bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thrombospondin‐1 worsens acetaminophen‐induced acute liver failure in mice through its activation of TGFβ1
Authors: McMillin Matthew , Jefferson Brandi , Grant Stephanie , Frampton Gabriel , Ali Malaika , DeMorrow Sharon 
Published: June 2021

IntroductionAcute liver failure results from a significant loss of liver function and has few effective treatments and poor clinical outcomes. Previously we have demonstrated that transforming growth factor beta 1 (TGFβ1) is upregulated during azoxymethane‐induced acute liver failure in mice and this signaling pathway promotes hepatic encephalopathy progression. Recently TGFβ1 has been shown to promote acetaminophen‐induced liver injury by promoting senescence of hepatocytes. TGFβ1 requires interactions with other proteins, such as thrombospondin‐1 (TSP‐1), to become activated and to be capable of binding its receptors. Therefore, we hypothesize that TSP‐1 activates TGFβ1 during acetaminophen‐induced acute liver failure worsening outcomes.MethodsMale C57Bl/6 mice or TSP‐1 knockout mice were injected with acetaminophen (APAP; 300 and 600 mg/kg) to generate acute liver injury. APAP‐treated mice had serum and liver collected at up to 24 hours post injection. Liver pathology was assessed by H&E staining, TUNEL staining, malondialdehyde assay, glutathione assay, nitrotyrosine expression and transaminase assessments. TGFβ1, TSP‐1, IL‐1β, IL‐6, TNF‐α, SOD1, iNOS and phosphorylated/total JNK expression were assessed by immunoblotting, immunohistochemistry, immunofluorescence, ELISA and/or real‐time PCR assays.ResultsMice injected with APAP had elevated hepatic TGFβ1 and TSP‐1 levels, which co‐localized primarily to hepatocytes. APAP‐treated mice with genetic knockout of TSP‐1 had reduced hepatic injury and hepatocyte necrosis as evident by improved serum transaminases, restored glutathione levels, reduced phosphorylated JNK signaling and less TUNEL staining compared to wildtype APAP‐treated mice. Expression of oxidative and nitrosative stress markers, as well as proinflammatory cytokines, were reduced in TSP‐1 knockout mice compared to wildtype mice administered APAP.ConclusionsStrategies employed to reduce TSP‐1 signaling in APAP‐treated mice reduced liver damage and pathology. Therefore, targeting TSP‐1 signaling may be a novel therapeutic target for the management of APAP‐induced acute liver failure.Support or Funding InformationThis study was funded by NIH R01 awards (DK082435 and DK112803) and a VA Merit award (BX002638) from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service to Dr. DeMorrow. This study was also funded by a VA Career Development award (BX003486) from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service to Dr. McMillin.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Insulin enhances presynaptic glutamate release via opioid receptor‐mediated disinhibition
Authors: Ferrario Carrie R. , Santana‐Rodriguez Zuleirys , Oginsky Max F. 
Published: June 2021

