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Sample records for activate endogenous opioid

  1. Opposite role of delta 1- and delta 2-opioid receptors activated by endogenous or exogenous opioid agonists on the endogenous cholecystokinin system: further evidence for delta-opioid receptor heterogeneity.

    PubMed

    Noble, F; Fournie-Zaluski, M C; Roques, B P

    1996-12-01

    Using the mouse caudate-putamen, where delta-opioid receptor subtypes have been shown to regulate adenylyl cyclase activity, we show in this study that endogenous enkephalins inhibit enzyme activity through activation of delta 1- and delta 2-opioid receptors. Thus, naltriben or 7-benzylidenenaltrexone as well as the delta-selective antagonist naltrindole (mixed delta 1 and delta 2 antagonist) antagonized inhibition of adenylyl cyclase activity induced by methionine- or leucine-enkephalin, while the micro-antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) was without effect. Furthermore, we have previously shown that activation of delta-opioid receptors increases cholecystokinin release in the central nervous system, resulting in a potentiation of micro-opioid antinociceptive responses, and the respective role of delta 1- and delta 2-opioid receptors in this facilitatory effect has now been evaluated. Activation of delta 2-opioid receptors, either by endogenous enkephalins protected from catabolism by the complete enkephalin-degrading enzyme inhibitor N-((R,S)-2-benzyl-3((S)(2-amino-4-methyl-thio) butyldithio)-1-oxopropyl)-L-phenyl-alanine benzyl ester (RB 101), or by the delta 2-selective agonist Tyr-D-Ser(O-tert-butyl)-Gly-Phe-Leu-Thr(O-tert-butyl) (BUBU), potentiated micro-opioid antinociceptive responses in the hot-plate test in mice. This effect was antagonized by a selective cholecystokinin-A antagonist. Activation of delta 1-opioid receptors by endogenous opioid peptides decreased the micro-opioid responses. These results suggest that stimulation of delta 2-opioid receptors potentiates micro-opioid analgesia in the hot-plate test in mice through an increase in endogenous cholecystokinin release, while activation of delta 1-opioid receptors could decrease it. Thus, the pre-existing physiological balance between opioid and cholecystokinin systems seems to be modulated in opposite directions depending on whether delta 1- or delta 2-opioid receptors are

  2. Endogenous opioids and reward.

    PubMed

    Van Ree, J M; Niesink, R J; Van Wolfswinkel, L; Ramsey, N F; Kornet, M M; Van Furth, W R; Vanderschuren, L J; Gerrits, M A; Van den Berg, C L

    2000-09-29

    The discovery of endogenous opioids has markedly influenced the research on the biology of addiction and reward brain processes. Evidence has been presented that these brain substances modulate brain stimulation reward, self-administration of different drugs of abuse, sexual behaviour and social behaviour. There appears to be two different domains in which endogenous opioids, present in separate and distinct brain regions, are involved. One is related to the modulation of incentive motivational processes and the other to the performance of certain behaviours. It is concluded that endogenous opioids may play a role in the vulnerability to certain diseases, such as addiction and autism, but also when the disease is present, such as alcoholism. PMID:11033317

  3. Endogenous Opioid Activity in the Anterior Cingulate Cortex Is Required for Relief of Pain

    PubMed Central

    Navratilova, Edita; Xie, Jennifer Yanhua; Meske, Diana; Qu, Chaoling; Morimura, Kozo; Okun, Alec; Arakawa, Naohisa; Ossipov, Michael; Fields, Howard L.

    2015-01-01

    Pain is aversive, and its relief elicits reward mediated by dopaminergic signaling in the nucleus accumbens (NAc), a part of the mesolimbic reward motivation pathway. How the reward pathway is engaged by pain-relieving treatments is not known. Endogenous opioid signaling in the anterior cingulate cortex (ACC), an area encoding pain aversiveness, contributes to pain modulation. We examined whether endogenous ACC opioid neurotransmission is required for relief of pain and subsequent downstream activation of NAc dopamine signaling. Conditioned place preference (CPP) and in vivo microdialysis were used to assess negative reinforcement and NAc dopaminergic transmission. In rats with postsurgical or neuropathic pain, blockade of opioid signaling in the rostral ACC (rACC) inhibited CPP and NAc dopamine release resulting from non-opioid pain-relieving treatments, including peripheral nerve block or spinal clonidine, an α2-adrenergic agonist. Conversely, pharmacological activation of rACC opioid receptors of injured, but not pain-free, animals was sufficient to stimulate dopamine release in the NAc and produce CPP. In neuropathic, but not sham-operated, rats, systemic doses of morphine that did not affect withdrawal thresholds elicited CPP and NAc dopamine release, effects that were prevented by blockade of ACC opioid receptors. The data provide a neural explanation for the preferential effects of opioids on pain affect and demonstrate that engagement of NAc dopaminergic transmission by non-opioid pain-relieving treatments depends on upstream ACC opioid circuits. Endogenous opioid signaling in the ACC appears to be both necessary and sufficient for relief of pain aversiveness. PMID:25948274

  4. Social touch modulates endogenous μ-opioid system activity in humans.

    PubMed

    Nummenmaa, Lauri; Tuominen, Lauri; Dunbar, Robin; Hirvonen, Jussi; Manninen, Sandra; Arponen, Eveliina; Machin, Anna; Hari, Riitta; Jääskeläinen, Iiro P; Sams, Mikko

    2016-09-01

    In non-human primates, opioid-receptor blockade increases social grooming, and the endogenous opioid system has therefore been hypothesized to support maintenance of long-term relationships in humans as well. Here we tested whether social touch modulates opioidergic activation in humans using in vivo positron emission tomography (PET). Eighteen male participants underwent two PET scans with [11C]carfentanil, a ligand specific to μ-opioid receptors (MOR). During the social touch scan, the participants lay in the scanner while their partners caressed their bodies in a non-sexual fashion. In the baseline scan, participants lay alone in the scanner. Social touch triggered pleasurable sensations and increased MOR availability in the thalamus, striatum, and frontal, cingulate, and insular cortices. Modulation of activity of the opioid system by social touching might provide a neurochemical mechanism reinforcing social bonds between humans. PMID:27238727

  5. The effects of estrogen and progestin on endogenous opioid activity in oophorectomized women.

    PubMed

    Shoupe, D; Montz, F J; Lobo, R A

    1985-01-01

    Sex steroids may modulate the secretion of beta-endorphin (beta-EP). Naloxone (Nal), an opioid antagonist, has been used as a probe of central opioid activity. Nal-evoked responses of PRL and LH were evaluated in the midluteal (ML) and late follicular (LF) phases of ovulatory women (Pre) and compared to responses of oophorectomized women before and after the administration of conjugated estrogens (CE) and again after CE and progestin administration. In the ML and LF phases, serum LH increased significantly (P less than 0.05 and P less than 0.01, respectively) during Nal infusion for 4 h, while PRL did not change. In oophorectomized women, there were no significant changes in LH or PRL during Nal infusion. After 3 weeks of CE treatment (1.25 mg daily), LH increased during Nal infusion (P less than 0.05), as did PRL (P less than 0.01). After treatment with CE and medroxyprogesterone acetate (MPA), LH and PRL both increased (P less than 0.05 and P less than 0.01, respectively). The area under the LH curve during Nal infusion after CE and MPA treatment was greater than that after CE alone. Both of these responses were comparable to those of the LF and ML phases of Pre women. During Nal infusion, LH pulse frequency increased in the ML compared to the LF phase of the cycle and, in oophorectomized women, was greater after CE and CE with MPA treatment compared to pretreatment values (P less than 0.05). LH amplitudes during Nal infusion were highest in the ML phase and after CE and MPA treatment in oophorectomized women, and these LH amplitudes were similar. No correlation was found between peripheral plasma beta-EP and Nal-evoked LH responses. No differences were evident in plasma beta-EP levels between Pre and oophorectomized women. In conclusion, 1) endogenous opioid activity is low in oophorectomized women; 2) treatment with estrogen increases opioid activity, and the addition of a progestin increases this activity further; and 3) these data support the contention that

  6. Endogenous opioids and excessive alcohol consumption.

    PubMed Central

    Gianoulakis, C

    1993-01-01

    Alcohol is one of the most popular drugs of abuse in our society, and alcoholism is an important cause of absenteeism at work and a major health and social problem. Ethanol induces a number of effects, such as disinhibition, a feeling of general well-being, tolerance and physical dependence. Since there are no specific receptors with which ethanol interacts, it has been proposed that ethanol exerts its effects by altering the activity of a number of neuronal and neuroendocrine systems. Studies have indicated that alcohol influences the activity of the dopaminergic, serotonergic and opioidergic systems. The implication of the endogenous opioid system in mediating some of the effects of ethanol is indicated by the observations that some of the behavioral and pharmacological effects of ethanol are similar to those of the opiates. Indeed, injections of small amounts of morphine increased ethanol consumption, while the administration of naltrexone decreased ethanol consumption among rats and other experimental animals, in a number of experimental paradigms, suggesting that endogenous opioids may play an important role in controlling voluntary ethanol consumption. This paper reviews studies of the effects of ethanol on the activity of the endogenous opioid system and on the importance of endogenous opioids in controlling alcohol consumption. PMID:7690585

  7. Sympathetic activation triggers endogenous opioid release and analgesia within peripheral inflamed tissue.

    PubMed

    Binder, Waltraud; Mousa, Shaaban A; Sitte, Nicolle; Kaiser, Myriam; Stein, Christoph; Schäfer, Michael

    2004-07-01

    Stress induces analgesia by mechanisms within and outside the brain. Here we show that the sympathetic nervous system is an essential trigger of intrinsic opioid analgesia within peripheral injured tissue. Noradrenaline, injected directly into inflamed hind paws of male Wistar rats, produced dose-dependent antinociception, reversible by alpha(1)-, alpha(2)- and beta(2)-antagonists. alpha(1)-, alpha(2)- and beta(2)-adrenergic receptors were demonstrated on beta-endorphin-containing immune cells and noradrenaline induced adrenergic receptor-specific release of beta-endorphin from immune cell suspensions. This antinociceptive effect of noradrenaline was reversed by micro - and delta-opioid antagonists as well as by anti-beta-endorphin. Stress-induced peripheral analgesia was abolished by chemical sympathectomy and by adrenergic antagonists. These findings indicate that sympathetic neuron-derived noradrenaline stimulates adrenergic receptors on inflammatory cells to release beta-endorphin, which induces analgesia via activation of peripheral opioid receptors. PMID:15245482

  8. Distinct roles of exogenous opioid agonists and endogenous opioid peptides in the peripheral control of neuropathy-triggered heat pain

    PubMed Central

    Labuz, Dominika; Celik, Melih Ö.; Zimmer, Andreas; Machelska, Halina

    2016-01-01

    Neuropathic pain often results from peripheral nerve damage, which can involve immune response. Local leukocyte-derived opioid peptides or exogenous opioid agonists inhibit neuropathy-induced mechanical hypersensitivity in animal models. Since neuropathic pain can also be augmented by heat, in this study we investigated the role of opioids in the modulation of neuropathy-evoked heat hypersensitivity. We used a chronic constriction injury of the sciatic nerve in wild-type and opioid peptide-knockout mice, and tested opioid effects in heat and mechanical hypersensitivity using Hargreaves and von Frey tests, respectively. We found that although perineural exogenous opioid agonists, including peptidergic ligands, were effective, the endogenous opioid peptides β-endorphin, Met-enkephalin and dynorphin A did not alleviate heat hypersensitivity. Specifically, corticotropin-releasing factor, an agent triggering opioid peptide secretion from leukocytes, applied perineurally did not attenuate heat hypersensitivity in wild-type mice. Exogenous opioids, also shown to release opioid peptides via activation of leukocyte opioid receptors, were equally analgesic in wild-type and opioid peptide-knockout mice, indicating that endogenous opioids do not contribute to exogenous opioid analgesia in heat hypersensitivity. Furthermore, exogenously applied opioid peptides were ineffective as well. Conversely, opioid peptides relieved mechanical hypersensitivity. Thus, both opioid type and sensory modality may determine the outcome of neuropathic pain treatment. PMID:27605249

  9. Distinct roles of exogenous opioid agonists and endogenous opioid peptides in the peripheral control of neuropathy-triggered heat pain.

