bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Toll‐like Receptor 4 Neuroinflammatory Signaling and the Effects of Fentanyl Citrate on CHME‐5 Human Microglial Cells
Authors: Figueroa‐Hall Leandra K , Das Subhas , Stevens Craig W , Davis Randall L 
Published: November 2023

Neuroinflammation is a key mediator of neuronal damage observed in various neuropathologies, thus understanding pro‐inflammatory pathways of human glia is important in identifying potential pharmacological strategies to modulate inflammatory signaling in these cells. Microglia‐derived cytokines and chemokines are instrumental in neuroinflammation and several pro‐inflammatory mediators activate these cells to include bacterial lipopolysaccharide (LPS) that signals through toll‐like receptor 4 (TLR4). Even though peripheral TLR4 signaling is well defined, human microglial TLR4 signaling is not. Furthermore, recent studies suggest the ability of opioid agents to modulate immune function in peripheral and central nervous system cells. Therefore, our goals are to characterize the molecular mechanisms of LPS‐induced TLR4 signaling and elucidate the effects of the mu opioid receptor (MOR) agonist, fentanyl citrate, on this signaling in human microglial cells, CHME‐5. In keeping with these goals, LPS‐induced TLR4 gene expression was significantly increased at 3, 6 and 18 hours, whilst TNFα was significantly increased at 6 hours. Additionally, activation of p65 NF‐κB and IκBα expression revealed optimal LPS dosage of 1000 ng/ml and significant up‐regulation at 10 and 30 minutes, respectively. Lastly, dose‐dependent co‐exposure to LPS and fentanyl citrate (3–100 μM) down‐regulated LPS‐induced NF‐κB binding activity. To date, our data suggest that CHME‐5 human microglial cells serve as an experimental model for analyzing the inflammatory actions of human microglial TLR4 signaling, which may be modulated by opioid compounds, specifically, fentanyl citrate. Thus, we have also initiated studies to elucidate the effects of LPS, morphine and other pharmacological agents on key TLR4 signaling proteins. Together, these ongoing studies are expected to further elucidate the mechanisms of LPS‐induced TLR4 signaling and the effects of opioid agents in human microglia.Support or Funding InformationSupport: NIH‐NS 062664 (RLD); OCAST HR10‐31 (CWS)
Mitochondrial dysfunction in iPSC‐derived neurons in subjects with Chronic Mountain Sickness
Authors: Zhao Huiwen , Perkins Guy , Callacondo David , Appenzeller Otto , Haddad Gabriel 
Published: November 2023

Chronic mountain sickness (CMS) is a disease that potentially threatens a large segment of the high altitude population (more than 140 million highlanders) during extended living over 2500m. Patients with CMS suffer from severe hypoxemia, erythrocytosis and neurologic manifestations including migraine, headache, mental fatigue, confusion, and memory loss. The only therapy, which is inadequate, is periodic phlebotomy. By understanding the mechanisms of CMS neuropathology, we wish to be able to develop better therapeutic strategies, not only for CMS but also for those diseases that are relevant at the sea level as well.In the current study, we used induced pluripotent stem cells (iPSCs)‐derived neurons from subjects with CMS and others without any evidence of CMS (non‐CMS) living at the same altitude, as a model to study CMS in vitro. We noticed that CMS neurons are more sensitive to the culture environment than non‐CMS, with more blebbing or beadings of dendrites after 3 weeks in culture. Although intracellular ATP level is significantly decreased in the CMS group, there was no difference in LDH release between the two groups. Transmission electron microscopic images illustrated that CMS neurons have a decreased mitochondrial volume density, cristae and mitochondrial length. Real‐time PCR analysis confirmed that CMS neurons have 1) decreased mitochondrial biogenesis gene such as PGC1 and increased mitophagy genes including PARKIN and PINK; 2) decreased fission and fusion genes including DRP1, FIS, OPA, and MFN2, as well as 3) many altered nuclear and mitochondrial gene including UCP2, ANT1, VDAC, BCL2‐XL, NMNAT1, and VEGF, suggesting the present of mitochondrial dysfunction in CMS neurons. Within these genes, NMNAT1, a central enzyme of NAD biogenesis, attracts attention because overexpression of NMNAT1 is believed to be neuroprotective in neuronal morphogenesis. Decreased NAD level, due to a down‐regulation of NMNAT1, has been shown to disrupt the nuclear‐mitochondrial communication and lead to mitochondrial dysfunction and render cells in a pseudohypoxic state under normoxia. Thus, we speculate that a similar phenomenon takes place in CMS neurons; indeed we have confirmed that both NMNAT1 gene expression and NAD level are lower in CMS neurons as compared to non‐CMS neurons. We conclude that a decreased NAD level might be one of reasons for mitochondrial dysfunction and results in a vulnerable survival phenotype in CMS neurons.Support or Funding Informationsupported by NIH 5P01HL098053
Characterizing the role of D2–like dopamine receptors in cocaine self‐administration in rats
Authors: Verduguez Randy Edgar , Wetzel Hanna , Norman Andrew 
Published: November 2023

