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Biomedicines Sep 2023Ghrelin is an orexigenic neuropeptide that is known for stimulating the release of growth hormone (GH) and appetite. In addition, ghrelin has been implicated in...
Ghrelin is an orexigenic neuropeptide that is known for stimulating the release of growth hormone (GH) and appetite. In addition, ghrelin has been implicated in addiction to drugs such as nicotine. Nicotine is the principal psychoactive component in tobacco and is responsible for the reward sensation produced by smoking. In our previous in vitro superfusion studies, it was demonstrated that ghrelin and nicotine stimulate equally the dopamine release in the rat amygdala, and ghrelin amplifies the nicotine-induced dopamine release in the rat striatum. However, less attention was paid to the actions of ghrelin and nicotine in the bed nucleus of the stria terminalis (BNST). Therefore, in the present study, nicotine and ghrelin were superfused to the BNST of male Wistar rats, and the dopamine release from the BNST was measured in vitro. In order to determine which receptors mediate these effects, mecamylamine, a non-selective nicotinic acetylcholine receptor (nAchR) antagonist, and GHRP-6, a selective growth hormone secretagogue receptor (GHS-R1A) antagonist, were also superfused to the rat BNST. Nicotine significantly increased the release of dopamine, and this effect was significantly inhibited by mecamylamine. Ghrelin increased dopamine release even more significantly than nicotine did, and this effect was significantly inhibited by GHRP-6. Moreover, when administered together, ghrelin significantly amplified the nicotine-induced release of dopamine in the BNST, and this additive effect was reversed partly by mecamylamine and partly by GHRP-6. Therefore, the present study provides a new base of evidence for the involvement of ghrelin in dopamine signaling implicated in nicotine addiction.
PubMed: 37760897
DOI: 10.3390/biomedicines11092456 -
Behavioural Pharmacology Sep 2020The α4β2* nicotinic acetylcholine receptor (nAChR) subtypes are targeted for the development of smoking cessation aids, and the use of drug discrimination in mice...
The α4β2* nicotinic acetylcholine receptor (nAChR) subtypes are targeted for the development of smoking cessation aids, and the use of drug discrimination in mice provides a robust screening tool for the identification of drugs acting through nAChRs. Here, we established that the α4β2* nAChR agonist epibatidine can function as a discriminative stimulus in mice. Male C57BL/6J mice discriminated epibatidine (0.0032 mg/kg, subcutaneously) and were tested with agonists varying in selectivity and efficacy for α4β2* nAChRs. The discriminative stimulus effects of epibatidine were characterized with the nonselective, noncompetitive nicotinic antagonist mecamylamine, with the selective β2-substype-containing nAChR antagonist dihydro-β-erythroidine hydrobromide (DHβE), and the α7 antagonist methyllycaconitine (MLA). Nicotine (0.32-1.0 mg/kg, subcutaneously), the partial nAChR agonist cytisine (1.0-5.6 mg/kg, subcutaneously), and the α7 nAChR agonist N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide (10-56 mg/kg, intraperitoneally) produced no more than 33% epibatidine-appropriate responding. The partial α4β2* nAChR agonists varenicline and 2'-fluoro-3'-(4-nitro-phenyl)deschloroepibatidine produced 61 and 69% epibatidine-appropriate responding, respectively. DHβE and mecamylamine, but not MLA, significantly antagonized the discriminative stimulus effects of epibatidine. These results show that epibatidine may be trained as a discriminative stimulus in mice and has utility in elucidating the in-vivo pharmacology of α4β2* nAChR ligands.
Topics: Aconitine; Animals; Bridged Bicyclo Compounds, Heterocyclic; Dihydro-beta-Erythroidine; Discrimination Learning; Male; Mecamylamine; Mice; Mice, Inbred C57BL; Pyridines
PubMed: 32209809
DOI: 10.1097/FBP.0000000000000555 -
Psychopharmacology Feb 2021Previous neuroimaging studies of cognition involving nicotinic acetylcholine receptor (nAChR) agonist administration have repeatedly found enhanced task-induced...