    PubMed

    Labuz, Dominika; Celik, Melih Ö; Zimmer, Andreas; Machelska, Halina

    2016-01-01

    Neuropathic pain often results from peripheral nerve damage, which can involve immune response. Local leukocyte-derived opioid peptides or exogenous opioid agonists inhibit neuropathy-induced mechanical hypersensitivity in animal models. Since neuropathic pain can also be augmented by heat, in this study we investigated the role of opioids in the modulation of neuropathy-evoked heat hypersensitivity. We used a chronic constriction injury of the sciatic nerve in wild-type and opioid peptide-knockout mice, and tested opioid effects in heat and mechanical hypersensitivity using Hargreaves and von Frey tests, respectively. We found that although perineural exogenous opioid agonists, including peptidergic ligands, were effective, the endogenous opioid peptides β-endorphin, Met-enkephalin and dynorphin A did not alleviate heat hypersensitivity. Specifically, corticotropin-releasing factor, an agent triggering opioid peptide secretion from leukocytes, applied perineurally did not attenuate heat hypersensitivity in wild-type mice. Exogenous opioids, also shown to release opioid peptides via activation of leukocyte opioid receptors, were equally analgesic in wild-type and opioid peptide-knockout mice, indicating that endogenous opioids do not contribute to exogenous opioid analgesia in heat hypersensitivity. Furthermore, exogenously applied opioid peptides were ineffective as well. Conversely, opioid peptides relieved mechanical hypersensitivity. Thus, both opioid type and sensory modality may determine the outcome of neuropathic pain treatment. PMID:27605249

  10. Tobacco/Nicotine and Endogenous Brain Opioids

    PubMed Central

    Xue, Yue; Domino, Edward F.

    2008-01-01

    Smoking is a major public health problem with devastating health consequences. Although many cigarette smokers are able to quit, equal numbers of others cannot! Standard medications to assist in smoking cessation, such as nicotine replacement therapies and bupropion, are ineffective in many remaining smokers. Recent developments in the neurobiology of nicotine dependence have identified several neurotransmitter systems that may contribute to the process of smoking maintenance and relapse. These include: especially dopamine, but also norepinephrine, 5-hydroxytryptamine, acetylcholine, endogenous opioids, gamma-aminobutyric acid (GABA), glutamate, and endocannabinoids. The present review examines the limited contribution of the endogenous opioid system to the complex effects of nicotine/tobacco smoking. PMID:18215788

  11. Food cravings, endogenous opioid peptides, and food intake: a review.

    PubMed

    Mercer, M E; Holder, M D

    1997-12-01

    Extensive research indicates a strong relationship between endogenous opioid peptides (EOPs) and food intake. In the present paper, we propose that food cravings act as an intervening variable in this opioid-ingestion link. Specifically, we argue that altered EOP activity may elicit food cravings which in turn may influence food consumption. Correlational support for this opioidergic theory of food cravings is provided by examining various clinical conditions (e.g. pregnancy, menstruation, bulimia, stress, depression) which are associated with altered EOP levels, intensified food cravings, and increased food intake. PMID:9468764

  12. Borderline personality disorder: a dysregulation of the endogenous opioid system?

    PubMed

    Bandelow, Borwin; Schmahl, Christian; Falkai, Peter; Wedekind, Dirk

    2010-04-01

    The neurobiology of borderline personality disorder (BPD) remains unclear. Dysfunctions of several neurobiological systems, including serotoninergic, dopaminergic, and other neurotransmitter systems, have been discussed. Here we present a theory that alterations in the sensitivity of opioid receptors or the availability of endogenous opioids constitute part of the underlying pathophysiology of BPD. The alarming symptoms and self-destructive behaviors of the affected patients may be explained by uncontrollable and unconscious attempts to stimulate their endogenous opioid system (EOS) and the dopaminergic reward system, regardless of the possible harmful consequences. Neurobiological findings that support this hypothesis are reviewed: Frantic efforts to avoid abandonment, frequent and risky sexual contacts, and attention-seeking behavior may be explained by attempts to make use of the rewarding effects of human attachment mediated by the EOS. Anhedonia and feelings of emptiness may be an expression of reduced activity of the EOS. Patients with BPD tend to abuse substances that target mu-opioid receptors. Self-injury, food restriction, aggressive behavior, and sensation seeking may be interpreted as desperate attempts to artificially set the body to survival mode in order to mobilize the last reserves of the EOS. BPD-associated symptoms, such as substance abuse, anorexia, self-injury, depersonalization, and sexual overstimulation, can be treated successfully with opioid receptor antagonists. An understanding of the neurobiology of BPD may help in developing new treatments for patients with this severe disorder. PMID:20438240

  13. Divergent short- and long-term effects of acute stress in object recognition memory are mediated by endogenous opioid system activation.

    PubMed

    Nava-Mesa, Mauricio O; Lamprea, Marisol R; Múnera, Alejandro

    2013-11-01

    Acute stress induces short-term object recognition memory impairment and elicits endogenous opioid system activation. The aim of this study was thus to evaluate whether opiate system activation mediates the acute stress-induced object recognition memory changes. Adult male Wistar rats were trained in an object recognition task designed to test both short- and long-term memory. Subjects were randomly assigned to receive an intraperitoneal injection of saline, 1 mg/kg naltrexone or 3 mg/kg naltrexone, four and a half hours before the sample trial. Five minutes after the injection, half the subjects were submitted to movement restraint during four hours while the other half remained in their home cages. Non-stressed subjects receiving saline (control) performed adequately during the short-term memory test, while stressed subjects receiving saline displayed impaired performance. Naltrexone prevented such deleterious effect, in spite of the fact that it had no intrinsic effect on short-term object recognition memory. Stressed subjects receiving saline and non-stressed subjects receiving naltrexone performed adequately during the long-term memory test; however, control subjects as well as stressed subjects receiving a high dose of naltrexone performed poorly. Control subjects' dissociated performance during both memory tests suggests that the short-term memory test induced a retroactive interference effect mediated through light opioid system activation; such effect was prevented either by low dose naltrexone administration or by strongly activating the opioid system through acute stress. Both short-term memory retrieval impairment and long-term memory improvement observed in stressed subjects may have been mediated through strong opioid system activation, since they were prevented by high dose naltrexone administration. Therefore, the activation of the opioid system plays a dual modulating role in object recognition memory. PMID:24036398

  14. Building up analgesia in humans via the endogenous μ-opioid system by combining placebo and active tDCS: a preliminary report.

    PubMed

    DosSantos, Marcos F; Martikainen, Ilkka K; Nascimento, Thiago D; Love, Tiffany M; DeBoer, Misty D; Schambra, Heidi M; Bikson, Marom; Zubieta, Jon-Kar; DaSilva, Alexandre F

    2014-01-01

    Transcranial Direct Current Stimulation (tDCS) is a method of non-invasive brain stimulation that has been frequently used in experimental and clinical pain studies. However, the molecular mechanisms underlying tDCS-mediated pain control, and most important its placebo component, are not completely established. In this pilot study, we investigated in vivo the involvement of the endogenous μ-opioid system in the global tDCS-analgesia experience. Nine healthy volunteers went through positron emission tomography (PET) scans with [11C]carfentanil, a selective μ-opioid receptor (MOR) radiotracer, to measure the central MOR activity during tDCS in vivo (non-displaceable binding potential, BPND)--one of the main analgesic mechanisms in the brain. Placebo and real anodal primary motor cortex (M1/2mA) tDCS were delivered sequentially for 20 minutes each during the PET scan. The initial placebo tDCS phase induced a decrease in MOR BPND in the periaqueductal gray matter (PAG), precuneus, and thalamus, indicating activation of endogenous μ-opioid neurotransmission, even before the active tDCS. The subsequent real tDCS also induced MOR activation in the PAG and precuneus, which were positively correlated to the changes observed with placebo tDCS. Nonetheless, real tDCS had an additional MOR activation in the left prefrontal cortex. Although significant changes in the MOR BPND occurred with both placebo and real tDCS, significant analgesic effects, measured by improvements in the heat and cold pain thresholds, were only observed after real tDCS, not the placebo tDCS. This study gives preliminary evidence that the analgesic effects reported with M1-tDCS, can be in part related to the recruitment of the same endogenous MOR mechanisms induced by placebo, and that such effects can be purposely optimized by real tDCS. PMID:25029273

  15. The panicolytic-like effect of fluoxetine in the elevated T-maze is mediated by serotonin-induced activation of endogenous opioids in the dorsal periaqueductal grey.

    PubMed

    Roncon, Camila M; Biesdorf, Carla; Santana, Rosangela G; Zangrossi, Hélio; Graeff, Frederico G; Audi, Elisabeth A

    2012-04-01

    Serotonin (5-HT), opioids and the dorsal periaqueductal grey (DPAG) have been implicated in the pathophysiology of panic disorder. In order to study 5-HT-opioid interaction, the opioid antagonist naloxone was injected either systemically (1 mg/kg, i.p.) or intra-DPAG (0.2 μg/0.5 μL) to assess its interference with the effect of chronic fluoxetine (10 mg/kg, i.p., daily for 21 days) or of intra-DPAG 5-HT (8 μg/0.5 μL). Drug effects were measured in the one-escape task of the rat elevated T-maze, an animal model of panic. Pretreatment with systemic naloxone antagonized the lengthening of escape latency caused by chronic fluoxetine, considered a panicolytic-like effect that parallels the drug's therapeutic response in the clinics. Pretreatment with naloxone injected intra-DPAG antagonized both the panicolytic effect of chronic fluoxetine as well as that of 5-HT injected intra-DPAG. Neither the performance of the inhibitory avoidance task in the elevated T-maze, a model of generalized anxiety nor locomotion measured in a circular arena was affected by the above drug treatments. These results indicate that the panicolytic effect of fluoxetine is mediated by endogenous opioids that are activated by 5-HT in the DPAG. They also allow reconciliation between the serotonergic and opioidergic hypotheses of panic disorder pathophysiology. PMID:22279131

  16. Endogenous opioids: opposing stress with a cost

    PubMed Central

    Van Bockstaele, Elisabeth

    2015-01-01

    The stress response is characterized by the coordinated engagement of central and peripheral neural systems in response to life-threatening challenges. It has been conserved through evolution and is essential for survival. However, the frequent or continual elicitation of the stress response by repeated or chronic stress, respectively, results in the dysfunction of stress response circuits, ultimately leading to stress-related pathology. In an effort to best respond to stressors, yet at the same time maintain homeostasis and avoid dysfunction, stress response systems are finely balanced and co-regulated by neuromodulators that exert opposing effects. These opposing systems serve to restrain certain stress response systems and promote recovery. However, the engagement of opposing systems comes with the cost of alternate dysfunctions. This review describes, as an example of this dynamic, how endogenous opioids function to oppose the effects of the major stress neuromediator, corticotropin-releasing hormone, and promote recovery from a stress response and how these actions can both protect and be hazardous to health. PMID:26097731

  17. Endogenous opioid peptides as neurotransmitters in the rat hippocampus

    SciTech Connect

    Neumaier, J.F.

