scholarly journals nor-BNI Antagonism of Kappa Opioid Agonist-Induced Reinstatement of Ethanol-Seeking Behavior

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Erin Harshberger ◽  
Emily A. Gilson ◽  
Kelli Gillett ◽  
Jasmine H. Stone ◽  
Laila El Amrani ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Wistar Rats ◽  
Ethanol Solution ◽  
Kappa Opioid Receptor ◽  
Opioid Agonist ◽  
Kappa Opioid ◽  
Seeking Behavior ◽  
Male Wistar Rats ◽  
Kappa Opioid Agonist ◽  
Time Point

Recent work suggests that the dynorphin (DYN)/kappa opioid receptor (KOR) system may be a key mediator in the behavioral effects of alcohol. The objective of the present study was to examine the ability of the KOR antagonist norbinaltorphimine (nor-BNI) to attenuate relapse to ethanol seeking due to priming injections of the KOR agonist U50,488 at time points consistent with KOR selectivity. Male Wistar rats were trained to self-administer a 10% ethanol solution, and then responding was extinguished. Following extinction, rats were injected with U50,488 (0.1–10 mg/kg, i.p.) or saline and were tested for the reinstatement of ethanol seeking. Next, the ability of the nonselective opioid receptor antagonist naltrexone (0 or 3.0 mg/kg, s.c.) and nor-BNI (0 or 20.0 mg/kg, i.p.) to block U50,488-induced reinstatement was examined. Priming injections U50,488 reinstated responding on the previously ethanol-associated lever. Pretreatment with naltrexone reduced the reinstatement of ethanol-seeking behavior. nor-BNI also attenuated KOR agonist-induced reinstatement, but to a lesser extent than naltrexone, when injected 24 hours prior to injections of U50,488, a time point that is consistent with KOR selectivity. While these results suggest that activation of KORs is a key mechanism in the regulation of ethanol-seeking behavior, U50,488-induced reinstatement may not be fully selective for KORs.

scholarly journals EXPRESS: Functional bias of morphine and oliceridine under conditions of minor injury

2021 ◽  
pp. 174480692098844
Author(s):  
Chinwe Nwaneshiudu ◽  
Xiao-You Shi ◽  
Peyman Sahbaie ◽  
J. David Clark
Keyword(s):  
Prefrontal Cortex ◽  
Nucleus Accumbens ◽  
Opioid Receptor ◽  
Medial Prefrontal Cortex ◽  
Receptor Activation ◽  
Kappa Opioid Receptor ◽  
Opioid Antagonist ◽  
Opioid Agonist ◽  
Kappa Opioid ◽  
Mu Opioid

Recent reports suggest pain from surgical injury may influence the risks associated with exposure to opioids. In mice, hind-paw incision attenuates morphine-primed reinstatement due to kappa opioid receptor activation by dynorphin. In this focused group of studies, we examined the hypotheses that kappa-opioid receptor activation in the nucleus accumbens mediates attenuated drug- primed reinstatement after incisional surgery, and the G-protein biased mu-opioid agonist, oliceridine, leads to less priming of the dynorphin effect in comparison to morphine. To address these hypotheses, adult C57BL/6 male mice underwent intracranial cannulation for administration of the selective kappa-opioid antagonist norBNI directly into the nucleus accumbens. After recovery, they were conditioned with morphine or oliceridine after hind-paw incisional injury, then underwent extinction followed by opioid-primed reinstatement. Intra-accumbal administration of norBNI was carried out prior to testing. The nucleus accumbens and medial prefrontal cortex were extracted and analyzed for expression of prodynorphin. We observed that animals conditioned with morphine in the setting of incisional injury demonstrated blunted responses to opioid-primed reinstatement, and that the blunted responses were reversed with intra-accumbal norBNI administration. Persistently elevated levels of prodynorphin expression in the medial prefrontal cortex and nucleus accumbens were observed in the incised morphine-treated animals. However, both behavioral and molecular changes were absent in animals with incisional injury conditioned with oliceridine. These findings suggest a role for prodynorphin expression in the nucleus accumbens with exposure to morphine after surgery that may protect individuals from relapse not shared with biased mu- opioid receptor agonists.

