bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavioral economic analysis of the effects of AHN 1‐055 and JHW 007, atypical dopamine uptake inhibitors, on cocaine self administration
Authors: Zanettini Claudio , Newman Amy H. , Wilkinson Derek , Katz Jonathan L. 
Published: November 2023

Benztropine analogs and other atypical dopamine uptake inhibitors selectively decrease cocaine self‐administration in rats at doses that do not affect responding maintained by other reinforcers. In the current study a behavioral economic approach was employed to further characterize the behavioral mechanisms of effects of benztropine analogs (AHN 1‐055, JHW 007) on responding maintained by cocaine injection in rats. Behavioral economic analyses represent a translational approach that take into account the price of the reinforcer as an important determinant of consumption. Two groups of rats were trained to respond for food (45 mg pellet) or cocaine (0.32 mg/kg/inj) under a fixed‐ratio (FR) 5 schedule in experimental sessions comprising five 20‐min components. In selected sessions the FR value was increased (5, 10, 20, 40, 80) during successive components to determine demand curves, which plot consumption (reinforcers obtained) against price (FR value). An exponential function was fitted to the data to derive the consumption at zero price (Q0) and the rate of decrease in consumption (essential value). AHN 1‐055 (1.78–10 mg/kg, IP), JHW 007 (3.2–10 mg/kg, IP) or vehicle was administered immediately before each demand curve determination. Consumption of cocaine or food decreased as the price (FR requirement) increased. At low doses AHN 1‐055 shifted downward and to the right the cocaine and the food demand curves. A larger dose shifted the curves leftward and downward. Analysis of the demand curve parameters indicated that AHN 1‐055 had equivalent effects on the essential value of cocaine or food but was more effective in decreasing Q0 for cocaine (%Δ= −83%) compared to food (%Δ=−27%). The effects of JHW 007 were less than those of AHN 1‐055, with only trends for decreases in Q0 for cocaine, and no significant difference in essential value for cocaine or food. Therefore, AHN 1‐055, but not JHW 007, selectively decreased consumption at zero price. The current findings obtained using an approach that takes in account the price of the reinforcer, indicate that AHN 1‐055 might be more effective than JHW 007 in reducing selectively consumption of cocaine.Support or Funding InformationThis work was supported by NIDA Intramural Research Program
The effects of cocaine self‐administration and abstinence on dopamine D2/D3 receptor availability in female cynomolgus monkeys
Authors: Nader Michael A. , Nader Susan H. , Duke Angela N. , Solingapuram Sai Kiran K. , Mintz Akiva 
Published: November 2023

Previous PET imaging studies have shown that individuals abusing many drugs of abuse, including cocaine, have lower measures of dopamine (DA) D2/D3 receptor availability compared to age‐matched controls; most of the human subjects in these studies are men. In monkeys, a within‐subjects design can be incorporated in which baseline measures of D2/D3 receptor availability can be obtained prior to any cocaine exposure and then assessed after a long cocaine self‐administration history and during abstinence. In male monkeys, we found intake‐dependent reductions in D2/D3 receptor availability over 1 year of self‐administration; recovery of receptor levels during abstinence was observed in approximately half the monkeys (Nader et al., 2006). The goal of the present study was to extend these findings to female monkeys. Ten experimentally naïve, individually housed, adult female cynomolgus macaques were trained to respond under a 4‐component multiple fixed‐interval (FI) schedule of food presentation. During this time, baseline measures of DA D2/D3 receptor availability using positron emission tomography and [11C]raclopride were obtained in each monkey. When the reinforcement schedule was changed to a multiple FI food (components 1 and 3) and cocaine (components 2 and 4) presentation, response rates maintained by a 0.2 mg/kg per injection cocaine did not correlate with baseline D2/D3 receptor availability. When monkeys (N=5) were rescanned after self‐administering 100 mg/kg and 1000 mg/kg cocaine, there were significant reductions in D2/D3 receptor availability in the caudate nucleus, putamen, and ventral striatum. This finding is consistent with those reported in male monkeys. These five female monkeys were also studied in abstinence with one showing recovery of D2/D3 receptor availability after 6 months and the other after 9 months of abstinence. In an effort to determine whether the