RATIONALE
Previous neuroimaging studies of cognition involving nicotinic acetylcholine receptor (nAChR) agonist administration have repeatedly found enhanced task-induced deactivation of regions of the default mode network (DMN), a group of brain systems that is more active at rest and mediates task-independent thought processes. This effect may be related to pro-cognitive nAChR agonist effects OBJECTIVES: The present study sought to test whether nAChR modulation of the DMN is bi-directional, i.e., whether a nAChR antagonist would reduce task-induced deactivation.
METHODS
Eighteen healthy non-smokers underwent functional magnetic resonance imaging while performing a letter N-back task. Scans were performed after nicotine administration (7 mg/24 h, transdermally), after administration of the nAChR antagonist mecamylamine (7.5 mg, p.o.), and after double placebo, in counterbalanced sequence. Blood-oxygen-level-dependent (BOLD) signal was analyzed within ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (PCC) regions of interest-central hubs of the DMN in which consistent nAChR agonist-induced changes had previously been identified.
RESULTS
Nicotine enhanced hit rate in both the 0-back and 2-back condition, while mecamylamine slowed reaction time in the 2-back condition. Mecamylamine reduced task-induced deactivation of vmPFC and PCC. Nicotine had no significant effects on the BOLD signal.
CONCLUSIONS
The finding that nAChR tone reduction by mecamylamine weakened task-induced DMN deactivation indicates that a constant tone of nAChR activation helps regulate DMN activity in healthy individuals. This suggests that low nAChR tone may play a causal role in DMN dysregulation seen in conditions such as mild cognitive impairment or Alzheimer's disease.
Topics: Adult; Brain; Cognition; Cognitive Dysfunction; Default Mode Network; Female; Gyrus Cinguli; Humans; Magnetic Resonance Imaging; Male; Mecamylamine; Middle Aged; Nicotine; Nicotinic Agonists; Nicotinic Antagonists; Prefrontal Cortex; Reaction Time; Receptors, Nicotinic; Task Performance and Analysis
PubMed: 33216167
DOI: 10.1007/s00213-020-05711-9 -
Translational Neuroscience 2015To investigate the effect of brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase (Trk) on potassium chloride cotransporter 2 (KCC2) in rats following...
PURPOSE
To investigate the effect of brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase (Trk) on potassium chloride cotransporter 2 (KCC2) in rats following nicotine withdrawal and the roles played by BDNF/Trk/KCC2 pathway in nicotine withdrawal-induced hyperalgesia.
METHODS
Seventy-eight rats were randomly assigned to five groups: control group (n = 12) without any treatment, normal saline group (NS group, n = 12) and nicotine withdrawal group (NW group, n = 30) receiving a subcutaneous injection of saline or nicotine for 7 days, respectively. The NW + dimethyl sulfoxide (DMSO) (n = 12) and NW+ Trk antagonist K252a groups (n = 12) received an intrathecal injection of DMSO (10 μl) and K252a (10 μg/10 μl) for 3 days after nicotine withdrawal, respectively. Nicotine withdrawal was precipitated by subcutaneous injection of nonselective and noncompetitive antagonist of nicotinic acetylcholine receptors mecamylamine. Pain was tested using thermal withdrawal latency (TWL). A Western blot was used to examine the expression of BDNF and KCC2.
RESULTS
The TWL was significantly decreased in NW group relative to control and NS groups ( < 0.01). Compared with the NW group, the NW+K252a group manifested a significantly higher latency ( < 0.01). The BDNF expression was increased and KCC2 was decreased in NW group compared with the control group ( < 0.01). K252a reduced KCC2 downregulation.
CONCLUSION
BDNF/Trk signaling may contribute to nicotine withdrawal-induced hyperalgesia via downregulation of KCC2.
PubMed: 28123805
DOI: 10.1515/tnsci-2015-0022 -
Bioscience Reports Dec 2022M2 macrophages have been reported to be important in the progression of coronary artery disease (CAD). Thus, the present study aims at exploring the diagnostic value of...
BACKGROUND
M2 macrophages have been reported to be important in the progression of coronary artery disease (CAD). Thus, the present study aims at exploring the diagnostic value of M2 macrophage-associated genes in CAD.