scholarly journals Evaluation of Antinociceptive Effects of Chitosan-Coated Liposomes Entrapping the Selective Kappa Opioid Receptor Agonist U50,488 in Mice

Medicina ◽  
2021 ◽  
Vol 57 (2) ◽  
pp. 138
Author(s):  
Liliana Mititelu Tartau ◽  
Maria Bogdan ◽  
Beatrice Rozalina Buca ◽  
Ana Maria Pauna ◽  
Cosmin Gabriel Tartau ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Receptor Agonist ◽  
Kappa Opioid Receptor ◽  
Tail Flick ◽  
Opioid Agonist ◽  
Kappa Opioid ◽  
Tail Flick Test ◽  
Writhing Test ◽  
Opioid Receptor Agonist ◽  
Antinociceptive Effects

Background and Objectives: The selective kappa opioid receptor agonist U50,488 was reported to have analgesic, cough suppressant, diuretic and other beneficial properties. The aim of our study was to analyze the effects of some original chitosan-coated liposomes entrapping U50,488 in somatic and visceral nociceptive sensitivity in mice. Materials and Methods: The influence on the somatic pain was assessed using a tail flick test by counting the tail reactivity to thermal noxious stimulation. The nociceptive visceral estimation was performed using the writhing test in order to evaluate the behavioral manifestations occurring as a reaction to the chemical noxious peritoneal irritation with 0.6% acetic acid (10 mL/kbw). The animals were treated orally, at the same time, with a single dose of: distilled water 0.1 mL/10 gbw; 50 mg/kbw U50,488; 50 mg/kbw U50,488 entrapped in chitosan-coated liposomes, according to the group they were randomly assigned. Results: The use of chitosan-coated liposomesas carriers for U50,488 induced antinociceptive effects that began to manifest after 2 h, andwere prolonged but with a lower intensity than those caused by the free selective kappa opioid in both tests. Conclusion: In this experimental model, the oral administration of nanovesicles containing the selective kappa opioid agonist U50,488 determined a prolonged analgesic outcome in the tail flick test, as well as in the writhing test.

scholarly journals Self-Administration of Entactogen Psychostimulants Dysregulates Gamma-Aminobutyric Acid (GABA) and Kappa Opioid Receptor Signaling in the Central Nucleus of the Amygdala of Female Wistar Rats

2021 ◽  
Vol 15 ◽  
Author(s):  
Sophia Khom ◽  
Jacques D. Nguyen ◽  
Sophia A. Vandewater ◽  
Yanabel Grant ◽  
Marisa Roberto ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Wistar Rats ◽  
Kappa Opioid Receptor ◽  
Female Rats ◽  
Central Nucleus ◽  
Self Administration ◽  
Kappa Opioid ◽  
Extended Access ◽  
Female Wistar Rats ◽  
Saline Vehicle

Male rats escalate intravenous self-administration of entactogen psychostimulants, 3,4-methylenedioxymethcathinone (methylone) and 3,4-methylenedioxymethamphetamine (MDMA) under extended access conditions, as with typical psychostimulants. Here, we investigated whether female rats escalate self-administration of methylone, 3,4-methylenedioxypentedrone (pentylone), and MDMA and then studied consequences of MDMA and pentylone self-administration on GABAA receptor and kappa opioid receptor (KOR) signaling in the central nucleus of the amygdala (CeA), a brain area critically dysregulated by extended access self-administration of alcohol or cocaine. Adult female Wistar rats were trained to self-administer methylone, pentylone, MDMA (0.5 mg/kg/infusion), or saline-vehicle using a fixed-ratio 1 response contingency in 6-h sessions (long-access: LgA) followed by progressive ratio (PR) dose-response testing. The effects of pentylone-LgA, MDMA-LgA and saline on basal GABAergic transmission (miniature post-synaptic inhibitory currents, mIPSCs) and the modulatory role of KOR at CeA GABAergic synapses were determined in acute brain slices using whole-cell patch-clamp. Methylone-LgA and pentylone-LgA rats similarly escalated their drug intake (both obtained more infusions compared to MDMA-LgA rats), however, pentylone-LgA rats reached higher breakpoints in PR tests. At the cellular level, baseline CeA GABA transmission was markedly elevated in pentylone-LgA and MDMA-LgA rats compared to saline-vehicle. Specifically, pentylone-LgA was associated with increased CeA mIPSC frequency (GABA release) and amplitude (post-synaptic GABAA receptor function), while mIPSC amplitudes (but not frequency) was larger in MDMA-LgA rats compared to saline rats. In addition, pentylone-LgA and MDMA-LgA profoundly disrupted CeA KOR signaling such as both KOR agonism (1 mM U50488) and KOR antagonism (200 nM nor-binaltorphimine) decreased mIPSC frequency suggesting recruitment of non-canonical KOR signaling pathways. This study confirms escalated self-administration of entactogen psychostimulants under LgA conditions in female rats which is accompanied by increased CeA GABAergic inhibition and altered KOR signaling. Collectively, our study suggests that CeA GABA and KOR mechanisms play a critical role in entactogen self-administration like those observed with escalation of alcohol or cocaine self-administration.

