymmetric neural activity. We propose that elevated glutamate in ubr-1 mutants, being the cause of the E/I shift, potentially contributes to Johanson Blizzard syndrome.

Transdermal carbon monoxide delivery.

Overuse injuries or acute trauma in joints often lead to painful tendinopathy, and pharmacological treatment effects are limited. The site of the disease is hard to reach with drugs, both systemically and through the skin. Therapeutic gases may close this gap, as they permeate easier through tissues than conventional small molecules. We present a patch device releasing the anti-inflammatory gas carbon monoxide (CO) through the skin to the subcutaneous tendons and tissues. CO is chemically generated upon device activation and its design maximizes CO exposure to the underlying skin and protects the patient from all side and degradation products. The patch delivered CO successfully through the intact skin, granting lasting, subcutaneous CO exposure for up to 16 h. Furthermore, the released CO induced the proliferation of fibroblasts and the polarization of monocytes into anti-inflammatory M2 macrophages. In conclusion, the CO-releasing device might open an entirely new treatment option against tendinopathies in case of a positive outcome of future in vivo studies.

Multifunctional BODIPY embedded non-woven fabric for CO release and singlet oxygen generation.

Materials that can simultaneously release CO and generate singlet oxygen upon visible light irradiation under ambient conditions are highly desirable for therapeutic applications. Furthermore, materials that can sequester the undesirable side products into the matrix without affecting the release of CO and singlet oxygen generation would allow them to be used for practical applications. Focussing on these aspects, we prepared two dipicolylamine appended BODIPY­manganese(I) tricarbonyl complexes wherein the metal core was systematically tethered at 5- and 8- positions of the BODIPY core. The complexes were embedded into a polymer matrix via electrospinning and the resulting non-woven fabrics showed CO release as well as singlet oxygen generation upon irradiation. While the hybrid materials were non-toxic in dark, they were strongly photocytotoxic to c6 cancer cells when exposed to light. Rapid CO release alongside significant singlet oxygen generation, indefinite dark stability, good biocompatibility and negligible dark toxicity makes these fabrics a potent candidate for phototherapeutic applications.

Light activated simultaneous release and recognition of biological signaling molecule carbon monoxide (CO).

The therapeutic action of carbon monoxide (CO) is very well known and has been studied on various types of tissues and animals. However, real-time spatial and temporal tracking and release of CO is still a challenging task. This paper reported an amphiphilic CO sensing probe NP and phospholipid 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) based nanoscale vesicular sensing system Ves-NP consisting of NP. The liposomal sensing system (Ves-NP) showed good selectivity and sensitivity for CO without any interference from other relevant biological analytes. Detection of CO is monitored by fluorescence OFF-ON signal. Ves-NP displayed LOD of 5.94 µM for CO detection with a response time of 5 min. Further, in a novel attempt, Ves-NP is co-embedded with the amphiphilic CO-releasing molecule 1-Mn(CO)3 to make an analyte replacement probe Ves-NP-CO. Having a both CO releasing and sensing moiety at the surface of the same liposomal system Ves-NP-CO play a dual role. Ves-NP-CO is used for the simultaneous release and recognition of CO that can be controlled by light. Thus, in this novel approach, for the first time we have attached both the release and recognition units of CO in the vesicular surface, both release and recognition simultaneously monitored by the change in fluorescent OFF-ON signal.

Partially Reduced MIL-100(Fe) as a CO Carrier for Sustained CO Release and Regulation of Macrophage Phenotypic Polarization.

Carbon monoxide (CO) is a bioactive molecule with high potential as it shows promising efficacy for regulating inflammation. Materials capable of storing and delivering CO are of great potential therapeutic value. Although CO-releasing molecules (CORMs) have been developed to deliver CO, the short CO duration of minutes to 2 h confines their practical use. In this study, partially reduced MIL-100(Fe) as a new CO-releasing nanoMOF was developed and used for sustained CO release and macrophage (MA) phenotypic polarization regulation. MIL-100(Fe) was synthesized and mildly annealed in vacuum for partial reduction. When the annealing temperature was lower than 250 °C, less Fe(II) present in MIL-100(Fe) and the subsequent CO adsorption and desorption profiles displayed typical features of physisorption. While it was annealed at 250 °C, it showed about 20% of Fe(III) was reduced, which resulted in chemisorption of CO due to the high coordination affinity of Fe(II) to CO. The loading amount of CO was increased, and the CO release was prolonged for about 24 h. Furthermore, the CO release from this nanoMOF could alter the lipopolysaccharide (LPS)-induced macrophage from M1 to the alternative M2 phenotype and promoted the growth of endothelial cells (ECs) by paracrine regulation of MA. It can be envisioned as a promising CO-releasing solid for biomedical application.