Both D1–like and D2–like dopamine receptor families appear to be involved in cocaine self‐administration behavior, but the ability of agonists selective for these dopamine receptor subtypes to maintain self‐administration behavior is not well established. In rats that reliably self‐administered cocaine i.v., it was not initially possible to determine whether the selective D2‐like dopamine receptor agonist quinpirole (LY171555), across a range of unit doses, reliably maintained self‐administration behavior. Therefore, the effects of single injections of quinpirole on cocaine self‐administration sessions were studied. Quinpirole (0.8–1.6 umol/kg i.v.) extended the interval during maintained cocaine self‐administration behavior consistent with it having a cocaine‐mimetic effect. Then the effect of single i.v. doses of quinpirole on extinction of cocaine‐induced lever‐pressing behavior was investigated. Typically, once access to cocaine was terminated, lever pressing behavior accelerated and then extinguished after approximately 26 min, presumably until the cocaine concentration was no longer sufficient to induce this behavior. In contrast, after a single dose of quinpirole was administered and then access to cocaine was terminated lever pressing behavior stopped and then after a delay resumed and continued for approximately 1.5–2 hours. This indicates that quinpirole can maintain lever‐pressing behavior and should be self‐administered. However, quinpirole appears to have a long elimination half‐life and inter‐injection intervals are likely to be long requiring very long sessions to measure. These data imply that D2‐like receptors have a role in mediating self‐administration behavior but both the pharmacodynamics potency and the pharmacokinetics of agonists must be considered when measuring this behavior.Support or Funding InformationRandy Verduguez was supported as a Dalton Zannoni Fellow of the American Society of Pharmacology and Experimental Therapeutics (ASPET) with funds generously provided by ASPET and the University of Cincinnati.Grant Award: DP1DA031386sUC 2015 ASPET SURF Fellowship
Methamphetamine Self‐Administration in Mice Results in Both Pre‐ and Postsynaptic Changes in Dendritic Dopamine Neurotransmission in Midbrain Dopaminergic Neurons
Authors: Hager Audrey M. , Branch Sarah Y. , Dominguez‐Lopez Sergio , Sharpe Amanda L. , Beckstead Michael J. 
Published: November 2023

Dopaminergic neurons of the ventral midbrain are key mediators of substance abuse and addiction‐related behaviors. In the midbrain, dopamine release activates inhibitory postsynaptic currents through D2 autoreceptors (D2‐IPSCs) and G protein‐coupled potassium (GIRK) channels. Methamphetamine is a highly addictive psychomotor stimulant that acutely enhances D2‐IPSCs by decreasing uptake of the neurotransmitter dopamine. Chronic methamphetamine exposure can induce neurophysiological adaptations in midbrain dopaminergic neurons, but data regarding specific synaptic adaptations following self‐administration of methamphetamine is limited.In this study we investigated the effects of methamphetamine self‐administration in mice on synaptic determinants of dopamine neuron excitability. Adult mice were trained to nose‐poke under a fixed ratio 3 (FR3) schedule for intravenous infusions of methamphetamine (0.05 mg/kg/infusion) in daily 2 h sessions for 8 to 12 days. Their average intake of methamphetamine was 1.3 mg/kg/day. Subsequently, patch clamp electrophysiology was performed in brain slices containing substantia nigra and ventral tegmental area dopamine neurons to examine both pre‐ and postsynaptic changes. Interestingly, self‐administration of methamphetamine produced an overall downward shift in the methamphetamine (100nM‐3μM) concentration‐response curve of D2‐IPSCs compared to drug‐naïve controls. In addition, self‐administration of methamphetamine produced an increase in the paired‐pulse ratio of D2‐IPSCs that persists with subsequent stimulus events, indicating presynaptic effects on dopamine release. These results indicate an overall decrease in the strength of inhibitory synaptic transmission between midbrain dopamine neurons following methamphetamine self‐administration. This would be expected to produce an increase in neuronal firing that could enhance the reinforcing properties of methamphetamine in experienced individuals.Support or Funding Information5R01DA032701‐03
Cocaine‐Induced Alterations in Blood Lipid Profiles for the Study of Addictive Behaviors
Authors: Pati Sumitra , Scholpa Natalie E , Wagner John J , Cummings Brian S 
Published: November 2023