reductions in D2/D3 receptor availability were permanent in the three monkeys that did not recover their baseline after 9 months of abstinence, they were treated them with raclopride (0.01 mg/kg per hour) via an osmotic pump for 30 days using a protocol that has been shown to increase D2/D3 receptor availability in male monkeys (Czoty et al., 2005). Chronic raclopride treatment increased D2/D3 receptor availability relative to their 9‐month abstinence levels by 10–20%. However, relative to their pre‐cocaine baselines, reductions were still apparent. These findings show that while the effects of long‐term cocaine self‐administration are similar in all monkeys, there are individual differences in rate of recovery and these reductions may be irreversible. Additional studies are necessary to determine whether there are behavioral characteristics or peripheral and central biomarkers predictive of DA receptor recovery.Support or Funding InformationDA017763
Active anti‐methamphetamine vaccination attenuates the effects of methamphetamine
Authors: Taffe Michael A , Nguyen Jacques D , Bremer Paul T , Vandewater Sophia A , Creehan Kevin M , Janda Kim D 
Published: November 2023

Successful treatment remains elusive for methamphetamine (MA) addiction, which remains a serious public health concern. Immunopharmacotherapy has been shown to attenuate many effects of MA in rodent models. This study further investigated the efficacy of an anti‐MA vaccine in rats with locomotor and self‐administration assays. Male and female rats were vaccinated with either a control keyhole‐limpet hemocyanin vaccine (KLH) or a candidate anti‐MA vaccine (MH6‐KLH conjugate). MH6‐KLH vaccination blocked the homecage locomotor stimulant effects of MA (i.p.) in a dose dependent manner in female rats. The MH6‐KLH vaccine also interfered with a suppression of wheel running activity observed 30 min after vapor inhalation of MA in male rats. The MH6‐KLH vaccine also reduced the reinforcing efficacy of MA, but not alpha‐PVP, in intravenous self‐administration under a Progressive Ratio dose substitution procedure in male rats. This study further confirms the efficacy of the MH6‐KLH candidate vaccine and more generally that active immunopharmacotherapy can attenuate the effects of MA.Support or Funding InformationNIH Grant R01 DA024705
Pharmacological Characterization of the Discriminative‐Stimulus Effects of the Nicotinic Agonist (+)‐Epibatidine in Squirrel Monkeys
Authors: Desai Rajeev I , Doyle Michelle R , Bergman Jack 
Published: November 2023

The present studies were undertaken to characterize the discriminative‐stimulus (SD) effects of (+)‐epibatidine (EPI)–an α4β2 selective nicotinic agonist that is pharmacologically similar and structurally distinct from nicotine (NIC). Using a standard two‐lever drug discrimination procedure, squirrel monkeys (n=4) were trained to discriminate i.m. injections of 0.001 mg/kg (+)‐epibatidine (EPI) from saline on a 10‐response fixed‐ratio schedule of stimulus‐termination. Results show that high efficacy nicotinic agonists [(+)‐EPI, (−)‐EPI, NIC] substituted fully for (+)‐EPI, whereas the highest doses of other nicotinic agonists produced intermediate levels of (+)‐EPI‐like SD effects [varenicline (VAR), cytisine (CYT), isoarecolone (ISO)] or did not substitute for (+)‐EPI (lobeline). Drugs from other pharmacological classes (methamphetamine, atropine, citalopram, arecoline) did not generalize for (+)‐EPI's stimulus effects. Pretreatment studies with nicotinic antagonists show that: a) mecamylamine (non‐selective) insurmountably antagonized (+)‐EPI's effects; b) dihydro‐β‐erthroidine (α4β2‐selective) surmountably (>3‐fold rightward shift) blocked (+)‐EPI's effects; and c) methyllycaconitine (α7 selective) failed to modify the SD effects of (+)‐EPI. Interestingly, the peripherally‐restricted nicotinic antagonist hexamethonium also appeared to block (+)‐EPI's SD effects (approximately 3‐fold rightward shift) suggesting that a peripheral component may also play a role in 0.001 mg/kg (+)‐EPI's discriminable effects. In further studies, pretreatment with the partial nicotinic agonists VAR and CYT did not block the SD effects of (+)‐EPI, and in fact, CYT pretreatment shifted the (+)‐EPI dose‐effect curve to the left (>3‐10‐fold). These results suggest that the discriminative‐stimulus effects of (+)‐EPI are mediated through α4β2 nicotinic receptor subtypes at which the partial agonists VAR and CYT do not exert partial antagonist actions.Support or Funding InformationSupported by NIH/NIDA DA031231
Expression of Nerve Membrane Proteins in a Naturally Occurring Ca2+ Channelopathy
Authors: Colón‐Carrion Nicole , Colón‐Rodriguez Alexandra , Atchison William D. 
