Neuroscience
Abstract
Authors
Rimas V. Lukas, Ruochen Du, Harrshavasan Congivaram, Kathleen McCortney, Karan Dixit, Craig Horbinski, Margaret Schwartz, Raymond Lezon, Lauren Singer, Ditte Primdahl, Jigisha Thakkar, Amy B. Heimberger, Roger Stupp, Priya Kumthekar
Potentiation of fentanyl-induced respiratory depression by alcohol is not fully reversed by naloxone
Abstract
The high frequency of opioid overdose deaths often involves co-use of alcohol, which is reported in approximately 30% of fentanyl fatalities. Both substances depress respiratory function, and their combined effects can be lethal. The present study investigated physiological parameters of respiratory-depressant effects of fentanyl when co-administered with alcohol and its sensitivity to naloxone reversal using whole-body plethysmography in male and female Long-Evans rats. Administration of a high, sedative-like dose of alcohol alone or fentanyl alone resulted in no mortality, but fentanyl+alcohol led to mortality rates of 42% and 33% in females and males, respectively. The fentanyl+alcohol combination reduced minute ventilation and increased apneic pauses compared with either drug alone. Lower, binge-like alcohol doses, when combined with fentanyl, also amplified respiratory depression. Pretreatment with naloxone did not fully restore normal respiration. Naloxone administered after fentanyl+alcohol transiently reversed the decrease in minute ventilation but did not reverse apneic pauses. Fentanyl-dependent rats were partially tolerant to fentanyl- and fentanyl+alcohol-induced respiratory depression, but alcohol-dependent rats exhibited sensitization to alcohol- and fentanyl+alcohol-induced apnea. These findings highlight physiological parameters of severe respiratory risks with fentanyl+alcohol co-use, which are inadequately reversed by naloxone, underscoring the need for targeted strategies to manage opioid+alcohol overdoses.
Authors
Emma V. Frye, Lyndsay E. Hastings, Aniah N. Matthews, Adriana Gregory-Flores, Janaina C.M. Vendruscolo, Lindsay A. Kryszak, Shelley N Jackson, Aidan J. Hampson, Nora D. Volkow, Leandro F. Vendruscolo, Renata C.N. Marchette, George F. Koob
Abstract
Acute severe joint pain is a major symptom in gouty arthritis (GA), and its adequate treatment represents an unmet medical need. Mrgprb2, a specific mast cell receptor, has been implicated in the generation of chronic pain by mobilizing mast cell degranulation, yet its significance in GA pain and joint inflammation is still not well defined. Here, we found that Mrgprb2 was expressed in mouse synovial mast cells. In a murine model of GA, acute blockade or genetic deletion of Mrgprb2 significantly attenuated arthritis pain and hyperexcitability of joint nociceptors with significant reductions in innate immune cell recruitment in the synovium. Under naive conditions, activation of synovial Mrgprb2 was sufficient to excite peripheral terminals of joint nociceptors to induce acute joint hypernociception via the mobilization of mast cell degranulation. Additionally, the level of the neuropeptide substance P (SP) was elevated in the synovium of GA model mice. Using humanized MRGPRX2-knockin mice, we revealed that SP contributed to joint pain and inflammation by activating mast cells through Mrgprb2/MRGPRX2. These findings suggest that synovial mast cell–expressed Mrgprb2/MRGPRX2 merits consideration as a key neuroimmune player and a potential therapeutic target for treating GA pain and joint inflammation.