NBIB EB016100‐01 BSCCocaine‐dependence is a worldwide public health concern, affecting more than a million users in the United States alone. Much research has focused on the development of pharmacotherapies for the treatment of cocaine‐dependence; however, less emphasis has been placed on strategies for the clinical determination of a patient's susceptibility to drug‐seeking behavior and relapse. We utilized a lipidomics approach to assess cocaine‐induced alterations of blood lipid profiles in Sprague‐Dawley rats exposed to cocaine in a non‐contingent model, conditioned place preference (CPP). Following drug‐paired conditioning, extinction and reinstatement tests were also performed to further assess drug‐seeking behavior. Lipids were extracted using the Bligh‐Dyer method from whole blood samples obtained throughout the behavioral protocol from cocaine‐ and saline‐treated rats. Blood lipid extracts were analyzed by electrospray ionization‐mass spectrometry (ESI‐MS) to characterize lipid profiles. The resulting data were assessed using principal component analysis (PCA), which indicated differences in the lipid profiles between cocaine‐ and saline‐treated rats. Significant m/z features indicated alterations in glycerophospholipids, glycerolipids, and fatty acyls. Several of these features, including 18:1 phosphatidylcholine (PC), 22:1 PC, 20:3 phosphatidic acid (PA), tetratriacontapentaenoic acid, eicosenoic acid, and 36:0 diacylglycerol (DG) correlated to drug‐seeking behavior in cocaine‐treated animals, specifically the initial CPP. Interestingly, the relative expression of these species increased during extinction and reinstatement in cocaine‐treated rats. Moreover, PCA within each treatment group suggested a role for cocaine in remodeling the lipidome over time. These findings indicate a potential effect of cocaine on lipidome remodeling that could be exploited for the identification of lipid species related to the occurrence of cocaine‐induced responses and drug‐seeking behaviors in human cocaine addicts.Support or Funding InformationGeorgia Research Alliance VentureLab (BSC and JJW)
Amphetamine Enhances Impulsive Behavior in Rats Responding under a Stop Signal Procedure
Authors: Maguire David Richard , France Charles P 
Published: November 2023