    1989-01-01

    The role of endogenous opioid peptides as neurotransmitters in the rat hippocampus was investigated by using extracellular recording and radioligand binding techniques in the hippocampal slice preparation. Synaptic conductances from endogenously released opioid peptides have been difficult to detect. This problem was approach by designing a novel assay of opioid peptide release, in which release was detected by measuring binding competition between endogenous opioids and added radioligand. Membrane depolarization displaced ({sup 3}H)-diprenorphine binding in a transient, calcium-dependent, and peptidase-sensitive manner. Autoradiographic localization of the sites of ({sup 3}H)-diprenorphine binding displacement showed that significant opioid peptide release and receptor occupancy occurred in each major subregion of the hippocampal slices. This assay method can not be used to define optimal electrical stimulation conditions for releasing endogenous opioids. The binding displacement method was extended to the study of the sigma receptor. Depolarization of hippocampal slices was found to reduce the binding of the sigma-selective radioligand ({sup 3}H)-ditolylguanidine in a transient and calcium-dependent manner with no apparent direct effects on sigma receptor affinity.

  18. Termination of Nociceptive Bahaviour at the End of Phase 2 of Formalin Test is Attributable to Endogenous Inhibitory Mechanisms, but not by Opioid Receptors Activation

    PubMed Central

    Azhdari-Zarmehri, Hassan; Mohammad-Zadeh, Mohammad; Feridoni, Masoud; Nazeri, Masoud

    2014-01-01

    Introduction Formalin injection induces nociceptive bahaviour in phase I and II, with a quiescent phase between them. While active inhibitory mechanisms are proposed to be responsible for initiation of interphase, the exact mechanisms which lead to termination of nociceptive response in phase II are not clear yet. Phase II is a consequence of peripheral and central sensitization processes, which can lead to termination of the noxious stimuli responses; 45-60 minutes after formalin injection via possible recruitment of active inhibitory mechanisms which we have investigated in this study. Methods To test our hypothesis, in the first set of experiments, we evaluated nociceptive response after two consecutive injection of formalin (50µL, 2%), with intervals of 5 or 60 minutes. In the next set, formalin tests were carried out in companion with injection of Naloxone Hydrochloride, a non-selective antagonist of opioid receptors, pre-formalin injection and 30 and 45 minutes post formalin injection. Results While normal nociceptive behaviour was observed in the group receiving one injection of formalin, a diminished response was observed in phases I and II of those receiving consequent injection of formalin, 60 minute after first injection. While second injection of formalin, 5 minute after first injection, had no effect. Administration of naloxone (1mg/kg) decreased nociception in phase 2A; but had no effect on delayed termination of formalin test. Discussion The results of this study suggest the existence of an active inhibitory mechanism, other than the endogenous opioids, that is responsible for termination of nociceptive behaviour at the end of formalin test. PMID:25436084

  19. Borderline Personality Disorder: A Dysregulation of the Endogenous Opioid System?

    ERIC Educational Resources Information Center

    Bandelow, Borwin; Schmahl, Christian; Falkai, Peter; Wedekind, Dirk

    2010-01-01

    The neurobiology of borderline personality disorder (BPD) remains unclear. Dysfunctions of several neurobiological systems, including serotoninergic, dopaminergic, and other neurotransmitter systems, have been discussed. Here we present a theory that alterations in the sensitivity of opioid receptors or the availability of endogenous opioids…

  20. Blockade of endogenous opioid neurotransmission enhances acquisition of conditioned fear in humans.

    PubMed

    Eippert, Falk; Bingel, Ulrike; Schoell, Eszter; Yacubian, Juliana; Büchel, Christian

    2008-05-21

    The endogenous opioid system is involved in fear learning in rodents, as opioid agonists attenuate and opioid antagonists facilitate the acquisition of conditioned fear. It has been suggested that an opioidergic signal, which is engaged through conditioning and acts inhibitory on unconditioned stimulus input, is the source of these effects. To clarify whether blockade of endogenous opioid neurotransmission enhances acquisition of conditioned fear in humans, and to elucidate the neural underpinnings of such an effect, we used functional magnetic resonance imaging in combination with behavioral recordings and a double-blind pharmacological intervention. All subjects underwent the same classical fear-conditioning paradigm, but subjects in the experimental group received the opioid antagonist naloxone before and during the experiment, in contrast to subjects in the control group, who received saline. Blocking endogenous opioid neurotransmission with naloxone led to more sustained responses to the unconditioned stimulus across trials, evident in both behavioral and blood oxygen level-dependent responses in pain responsive cortical regions. This effect was likely caused by naloxone blocking conditioned responses in a pain-inhibitory circuit involving opioid-rich areas such as the rostral anterior cingulate cortex, amygdala, and periaqueductal gray. Most importantly, naloxone enhanced the acquisition of fear on the behavioral level and changed the activation profile of the amygdala: whereas the control group showed rapidly decaying conditioned responses across trials, the naloxone group showed sustained conditioned responses in the amygdala. Together, these results demonstrate that in humans the endogenous opioid system has an inhibitory role in the acquisition of fear. PMID:18495880

  1. Endogenous opioids: The downside of opposing stress

    PubMed Central

    Valentino, Rita J.; Van Bockstaele, Elisabeth

    2014-01-01

    Our dynamic environment regularly exposes us to potentially life-threatening challenges or stressors. To answer these challenges and maintain homeostasis, the stress response, an innate coordinated engagement of central and peripheral neural systems is initiated. Although essential for survival, the inappropriate initiation of the stress response or its continuation after the stressor is terminated has pathological consequences that have been linked to diverse neuropsychiatric and medical diseases. Substantial individual variability exists in the pathological consequences of stressors. A theme of this Special Issue is that elucidating the basis of individual differences in resilience or its flipside, vulnerability, will greatly advance our ability to prevent and treat stress-related diseases. This can be approached by studying individual differences in “pro-stress” mediators such as corticosteroids or the hypothalamic orchestrator of the stress response, corticotropin-releasing factor. More recently, the recognition of endogenous neuromodulators with “anti-stress” activity that have opposing actions or that restrain stress-response systems suggests additional bases for individual differences in stress pathology. These “anti-stress” neuromodulators offer alternative strategies for manipulating the stress response and its pathological consequences. This review uses the major brain norepinephrine system as a model stress-response system to demonstrate how co-regulation by opposing pro-stress (corticotropin-releasing factor) and anti-stress (enkephalin) neuromodulators must be fine-tuned to produce an adaptive response to stress. The clinical consequences of tipping this fine-tuned balance in the direction of either the pro- or anti-stress systems are emphasized. Finally, that each system provides multiple points at which individual differences could confer stress vulnerability or resilience is discussed. PMID:25506603

  2. Opioid glycopeptide analgesics derived from endogenous enkephalins and endorphins

    PubMed Central

    Li, Yingxue; Lefever, Mark R; Muthu, Dhanasekaran; Bidlack, Jean M; Bilsky, Edward J; Polt, Robin

    2012-01-01

    Over the past two decades, potent and selective analgesics have been developed from endogenous opioid peptides. Glycosylation provides an important means of modulating interaction with biological membranes, which greatly affects the pharmacodynamics and pharmacokinetics of the resulting glycopeptide analogues. Furthermore, manipulation of the membrane affinity allows penetration of cellular barriers that block efficient drug distribution, including the blood–brain barrier. Extremely potent and selective opiate agonists have been developed from endogenous peptides, some of which show great promise as drug candidates. PMID:22300099

  3. Involvement of the endogenous opioid system in the psychopharmacological actions of ethanol: the role of acetaldehyde

    PubMed Central

    Font, Laura; Luján, Miguel Á.; Pastor, Raúl

    2013-01-01

    Significant evidence implicates the endogenous opioid system (EOS) (opioid peptides and receptors) in the mechanisms underlying the psychopharmacological effects of ethanol. Ethanol modulates opioidergic signaling and function at different levels, including biosynthesis, release, and degradation of opioid peptides, as well as binding of endogenous ligands to opioid receptors. The role of β-endorphin and µ-opioid receptors (OR) have been suggested to be of particular importance in mediating some of the behavioral effects of ethanol, including psychomotor stimulation and sensitization, consumption and conditioned place preference (CPP). Ethanol increases the release of β-endorphin from the hypothalamic arcuate nucleus (NArc), which can modulate activity of other neurotransmitter systems such as mesolimbic dopamine (DA). The precise mechanism by which ethanol induces a release of β-endorphin, thereby inducing behavioral responses, remains to be elucidated. The present review summarizes accumulative data suggesting that the first metabolite of ethanol, the psychoactive compound acetaldehyde, could participate in such mechanism. Two lines of research involving acetaldehyde are reviewed: (1) implications of the formation of acetaldehyde in brain areas such as the NArc, with high expression of ethanol metabolizing enzymes and presence of cell bodies of endorphinic neurons and (2) the formation of condensation products between DA and acetaldehyde such as salsolinol, which exerts its actions via OR. PMID:23914161

  4. Stress-induced analgesia and endogenous opioid peptides: the importance of stress duration.

    PubMed

    Parikh, Drupad; Hamid, Abdul; Friedman, Theodore C; Nguyen, Khanh; Tseng, Andy; Marquez, Paul; Lutfy, Kabirullah

    2011-01-15

    Stress is known to elicit pain relief, a phenomenon referred to as stress-induced analgesia. Based on stress parameters, opioid and non-opioid intrinsic pain inhibitory systems can be activated. In the present study, we assessed whether changing the duration of stress would affect the involvement of endogenous opioids in antinociception elicited by swim in warm water (32 °C), known to be opioid-mediated. Using mice lacking beta-endorphin, enkephalins or dynorphins and their respective wild-type littermates, we assessed the role of each opioid peptide in antinociception induced by a short (3 min) vs. long (15 min) swim. Mice were tested for baseline hot plate latency, exposed to swim (3 or 15 min) in warm water (32 °C) and then tested for antinociception at 5, 15 and 30 min. Our results revealed that both swim paradigms induced significant antinociception in wild-type mice. However, the short swim failed to induce antinociception in beta-endorphin-deficient mice, illustrating that beta-endorphin is important in this form of stress-induced antinociception. On the other hand, antinociception elicited by the long swim was only slightly reduced in beta-endorphin-deficient mice despite pretreatment with naloxone, a non-selective opioid receptor antagonist, significantly attenuated the antinociception elicited by the long swim. Nevertheless, a delayed hyperalgesic response developed in mice lacking beta-endorphin following exposure to either swim paradigm. On the other hand, mice lacking enkephalins or dynorphins and their respective wild-type littermates expressed a comparable antinociceptive response and did not exhibit the delayed hyperalgesic response. Together, our results suggest that the endogenous opioid peptide beta-endorphin not only mediates antinociception induced by the short swim but also prevents the delayed hyperalgesic response elicited by either swim paradigm. PMID:21044625