scholarly journals Repeated Ethanol Exposure Alters DNA Methylation Status and Dynorphin/Kappa-Opioid Receptor Expression in Nucleus Accumbens of Alcohol-Preferring AA Rats

2021 ◽  
Vol 12 ◽  
Author(s):  
Kerly Niinep ◽  
Kaili Anier ◽  
Tony Eteläinen ◽  
Petteri Piepponen ◽  
Anti Kalda
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Opioid Receptor ◽  
Wistar Rats ◽  
Kappa Opioid Receptor ◽  
Mrna Levels ◽  
Kappa Opioid ◽  
Receptor System ◽  
Ethanol Group ◽  
Aberrant Dna Methylation

Growing evidence suggests that epigenetic mechanisms, such as DNA methylation and demethylation, and histone modifications, are involved in the development of alcohol and drug addiction. However, studies of alcohol use disorder (AUD) that are focused on epigenetic DNA modifications and gene expression changes remain conflicting. Our aim was to study the effect of repeated ethanol consumption on epigenetic regulatory enzymes such as DNA methyltransferase and demethylase enzymes and whether those changes affected dynorphin/kappa-opioid receptor system in the Nucleus Accumbens (NAc). Two groups of male alcohol-preferring Alko Alcohol (AA) rats, rats which are selectively bred for high voluntary alcohol consumption and one group of male Wistar rats were used. The first group of AA rats had access to alcohol (10% ethanol solution) for 90 min on Mondays, Wednesdays and Fridays over a period of 3 weeks to establish a stable baseline of ethanol intake (AA-ethanol). The second group of AA rats (AA-water) and the Wistar rats (Wistar-water) were provided with water. Using qPCR, we found that voluntary alcohol drinking increased Dnmt1, −3a, and −3b mRNA levels and did not affect Tet family transcripts in the AA-ethanol group when compared with AA- and Wistar-water rats. DNMT and TET enzymatic activity measurements showed similar results to qPCR, where DNMT activity was increased in AA-ethanol group compared with AA-water and Wistar-water groups, with no statistically significant difference between groups in TET enzyme activity. In line with previous data, we found an increased percentage of global DNA methylation and hydroxymethylation in the AA-ethanol group compared with control rats. Finally, we investigated changes of selected candidate genes from dynorphin/kappa-opioid receptor system (Pdyn, Kor) and Dnmt3a genes that might be important in AUD-related behaviour. Our gene expression and promoter methylation analysis revealed a significant increase in the mRNA levels of Pdyn, Kor, and Dnmt3a in the AA-ethanol group, however, these changes can only be partially associate with the aberrant DNA methylation in promoter areas of the selected candidate genes. Thus, our findings suggest that the aberrant DNA methylation is rather one of the several mechanisms involved in gene expression regulation in AA rat model.

New C(2)-sulfonyl ester-type Salvinorin A ligands to the kappa-opioid receptor

Planta Medica ◽  
2015 ◽  
Vol 81 (05) ◽  
Author(s):  
PR Polepally ◽  
A Keasling ◽  
K White ◽  
E Vardy ◽  
BL Roth ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Kappa Opioid Receptor ◽  
Salvinorin A ◽  
Kappa Opioid
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