Authors
Lin Yang, Chengxi Liu, Jin Xiao, Yu Song, Huan Chen, Dan Li, Cong Zou, Tao Hong, Yinglan Liu, Dake Qi, Nathachit Limjunyawong, Wenjie Liu, Lintao Qu
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease. Emerging evidence suggests manifestations beyond the neuromuscular system. Bone alterations are part of the ALS clinical picture; it remains unclear whether they are secondary to muscle denervation or due to an autonomous process. We investigated skeletal involvement in the SOD1(G93A) mouse model at presymptomatic (P45) and symptomatic (P110) stage through biomechanical and transcriptomic approaches. Three-point bending revealed significant reductions in femoral rigidity and maximum bending force in SOD1 mutants at P45, indicating early structural deficits. Micro-CT analysis demonstrated reduced trabecular bone mineral density and thickness at P45, with progressive trabecular loss and cortical thinning by P110. Histological examination revealed marked osteoblast loss at P45 suggesting impaired bone formation as the primary early mechanism. Transcriptomics of bulk bone and cultured osteoblasts from P45 mice identified dysregulation of bone differentiation, including downregulation of osteoblast differentiation genes and upregulation of negative regulators of ossification and increased cell senescence signatures. Unfolded protein response was upregulated in SOD1 osteoblasts. Immunohistochemistry confirmed the senescence phenotype with increased p16Ink4a level in SOD1 osteoblasts. These findings suggest that bone deterioration precede overt motor symptoms and are linked to osteoblast premature senescence.
Authors
Burak Özkan, Jan-Moritz Ramge, Diana Wiesner, Jelena Scekic-Zahirovic, Stefano Antonucci, Sandra Nungeß, Dorothea Gebauer, Anita Ignatius, Jochen H. Weishaupt, Melanie Haffner-Luntzer, Francesco Roselli
Abstract
Commotio retinae (CR) resulting from retinal trauma can lead to focal photoreceptor degeneration and permanent vision loss. Currently no therapies exist for CR-induced retinal degeneration, in part due to a lacking large animal model that replicates human injury pathology and allows testing of therapeutics. Severe CR is clinically characterized by subretinal fluid and focal photoreceptor outer nuclear layer thinning. To develop a porcine CR model, we developed a laser-guided projectile apparatus and optimized projectile delivery procedure using porcine cadaveric eyes embedded in a 3D-printed porcine skull. Scleral and corneal impacts, resulted in retinal damage consistent with patient injury but corneal impacts also led to cornea damage and opacification, which precluded follow up imaging. In live porcine eyes, scleral impacts of 39.5 m/s induced transient blood retinal barrier breakdown evidenced by subretinal fluid on optical coherence tomography (OCT), leakage observed on fluorescein and indocyanine green angiography, and transient photoreceptor outer segment disruption seen by OCT and multifocal electroretinography. Impacts above 39.5 m/s induced longer-lasting photoreceptor degeneration, but only transient blood retinal barrier breakdown. This porcine model, combined with clinically relevant imaging and diagnostic modalities will be valuable for testing the safety and efficacy of therapies to restore vision after focal photoreceptor degeneration.
Authors
Juan Amaral, Irina Bunea, Arvydas Maminishkis, Maria M. Campos, Francesca Barone, Rohan Gupta, Mitra Farnoodian, Jonathan Newport, M. Joseph Phillips, Ruchi Sharma, David M. Gamm, Kapil Bharti, Richard J. Blanch
Abstract
The central nervous system (CNS) parenchyma has conventionally been believed to lack lymphatic vasculature, likely owing to a non-permissive microenvironment that hinders the formation and growth of lymphatic endothelial cells (LECs). Recent findings of ectopic expression of LEC markers including prospero homeobox 1 (PROX1), a master regulator of lymphatic differentiation, and the vascular permeability marker plasmalemma vesicle–associated protein (PLVAP) in certain glioblastomas (GBM) and brain arteriovenous malformations have prompted investigation into their roles in cerebrovascular malformations, tumor environments, and blood-brain barrier (BBB) abnormalities. To explore the relationship between ectopic LEC properties and BBB disruption, we used endothelial cell–specific Prox1 overexpression mutants. When induced during embryonic stages of BBB formation, endothelial Prox1 expression induces hybrid blood-lymphatic phenotypes in the developing CNS vasculature. This effect is not observed when Prox1 is overexpressed during postnatal BBB maturation. Ectopic Prox1 expression leads to significant vascular malformations and enhanced vascular leakage, resulting in BBB disruption when induced during both embryonic and postnatal stages. Mechanistically, PROX1 downregulates critical BBB-associated genes, including β-catenin and claudin-5, which are essential for BBB development and maintenance. These findings suggest that PROX1 compromises BBB integrity by negatively regulating BBB-associated gene expression and Wnt/β-catenin signaling.