Impulsivity might contribute to the persistence of stimulant (e.g., amphetamine) abuse and stimulant use can enhance impulsivity. The dynamic relationship between stimulant use and impulsivity has been well‐documented; however, the exact nature of the relationship remains unclear, in part, because of the multidimensionality of impulsivity. This study examined effects of amphetamine in rats (n=9) responding under a stop signal procedure which measured two different aspects of motor impulsivity: 1) responding before presentation of a go signal; and 2) responding after presentation of a stop signal. Rats were trained to press one lever (e.g., left) and then another lever (e.g., right) in order to obtain food. On 80% of trials (go trials), completion of the second response within a limited hold delivered food; failure to complete the second response initiated a timeout. On the remaining 20% of trials (stop trials), a tone was presented after the first response signaling that food would be presented only if the second response was withheld; responses after presentation of the tone initiated a timeout. Trials were separated by an inter‐trial interval; responses during the inter‐trial interval initiated a timeout, and responses during a timeout extended the timeout. Responding on stop trials (false alarms) and during the inter‐trial interval (premature responses) were measures of motor impulsivity. Under baseline conditions, rats responded on at least 90% of go trials and on no more than 10% of stop trials, while making fewer than 10 premature responses per session. Amphetamine (0.1–1.78 mg/kg) impaired response accuracy by significantly decreasing responses during go trials and increasing responses during stop trials. Amphetamine also significantly increased premature responding but did not impact timeout responding. Increased premature responding occurred with doses of amphetamine (0.32 and 1.0 mg/kg) smaller than the dose (1.78 mg/kg) that significantly increased false alarms. These data indicate that amphetamine enhances two types of motor impulsivity as measured with a stop signal procedure. However, increased premature responding occurred with doses of amphetamine that were 5‐fold smaller than the smallest dose that increased stop trial responding. Taken together, these data suggest that although amphetamine increases different behaviors thought to reflect motor impulsivity, sensitivity to amphetamine differs across measures. Thus, the impact of stimulant use on impulsivity might depend upon which aspect is being measured.Support or Funding InformationSupported, in part, by NIH grant K05DA017918 (CPF).
Insulin Enhancement of Dopamine Reuptake in the Nucleus Accumbens Is Blocked by Consumption of a High Fat diet in C57BL/6 Mice
Authors: Fordahl Steven , Jones Sara 
Published: November 2023

Systemically released insulin crosses the blood brain barrier and binds to insulin receptors on dopamine and other neurons. Insulin is thought to contribute to satiety by reducing dopamine signaling in response to food, and has been shown to decrease dopamine neuron firing, increase dopamine reuptake, and reduce the intake of palatable food in sated animals. Here we show that high fat (HF) diet‐induced insulin resistance blocks insulin's novel facilitatory effect on dopamine reuptake in the nucleus accumbens core (NAcc). Mice fed a HF diet (60% kcals from fat) were considered insulin resistant compared to chow fed littermates by displaying significantly higher fasting blood glucose (175 and 99 mg/dL, respectively; p < 0.001) and reduced blood glucose clearance after an intraperitoneal glucose tolerance test (p < 0.001). Using fast scan cyclic voltammetry to measure dopamine in brain slices containing the NAcc, HF fed mice exhibited reduced maximal dopamine reuptake (Vmax) compared to chow fed mice (2.3 ± 0.1μM and 3.2 ± 0.2μM, respectively) (p < 0.001). Moreover, reductions in glucose clearance were negatively correlated with Vmax (r2=0.68; p=0.0019). Insulin (10nM‐1μM) dose dependently increased Vmax in chow fed mice by a maximal 77% compared with 4% in the HF group (p < 0.0001); however, the small molecule insulin receptor sensitizing agent (TCS 401, 300nM) restored Vmax in HF fed mice to chow levels, and a small molecule inhibitor of the insulin receptor (BMS 536924, 300nM) reproduced the low Vmax HF phenotype in chow fed mice. These data show that a HF diet impairs dopamine reuptake by attenuating insulin signaling at dopamine terminals. This suggests that prolonged consumption of a HF diet may block homeostatic mechanisms that contribute to satiety, thereby promoting excessive food intake.Support or Funding Information5T32AA007565‐22
Dietary Supplementation with Fish Oil Prevents High Fat Diet‐Induced Enhancement of Sensitivity to the Locomotor Stimulating Effects of Cocaine
Authors: Labay Caitlin , Serafine Katherine , France Charles 
Published: November 2023