METHODS
Transcriptome profile of CAD and control samples were downloaded from Gene Expression Omnibus database. The proportion of immune cells was analyzed using cell type identification by estimating relative subsets of RNA transcripts. Weighted Gene Co-expression Network Analysis (WGCNA) was carried out to screen the relevant module associated with M2 macrophages. Differential CAD and control samples of expressed genes (DEGs) were identified by the limma R package. Functional enrichment analysis by means of the clusterProfiler R package. Least absolute shrinkage and selection operator (LASSO) and random forest (RF) algorithms were carried out to select signature genes. Receiver operating curves (ROC) were plotted to evaluate the diagnostic value of selected signature genes. The expressions of potential diagnostic markers were validated by RT-qPCR. The ceRNA network of diagnostic biomarkers was constructed via miRwalk and Starbase database. CMap database was used to screen candidate drugs in the treatment of CAD by targeting diagnostic biomarkers.
RESULTS
A total of 166 M2 macrophage-associated genes were identified by WGCNA. By intersecting those genes with 879 DEGs, 53 M2 macrophage-associated DEGs were obtained in the present study. By LASSO, RF, and ROC analyses, C1orf105, CCL22, CRYGB, FRK, GAP43, REG1P, CALB1, and PTPN21 were identified as potential diagnostic biomarkers. RT-qPCR showed the consistent expression patterns of diagnostic biomarkers between GEO dataset and clinical samples. Perhexiline, alimemazine and mecamylamine were found to be potential drugs in the treatment of CAD.
CONCLUSION
We identified eight M2 macrophage-associated diagnostic biomarkers and candidate drugs for the CAD treatment.
Topics: Humans; Coronary Artery Disease; Gene Regulatory Networks; Gene Expression Profiling; Transcriptome; Macrophages; Biomarkers
PubMed: 36222281
DOI: 10.1042/BSR20221394 -
Addiction Biology May 2021Alcohol use disorder is a chronic, relapsing brain disorder causing substantial morbidity and mortality. Cholinergic interneurons (CIN) within the nucleus accumbens...
Alcohol use disorder is a chronic, relapsing brain disorder causing substantial morbidity and mortality. Cholinergic interneurons (CIN) within the nucleus accumbens (nAc) have been suggested to exert a regulatory impact on dopamine (DA) neurotransmission locally, and defects in CIN have been implied in several psychiatric disorders. The aim of this study was to investigate the role of CIN in regulation of basal extracellular levels of DA and in modulation of nAc DA release following ethanol administration locally within the nAc of male Wistar rats. Using reversed in vivo microdialysis, the acetylcholinesterase inhibitor physostigmine was administered locally in the nAc followed by addition of either the muscarinic acetylcholine (ACh) receptor antagonist scopolamine or the nicotinic ACh receptor antagonist mecamylamine. Further, ethanol was locally perfused in the nAc following pretreatment with scopolamine and/or mecamylamine. Lastly, ethanol was administered locally into the nAc of animals with accumbal CIN-ablation induced by anticholine acetyl transferase-saporin. Physostigmine increased accumbal DA levels via activation of muscarinic ACh receptors. Neither scopolamine and/or mecamylamine nor CIN-ablation altered basal DA levels, suggesting that extracellular DA levels are not tonically controlled by ACh in the nAc. In contrast, ethanol-induced DA elevation was prevented following coadministration of scopolamine and mecamylamine and blunted in CIN-ablated animals, suggesting involvement of CIN-ACh in ethanol-mediated DA signaling. The data presented in this study suggest that basal extracellular levels of DA within the nAc are not sustained by ACh, whereas accumbal CIN-ACh is involved in mediating ethanol-induced DA release.
Topics: Acetylcholine; Animals; Cholinergic Antagonists; Dopamine; Ethanol; Male; Mecamylamine; Microdialysis; Nicotinic Antagonists; Nucleus Accumbens; Rats; Rats, Wistar; Scopolamine; Ventral Tegmental Area
PubMed: 32789970
DOI: 10.1111/adb.12959 -
Journal of Leukocyte Biology Apr 2021Lung cancer is the leading cause of cancer deaths worldwide, with a high morbidity and less than 20% survival rate. Therefore, new treatment strategies and drugs are...