Recent studies show that insulin modulates the function of brain reward and motivation systems. For example, insulin receptor activation enhances dopamine release in the nucleus accumbens (NAc), reduces excitatory transmission in the VTA, and decreases food intake when infused into the NAc. Excitatory transmission in the NAc plays critical roles in motivation, and diet‐induced obesity alters NAc activity and peripheral sensitivity to insulin. However, insulin's effects on NAc excitatory transmission are unknown. Therefore here, we used whole‐cell patch clamp recordings in adult rat brain slices to determine how insulin affects excitatory transmission onto NAc medium spiny neurons (MSNs) and the mechanisms involved. Importantly, in addition to insulin receptors, insulin‐like growth factor receptors (IGFRs) are also expressed in the NAc and can be activated by moderate to high concentrations of insulin. Thus, a wide range of insulin concentrations were examined here (30–500 nM), and the contribution of insulin receptor activation vs. IGFR activation to insulin's effects was determined using pharmacological approaches. We find that insulin receptor activation increases presynaptic glutamate release via a previously unidentified form of opioid receptor‐mediated disinhibition, whereas activation of IGF receptors by insulin decreases presynaptic glutamate release. Furthermore, diet‐induced obesity (60% high‐fat; Open Source Diets D12492, 8 weeks) resulted in a loss of insulin receptor‐mediated increases and a reduction in NAc insulin receptor surface expression compared to chow fed controls (Lab Diet 5001, 13% fat), while preserving reductions in transmission mediated by IGRFs. These results provide the first insights into how insulin influences excitatory transmission in the adult brain and have broad implications for the regulation of motivation and reward related processes by peripheral hormones.Support or Funding InformationThis work was supported by NIDDK R01DK106188, R01DK115526, and the Brain and Behavior Research Foundation N018940 awards to CRF; MFO was supported by NIDA T32DA007268 and NIDDK FDK112627A. The authors declare no competing financial interests. Studies utilized the Chemistry Core of the Michigan Diabetes Research and Training Center funded by DK020572, and the University of Michigan Animal Phenotyping Core supported by P30 grants DK020572 (MDRC) and DK089503 (MNORC). We thank Drs. Marina Wolf, Larry Reagan, William Birdsong, Travis Brown and Garret Stuber for helpful conversations and Dr. Kenner C. Rice (Drug Design and Synthesis Section, NIDA IRP) for the gift of (+)‐naloxone.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
κ‐Opioid Receptor Activation Induces the Autophagic Machinery and Alters Dendritic Spine Density
Authors: Georgoussi Zafiroula , Karoussiotis Christos 
Published: June 2021

It is already evident that opioid receptors modulate the neuronal function by regulating neurite outgrowth and neurotransmission with unknown yet mechanisms (1, 2). Autophagy is a lysosomal degradation pathway which eliminates misfolded proteins and dysfunctional organelles essential for neuronal function and homeostasis (3). Recent observations have shown that G‐protein coupled receptors could mediate the autophagic machinery and that methamphetamine induces autophagy in endothelial cells through the κ‐OR (4). However, it is unknown whether specific κ‐opioid agonists mediate these effects and whether opiodergic alterations in neuronal cells could be controlled through induction of autophagy. Our data indicate that administration of κ‐selective agonists increase the levels of the autophagosome marker LC3‐II (Fig. 1) and the pre‐autophagosomal proteins Beclin 1 and ATG5 respectively in a dose and time dependent manner. These effects are reversed upon exposure of neuroblastoma cells and cortical neurons with the opioid receptor antagonist naloxone, suggesting that it is a κ‐OR‐mediated effect. Pre‐treatment of cells with pertussis toxin blocked the κ‐OR mediated Beclin 1 upregulation and LC3‐II formation, suggesting that Gi/Go proteins are involved in κ‐OR induced autophagy. Futhermore, κ‐opioid agonist exposure of primary neuronal cortical cultures decreased the levels of Neurabin II, a neuronal protein enriched in dendritic spines, and the levels of Synaptophysin, a synaptic terminal protein, suggesting that these proteins are engulfed in the κ‐OR mediated autophagic cargo. Collectively, the present results demonstrate a novel regulatory mechanism via which specifιc κ‐OR agonists affect dendritic spine morphology via induction of autophagy.Support or Funding InformationThis work was supported mainly by the GSRT Excellence II grant, 3722 entitled “Neurite Outrgowth: ALternative G‐ protein coupled Opioid receptor Signaling”‐ “NO‐ALGOS” to Z.G. We acknowledge support of this work also by the project “Target Identification and Development of Novel Approaches for Health and Environmental Applications” (MIS 5002514) which is implemented under the Action for the Strategic Development on the Research and Technological Sectors, funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014–2020) and co‐financed by Greece and the European Union (European Regional Development Fund). The facilities of the Hellenic Research Infrastructure OPENSCREEN‐GR were used.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Morphine drug discrimination: A behavioral model to assess novel synthetic opioid substances
Authors: Eneanya Chidubem , Walker Teneille , Tella Srihari , Akinfiresoye Luli , Walker Ellen 
Published: June 2021