Authors
Sara González-Hernández, Ryo Sato, Yuya Sato, Chang Liu, Wenling Li, Zulfeqhar A. Syed, Chengyu Liu, Sadhana Jackson, Yoshiaki Kubota, Yoh-suke Mukouyama
Abstract
Multisystemic Smooth Muscle Dysfunction Syndrome (MSMDS) is a rare disorder caused by ACTA2 mutations, including the R179H variant, which alters actin filament stability and dynamics and smooth muscle contractility. While cardiovascular complications dominate its clinical presentation, gastrointestinal (GI) dysfunction significantly impacts quality of life. To investigate the structural, functional, and cellular basis of gut dysmotility in MSMDS, we reviewed clinical data from 24 MSMDS patients and studied the ACTA2 R179H mouse model Patients exhibited severe gut dysmotility, with 75% requiring medication for chronic constipation. ACTA2 mutant mice displayed cecal and colonic dilatation, reduced intestinal length, and disrupted colonic migrating motor complexes (CMMCs). Delayed whole-gut transit and impaired contractile responses to electrical and pharmacological stimulation were observed. Transcriptomic analysis revealed significant actin cytoskeleton-related gene changes in smooth muscle cells, and immune profiling identified increased lymphocytic infiltration. Despite functional abnormalities, there were no obvious changes in the enteric nervous system. These findings establish ACTA2 mice as a robust model for studying GI pathology in MSMDS, elucidating the role of smooth muscle dysfunction in gut dysmotility. This model provides a foundation for developing targeted therapies aimed at restoring intestinal motility by directly addressing actin cytoskeletal disruptions in smooth muscle cells.
Authors
Ahmed A. Rahman, Rhian Stavely, Leah C. Ott, Christopher Y. Han, Kensuke Ohishi, Ryo Hotta, Alan J. Burns, Sabyasachi Das, Emily Da Cruz, Diana Tambala, Mark E. Lindsay, Patricia L. Musolino, Allan M. Goldstein
Abstract
Enhanced lipid metabolism, which involves the active import, storage, and utilization of fatty acids from the tumor microenvironment, plays a contributory role in malignant glioma transformation; thereby, serving as an important gain of function. In this work, through studies initially designed to understand and reconcile possible mechanisms underlying the anti-tumor activity of a high-fat ketogenic diet, we discovered that this phenotype of enhanced lipid metabolism observed in glioblastoma may also serve as a metabolic vulnerability to diet modification. Specifically, exogenous polyunsaturated fatty acids (PUFA) demonstrate the unique ability of short-circuiting lipid homeostasis in glioblastoma cells. This leads to lipolysis-mediated lipid droplet breakdown, an accumulation of intracellular free fatty acids, and lipid peroxidation-mediated cytotoxicity, which was potentiated when combined with radiation therapy. Leveraging this data, we formulated a PUFA-rich modified diet that does not require carbohydrate restriction, which would likely improve long-term adherence when compared to a ketogenic diet. The modified PUFA-rich diet demonstrated both anti-tumor activity and potent synergy when combined with radiation therapy in mouse glioblastoma models. Collectively, this work offers both a mechanistic understanding and a potentially translatable approach of targeting this metabolic phenotype in glioblastoma through diet modification and/or nutritional supplementation that may be readily integrated into clinical practice.