Synaptic Projections of Motoneurons Within the Spinal Cord.

Motoneurons have long been considered as the final common pathway of the nervous system, transmitting the neural impulses that are transduced into action.While many studies have focussed on the inputs that motoneurons receive from local circuits within the spinal cord and from other parts of the CNS, relatively few have investigated the targets of local axonal projections from motoneurons themselves, with the notable exception of those contacting Renshaw cells or other motoneurons.Recent research has not only characterised the detailed features of the excitatory connections between motoneurons and Renshaw cells but has also established that Renshaw cells are not the only target of motoneurons axons within the spinal cord. Motoneurons also form synaptic contacts with other motoneurons as well as with a subset of ventrally located V3 interneurons. These findings indicate that motoneurons cannot be simply viewed as the last relay station delivering the command drive to muscles, but perform an active role in the generation and modulation of motor patterns.

Mesoporous Bioactive Glasses Incorporated into an Injectable Thermosensitive Hydrogel for Sustained Co-Release of Sr2+ Ions and N-Acetylcysteine.

An injectable delivery platform for promoting delayed bone healing has been developed by combining a thermosensitive polyurethane-based hydrogel with strontium-substituted mesoporous bioactive glasses (MBG_Sr) for the long-term and localized co-delivery of pro-osteogenic Sr2+ ions and an osteogenesis-enhancing molecule, N-Acetylcysteine (NAC). The incorporation of MBG_Sr microparticles, with a final concentration of 20 mg/mL, did not alter the overall properties of the thermosensitive hydrogel, in terms of sol-to-gel transition at a physiological-like temperature, gelation time, injectability and stability in aqueous environment at 37 °C. In particular, the hydrogel formulations (15% w/v polymer concentration) showed fast gelation in physiological conditions (1 mL underwent complete sol-to-gel transition within 3-5 min at 37 °C) and injectability in a wide range of temperatures (5-37 °C) through different needles (inner diameter in the range 0.4-1.6 mm). In addition, the MBG_Sr embedded into the hydrogel retained their full biocompatibility, and the released concentration of Sr2+ ions were effective in promoting the overexpression of pro-osteogenic genes from SAOS2 osteoblast-like cells. Finally, when incorporated into the hydrogel, the MBG_Sr loaded with NAC maintained their release properties, showing a sustained ion/drug co-delivery along 7 days, at variance with the MBG particles as such, showing a strong burst release in the first hours of soaking.

Divergent properties and independent regulation of striatal dopamine and GABA co-transmission.

Substantia nigra pars compacta (SNc) dopamine neurons play a key role in regulating the activity of striatal circuits within the basal ganglia. In addition to dopamine, these neurons release several other transmitters, including the major inhibitory neurotransmitter γ-aminobutyric acid (GABA). Both dopamine and GABA are loaded into SNc synaptic vesicles by the vesicular monoamine transporter 2 (VMAT2), and co-release of GABA provides strong inhibition to the striatum by directly inhibiting striatal medium spiny projection neurons (MSNs) through activation of GABAA receptors. Here, we found that despite both dopamine and GABA being co-packaged by VMAT2, the properties of transmission, including Ca2+ sensitivity, release probability, and requirement of active zone scaffolding proteins, differ between the two transmitters. Moreover, the extent by which presynaptic neuromodulators inhibit co-transmission also varied. Differences in modulation and the mechanisms controlling release allow for independent regulation of dopamine and GABA signals despite both being loaded via similar mechanisms.

An atlas of transcriptionally defined cell populations in the rat ventral tegmental area.