  5. Stress-induced analgesia and endogenous opioid peptides: the importance of stress duration

    PubMed Central

    Parikh, Drupad; Hamid, Abdul; Friedman, Theodore C.; Nguyen, Khanh; Tseng, Andy; Marquez, Paul; Lutfy, Kabirullah

    2010-01-01

    Stress is known to elicit pain relief, a phenomenon referred to as stress-induced analgesia. Based on stress parameters, opioid and non-opioid intrinsic pain inhibitory systems can be activated. In the present study, we assessed whether changing the duration of stress would affect the involvement of endogenous opioids in antinociception elicited by swim in warm water (32°C), known to be opioid-mediated. Using mice lacking beta-endorphin, enkephalins or dynorphins and their respective wild-type littermates, we assessed the role of each opioid peptide in antinociception induced by a short (3 min) vs. long (15 min) swim. Mice were tested for baseline hot plate latency, exposed to swim (3 or 15 min) in warm water (32°C) and then tested for antinociception at 5, 15 and 30 min. Our results revealed that both swim paradigms induced significant antinociception in wild-type mice. However, the short swim failed to induce antinociception in beta-endorphin-deficient mice, illustrating that beta-endorphin is important in this form of stress-induced antinociception. On the other hand, antinociception elicited by the long swim was only slightly reduced in beta-endorphin-deficient mice despite pretreatment with naloxone, a non-selective opioid receptor antagonist, significantly attenuated the antinociception elicited by the long swim. Nevertheless, a delayed hyperalgesic response developed in mice lacking beta-endorphin following exposure to either swim paradigm. On the other hand, mice lacking enkephalins or dynorphins and their respective wild-type littermates expressed a comparable antinociceptive response and did not exhibit the delayed hyperalgesic response. Together, our results suggest that the endogenous opioid peptide beta-endorphin not only mediates antinociception induced by the short swim but also prevents the delayed hyperalgesic response elicited by either swim paradigm. PMID:21044625

  6. Microwave-induced post-exposure hyperthermia: Involvement of endogenous opioids and serotonin

    SciTech Connect

    Lai, H.; Chou, C.K.; Guy, A.W.; Horita, A.

    1984-08-01

    Acute exposure to pulsed microwaves (2450 MHz, 1 mW/ cm/sup 2/, SAR 0.6 W/kg, 2-..mu..s pulses, 500 pulses/s) induces a transient post-exposure hyperthermia in the rat. The hyperthermia was attenuated by treatment with either the narcotic antagonist naltrexone or one of the serotonin antagonists cinanserin, cyproheptadine, or metergoline. It was not affected, however, by treatment with the peripheral serotonin antagonist xylamidine nor the dopamine antagonist haloperidol. It thus appears that both endogenous opioids and central serotonin are involved. It is proposed that pulsed microwaves activate endogenous opioid systems, and that they in turn activate a serotonergic mechanism that induces the rise in body temperature.

  7. Central antinociception induced by ketamine is mediated by endogenous opioids and μ- and δ-opioid receptors.

    PubMed

    Pacheco, Daniela da Fonseca; Romero, Thiago Roberto Lima; Duarte, Igor Dimitri Gama

    2014-05-01

    It is generally believed that NMDA receptor antagonism accounts for most of the anesthetic and analgesic effects of ketamine, however, it interacts at multiple sites in the central nervous system, including NMDA and non-NMDA glutamate receptors, nicotinic and muscarinic cholinergic receptors, and adrenergic and opioid receptors. Interestingly, it was shown that at supraspinal sites, ketamine interacts with the μ-opioid system and causes supraspinal antinociception. In this study, we investigated the involvement of endogenous opioids in ketamine-induced central antinociception. The nociceptive threshold for thermal stimulation was measured in Swiss mice using the tail-flick test. The drugs were administered via the intracerebroventricular route. Our results demonstrated that the opioid receptor antagonist naloxone, the μ-opioid receptor antagonist clocinnamox and the δ-opioid receptor antagonist naltrindole, but not the κ-opioid receptor antagonist nor-binaltorphimine, antagonized ketamine-induced central antinociception in a dose-dependent manner. Additionally, the administration of the aminopeptidase inhibitor bestatin significantly enhanced low-dose ketamine-induced central antinociception. These data provide evidence for the involvement of endogenous opioids and μ- and δ-opioid receptors in ketamine-induced central antinociception. In contrast, κ-opioid receptors not appear to be involved in this effect. PMID:24675031

  8. The endogenous opioid system in cocaine addiction: what lessons have opioid peptide and receptor knockout mice taught us?

    PubMed Central

    Yoo, Ji Hoon; Kitchen, Ian; Bailey, Alexis

    2012-01-01

    Cocaine addiction has become a major concern in the UK as Britain tops the European ‘league table’ for cocaine abuse. Despite its devastating health and socio-economic consequences, no effective pharmacotherapy for treating cocaine addiction is available. Identifying neurochemical changes induced by repeated drug exposure is critical not only for understanding the transition from recreational drug use towards compulsive drug abuse but also for the development of novel targets for the treatment of the disease and especially for relapse prevention. This article focuses on the effects of chronic cocaine exposure and withdrawal on each of the endogenous opioid peptides and receptors in rodent models. In addition, we review the studies that utilized opioid peptide or receptor knockout mice in order to identify and/or clarify the role of different components of the opioid system in cocaine-addictive behaviours and in cocaine-induced alterations of brain neurochemistry. The review of these studies indicates a region-specific activation of the µ-opioid receptor system following chronic cocaine exposure, which may contribute towards the rewarding effect of the drug and possibly towards cocaine craving during withdrawal followed by relapse. Cocaine also causes a region-specific activation of the κ-opioid receptor/dynorphin system, which may antagonize the rewarding effect of the drug, and at the same time, contribute to the stress-inducing properties of the drug and the triggering of relapse. These conclusions have important implications for the development of effective pharmacotherapy for the treatment of cocaine addiction and the prevention of relapse. PMID:22428846

  9. Sensory Neuropeptides and Endogenous Opioids Expression in Human Dental Pulp with Asymptomatic Inflammation: In Vivo Study

    PubMed Central

    Chavarria-Bolaños, Daniel; Flores-Reyes, Hector; Lombana-Sanchez, Nelson; Cerda-Cristerna, Bernardino; Pozos-Guillen, Amaury

    2015-01-01

    Purpose. This study quantified the expression of substance P (SP), calcitonin gene-related peptide (CGRP), β-endorphins (β-End), and methionine-enkephalin (Met-Enk) in human dental pulp following orthodontic intrusion. Methods. Eight patients were selected according to preestablished inclusion criteria. From each patient, two premolars (indicated for extraction due to orthodontic reasons) were randomly assigned to two different groups: the asymptomatic inflammation group (EXPg), which would undergo controlled intrusive force for seven days, and the control group (CTRg), which was used to determine the basal levels of each substance. Once extracted, dental pulp tissue was prepared to determine the expression levels of both neuropeptides and endogenous opioids by radioimmunoassay (RIA). Results. All samples from the CTRg exhibited basal levels of both neuropeptides and endogenous opioids. By day seven, all patients were asymptomatic, even when all orthodontic-intrusive devices were still active. In the EXPg, the SP and CGRP exhibited statistically significant different levels. Although none of the endogenous opioids showed statistically significant differences, they all expressed increasing trends in the EXPg. Conclusions. SP and CGRP were identified in dental pulp after seven days of controlled orthodontic intrusion movement, even in the absence of pain. PMID:26538838

  10. Supraspinal peroxynitrite modulates pain signaling by suppressing the endogenous opioid pathway.

    PubMed

    Little, Joshua W; Chen, Zhoumou; Doyle, Timothy; Porreca, Frank; Ghaffari, Mahsa; Bryant, Leesa; Neumann, William L; Salvemini, Daniela

    2012-08-01

    Peroxynitrite (PN, ONOO(-)) is a potent oxidant and nitrating agent that contributes to pain through peripheral and spinal mechanisms, but its supraspinal role is unknown. We present evidence here that PN in the rostral ventromedial medulla (RVM) is essential for descending nociceptive modulation in rats during inflammatory and neuropathic pain through PN-mediated suppression of opioid signaling. Carrageenan-induced thermal hyperalgesia was associated with increased 3-nitrotyrosine (NT), a PN biomarker, in the RVM. Furthermore, intra-RVM microinjections of the PN decomposition catalyst Fe(III)-5,10,15,20-tetrakis(N-methyl-pyridinium-4-yl)porphyrin (FeTMPyP(5+)) dose-dependently reversed this thermal hyperalgesia. These effects of FeTMPyP(5+) were abrogated by intra-RVM naloxone, implicating potential interplay between PN and opioids. In support, we identified NT colocalization with the endogenous opioid enkephalin (ENK) in the RVM during thermal hyperalgesia, suggesting potential in situ interactions. To address the functional significance of such interactions, we exposed methionine-enkephalin (MENK) to PN and identified the major metabolite, 3-nitrotyrosine-methionine-sulfoxide (NSO)-MENK, using liquid chromatography-mass spectrometry. Next, we isolated, purified, and tested NSO-MENK for opioid receptor binding affinity and analgesic effects. Compared to MENK, this NSO-MENK metabolite lacked appreciable binding affinity for δ, μ, and κ opioid receptors. Intrathecal injection of NSO-MENK in rats did not evoke antinociception, suggesting that PN-mediated chemical modifications of ENK suppress opioid signaling. When extended to chronic pain, intra-RVM FeTMPyP(5+) produced naloxone-sensitive reversal of mechanical allodynia in rats following chronic constriction injury of the sciatic nerve. Collectively, our data reveal the central role of PN in RVM descending facilitation during inflammatory and neuropathic pain potentially through anti-opioid activity. PMID

  11. Neurobiological mechanisms involved in nicotine dependence and reward: participation of the endogenous opioid system

    PubMed Central

    Berrendero, Fernando; Robledo, Patricia; Trigo, José Manuel; Martín-García, Elena; Maldonado, Rafael

    2010-01-01

    Nicotine is the primary component of tobacco that maintains the smoking habit and develops addiction. The adaptive changes of nicotinic acetylcholine receptors produced by repeated exposure to nicotine play a crucial role in the establishment of dependence. However, other neurochemical systems also participate in the addictive effects of nicotine including glutamate, cannabinoids, GABA and opioids. This review will cover the involvement of these neurotransmitters in nicotine addictive properties, with a special emphasis on the endogenous opioid system. Thus, endogenous enkephalins and beta-endorphins acting on mu-opioid receptors are involved in nicotine rewarding effects, whereas opioid peptides derived from prodynorphin participate in nicotine aversive responses. An upregulation of mu-opioid receptors has been reported after chronic nicotine treatment that could counteract the development of nicotine tolerance, whereas the downregulation induced on kappa-opioid receptors seems to facilitate nicotine tolerance. Endogenous enkephalins acting on mu-opioid receptors also play a role in the development of physical dependence to nicotine. In agreement with these actions of the endogenous opioid system, the opioid antagonist naltrexone has shown to be effective for smoking cessation in certain subpopulations of smokers. PMID:20170672