Published: November 2023

Neuronal voltage gated calcium channels (VGCC) are essential for numerous cellular functions including synaptogenesis and neurotransmitter release. Mutations in individual subunits of the VGCC are known to result in many neurological disorders. In tottering (tg) mice, the mutation in the α1A subunit of the P/Q calcium channel leads to ataxia and motor seizures that result in absence epilepsy in humans. Studies done with tg mice have also implied that GABAA receptor function is impaired. Consequently, we compared the expression of GABAA receptor subunits and VGCC subunits in the forebrain (FB), which is not a specific target of the tg mutation with that in the cerebellum (CB), which is a primary target. Previous functional studies have shown that Ca2+ channels subtypes such as the L and N type are upregulated and the inhibitory GABAA receptor expression is decreased in the CB of tg mice. Our hypothesis was that gene expression of L, N, R, & T type VGCCs will be upregulated and certain GABAA receptors subunits specific to CB will be downregulated in the CB and not the FB of tg mice. QPCR was performed on reverse transcript (cDNA) of RNA isolated from CB and FB tissue of 6mo old male wt, heterozygote (+/−) and homozygote (+/+) tg mice. VGCC α1A (P/Q type), α1B (N type), α1C (L type), α1E (R type), β1, β2, β3, and β4 subunits as well as GABAA α1, α6, β1, β3, γ2 and δ subunit expression was measured in CB and FB of mice. In the CB α1A, α1B, α1C, α1E subunit of the (+/−) tg mice were at control levels. The (+/+) tg mice showed a downregulation of the α1A, as expected, and an upregulation of the α1B. This suggests that the α1B subunit is compensating for the loss of α1A subunit expression as it has been shown previously. In the FB, (+/−) tg mice had all α1 subunits expressed similar to control, while the (+/+) tg mice displayed a downregulation. In the CB the β3 subunit for the (+/−) tg mice was upregulated. In the FB the β subunits were upregulated for the (+/−) tg mice, and no significant change was observed for the (+/+) tg mice. Expression of GABAA α1, α6, γ2 and δ was increased in the CB of (+/−) and (+/+) tg mice. However in the FB there was no significant difference in expression of GABAA receptor subunits in the (+/−) compared to control; there was a downregulation of the γ2 subunit in the (+/+) tg mice. Our results demonstrate that VGCC and GABAA receptor subunit expression is altered as a result of the homozygous mutation of the α1A subunit of the VGCC. These results suggest that alterations in expression of these nerve membrane proteins can be contributing to the observed alterations in synaptic transmission and phenotypic changes observed in the tg mouse model.Support or Funding InformationSupported by NIH NIEHS grants R25ES025060, T32ES007255 and R01ES024064.