A large number of novel psychoactive substances including opioid‐like compounds have appeared on the illicit market in the past decade. Several substances structurally related to fentanyl are being abused alone and in combination with other drugs (e.g., heroin and/or cocaine), resulting in overdoses at an alarming rate. There is a paucity of information about the pharmacology of these novel synthetic substances. In this study, we evaluated the opioid‐like stimulus effects of crotonyl fentanyl, thiophene fentanyl, benzodioxole fentanyl, and methoxyacetyl fentanyl, four newly identified substances structurally related to fentanyl. We compared the potencies of these new substances to schedule II opioid analgesics such as fentanyl and morphine using a preclinical abuse liability assessment model called drug discrimination. We also studied the susceptibility of the stimulus effects of these test drugs to antagonism by the opioid antagonist naltrexone, a drug used in patients to reverse the overdose effects of heroin and fentanyl. Using a two‐lever operant experimental chamber under a fixed ratio‐10 schedule for food delivery, rats (Sprague Dawley) were trained to discriminate between 3.2 mg/kg morphine and saline, subcutaneously. We evaluated saline and multiple doses of morphine, fentanyl, crotonyl fentanyl, thiophene fentanyl, benzodioxole fentanyl, and methoxyacetyl fentanyl. Crotonyl fentanyl, thiophene fentanyl, and methoxyacetyl fentanyl, similar to morphine and fentanyl, fully substituted for the morphine discriminative stimulus and decreased response rates with slightly differing potencies. Benzodioxole fentanyl failed to produce significant morphine‐like responding or rate‐decreasing effects at any dose although testing was limited by solubility issues. Crotonyl fentanyl, thiophene fentanyl, and methoxyacetyl fentanyl were blocked by naltrexone indicating that mechanisms of action of these three drugs are similar to that of morphine and fentanyl. The opioid‐like discriminative stimulus effects of crotonyl fentanyl, thiophene fentanyl, and methoxyacetyl fentanyl indicate that subjective effects and abuse liability of these three novel substances are likely to be similar to that of morphine and fentanyl.Support or Funding InformationDJD‐17‐HQ‐P‐0646This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effects of the Kappa Agonist U69,593 on Naltrexone's Discriminative Stimulus Effects in Subjects Given Chronic, Intermittent Sucrose Access
Authors: Marek Morgan , Schulz Emily , Fruit Nicholas , Vile Oriana , Rothbauer Dylan , Brandt Lucas , Jewett David 
Published: June 2021

Naltrexone (NTX) is a nonspecific opioid antagonist that binds to mu‐, kappa‐, and delta‐opioid receptors. Previous research has demonstrated that rats given chronic, intermittent sucrose access have increased endorphin function. We have shown that rats given chronic, intermittent sucrose can discriminate 1.0 mg/kg NTX from saline in a two‐lever, operant choice procedure. We wondered if NTX's discriminative stimulus effects were mediated by kappa‐opioid receptors. To examine this possibility, we tested the effects of the kappa‐opioid agonist U69,593 in our discrimination procedure. Male Sprague‐Dawley rats were given access to 12‐hour access to a 25% sucrose solution and trained to discriminate NTX (1.0 mg/kg) from saline. Once discrimination criteria (80% or greater condition‐appropriate responding for 8 of 10 consecutive sessions) were reached, generalization testing began. We used a cumulative dosing procedure to determine if U69,593 alters the ability of NTX to produce its discriminative stimulus effects. Subjects were pretreated with U69,593 (0.0001 mg/kg – 0.1 mg/kg, s.c.) followed by increasing doses of NTX (0.001 mg.kg – 10.0 mg/kg, s.c.). Fifteen to 30 minutes after the injection, a test session began. Injections continued until response rates were suppressed or 10.0 mg/kg NTX was administered. Reversal tests were also conducted. During these tests, the training dose of NTX was administered and a test session began 15 minutes later. Then a single dose of U69,593 (0.001 mg/kg – 0.1 mg/kg, s.c.) was administered, followed by test sessions 15 to 120 minutes after the injection. U69,593 did not significantly alter the discriminative stimulus effects of NTX. This suggests that kappa‐opioid receptor antagonism is not sufficient to produce NTX's discriminative stimulus effects in rats given chronic, intermittent sucrose access.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Effects of Serotonin‐2A Receptor Modulation on Glutamate Levels in the Medial Prefrontal Cortex following Methamphetamine Self‐Administration
Authors: Dolezal Alexandra , McFadden Lisa , Severson Marie 
Published: June 2021