Lung cancer is the leading cause of cancer deaths worldwide, with a high morbidity and less than 20% survival rate. Therefore, new treatment strategies and drugs are needed to reduce the mortality of patients with lung cancer. α7 nicotinic acetylcholine receptor (α7 nAChR), as a receptor of nicotine and its metabolites, is a potential target for lung cancer treatment. Our previous studies revealed that sinomenine plays anti-inflammation roles via α7 nAChR and down-regulates the expression of this receptor, thus increasing the inflammatory response. Hence, sinomenine is possibly a natural ligand of this receptor. In the present study, the effects of sinomenine on lung cancer A549 cells and tumor-bearing mice were determined to investigate whether this alkaloid has an inhibitory effect on lung cancer via α7 nAChR. CCK-8 assay, wound-healing test, and flow cytometry were performed for cell proliferation, cell migration, and apoptosis analysis in vitro, respectively. Xenograft mice were used to evaluate the effects of sinomenine in vivo. Results showed that sinomenine decreased cell proliferation and migration abilities but increased the percentage of apoptotic cells. Tumor volume in tumor-bearing mice was significantly reduced after sinomenine treatment compared with that in the vehicle group mice (p < 0.05). Furthermore, the effects of sinomenine were abolished by the α7 nAChR antagonist mecamylamine and the allosteric modulator PNU-120596, but no change occurred when the mice were pretreated with the muscarinic acetylcholine receptor antagonist atropine. Meanwhile, sinomenine suppressed α7 nAChR expression in vitro and in vivo, as well as the related signaling molecules pERK1/2 and ERK1/2 and the transcription factors TTF-1 and SP-1. By contrast, sinomenine up-regulated the expression of another transcription factor, Egr-1. These effects were restricted by mecamylamine and PNU but not by atropine. Results suggested that sinomenine can inhibit lung cancer via α7 nAChR in a negative feedback mode.
Topics: A549 Cells; Animals; Antineoplastic Agents; Humans; Lung Neoplasms; Male; Mice, Inbred C57BL; Morphinans; Signal Transduction; Transcription Factors; alpha7 Nicotinic Acetylcholine Receptor; Mice
PubMed: 32726882
DOI: 10.1002/JLB.6MA0720-344RRR -
Developmental Biology Dec 2022We recently described calcium signaling in the appendicularian tunicate Oikopleura dioica during pre-gastrulation stages, and showed that regularly occurring calcium...
We recently described calcium signaling in the appendicularian tunicate Oikopleura dioica during pre-gastrulation stages, and showed that regularly occurring calcium waves progress throughout the embryo in a characteristic spatiotemporal pattern from an initiation site in muscle lineage blastomeres. Here, we have extended our observations to the period spanning from gastrulation to post-hatching stages. We find that repetitive Ca2+ waves persist throughout this developmental window, albeit with a gradual increase in frequency. The initiation site of the waves shifts from muscle cells at gastrulation and early tailbud stages, to the central nervous system at late tailbud and post-hatching stages, indicating a transition from muscle-driven to neurally driven events as tail movements emerge. At these later stages, both the voltage gated Na+ channel blocker tetrodotoxin (TTX) and the T-type Ca2+ channel blocker and nAChR antagonist mecamylamine eliminate tail movements. At late post-hatching stages, mecamylamine blocks Ca2+ signals in the muscles but not the central nervous system. Post-gastrulation Ca2+ signals also arise in epithelial cells, first in a haphazard pattern in scattered cells during tailbud stages, evolving after hatching into repetitive rostrocaudal waves with a different frequency than the nervous system-to-muscle waves, and insensitive to mecamylamine. The desynchronization of Ca2+ waves arising in different parts of the body indicates a shift from whole-body to tissue/organ-specific Ca2+ signaling dynamics as organogenesis occurs, with neurally driven Ca2+ signaling dominating at the later stages when behavior emerges.
Topics: Animals; Gastrulation; Urochordata; Calcium Signaling; Calcium; Mecamylamine
PubMed: 36162551
DOI: 10.1016/j.ydbio.2022.09.004 -
Pharmacology, Biochemistry, and Behavior Jun 2021Relief from increases in anxiety during nicotine withdrawal contributes to tobacco addiction. While a variety of anxiogenic stimuli elicit avoidance of the center of an...
Magnitude of open-field thigmotaxis during mecamylamine-precipitated nicotine withdrawal in rats is influenced by mecamylamine dose, duration of nicotine infusion, number of withdrawal episodes, and age.