Homo‐Oligomerization of Regulator Of G Protein Signaling 7 (RGS7)
Authors: Slepak Vladlen Z , Tayou Junior , Wang Qiang , Pronin Alexey 
Published: November 2023

RGS proteins belonging to the R7 subfamily (RGS6, 7, 9 and 11) are highly expressed in the CNS neurons and to a much lesser extent in glands and heart where they regulate many physiological processes. R7 proteins contain several distinct domains and form obligatory dimers with the atypical Gβ subunit, Gβ5, which is essential for the stability of these complexes. They also interact with other proteins such as R7BP (R7‐binding protein), R9AP (R9‐anchoring protein) and the orphan G protein coupled receptors, GPR158 and GPR179. These interactions modulate the function of R7 proteins, facilitate their stability and targeting to plasma membranes. In neurons and transfected cells, RGS7 localizes not only to the plasma membrane but also to cytoplasmic granules where its function is unknown. Here, using chemical cross‐linking, immunoprecipitation and mass spectrometry approaches, we sought to identify new binding partners of granular RGS7. We found that RGS7 can exist as a homo‐oligomer that after cross‐linking has the apparent molecular weight of approximately 150 kDa upon resolution by SDS PAGE. Formation of this oligomeric complex was confirmed by co‐immunoprecipitation assays with or without cross‐linking. The RGS7‐RGS7 interaction requires the DEP domain, but not the RGS, DHEX domains or the obligatory subunit of RGS7, Gβ5. We also demonstrated that oligomerization of RGS7 was inhibited in the presence of R7BP or constitutively activated Gαo. However, GPR158 could bind to the oligomeric form of RGS7. While oligomerization of other proteins in G protein signaling (e.g., GPCRs or arresting) is known, or results for the first time show the existence of RGS protein homo‐oligomers.Support or Funding InformationThis work is supported by NIH Grant R01DK105427 (VZS)
The IBMX‐insensitive PDE8A is expressed in human airway smooth muscle cells and selectively regulates signaling through AC6
Authors: Hill Kaitlyn , Li Fengying , Bogard Amy S. , Ostrom Rennolds S. 
Published: November 2023

The second messenger cAMP is produced by several different adenylyl cyclase (AC) isoforms in human airway smooth muscle (HASM). We previously defined two distinct cAMP signaling compartments in these cells, one containing AC6 and another containing AC2 (Naunyn‐Schmiedebergs Arch Pharmacol, 387(4):329–39, 2014). We hypothesized that phosphodiesterase (PDE) isozymes may also be compartmentized in HASM. We detected mRNA and protein expression of the IBMX‐insensitive PDE8A in cultured HASM cells. Using lentiviral delivery of shRNA we knocked down PDE8A expression and measured cAMP levels stimulated by forskolin. The broad‐spectrum PDE inhibitor, IBMX, was included in these assays to eliminate contributions by most other PDE isoforms. 1 μM forskolin stimulated 2‐fold higher cAMP in HASM with PDE8A knockdown than in cells treated with control lentivirus. Overexpression of AC2 did not alter this response, but overexpression of AC6 increased this response an additional 80%. We used TaqMan PCR to quantify the expression of AREG (a gene whose expression is regulated by cAMP from both AC2 and AC6) and NR4A2 (a gene regulated only by cAMP from AC6). PDE8A knockdown increased forskolin‐stimulated AREG and NR4A2 expression in AC6 overexpressing HASM but had no effect on either of these genes when AC2 was overexpressed. Quantitative phosphoproteomic analysis of whole cell lysates show that forskolin treatment causes PDE8A phosphorylation in HASM but that only AC6 overexpression increased this phosphorylation. To determine receptor‐mediated signaling regulated by PDE8A, we examined cAMP production in response to isoproterenol (β2AR, which couple primarily to AC6) and butaprost (EP2R, which