Methamphetamine (METH) use can lead to psychosis‐like behaviors. Previous studies have indicated that there is an increase in frontal cortex serotonin (5HT)‐2A receptors as well as observed hallucinogenic‐drug induced behaviors following METH self‐administration. The 5HT‐2A receptor is thought to play a role not only in psychosis‐like behaviors, but also the regulation of glutamate in the frontal cortex. Our research seeks to determine if METH self‐administration will lead to alterations in METH ‐induced glutamate release in the frontal cortex. Further, the role of the 5HT‐2A receptor in these changes will be explored. Male Sprague‐Dawley rats received METH or saline self‐administration 8 hours/day for 7 days. Two days following self‐administration, a microdialysis probe was inserted into the medial prefrontal cortex. Following basal assessment, animals received an injection of the 5HT‐2A antagonist or vehicle followed by a 5 mg/kg injection of METH or saline. Basal and METH ‐induced glutamate levels were assessed. Preliminary results suggest that prior METH self‐administration result in higher glutamate levels in the medial prefrontal cortex following a vehicle injection and a METH challenge. Ongoing efforts will determine if pretreatment with the 5HT‐2A antagonist will reduce these changes in glutamate. Overall, the results of this study will determine the role of the 5HT‐2A receptor in regulating glutamatergic activity in the frontal cortex following METH self‐administration.Support or Funding InformationThis research was supported by the National Institute on Drug Abuse of the National Institutes of Health (DA036012) and provided by the NIDA grant (R25‐DA033674).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
EAAT3 endocytosis activated by psychostimulants in diverse populations of neurons
Authors: Underhill Suzanne , Colt Mark , Amara Susan 
Published: June 2021

The primary mechanism of action of psychostimulants, including amphetamine (AMPH), has largely been attributed generally to an increase in extracellular dopamine. Dopamine potentiation has been ascribed to several mechanisms including endocytosis of the dopamine transporter, DAT. We have found that this cascade involves entry of AMPH into the cell through DAT, stimulation of an intracellular GPCR for trace amines, TAAR1, and activation of the small GTPase, RhoA. Changes in extracellular glutamate concentrations have also been reported in response to AMPH and we have found that the neuronal glutamate transporter, EAAT3, also undergoes endocytosis via this cascade in dopamine neuron cultures, in acute brain slices and in vivo. EAAT3 is broadly expressed in neuronal populations throughout the brain, suggesting additional actions of AMPH on glutamatergic signaling in cells other than dopamine neurons. AMPH is a transported inhibitor of DAT as well as the norepinephrine transporter, NET, so we explored AMPH‐induced EAAT3 trafficking in NET(+) neurons. By total internal reflection fluorescence (TIRF) microscopy we found that AMPH can cause endocytosis of EAAT3 as well as NET. We developed NET(+) primary cultures derived from E15 murine locus coeruleus. Catecholamine neurotransmitters enter these cells through a desipramine‐sensitive pathway, indicating that this transport is mediated by NET. These cultures also exhibit sodium‐dependent and dihydrokainate‐insensitive tritiated‐glutamate uptake that is mediated by EAAT3. Pretreatment with AMPH decreases both NET and EAAT3 transport capacity in these cultures. Furthermore, through the use of a RhoA inhibitor, we determined that this loss depends on activation of RhoA, as seen previously for AMPH‐mediated internalization of DAT and EAAT3 in midbrain dopamine neuronal cultures. These data indicate that TAAR1 agonists, such as AMPH and dopamine, can affect glutamate signaling through internalization of EAAT3 in noradrenergic as well as dopaminergic neurons.Support or Funding InformationThis work was supported by Intramural Research at the NIH, NIMH.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Abuse Potential of Phendimetrazine and its Effects on Cocaine Self‐Administration in Rhesus Monkeys
Authors: Minkiewicz Molly L. , Czoty Paul W. , Blough Bruce E. , Nader Michael A. 
Published: June 2021