  12. Pleasure-related analgesia activates opioid-insensitive circuits.

    PubMed

    Kut, Elvan; Candia, Victor; von Overbeck, Jan; Pok, Judit; Fink, Daniel; Folkers, Gerd

    2011-03-16

    Recent findings suggest that pain and pleasure share common neurochemical circuits, and studies in animals and humans show that opioid-mediated descending pathways can inhibit or facilitate pain. We explored the role of endogenous opioid neurotransmission in pleasure-related analgesia. μ-Opioidergic activity was blocked with 0.2 mg/kg naloxone to assess its effects on hedonic responses to pleasant emotional pictures (International Affective Picture System) and its modulating effects on heat pain tolerance. Naloxone did not alter subjective and autonomous reactions to pleasure induction or overall mood of participants. In addition, pleasure-related increases in pain tolerance persisted after reversal of endogenous μ-opioidergic neurotransmission. Subjective pain intensity and unpleasantness ratings increased after naloxone administration. These findings suggest that, in addition to opioid-sensitive circuits, mainly opioid-insensitive pain-modulating circuits are activated during pleasure-related analgesia. PMID:21411655

  13. Pain-Related Effects of Trait Anger Expression: Neural Substrates and the Role of Endogenous Opioid Mechanisms

    PubMed Central

    Bruehl, Stephen; Burns, John W.; Chung, Ok Y.; Chont, Melissa

    2009-01-01

    Literature is reviewed indicating that greater tendency to manage anger via direct verbal or physical expression (trait anger-out) is associated with increased acute and chronic pain responsiveness. Neuroimaging data are overviewed supporting overlapping neural circuits underlying regulation of both pain and anger, consisting of brain regions including the rostral anterior cingulate cortex, orbitofrontal cortex, anterior insula, amygdala, and periaqueductal gray. These circuits provide a potential neural basis for observed positive associations between anger-out and pain responsiveness. The role of endogenous opioids in modulating activity in these interlinked brain regions is explored, and implications for understanding pain-related effects of anger-out are described. An opioid dysfunction hypothesis is presented in which inadequate endogenous opioid inhibitory activity in these brain regions contributes to links between trait anger-out and pain. A series of studies is presented that supports the opioid dysfunction hypothesis, further suggesting that gender and genetic factors may moderate these effects. Finally, possible implications of interactions between trait anger-out and state behavioral anger expression on endogenous opioid analgesic activity are described. PMID:19146872

  14. Toll like receptor (TLR)-4 as a regulator of peripheral endogenous opioid-mediated analgesia in inflammation

    PubMed Central

    2014-01-01

    Background Leukocytes containing opioid peptides locally control inflammatory pain. In the early phase of complete Freund’s adjuvant (CFA)-induced hind paw inflammation, formyl peptides (derived e.g. from Mycobacterium butyricum) trigger the release of opioid peptides from neutrophils contributing to tonic basal antinociception. In the later phase we hypothesized that toll-like-receptor-(TLR)-4 activation of monocytes/macrophages triggers opioid peptide release and thereby stimulates peripheral opioid-dependent antinociception. Results In Wistar rats with CFA hind paw inflammation in the later inflammatory phase (48–96 h) systemic leukocyte depletion by cyclophosphamide (CTX) or locally injected naloxone (NLX) further decreased mechanical and thermal nociceptive thresholds. In vitro β-endorphin (β-END) content increased during human monocyte differentiation as well as in anti-inflammatory CD14+CD16- or non-classical M2 macrophages. Monocytes expressing TLR4 dose-dependently released β-END after stimulation with lipopolysaccharide (LPS) dependent on intracellular calcium. Despite TLR4 expression proinflammatory M1 and anti-inflammatory M2 macrophages only secreted opioid peptides in response to ionomycin, a calcium ionophore. Intraplantar injection of LPS as a TLR4 agonist into the inflamed paw elicited an immediate opioid- and dose-dependent antinociception, which was blocked by TAK-242, a small-molecule inhibitor of TLR4, or by peripheral applied NLX. In the later phase LPS lowered mechanical and thermal nociceptive thresholds. Furthermore, local peripheral TLR4 blockade worsened thermal and mechanical nociceptive pain thresholds in CFA inflammation. Conclusion Endogenous opioids from monocytes/macrophages mediate endogenous antinociception in the late phase of inflammation. Peripheral TLR4 stimulation acts as a transient counter-regulatory mechanism for inflammatory pain in vivo, and increases the release of opioid peptides from monocytes in vitro. TLR4

  15. Partial characterization of a novel endogenous opioid in human cerebrospinal fluid.

    PubMed

    Miller, B E; Lipman, J J; Byrne, W L

    1987-12-01

    Human cerebrospinal fluid (CSF) contains many uncharacterized endogenous opioids, in addition to the known enkephalins, endorphins, and dynorphins. These opioids may be separated by gel filtration chromatography and identified by radioreceptor assay for opioid activity. One region of the chromatographic elution profile, designated "Peak B" has previously been shown to be related to the pain status of chronic pain patients. We now report that human Peak B isolated from the CSF of pain-free elective surgery patients is present at a typical concentration equivalent in activity to 1.4 pmol of morphine sulfate per ml of CSF measured by radioreceptor assay. At a dose of 0.06 and 0.12 pmol morphine sulfate equivalents of CSF (MSE), injected into the cerebroventricular system of the mouse, Peak B produced an antinociceptive effect, the intensity and duration of which was dose-dependent and which was antagonized by naloxone. The mouse vas deferens (MVD) preparation was inhibited by Peak B in a manner that was sensitive to antagonism by naloxone only at low (less than 1.0 microM) but not at higher (greater than 6.0 microM) concentrations of the antagonist. Peak B activity in the MVD assay was unaffected by treatment with trypsin or alpha-chymotrypsin. PMID:3683089

  16. Partial characterization of a novel endogenous opioid in human cerebrospinal fluid

    SciTech Connect

    Miller, B.E.; Lipman, J.J.; Byrne, W.L.

    1987-12-07

    Human cerebrospinal fluid (CSF) contains many uncharacterized endogenous opioids, in addition to the known enkephalins, endorphins, and dynorphins. These opioids may be separated by gel filtration chromatography and identified by radioreceptor assay for opioid activity. One region of the chromatographic elution profile, designated Peak B has previously been shown to be related to the pain status of chronic pain patients. The authors now report that human Peak B isolated from the CSF of pain-free elective surgery patients is present at a typical concentration equivalent in activity to 1.4 pmol of morphine sulfate per ml of CSF measured by radioreceptor assay. At a dose of 0.06 and 0.12 pmol morphine sulfate equivalents of CSF (MSE), injected into the cerebroventricular system of the mouse, Peak B produced an antinociceptive effect, the intensity and duration of which was dose-dependent and which was antagonized by naloxone. The mouse vas deferens (MVD) preparation was inhibited by Peak B in a manner that was sensitive to antagonism by naloxone only at low (< 1.0 ..mu..M) but not at higher (>6.0 ..mu..M) concentrations of the antagonist. Peak B activity in the MVD assay was unaffected by treatment with trypsin or ..cap alpha..-chymotrypsin. 32 references, 4 figures, 1 table.

  17. Endogenous opioids and feeding behavior: A decade of further progress (2004-2014). A Festschrift to Dr. Abba Kastin.

    PubMed

    Bodnar, Richard J

    2015-10-01

    Functional elucidation of the endogenous opioid system temporally paralleled the creation and growth of the journal, Peptides, under the leadership of its founding editor, Dr. Abba Kastin. He was prescient in publishing annual and uninterrupted reviews on Endogenous Opiates and Behavior that served as a microcosm for the journal under his stewardship. This author published a 2004 review, "Endogenous opioids and feeding behavior: a thirty-year historical perspective", summarizing research in this field between 1974 and 2003. The present review "closes the circle" by reviewing the last 10 years (2004-2014) of research examining the role of endogenous opioids and feeding behavior. The review summarizes effects upon ingestive behavior following administration of opioid receptor agonists, in opioid receptor knockout animals, following administration of general opioid receptor antagonists, following administration of selective mu, delta, kappa and ORL-1 receptor antagonists, and evaluating opioid peptide and opioid receptor changes in different food intake models. PMID:25843025

  18. Endogenous Opioid Signaling in the Medial Prefrontal Cortex is Required for the Expression of Hunger-Induced Impulsive Action.

    PubMed

    Selleck, Ryan A; Lake, Curtis; Estrada, Viridiana; Riederer, Justin; Andrzejewski, Matthew; Sadeghian, Ken; Baldo, Brian A

    2015-09-01

    Opioid transmission and dysregulated prefrontal cortex (PFC) activity have both been implicated in the inhibitory-control deficits associated with addiction and binge-type eating disorders. What remains unknown, however, is whether endogenous opioid transmission within the PFC modulates inhibitory control. Here, we compared intra-PFC opioid manipulations with a monoamine manipulation (d-amphetamine), in two sucrose-reinforced tasks: progressive ratio (PR), which assays the motivational value of an incentive, and differential reinforcement of low response rates (DRLs), a test of inhibitory control. Intra-PFC methylnaloxonium (M-NX, a limited diffusion opioid antagonist) was given to rats in a 'low-drive' condition (2-h food deprivation), and also after a motivational shift to a 'high-drive' condition (18-h food deprivation). Intra-PFC DAMGO (D-[Ala2,N-MePhe4, Gly-ol]-enkephalin; a μ-opioid agonist) and d-amphetamine were also tested in both tasks, under the low-drive condition. Intra-PFC M-NX nearly eliminated impulsive action in DRL engendered by hunger, at a dose (1 μg) that significantly affected neither hunger-induced PR enhancement nor hyperactivity. At a higher dose (3 μg), M-NX eliminated impulsive action and returned PR breakpoint to low-drive levels. Conversely, intra-PFC DAMGO engendered 'high-drive-like' effects: enhancement of PR and impairment of DRL performance. Intra-PFC d-amphetamine failed to produce effects in either task. These results establish that endogenous PFC opioid transmission is both necessary and sufficient for the expression of impulsive action in a high-arousal, high-drive appetitive state, and that PFC-based opioid systems enact functionally unique effects on food impulsivity and motivation relative to PFC-based monoamine systems. Opioid antagonists may represent effective treatments for a range of psychiatric disorders with impulsivity features. PMID:25865930

  19. Interacting Effects of Trait Anger and Acute Anger Arousal on Pain: The Role of Endogenous Opioids

    PubMed Central

    Bruehl, Stephen; Burns, John W.; Chung, Ok Yung; Chont, Melissa

    2011-01-01

    Objective Elevated trait anger (TRANG; heightened propensity to experience anger) is associated with greater pain responsiveness, possibly via associations with deficient endogenous opioid analgesia. This study tested whether acute anger arousal moderates the impact of TRANG on endogenous opioid analgesia. Methods 94 chronic low back pain participants (LBP) and 85 healthy controls received opioid blockade (8mg naloxone) or placebo in randomized, counterbalanced order in separate sessions. Participants were randomly assigned to undergo either a 5-minute anger recall interview (ARI) or neutral control interview (NCI) across both drug conditions. Immediately following the assigned interview, participants engaged sequentially in finger pressure and ischemic forearm pain tasks. Opioid blockade effects were derived (blockade minus placebo condition pain ratings) to index opioid antinociceptive function. Results Placebo condition TRANG × Interview interactions (p’s<.05) indicated that TRANG was hyperalgesic only in the context of acute anger arousal (ARI condition; p’s<.05). Blockade effect analyses suggested these hyperalgesic effects were related to deficient opioid analgesia. Significant TRANG × Interview interactions (p’s<.05) for both pain tasks indicated that elevated TRANG was associated with smaller blockade effects (less endogenous opioid analgesia) only in the ARI condition (p’s<.05). Results for ischemic task VAS intensity blockade effects suggested that associations between TRANG and impaired opioid function were most evident in LBP participants when experiencing anger (Type × Interview × TRANG Interaction; p<.05). Conclusions Results indicate that hyperalgesic effects of TRANG are most prominent when acute anger is aroused, and suggest that endogenous opioid mechanisms contribute. PMID:21862829

  20. Endogenous Opioid Antagonism in Physiological Experimental Pain Models: A Systematic Review

    PubMed Central

    Werner, Mads U.; Pereira, Manuel P.; Andersen, Lars Peter H.; Dahl, Jørgen B.