Authors
Shiva Kant, Yi Zhao, Pravin Kesarwani, Kumari Alka, Jacob F. Oyeniyi, Ghulam Mohammad, Nadia Ashrafi, Stewart F. Graham, C. Ryan Miller, Prakash Chinnaiyan
Abstract
The complex and heterogeneous genetic architecture of neuropsychiatric illnesses compels us to look beyond individual risk genes for therapeutic strategies and target the interactive dynamics and convergence of their protein products. A mechanistic substrate for convergence of synaptic neuropsychiatric risk genes are protein-protein interactions (PPIs) in the NMDAR complex. NMDAR hypofunction in schizophrenia is associated with hypoactivity of Src kinase, resulting from convergent alterations in PPIs of Src with its partners. Of these, the association of Src with PSD-95, which inhibits the activity of this kinase in the NMDAR complex, is known to be increased in schizophrenia. Here, we devised a strategy to suppress the inhibition of Src by PSD-95 by employing a cell penetrating and Src activating PSD-95 inhibitory peptide (TAT-SAPIP). TAT-SAPIP enhanced synaptic NMDAR currents in Src+/- and Sdy-/- mice manifesting NMDAR hypofunction phenotypes. Chronic ICV injection of TAT-SAPIP rescued cognitive deficits in trace fear conditioning in Src +/- mice. Moreover, TAT-SAPIP enhanced Src activity in synaptoneurosomes derived from dorsolateral prefrontal cortex of 14 subjects including patients and healthy subjects. We propose blockade of the Src-PSD-95 interaction as a proof of concept for the use of interfering peptides as a therapeutic strategy to reverse NMDAR hypofunction in schizophrenia and other illnesses.
Authors
Robert E. Featherstone, Hongbin Li, Ameet S. Sengar, Karin E. Borgmann-Winter, Olya Melnychenko, Lindsey M. Crown, Ray L. Gifford, Felix Amirfathi, Anamika Banerjee, AiVi Tran, Krishna Parekh, Margaret Heller, Wenyu Zhang, Robert J. Gallop, Adam D. Marc, Pragya Komal, Michael W. Salter, Steven J. Siegel, Chang-Gyu Hahn
Abstract
Neurocognitive impairment is a prevalent co-morbidity in virologically suppressed people living with HIV (PLWH), yet the underlying mechanisms remain elusive and treatments lacking. We explored use of participant-derived directly induced neurons (iNs) to model neuronal biology and injury in PLWH. iNs retain age- and disease-related donor features, providing unique opportunities to reveal important aspects of neurological disorders. We obtained primary dermal fibroblasts from six virologically suppressed PLWH (range: 27-64 years, median: 53; 83% Male) and seven matched people without HIV (PWOH) (range: 27-66, median: 55; 71% Male). iNs were generated using transcription factors NGN2 and ASCL1, and validated by immunocytochemistry, single-cell-RNAseq, and electrophysiological recordings. Transcriptomic aging analyses confirmed retention of donor age-related signatures. Bulk-RNAseq identified 29 significantly differentially expressed genes between PLWH and PWOH iNs. Of these, 16 were downregulated and 13 upregulated in PLWH iNs. Protein-protein interaction network mapping indicates iNs from PLWH exhibit differences in extracellular matrix organization and synaptic transmission. IFI27 was upregulated in PLWH iNs, complementing independent post-mortem studies demonstrating elevated IFI27 expression in PLWH-derived brain tissue. FOXL2NB-FOXL2-LINC01391 expression was reduced in PLWH iNs and negatively correlated with neurocognitive impairment. Thus, we identified an iN gene signature of HIV revealing mechanisms of neurocognitive impairment in PLWH.
Authors
Philipp N. Ostermann, Youjun Wu, Scott Bowler, Samuel Martínez-Meza, Mohammad A. Siddiqui, David H. Meyer, Alberto Herrera, Brandon A. Sealy, Mega Sidharta, Kiran Ramnarine, Leslie Ann St. Bernard, Desiree Byrd, R. Jones, Masahiro Yamashita, Douglas F. Nixon, Lishomwa C. Ndhlovu, Ting Zhou, Teresa H. Evering
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