Relief from increases in anxiety during nicotine withdrawal contributes to tobacco addiction. While a variety of anxiogenic stimuli elicit avoidance of the center of an open field (thigmotaxis) in rodents, effects of nicotine withdrawal on thigmotaxis have not been studied extensively. The goal of this study was to evaluate determinants of increases in thigmotaxis during mecamylamine-precipitated nicotine withdrawal in rats. We evaluated several variables implicated in severity of other measures of precipitated nicotine withdrawal: mecamylamine dose, duration of nicotine infusion, number of withdrawal episodes, and age. In Experiment 1, mecamylamine elicited increases in thigmotaxis in adult rats receiving a chronic nicotine infusion (3.2 mg/kg/day for >7 days) at only the highest mecamylamine dose tested (4.0 mg/kg). In Experiment 2, repeated administration of 4.0 mg/kg mecamylamine throughout the course of a 2-week chronic nicotine infusion (3.2 mg/kg/day) did not affect thigmotaxis when administered following 2 days of the infusion, but elicited significant increases in thigmotaxis at longer infusion durations. In Experiment 3, adolescents tested under the same protocol used in adults in Experiment 2 did not exhibit increased thigmotaxis at any point during the 2-week nicotine infusion, even though we used higher nicotine doses (4.7 or 6.4 mg/kg/day) to account for the faster metabolism of nicotine in adolescents compared to adults. Our findings provide the first systematic characterization of determinants of increases in thigmotaxis during precipitated nicotine withdrawal in rats. Further use of this model may be useful for characterizing the mechanisms underlying the anxiogenic component of nicotine withdrawal.
Topics: Age Factors; Animals; Avoidance Learning; Dose-Response Relationship, Drug; Locomotion; Male; Mecamylamine; Nicotine; Nicotinic Agonists; Nicotinic Antagonists; Rats; Rats, Wistar; Substance Withdrawal Syndrome; Taxis Response; Time Factors
PubMed: 33831460
DOI: 10.1016/j.pbb.2021.173185 -
Archives of Toxicology Jun 2021Neonicotinoid pesticides, originally developed to target the insect nervous system, have been reported to interact with human receptors and to activate rodent neurons.... (Comparative Study)
Comparative Study
Neonicotinoid pesticides, originally developed to target the insect nervous system, have been reported to interact with human receptors and to activate rodent neurons. Therefore, we evaluated in how far these compounds may trigger signaling in human neurons, and thus, affect the human adult or developing nervous system. We used SH-SY5Y neuroblastoma cells as established model of nicotinic acetylcholine receptor (nAChR) signaling. In parallel, we profiled dopaminergic neurons, generated from LUHMES neuronal precursor cells, as novel system to study nAChR activation in human post-mitotic neurons. Changes of the free intracellular Ca concentration ([Ca]) were used as readout, and key findings were confirmed by patch clamp recordings. Nicotine triggered typical neuronal signaling responses that were blocked by antagonists, such as tubocurarine and mecamylamine. Pharmacological approaches suggested a functional expression of α7 and non-α7 nAChRs on LUHMES cells. In this novel test system, the neonicotinoids acetamiprid, imidacloprid, clothianidin and thiacloprid, but not thiamethoxam and dinotefuran, triggered [Ca] signaling at 10-100 µM. Strong synergy of the active neonicotinoids (at low micromolar concentrations) with the α7 nAChR-positive allosteric modulator PNU-120596 was observed in LUHMES and SH-SY5Y cells, and specific antagonists fully inhibited such signaling. To provide a third line of evidence for neonicotinoid signaling via nAChR, we studied cross-desensitization: pretreatment of LUHMES and SH-SY5Y cells with active neonicotinoids (at 1-10 µM) blunted the signaling response of nicotine. The pesticides (at 3-30 µM) also blunted the response to the non-α7 agonist ABT 594 in LUHMES cells. These data show that human neuronal cells are functionally affected by low micromolar concentrations of several neonicotinoids. An effect of such signals on nervous system development is a toxicological concern.
Topics: Calcium; Cell Line; Cell Line, Tumor; Dopaminergic Neurons; Dose-Response Relationship, Drug; Humans; Neonicotinoids; Neuroblastoma; Patch-Clamp Techniques; Pesticides; Receptors, Nicotinic; Signal Transduction
PubMed: 33778899
DOI: 10.1007/s00204-021-03031-1