    2015-01-01

    Opioid antagonists are pharmacological tools applied as an indirect measure to detect activation of the endogenous opioid system (EOS) in experimental pain models. The objective of this systematic review was to examine the effect of mu-opioid-receptor (MOR) antagonists in placebo-controlled, double-blind studies using ʻinhibitoryʼ or ʻsensitizingʼ, physiological test paradigms in healthy human subjects. The databases PubMed and Embase were searched according to predefined criteria. Out of a total of 2,142 records, 63 studies (1,477 subjects [male/female ratio = 1.5]) were considered relevant. Twenty-five studies utilized ʻinhibitoryʼ test paradigms (ITP) and 38 studies utilized ʻsensitizingʼ test paradigms (STP). The ITP-studies were characterized as conditioning modulation models (22 studies) and repetitive transcranial magnetic stimulation models (rTMS; 3 studies), and, the STP-studies as secondary hyperalgesia models (6 studies), ʻpainʼ models (25 studies), summation models (2 studies), nociceptive reflex models (3 studies) and miscellaneous models (2 studies). A consistent reversal of analgesia by a MOR-antagonist was demonstrated in 10 of the 25 ITP-studies, including stress-induced analgesia and rTMS. In the remaining 14 conditioning modulation studies either absence of effects or ambiguous effects by MOR-antagonists, were observed. In the STP-studies, no effect of the opioid-blockade could be demonstrated in 5 out of 6 secondary hyperalgesia studies. The direction of MOR-antagonist dependent effects upon pain ratings, threshold assessments and somatosensory evoked potentials (SSEP), did not appear consistent in 28 out of 32 ʻpainʼ model studies. In conclusion, only in 2 experimental human pain models, i.e., stress-induced analgesia and rTMS, administration of MOR-antagonist demonstrated a consistent effect, presumably mediated by an EOS-dependent mechanisms of analgesia and hyperalgesia. PMID:26029906

  1. Examining the Role of Endogenous Opioids in Learned Odor-Stroke Associations in Infant Rats

    PubMed Central

    Roth, Tania L.; Sullivan, Regina M.

    2006-01-01

    Maternal touch profoundly regulates infant neural and behavioral development, and supports learned odor associations necessary for infant attachment. Endogenous opioids are well characterized to mediate the calming and analgesic properties of maternal touch; yet their role in learned odor-touch associations is unknown. We administered naltrexone, an opioid receptor antagonist, before or immediately following classical conditioning with peppermint odor and tactile stimulation (stroking) in rat neonates. Results indicate odor-stroke conditioning produces odor preferences facilitated by endogenous opioids during acquisition and memory consolidation. These results provide additional evidence for the modulatory role of opioids in neonate learning and memory. Disturbances to this system may alter the impact of touch on infant development, particularly in the realm of learning necessary for attachment. PMID:16381030

  2. Role of endogenous opioid peptides in the pathogenesis of motion sickness

    SciTech Connect

    Yasnetsov, V.V.; Il'ina, S.L.; Karsanova, S.K.; Medvedev, O.S.; Mokrousova, A.V.; Sabaev, V.V.; Shashkov, V.A.; Tigranyan, R.A.; Vakulina, O.P

    1986-01-01

    This paper examines the pathogenesis of motion sickness and the role of the various neurochemical systems of the body in the genesis of the condition. It has been shown that the endogenous opioid system participates in the genesis of several pathological processes; this was the motivation for the study. The plasma beta-endorphin level was determined in samples from 19 clinically healthy males. Considering the positive prophylactic and therapeutic effect of naloxone against motion sickness it can be postulated that endogenous opioid peptides participate in the genesis of the vestibulo-autonomic disorders in motion sickness.

  3. Baseline reward circuitry activity and trait reward responsiveness predict expression of opioid analgesia in healthy subjects

    PubMed Central

    Wanigasekera, Vishvarani; Lee, Michael C.; Rogers, Richard; Kong, Yazhuo; Leknes, Siri; Andersson, Jesper; Tracey, Irene

    2012-01-01

    Variability in opioid analgesia has been attributed to many factors. For example, genetic variability of the μ-opioid receptor (MOR)-encoding gene introduces variability in MOR function and endogenous opioid neurotransmission. Emerging evidence suggests that personality trait related to the experience of reward is linked to endogenous opioid neurotransmission. We hypothesized that opioid-induced behavioral analgesia would be predicted by the trait reward responsiveness (RWR) and the response of the brain reward circuitry to noxious stimuli at baseline before opioid administration. In healthy volunteers using functional magnetic resonance imaging and the μ-opioid agonist remifentanil, we found that the magnitude of behavioral opioid analgesia is positively correlated with the trait RWR and predicted by the neuronal response to painful noxious stimuli before infusion in key structures of the reward circuitry, such as the orbitofrontal cortex, nucleus accumbens, and the ventral tegmental area. These findings highlight the role of the brain reward circuitry in the expression of behavioral opioid analgesia. We also show a positive correlation between behavioral opioid analgesia and opioid-induced suppression of neuronal responses to noxious stimuli in key structures of the descending pain modulatory system (amygdala, periaqueductal gray, and rostral–ventromedial medulla), as well as the hippocampus. Further, these activity changes were predicted by the preinfusion period neuronal response to noxious stimuli within the ventral tegmentum. These results support the notion of future imaging-based subject-stratification paradigms that can guide therapeutic decisions. PMID:23045652

  4. Dynamic changes of the endogenous cannabinoid and opioid mesocorticolimbic systems during adolescence: THC effects

    PubMed Central

    Ellgren, M.; Artmann, A.; Tkalych, O.; Gupta, A.; Hansen, H.S.; Hansen, S.H.; Devi, L.A.; Hurd, Y.L.

    2008-01-01

    Adolescence is a critical phase of active brain development often characterized by the initiation of marijuana (Cannabis sativa) use. Limited information is known regarding the endogenous cannabinoid system of the adolescent brain as well as related neurotransmitters that appear sensitive to cannabis exposure. We recently observed that adult rats pre-exposed to Δ-9-tetrahydrocannabinol (THC) during adolescence self-administered higher amounts of heroin and had selective impairments of the enkephalin opioid system within the nucleus accumbens (NAc) implicated in reward-related behavior. To explore the ontogeny of the cannabinoid and opioid neuronal systems in association with adolescence THC exposure, rats were examined at different adolescent stages during an intermittent THC paradigm (1.5 mg/kg i.p. every third day) from postnatal days (PNDs) 28–49. Rat brains were examined 24 hours after injection at PND 29 (early adolescence), PND 38 (mid adolescence) and PND 50 (late adolescence) and analyzed for endocannabinoids (anandamide and 2-arachidonoylglycerol), Met-enkephalin, cannabinoid CB1 receptors and µ opioid receptors (µOR) in the NAc, caudate-putamen and prefrontal cortex (PFC). Of the markers studied, the endocannabinoid levels had the most robust alterations throughout adolescence and were specific to the PFC and NAc. Normal correlations between anandamide and 2-arachidonoylglycerol concentrations in the NAc (positive) and PFC (negative) were reversed by THC. Other significant THC-induced effects were confined to the NAc — increased anandamide, decreased Met-enkephalin and decreased µORs. These findings emphasize the dynamic nature of the mesocorticolimbic endocannabinoid system during adolescence and the selective mesocorticolimbic disturbance as a consequence of adolescent cannabis exposure. PMID:18674887

  5. Neuropeptide Regulation of Fear and Anxiety: Implications of Cholecystokinin, Endogenous Opioids, and Neuropeptide Y

    PubMed Central

    Bowers, Mallory E.; Choi, Dennis C.; Ressler, Kerry J.

    2012-01-01

    The neural circuitry of fear likely underlies anxiety and fear-related disorders such as specific and social phobia, panic disorder, and posttraumatic stress disorder. The primary pharmacological treatments currently utilized for these disorders include benzodiazepines, which act on the GABAergic receptor system, and antidepressants, which modulate the monamine systems. However, recent work on the regulation of fear neural circuitry suggests that specific neuropeptide modulation of this system is of critical importance. Recent reviews have examined the roles of the hypothalamic-pituitary-adrenal axis neuropeptides as well as the roles of neurotrophic factors in regulating fear. The present review, instead, will focus on three neuropeptide systems which have received less attention in recent years but which are clearly involved in regulating fear and its extinction. The endogenous opioid system, particularly activating the μ opioid receptors, has been demonstrated to regulate fear expression and extinction, possibly through functioning as an error signal within the amygdala to mark unreinforced conditioned stimuli. The cholecystokinin (CCK) system initially led to much excitement through its potential role in panic disorder. More recent work in the CCK neuropeptide pathway suggests that it may act in concordance with the endogenous cannabinoid system in the modulation of fear inhibition and extinction. Finally, older as well as very recent data suggests that neuropeptide Y (NPY) may play a very interesting role in counteracting stress effects, enhancing extinction, and enhancing resilience in fear and stress preclinical models. Future work in understanding the mechanisms of neuropeptide functioning, particularly within well-known behavioral circuits, are likely to provide fascinating new clues into the understanding of fear behavior as well as suggesting novel therapeutics for treating disorders of anxiety and fear dysregulation. PMID:22429904

  6. Blunted Endogenous Opioid Release Following an Oral Amphetamine Challenge in Pathological Gamblers

    PubMed Central

    Mick, Inge; Myers, Jim; Ramos, Anna C; Stokes, Paul R A; Erritzoe, David; Colasanti, Alessandro; Gunn, Roger N; Rabiner, Eugenii A; Searle, Graham E; Waldman, Adam D; Parkin, Mark C; Brailsford, Alan D; Galduróz, José C F; Bowden-Jones, Henrietta; Clark, Luke; Nutt, David J; Lingford-Hughes, Anne R