Eating a diet high in fat can lead to severe negative health consequences, including obesity, insulin resistance, and increased inflammation in both peripheral tissues as well as in the brain. For example, eating a diet high in fat causes inflammation as evidenced by increased concentrations of the pro‐inflammatory markers interleukin‐6 and tumor necrosis factor‐α in the hypothalamus. Dietary supplements that are rich in omega‐3 polyunsaturated fatty acids (e.g., fish oil) can reduce or prevent high fat diet‐induced obesity, insulin resistance, and hypothalamic inflammation in rats. Eating a high fat diet also enhances sensitivity of rats to the locomotor stimulating effects of cocaine, particularly in adolescent female rats. To test the hypothesis that dietary supplementation with fish oil prevents high fat diet‐induced enhanced sensitivity to a behavioral effect of cocaine caused by a possible reduction in inflammation, adolescent female rats ate standard laboratory chow (17% kcal from fat; n = 6), high fat chow (60% kcal from fat; n = 7), or high fat chow supplemented with 20% fish oil (w/w; 68% kcal from fat; n = 7). Similar to previous reports, the rats eating high fat chow without fish oil were more sensitive than rats eating standard chow to the locomotor stimulating effects of cocaine (1–17.8 mg/kg). Although sensitization to once weekly tests with cocaine for 6 weeks developed in all groups, there was no statistical difference in sensitization between rats eating the standard chow and those eating a high fat chow with fish oil, indicating that supplementation with fish oil prevented the greater sensitization that occurs in rats eating only high fat chow. However, there were no significant differences among groups in the pro‐inflammatory markers tumor necrosis factor‐α or interleukin‐6 in the hypothalamus, no difference in body weight or caloric intake, and no development of insulin resistance. Thus, fish oil supplementation prevented high fat diet‐induced enhancement in sensitivity to cocaine without altering inflammatory markers, body weight, or insulin status. These results suggest that while diets high in fat increase sensitivity of individuals to drugs acting on dopamine systems in ways that might be relevant to drug abuse, dietary supplementation with fish oil can prevent these effects, although the mechanism for this effect remains to be determined. These data add to a growing literature demonstrating the complex relationship between diet and drug abuse, and the health benefits of fish oil.Support or Funding InformationSupported by USPHS Grants K05 DA017918 (CPF), T32 DA031115 (KMS), and the ASPET SURF program (CEL)
Atypical Dopamine Transporter Inhibitors R‐Modafinil and JHW007 Differentially Alter D2 Autoreceptor Currents and Firing Rate in Midbrain Dopamine Neurons
Authors: Avelar Alicia J , Newman Amy H , Beckstead Michael J 
Published: November 2023

Psychostimulants increase attention and induce euphoria, but despite decades of work there still are no FDA approved clinical treatments for their abuse. Psychostimulants act on dopamine (DA) signaling of midbrain DA neurons to cause reinforcement. D2 autoreceptors on these neurons powerfully inhibit cell firing and have been inversely associated with psychostimulant use. D2 autoreceptor signaling is tightly controlled by DA transporters (DATs), which clear DA from the extracellular space. Cocaine, a typical DAT inhibitor, blocks DA reuptake and causes hyperlocomotion and reinforcement. Behavioral studies suggest that atypical DAT inhibitors are potential therapeutics to decrease cocaine abuse. Atypical DAT inhibitors bind to the transporter, but are less likely to cause hyperlocomotion and reinforcement than the cocaine. To date, there have been no investigations into the synaptic actions of these compounds. Here we determined the effects of atypical DAT inhibitors on D2 autoreceptor‐mediated currents and DA neuron excitability. To address this, we performed patch‐clamp electrophysiology of midbrain DA neurons in brain slices from DBA/2J mice. We utilized electrical stimulation, DA iontophoresis, and bath perfusion of atypical DAT inhibitors R‐Modafinil (10 and 100 μM) or JHW007 (100nM, 1 and 10 μM) to investigate their synaptic actions on D2 autoreceptor currents. Additionally, we recorded DA neuron firing before and after bath perfusion of R‐Modafinil (100 μM) and JHW007 (10 μM) and with or without the D2 receptor antagonist sulpiride (200 nM). These experiments show that, R‐Modafinil and JHW007 differentially affect D2 autoreceptor currents and DA neuron firing. R‐Modafinil increased D2 autoreceptor current amplitude and width and decreased DA neuron firing rate in a D2 autoreceptor dependent manner. Conversely, JHW007 primarily decreased D2 autoreceptor current amplitude, had little effect on width, and increased DA neuron firing rate in a D2 autoreceptor independent manner. These findings suggest that, despite both being atypical DAT inhibitors; these two compounds exhibit profoundly different effects on DA neuron excitability.Support or Funding InformationThis project was supported by NIH training grant T32 NS 082145, funded by the Jointly Sponsored NIH Predoctoral Training Program in the Neurosciences. Funding also provided by: NIH R01 DA 32701 and a diversity supplement.