Cocaine use disorder (CUD) continues to be a major public health and social problem with >1.5 million users resulting in 14,556 deaths in 2017 in the United States and with no FDA‐approved medications available (Volkow and Koob, 2016). Preclinical studies in nonhuman primates have shown that monoamine releasers such as amphetamine can reduce the reinforcing strength of cocaine under several schedules of cocaine self‐administration (SA; Czoty et al. 2010; Negus et al. 2003a, b). However, the high abuse potential of this category of drugs has hindered advancement of their clinical use for treatment of CUD. More recently, preclinical researchers have investigated phendimetrazine (PDM), an FDA‐approved Schedule III anorectic agent, with evidence of efficacy in animal models (Banks and Negus, 2013; Czoty et al. 2016). As a pro‐drug for the monoamine releaser phenmetrazine, PDM has a slow onset and long duration of action. Only two studies (Griffiths et al. 1976; Corwin et al. 1987) have evaluated the reinforcing effects of PDM, with opposite conclusions. The goal of the present study was to compare, in the same subjects, the efficacy of PDM to decrease cocaine SA and the reinforcing strength of PDM relative to cocaine. For 5 consecutive days, three adult male rhesus monkeys responded under a daily fixed‐ratio 20 schedule of food presentation, which, on the fifth day, was followed by a progressive‐ratio (PR) schedule of cocaine (0.003–0.3 mg/kg/injection) presentation (limited hold 30‐min, maximum 4‐hr). PDM was administered daily (1.0–6.0 mg/kg, PO, BID). The primary dependent variable under the PR schedule was the number of injections delivered. Under baseline conditions, monkeys typically earned 10 food reinforcers and the number of cocaine injections was characterized as an inverted U‐shaped function of dose. Under treatment conditions, in two subjects, food‐maintained responding was disrupted at higher PDM doses that also decreased cocaine SA. In the third subject, food reinforcement was not affected and PDM did not show efficacy in decreasing cocaine SA. When PDM (0.1–1.0 mg/kg/injection) was substituted for cocaine, it functioned as a reinforcer in all three subjects; the number of injections observed at peak doses of PDM (0.3 and 1.0 mg/kg/injection) were similar to those observed at the peak dose of cocaine (0.03 mg/kg/injection). These findings suggest that PDM has abuse liability and was ineffective in decreasing cocaine SA. These data do not support the use of PDM as a potential treatment for CUD.Support or Funding InformationP50 DA06634‐27This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Distinct regulation of sigma‐1 receptor multimerization by its agonists and antagonists
Authors: Hong W. Conrad 
Published: June 2021

Since its initial proposal four decades ago, extensive studies have shown that the sigma‐1 receptor (σ1R) interacts with and modulates the activity of multiple proteins with important functions. Recent crystal structures of σ1R as a homo‐trimer differ from a dimer‐tetramer model postulated by early work. Further it is not clear whether ligand binding regulates σ1R multimerization. Here I conducted mutational analyses and examined ligands' effects on σ1R oligomerization using novel non‐denaturing gels. In transfected cells σ1R exhibited as monomer, dimer, and mainly as high‐order multimers. Agonists ((+)pentazocine, (+)SKF10,047, DTG, PRE‐084) decreased, whereas antagonists (BD1008, BD1047, BD1063, haloperidol, NE‐100, progesterone) increased σ1R multimers, suggesting that agonists and antagonists differentially affect the stability of σ1R multimers. Mutations at key residues lining the trimerization interface abolished multimerization but preserved dimerization. Intriguingly, deletion of the transmembrane domain (TM) reduced σ1R to monomer. These results demonstrate that multiple domains play crucial roles in coordinating high‐order quaternary organization of σ1R, which may comprise interconvertible oligomeric states in a dynamic equilibrium. σ1R multimers exhibited high‐affinity and high‐capacity [3H](+)pentazocine binding, whereas monomers lacked binding. In competition binding the antagonist haloperidol appeared to show an apparent 10‐fold higher potency in wild‐type σ1R than in mutants with only dimers, which might explain why haloperidol binding increased σ1R multimers. Further, a σ1R mutant (E102Q) implicated in early‐onset amyotrophic lateral sclerosis exhibited as dimer only, suggesting that dysregulation of σ1R quaternary structure impairs its physiological function. Further exploration of ligand‐regulated σ1R multimerization may provide novel approaches to modulate the function of σ1R and its interacting proteins.Support or Funding InformationButler University Faculty Startup FundThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.