    2016-01-01

    Pathological gambling is a psychiatric disorder and the first recognized behavioral addiction, with similarities to substance use disorders but without the confounding effects of drug-related brain changes. Pathophysiology within the opioid receptor system is increasingly recognized in substance dependence, with higher mu-opioid receptor (MOR) availability reported in alcohol, cocaine and opiate addiction. Impulsivity, a risk factor across the addictions, has also been found to be associated with higher MOR availability. The aim of this study was to characterize baseline MOR availability and endogenous opioid release in pathological gamblers (PG) using [11C]carfentanil PET with an oral amphetamine challenge. Fourteen PG and 15 healthy volunteers (HV) underwent two [11C]carfentanil PET scans, before and after an oral administration of 0.5 mg/kg of d-amphetamine. The change in [11C]carfentanil binding between baseline and post-amphetamine scans (ΔBPND) was assessed in 10 regions of interest (ROI). MOR availability did not differ between PG and HV groups. As seen previously, oral amphetamine challenge led to significant reductions in [11C]carfentanil BPND in 8/10 ROI in HV. PG demonstrated significant blunting of opioid release compared with HV. PG also showed blunted amphetamine-induced euphoria and alertness compared with HV. Exploratory analysis revealed that impulsivity positively correlated with caudate baseline BPND in PG only. This study provides the first evidence of blunted endogenous opioid release in PG. Our findings are consistent with growing evidence that dysregulation of endogenous opioids may have an important role in the pathophysiology of addictions. PMID:26552847

  7. Blunted Endogenous Opioid Release Following an Oral Amphetamine Challenge in Pathological Gamblers.

    PubMed

    Mick, Inge; Myers, Jim; Ramos, Anna C; Stokes, Paul R A; Erritzoe, David; Colasanti, Alessandro; Gunn, Roger N; Rabiner, Eugenii A; Searle, Graham E; Waldman, Adam D; Parkin, Mark C; Brailsford, Alan D; Galduróz, José C F; Bowden-Jones, Henrietta; Clark, Luke; Nutt, David J; Lingford-Hughes, Anne R

    2016-06-01

    Pathological gambling is a psychiatric disorder and the first recognized behavioral addiction, with similarities to substance use disorders but without the confounding effects of drug-related brain changes. Pathophysiology within the opioid receptor system is increasingly recognized in substance dependence, with higher mu-opioid receptor (MOR) availability reported in alcohol, cocaine and opiate addiction. Impulsivity, a risk factor across the addictions, has also been found to be associated with higher MOR availability. The aim of this study was to characterize baseline MOR availability and endogenous opioid release in pathological gamblers (PG) using [(11)C]carfentanil PET with an oral amphetamine challenge. Fourteen PG and 15 healthy volunteers (HV) underwent two [(11)C]carfentanil PET scans, before and after an oral administration of 0.5 mg/kg of d-amphetamine. The change in [(11)C]carfentanil binding between baseline and post-amphetamine scans (ΔBPND) was assessed in 10 regions of interest (ROI). MOR availability did not differ between PG and HV groups. As seen previously, oral amphetamine challenge led to significant reductions in [(11)C]carfentanil BPND in 8/10 ROI in HV. PG demonstrated significant blunting of opioid release compared with HV. PG also showed blunted amphetamine-induced euphoria and alertness compared with HV. Exploratory analysis revealed that impulsivity positively correlated with caudate baseline BPND in PG only. This study provides the first evidence of blunted endogenous opioid release in PG. Our findings are consistent with growing evidence that dysregulation of endogenous opioids may have an important role in the pathophysiology of addictions. PMID:26552847

  8. Electroacupuncture suppresses capsaicin-induced secondary hyperalgesia through an endogenous spinal opioid mechanism

    PubMed Central

    Kim, Hee Young; Wang, Jigong; Lee, Inhyung; Kim, Hee Kee; Chung, Kyungsoon; Chung, Jin Mo

    2009-01-01

    Central sensitization, caused either by tissue inflammation or peripheral nerve injury, plays an important role in persistent pain. An animal model of capsaicin-induced pain has well-defined peripheral and central sensitization components, thus is useful for studying the analgesic effect on two separate components. The focus of this study is to examine the analgesic effects of electroacupuncture (EA) on capsaicin-induced secondary hyperalgesia, which represents central sensitization. Capsaicin (0.5%, 10 μl) was injected into the plantar side of the left hind paw, and foot withdrawal thresholds in response to von Frey stimuli (mechanical sensitivity) were determined for both primary and secondary hyperalgesia in rats. EA (2 Hz, 3 mA) was applied to various pairs of acupoints, GB30-GB34, BL40-BL60, GV2-GV6, LI3-LI6 and SI3-TE8, for 30 min under isofluraine anesthesia and then the effect of EA on mechanical sensitivity of paw was determined. EA applied to the ipsilateral SI3-TE8, but none the other acupoints, significantly reduced capsaicin-induced secondary hyperalgesia but not primary hyperalgesia. EA analgesic effect was inhibited by a systemic non-specific opioid receptor (OR) antagonist or an intrathecal μ- or δ-OR antagonist. EA analgesic effect was not affected by an intrathecal κ-OR antagonist or systemic adrenergic receptor antagonist. This study demonstrates that EA produces a stimulation point specific analgesic effect on capsaicin-induced secondary hyperalgesia (central sensitization), mediated by activating endogenous spinal μ and δ opioid receptors. PMID:19646817

  9. Differential effects of exercise on brain opioid receptor binding and activation in rats.

    PubMed

    Arida, Ricardo Mario; Gomes da Silva, Sérgio; de Almeida, Alexandre Aparecido; Cavalheiro, Esper Abrão; Zavala-Tecuapetla, Cecilia; Brand, Serge; Rocha, Luisa

    2015-01-01

    Physical exercise stimulates the release of endogenous opioid peptides supposed to be responsible for changes in mood, anxiety, and performance. Exercise alters sensitivity to these effects that modify the efficacy at the opioid receptor. Although there is evidence that relates exercise to neuropeptide expression in the brain, the effects of exercise on opioid receptor binding and signal transduction mechanisms downstream of these receptors have not been explored. Here, we characterized the binding and G protein activation of mu opioid receptor, kappa opioid receptor or delta opioid receptor in several brain regions following acute (7 days) and chronic (30 days) exercise. As regards short- (acute) or long-term effects (chronic) of exercise, overall, higher opioid receptor binding was observed in acute-exercise animals and the opposite was found in the chronic-exercise animals. The binding of [(35) S]GTPγS under basal conditions (absence of agonists) was elevated in sensorimotor cortex and hippocampus, an effect more evident after chronic exercise. Divergence of findings was observed for mu opioid receptor, kappa opioid receptor, and delta opioid receptor receptor activation in our study. Our results support existing evidence of opioid receptor binding and G protein activation occurring differentially in brain regions in response to diverse exercise stimuli. We characterized the binding and G protein activation of mu, kappa, and delta opioid receptors in several brain regions following acute (7 days) and chronic (30 days) exercise. Higher opioid receptor binding was observed in the acute exercise animal group and opposite findings in the chronic exercise group. Higher G protein activation under basal conditions was noted in rats submitted to chronic exercise, as visible in the depicted pseudo-color autoradiograms. PMID:25330347

  10. Possible role of a dysregulation of the endogenous opioid system in antisocial personality disorder.

    PubMed

    Bandelow, Borwin; Wedekind, Dirk

    2015-11-01

    Around half the inmates in prison institutions have antisocial personality disorder (ASPD). A recent theory has proposed that a dysfunction of the endogenous opioid system (EOS) underlies the neurobiology of borderline personality disorder (BPD). In the present theoretical paper, based on a comprehensive database and hand search of the relevant literature, this hypothesis is extended to ASPD, which may be the predominant expression of EOS dysfunction in men, while the same pathology underlies BPD in women. According to evidence from human and animal studies, the problematic behaviours of persons with antisocial, callous, or psychopathic traits may be seen as desperate, unconscious attempts to stimulate their deficient EOS, which plays a key role in brain reward circuits. If the needs of this system are not being met, the affected persons experience dysphoric mood, discomfort, or irritability, and strive to increase binding of endogenous opioids to receptors by using the rewarding effects of aggression by exertion of physical or manipulative power on others, by abusing alcohol or substances that have the reward system as target, by creating an "endorphin rush" by self-harm, by increasing the frequency of their sexual contacts, or by impulsive actions and sensation seeking. Symptoms associated with ASPD can be treated with opioid antagonists like naltrexone, naloxone, or nalmefene. PMID:26250442

  11. Endogenous opioids modify dyspnoea during treadmill exercise in patients with COPD.

    PubMed

    Mahler, D A; Murray, J A; Waterman, L A; Ward, J; Kraemer, W J; Zhang, X; Baird, J C

    2009-04-01

    Exogenous opioid drugs, such as morphine, relieve breathlessness. The present study hypothesis was that endogenous opioids, released during the stress of exercise, modify dyspnoea in patients with chronic obstructive pulmonary disease. After familiarisation, patients performed an incremental treadmill exercise test followed by constant work on the treadmill for 10 min. At subsequent visits (2 to 3 days apart), patients received two puffs of albuterol, had a catheter placed in an arm vein for removal of blood to measure beta-endorphin immunoreactivity, received normal saline or 10 mg of naloxone intravenously in randomised order, and then performed high-intensity constant work rate exercise on the treadmill. The mean+/-sd age of the 17 patients (eight females and nine males) was 63+/-7 yrs, and post-bronchodilator forced expiratory volume in one second was 50+/-17% predicted. In both conditions, beta-endorphin levels increased three-fold from rest to end-exercise. The regression slope of breathlessness as a function of oxygen consumption (primary outcome), mean ratings of breathlessness throughout exercise and peak ratings of breathlessness were significantly higher with naloxone than normal saline. There were no differences in physiological responses throughout exercise between conditions. In conclusion, endogenous opioids modify dyspnoea during treadmill exercise in patients with chronic obstructive pulmonary disease by apparent alteration of central perception. PMID:19213787

  12. Release of endogenous opioids from duodenal enteroendocrine cells requires Trpm5

    PubMed Central

    Kokrashvili, Zaza; Rodriguez, Deniliz; Yevshayeva, Valeriya; Zhou, Hang; Margolskee, Robert F

    2009-01-01

    Background & Aims Enteroendocrine cells, the largest and most diverse population of mammalian endocrine cells, comprise a number of different cell types in the gut mucosa that produce, store, and secrete small molecules, peptides and/or larger proteins that regulate many aspects of gut physiology. Little is known about less-typical endocrine cells in the intestinal mucosa that do not contain secretory granules, such as brush or caveolated cells. We studied a subset of these enteroendocrine cells in duodenum that produce several peptides, including endogenous opioids, and that also express the Trpm5 cation channel. Methods We studied expression patterns of Trpm5 and other molecules by immunohistochemical and ELISA analyses of intestinal tissues from transgenic mice that express green fluorescent protein from theTrpm5 promoter, as well as wild-type and Trpm5-null mice. Results We describe a type of enteroendocrine cell in mouse duodenum that is defined by the presence of the Trpm5, that does not contain typical secretory granules, yet expresses endogenous opioids (β-endorphin and Met-enkephalin) and uroguanylin in apical compartments close to the lumen of the gut. Conclusion Solitary chemosensory cells that co-express β-endorphin, Met-enkephalin, uroguanylin and Trpm5 exist in mouse duodenum. These cells are likely to secrete the bioactive peptides into the intestinal lumen in response to dietary factors; release of the opioid peptides requires the Trpm5 ion channel. PMID:19272386