The ventral tegmental area (VTA) is a complex brain region that is essential for reward function and frequently implicated in neuropsychiatric disease. While decades of research on VTA function have focused on dopamine neurons, recent evidence has identified critical roles for GABAergic and glutamatergic neurons in reward processes. Additionally, although subsets of VTA neurons express genes involved in the synthesis and transport of multiple neurotransmitters, characterization of these combinatorial populations has largely relied on low-throughput methods. To comprehensively define the molecular architecture of the VTA, we performed single-nucleus RNA sequencing on 21,600 cells from the rat VTA. Analysis of neuronal subclusters identifies selective markers for dopamine and combinatorial neurons, reveals expression profiles for receptors targeted by drugs of abuse, and demonstrates population-specific enrichment of gene sets linked to brain disorders. These results highlight the heterogeneity of the VTA and provide a resource for further exploration of VTA gene expression.

X-ray-Triggered CO Release Based on GdW10/MnBr(CO)5 Nanomicelles for Synergistic Radiotherapy and Gas Therapy.

Carbon monoxide (CO) therapy has become a hot topic in the field of gas therapy because of its application prospect in the treatment of various diseases. Due to the high affinity for human hemoglobin, the main challenge of CO-loaded nanomedicine is the lack of selectivity and toxicity in the delivery process. Although many commercial CO-releasing molecules (CORMs) have been widely developed because of their ability to deliver CO, CORMs still have some disadvantages, including difficult on-demand controlled CO release, poor solubility, and potential toxicity, which are limiting their further application. Herein, an X-ray-triggered CO-releasing nanomicelle system (GW/MnCO@PLGA) based on GdW10 nanoparticles (NPs) (GW) and MnBr(CO)5 (MnCO) encapsulating in the poly(lactic-co-glycolic acid) (PLGA) polymer was constructed for synergistic CO radiotherapy (RT). The production of strongly oxidative superoxide anion (O2-•) active species can lead to cell apoptosis under the X-ray sensitization of GW. Moreover, strongly oxidative O2-• radicals further oxidize and compete with the Mn center, resulting in the on-demand release of CO. The radio/gas therapy synergy to enhance the efficient tumor inhibition of the nanomicelles was investigated in vivo and in vitro. Therefore, the establishment of an X-ray-triggered controlled CO release system has great application potential for further synergistic RT CO therapy in deep tumor sites.

Co-packaging of opposing neurotransmitters in individual synaptic vesicles in the central nervous system.

Many mammalian neurons release multiple neurotransmitters to activate diverse classes of postsynaptic ionotropic receptors. Entopeduncular nucleus somatostatin (EP Sst+) projection neurons to the lateral habenula (LHb) release both glutamate and GABA, but it is unclear whether these are packaged into the same or segregated pools of synaptic vesicles. Here, we describe a method combining electrophysiology, spatially patterned optogenetics, and computational modeling designed to analyze the mechanism of glutamate/GABA co-release in mouse brain. We find that the properties of postsynaptic currents elicited in LHb neurons by optogenetically activating EP Sst+ terminals are only consistent with co-packaging of glutamate/GABA into individual vesicles. Furthermore, presynaptic neuromodulators that weaken EP Sst+ to LHb synapses maintain the co-packaging of glutamate/GABA while reducing vesicular release probability. Our approach is applicable to the study of multi-transmitter neurons throughout the brain, and our results constrain the mechanisms of neuromodulation and synaptic integration in LHb.

Roles of VGLUT2 and Dopamine/Glutamate Co-Transmission in Selective Vulnerability to Dopamine Neurodegeneration.

Growing evidence has established that a subset of dopamine (DA) neurons co-release glutamate and express vesicular glutamate transporter 2 (VGLUT2). VGLUT2 expression in DA neurons plays a key role in selective vulnerability to DA neurodegeneration in Parkinson's disease (PD). In this review, we summarize recent findings on impacts of VGLUT2 expression and glutamate co-release from DA neurons on selective DA neuron vulnerability. We present evidence that DA neuron VGLUT2 expression may be neuroprotective, boosting DA neuron resilience in the context of ongoing neurodegenerative processes in PD. We highlight genetic and pesticide models of PD that have provided mechanistic insights into selective DA neuron vulnerability. Finally, we discuss potential neuroprotective mechanisms, focusing on roles of VGLUT2 and glutamate in promoting mitochondrial health and diminishing oxidative stress and excitotoxicity. Elucidating these mechanisms may ultimately lead to more effective treatments to boost DA neuron resilience that can slow or even prevent DA neurodegeneration.