couple to only AC2). PDE8A knockdown did not alter butaprost‐stimulated cAMP in HASM overexpressing AC2, consistent with no role of this PDE isoform in AC2‐mediated cAMP signaling. Isoproterenol‐stimulated cAMP was reduced by 70% in HASM overexpressing AC6, as effect opposite of what was predicted based on forskolin‐mediated responses. We conclude that PDE8A selectively hydrolyzes cAMP produced by AC6 with no effect on cAMP emanating from AC2. However, knockdown of PDE8A expression causes an uncoupling of β2AR to cAMP production through an undetermined mechanism.Support or Funding InformationSupported by NIH (GM107094) and AHA (14GRNT20380762)
Evaluating the Specificity and Potency of Activators and Inhibitors of the cAMP Sensors PKA, Epac2/Rapgef4, and NCS/Rapgef2 Using Cell‐Based Assays for Activation of CREB, p38 MAPK, and ERK
Authors: Emery Andrew C , Eiden Maribeth V , Eiden Lee E 
Published: November 2023

Cyclic AMP elevation is well known to cause dividing neuroendocrine (e.g. PC12) cells to differentiate through a process that includes growth arrest, neurite extension, and induction of neuronal genes. Using the PC12 subclone NS‐1, we have previously shown that downstream of cAMP, signaling for differentiation is mediated by three insulated signaling pathways, initiated by cAMP activation of Epac2/Rapgef4, NCS/Rapgef2, and PKA, which regulate the activation of p38 MAP kinase, ERK, and CREB, respectively. These, in turn, are individually necessary for growth arrest (Epac2/Rapgef4), neurite extension (NCS/Rapgef2), and neuron‐specific gene expression (PKA) (Emery et al., 2014, J Biol Chem, 289:10126–39). Specific inhibitors and activators of PKA, Epac, and NCS/Rapgef2 would be useful to further explore the unique physiological functions of these three cAMP sensors in the CNS. Several compounds that show differential activity with respect to PKA and Epac exist, however, the selectivity of these agents across all three neuroendocrine cAMP sensors is not yet known. The goal of the work reported here was to identify cAMP analogs that provide specific activation and inhibition of each of these cAMP sensors. To this end, we have used a medium‐throughput assay platform that allows for quantitative measurement of the phosphorylation status of ERK, CREB, and p38 MAPK, which serve as read‐outs for activation of NCS/Rapgef2, PKA, and Epac2, respectively. 8‐CPT‐cAMP was found to be a full agonist with a similar potency at each sensor, while 8‐CPT‐2′‐O‐Me‐cAMP was highly specific for Epac relative to PKA (as reported by Enserink et al., 2002, Nat Cell Biol, 4:901–6) and also NCS/Rapgef2. We examined previously characterized PKA site‐specific agonists, i.e. compounds that stimulate PKA holoenzyme activity only when applied in combination, to determine if any of these provide SAR entree to further development of Epac or NCS/Rapgef2‐specific agonists. Our preliminary evidence suggests that several B site‐specific compounds, when administered singly, show significant activity at NCS/Rapgef2 without stimulating either Epac or the PKA holoenzyme. None of the cyclic nucleotide antagonists (Rp diastereomeric cAMP analogs) that we tested effectively inhibited cAMP‐dependent NCS/Rapgef2 signaling. Based on our previous work indicating that the nucleoside adenylate cyclase inhibitor SQ22,536 inhibits NCS/Rapgef2 (Emery et al., 2013, Mol Pharmacol, 83:95–105), along with new insights into structure‐activity relationships for NCS/Rapgef2 gleaned from our survey of B‐site‐specific activators, we propose that the development of a cell‐permeant, highly specific inhibitor of NCS/Rapgef2 is feasible.Support or Funding InformationSupported by NIMH‐IRP project ZO1‐MH002386
Evaluations of the Inhibitory effects of Psoralea Corylifolia Benzopyrone Derivatives in Human Monoamine Oxidase A and B
Authors: Zarmouh Najla O , Soliman Karam F. 