Co-transport and co-release of Eu(III) with bentonite colloids in saturated porous sand columns: Controlling factors and governing mechanisms.

Accurate prediction of the colloid-driven transport of radionuclides in porous media is critical for the long-term safety assessment of radioactive waste disposal repository. However, the co-transport and corelease process of radionuclides with colloids have not been well documented, the intrinsic mechanisms for colloids-driven retention/transport of radionuclides are still pending for further discussion. Thus the controlling factors and governing mechanisms of co-transport and co-release behavior of Eu(III) with bentonite colloids (BC) were discussed and quantified by combining laboratory-scale column experiments, colloid filtration theory and advection dispersion equation model. The results showed that the role of colloids in facilitating or retarding the Eu(III) transport in porous media varied with cations concentration, pH, and humic acid (HA). The transport of Eu(III) was facilitated by the dispersed colloids under the low ionic strength and high pH conditions, while was impeded by the aggregated colloids cluster. The enhancement of Eu(III) transport was not monotonically risen with the increase of colloids concentration, the most optimized colloids concentration in facilitating Eu(III) transport was approximately 150 mg L-1. HA showed significant promotion on both Eu(III) and colloid transport because of not only its strong Eu(III) complexion ability but also the increased dispersion of HA-coated colloid particles. The HA and BC displayed a synergistic effect on Eu(III) transport, the co-transport occurred by forming the ternary BC-HA-Eu(III) hybrid. The transport patterns could be simulated well with a two-site model that used the advection dispersion equation by reflecting the blocking effect. The retarded Eu(III) on the stationary phase was released and remobilized by the introduction of colloids, or by a transient reduction in cation concentration. The findings are essential for predicting the geological fate and the migration risk of radionuclides in the repository environment.

Midbrain Dopamine Neurons Defined by TrpV1 Modulate Psychomotor Behavior.

Dopamine (DA) neurons of the ventral tegmental area (VTA) continue to gain attention as far more heterogeneous than previously realized. Within the medial aspect of the VTA, the unexpected presence of TrpV1 mRNA has been identified. TrpV1 encodes the Transient Receptor Potential cation channel subfamily V member 1, TRPV1, also known as the capsaicin receptor, well recognized for its role in heat and pain processing by peripheral neurons. In contrast, the brain distribution of TrpV1 has been debated. Here, we hypothesized that the TrpV1+ identity defines a distinct subpopulation of VTA DA neurons. To explore these brain TrpV1+ neurons, histological analyses and Cre-driven mouse genetics were employed. TrpV1 mRNA was most strongly detected at the perinatal stage forming a band of scattered neurons throughout the medial VTA, reaching into the posterior hypothalamus. Within the VTA, the majority of TrpV1 co-localized with both Tyrosine hydroxylase (Th) and Vesicular monoamine transporter 2 (Vmat2), confirming a DA phenotype. However, TrpV1 also co-localized substantially with Vesicular glutamate transporter 2 (Vglut2), representing the capacity for glutamate (GLU) release. These TrpV1+/Th+/Vglut2+/Vmat2+ neurons thus constitute a molecularly and anatomically distinct subpopulation of DA-GLU co-releasing neurons. To assess behavioral impact, a TrpV1Cre -driven strategy targeting the Vmat2 gene in mice was implemented. This manipulation was sufficient to alter psychomotor behavior induced by amphetamine. The acute effect of the drug was accentuated above control levels, suggesting super-sensitivity in the drug-na ve state resembling a "pre-sensitized" phenotype. However, no progressive increase with repeated injections was observed. This study identifies a distinct TrpV1+ VTA subpopulation as a critical modulatory component in responsiveness to amphetamine. Moreover, expression of the gene encoding TRPV1 in selected VTA neurons opens up for new possibilities in pharmacological intervention of this heterogeneous, but clinically important, brain area.