Published: November 2023

The classical inhibitors of monoamine oxidases (MAOs) are effectively used in the therapeutic management of neurological disorders with rare, but serious, side‐effects. In our investigation for safe and natural MAO‐B inhibitors, Psoralea corylifolia Linn seeds (PCS) ethanolic extract (PCSEE) and seven of its benzopyrone constituents were investigated for their recombinant human (h) MAO‐A and B inhibition and selectivity. The extensively extracted PCSEE selectively inhibited MAO‐B (IC50 of 3.03 μg/ml) more than A. PCS benzopyrones showed weak to potent hMAO‐A and B hydrogen peroxide (H2O2) byproduct inhibition. MAO‐A inhibition potencies of PCSEE common compounds were in biochanin‐A (BIO‐A) > isopsoralen > genistein > 6‐prenylnaringenin > neobavaisoflavone > psoralen. Meanwhile, MAO‐B inhibition potencies were in BIO‐A > genistein > 6‐prenylnaringenin > isopsoralen > neobavaisoflavone > psoralen. Psoralidin was inactive in both isozymes. Compared to PCSEE and its tested benzopyrones, BIO‐A and genistein, showed the most potent hMAO‐A and B inhibition, equal or more potent than PCSEE. Furthermore, the most potent MAOI, BIO‐A, reversibly inhibited both isozymes. BIO‐A reversibility was supported by docking and kinetics studies. BIO‐A was predicted to form reversible interactions with FAD of MAO‐A, and with threonine 201 and p phenylalanine 168 in MAO‐B active site. Michaelis‐Menten kinetics studies also showed a competitive mode of BIO‐A inhibition on both isozymes. The obtained data indicate that PCSEE benzopyrones may contribute to its MAOs inhibitory activities and could be utilized as a natural neuroprotective source in neurological disorders.Support or Funding InformationSupported by NIH grants from NIMHD G12 MD007582 and P20 MD006738
Natural compounds ursolic acid and isoliquiritigenin target GRP78 to enhance human gastric cancer cell chemosensitivity by 5‐fluorouracil
Authors: Lin Mingwei , Wu Dengchyang , Huang Yawbin 
Published: November 2023

Gastric cancer is one of the most common malignancies worldwide, accounting for nearly half of cancer‐related mortality. Chemotherapy is the treatment of choice for gastric cancer, but the currently available therapeutic drugs for the treatment have limited efficacy. Recent studies suggested that gastric cancer stem cells may play an important role in drug resistance of chemotherapy. Therefore, new agents that selectively target gastric cancer stem cells in gastric tumor are urgently needed. Regarding to this concept, natural products may gain considerable important in this area for both cancer cell and cancer stem cell targeting. Ursolic acid (UA), a pentacyclic triterpenoid isolated from Catharanthus trichophyllus roots, and isoliquiritigenin (ISL), a chalconetype dietary compound derived from licorice, have been reported to process anti‐tumor properties. However, the potential role of UA and ISL in the improvement of chemotherapy sensitivity of gastric cancer has not been evaluated. The data from our study indicated that UA and ISL promoted human gastric cancer MKN45 cell apoptosis, and enhanced chemosensitivity with combination of 5‐fluorouracil by elimination of endoplasmic reticulum chaperone protein, glucose‐regulated protein 78 (GRP78), and down‐regulation of cancer stem cell surface marker, adenosine triphosphate‐binding cassette subfamily G2, LGR5, CD24 and CD44. UA not only induced excessive ER stress in cancer cell, but also inhibited the expression of GRP78 by down‐regulation of the transcription factor YY1. Taken together, UA and ISL may be suggested as promising agents in anti‐gastric tumor therapy.Support or Funding InformationThis work was supported by the slow aging program, “Aim for the Top Universities Grant” (KMU‐TP104G00 & KMU‐TP104G01) at Kaohsiung Medical University, and the Ministry of Science and Technology of Taiwan, MOST, 104‐2314‐B‐037‐003.