  13. Role of renal nerves in excretory responses to exogenous and endogenous opioid peptides.

    PubMed

    Kapusta, D R; Jones, S Y; Kopp, U C; Dibona, G F

    1989-03-01

    The present study was designed to investigate opioid peptide-mediated changes in renal function in conscious Sprague-Dawley rats after administration of the native opioid agonist methionine enkephalin (ME), its synthetic analog D-Ala2-methionine enkephalinamide (DALA) and the opioid antagonist naloxone. Intravenous infusion of DALA (25 micrograms/kg/min) and ME (75 micrograms/kg/min) produced no changes in mean arterial pressure, heart rate, glomerular filtration rate or effective renal plasma flow in rats with intact or bilaterally denervated kidneys. In contrast, i.v. infusion of these opioid agonists produced differing effects on the renal excretion of water and sodium; DALA produced an increase in urinary flow rate and sodium excretion and ME produced a decrease in these parameters. Changes in renal sympathetic nerve activity were not involved in producing these effects as supported by measurements of renal sympathetic nerve activity and the finding that prior bilateral renal denervation did not alter the renal responses to either agonist. The renal excretory responses to both DALA and ME infusion were prevented by pretreatment with the opioid receptor antagonist naloxone, thus suggesting an opioid receptor-mediated effect of both agonists. Intravenous bolus injections of naloxone alone produced a dose-dependent diuresis and natriuresis without producing changes in systemic or renal hemodynamics or renal sympathetic nerve activity. These studies, therefore, provide evidence that the administration of opioid receptor agonists and antagonists produce changes in the renal excretion of water and sodium via an action on renal tubular reabsorptive mechanisms which are independent of changes in systemic or renal hemodynamics or renal sympathetic nerve activity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2703962

  14. Effects of genetic deletion of endogenous opioid system components on the reinstatement of cocaine-seeking behavior in mice.

    PubMed

    Gutiérrez-Cuesta, Javier; Burokas, Aurelijus; Mancino, Samantha; Kummer, Sami; Martín-García, Elena; Maldonado, Rafael

    2014-12-01

    The repeated cycles of cessation of consumption and relapse remain the major clinical concern in treating drug addiction. The endogenous opioid system is a crucial component of the reward circuit that participates in the adaptive changes leading to relapse in the addictive processes. We have used genetically modified mice to evaluate the involvement of μ-opioid receptor (MOR) and δ-opioid receptor (DOR) and their main endogenous ligands, the enkephalins derived from proenkephalin (PENK) and prodynorphin (PDYN), in the reinstatement of cocaine-seeking behavior. Constitutive knockout mice of MOR, DOR, PENK, and PDYN, and their wild-type littermates were trained to self-administer cocaine or to seek for palatable food, followed by a period of extinction and finally tested on a cue-induced reinstatement of seeking behavior. The four lines of knockout mice acquired operant cocaine self-administration behavior, although DOR and PENK knockout mice showed less motivation for cocaine than wild-type littermates. Moreover, cue-induced relapse was significantly decreased in MOR and DOR knockout mice. In contrast, PDYN knockout mice showed a slower extinction and increased relapse than wild-type littermates. C-Fos expression analysis revealed differential activation in brain areas related with memory and reward in these knockout mice. No differences were found in any of the four genotypes in operant responding to obtain palatable food, indicating that the changes revealed in knockout mice were not due to unspecific deficit in operant performance. Our results indicate that MOR, DOR, and PDYN have a differential role in cue-induced reinstatement of cocaine-seeking behavior. PMID:24943644

  15. Evidence for altered opioid activity in patients with cancer.

    PubMed Central

    Lissoni, P.; Barni, S.; Paolorossi, F.; Crispino, S.; Rovelli, F.; Ferri, L.; Delitala, G.; Tancini, G.

    1987-01-01

    Endogenous opioid peptides have been shown to be involved in the regulation of tumour growth. At present, however, no data are available about the secretion of opioid peptides in cancer patients. To draw some preliminary conclusions on opioid brain function in human neoplasms, we evaluated hypophyseal hormone responses to the administration of a met-enkephalin analogue, FK 33-824. The study included 14 patients affected by early or advanced neoplastic disease, 12 healthy subjects and 7 patients with a chronic medical illness other than cancer. FK 33-824 was given intravenously at a dose of 0.3 mg. Venous blood samples were collected at zero time, and 30, 60 and 120 min after drug administration. In each sample, PRL, GH, LH, cortisol and beta-endorphin levels were measured by RIA. In all normal subjects and in patients with non-neoplastic chronic illness, FK 33-824 induced a rise in PRL and GH levels, and a decrease in LH, cortisol and beta-endorphin. A normal endocrine response to FK 33-824 was seen in our cancer patient only, while in the other cases with tumour no hormonal changes or a paradoxical response were seen after FK 33-824. Based on the fact that an abnormal endocrine response to FK 33-824 has been described in hypothalamic-pituitary disorders, in which anomalous brain opioid activity has been demonstrated, these results suggest the existence of an altered function of the opioid system in cancer patients, the clinical importance of which remains to be determined. PMID:2963662

  16. Endogenous opioids and attenuated hypothalamic-pituitary-adrenal axis responses to immune challenge in pregnant rats.

    PubMed

    Brunton, Paula J; Meddle, Simone L; Ma, Shuaike; Ochedalski, Tomasz; Douglas, Alison J; Russell, John A

    2005-05-25

    In late pregnant rats, the hypothalamic-pituitary-adrenal (HPA) axis is hyporesponsive to psychogenic stressors. Here, we investigated attenuated HPA responses to an immune challenge and a role for endogenous opioids. ACTH and corticosterone were assayed in blood samples from virgin and 21 d pregnant rats before and after endotoxin [lipopolysaccharide (LPS); 1 microg/kg, i.v.], interleukin-1beta (IL-1beta; 500 ng/kg, i.v.), or vehicle. In virgins, plasma ACTH concentrations increased 1 h after LPS and 15 min after IL-1beta, as did corticosterone, with no responses in pregnant rats. In situ hybridization revealed increased corticotrophin releasing hormone (CRH) mRNA expression in the dorsomedial parvocellular paraventricular nucleus (pPVN) and increased anterior pituitary pro-opiomelanocortin mRNA expression 4 h after IL-1beta in virgins; these responses were absent in pregnant rats. In contrast, immunocytochemistry showed that Fos expression was similarly increased in the nucleus tractus solitarius (NTS) A2 region in virgin and pregnant rats 90 min and 4 h after IL-1beta. Naloxone pretreatment (5 mg/kg, i.v.) restored ACTH and pPVN CRH mRNA responses after IL-1beta in pregnant rats but reduced the CRH mRNA response in virgins without affecting ACTH. Proenkephalin-A and mu-opioid receptor mRNA expression in the NTS was significantly increased in the pregnant rats, indicating upregulated brainstem opioid mechanisms. IL-1beta increased noradrenaline release in the PVN of virgin, but not pregnant, rats. However, naloxone infused directly into the PVN increased noradrenaline release after IL-1beta in pregnant rats. Thus, the HPA axis responses to immune signals are suppressed in pregnancy at the level of pPVN CRH neurons through an opioid mechanism, possibly acting by preterminal autoinhibition of NTS projections to the pPVN. PMID:15917452

  17. Endogenous opioid system influences depressive reactions to socially painful targeted rejection life events.

    PubMed

    Slavich, George M; Tartter, Molly A; Brennan, Patricia A; Hammen, Constance

    2014-11-01

    Although exposure to a recent major life event is one of the strongest known risk factors for depression, many people who experience such stress do not become depressed. Moreover, the biological mechanisms underlying differential emotional reactions to social adversity remain largely unknown. To investigate this issue, we examined whether the endogenous opioid system, which is known to influence sensitivity to physical pain, is also implicated in differential risk for depression following socially painful targeted rejection versus non-targeted rejection life events. Adolescents (n=420) enrolled in a large longitudinal birth cohort study had their recent stress exposure and current mental health status assessed using self-report and interview-based methods. Participants were also genotyped for the A118G polymorphism in the μ-opioid receptor gene (OPRM1, rs1799971), which has been found to influence neural and psychological responses to rejection, likely by affecting opioid receptor expression and signaling efficiency. As hypothesized, G allele carriers, who are known to exhibit less opioid receptor expression and signaling efficiency, were more severely depressed and twice as likely to meet criteria for major depressive disorder following a recent targeted rejection major life event (e.g., being broken up with, getting fired) relative to A/A homozygotes who experienced such stress. However, A118G genotype did not moderate the effects of other similarly severe major life events on depression. These data thus elucidate a biological pathway that may specifically influence sensitivity to social pain and rejection, which in turn has implications for understanding differential risk for depression and several other social stress-related disorders. PMID:25086307

  18. The role of opioid antagonist efficacy and constitutive opioid receptor activity in the opioid withdrawal syndrome in mice.

    PubMed

    Navani, Dipesh M; Sirohi, Sunil; Madia, Priyanka A; Yoburn, Byron C

    2011-10-01

    On the basis of efficacy, opioid antagonists are classified as inverse opioid agonists (e.g. naltrexone) or neutral opioid antagonists (e.g. 6β-naltrexol). This study examined the interaction between naltrexone and 6β-naltrexol in the precipitated opioid withdrawal syndrome in morphine dependent mice. Furthermore, the possible contribution of constitutive opioid receptor activity to precipitated withdrawal was evaluated using increasing levels of morphine dependence. In the first experiment, low doses of 6β-naltrexol antagonized naltrexone precipitated withdrawal while high doses acted additively. All doses of naltrexone increased 6β-naltrexol's potency to precipitate withdrawal. The next experiment examined changes in antagonist potency to precipitate withdrawal with increasing morphine dependence. Mice were exposed to morphine for 1-6 days and then withdrawal was precipitated. Naltrexone was more potent than 6β-naltrexol at all the time points. The ED(50) of both drugs decreased at the same rate suggesting that increased dependence produced no change in constitutive opioid receptor activity. Taken together these results indicate that the functional efficacy of 6β-naltrexol is dose-dependent and that constitutive opioid receptor activity did not change as opioid dependence increased from 1 to 6 days. PMID:21736895

  19. The pharmacological basis of opioids

    PubMed Central

    Ghelardini, Carla; Di Cesare Mannelli, Lorenzo; Bianchi, Enrica

    2015-01-01

    Summary An opioid is a chemical that binds to opioid receptors, which are widely distributed in the central and peripheral nervous system and gastrointestinal tract. The different effects elicited by activation of these receptors are due to their specific neuronal and extraneuronal distribution. The painkiller effect of opioids is induced by the synergy of the two events, namely reduction of pain threshold and emotional detachment from pain. The opioid effects transcending analgesia include sedation, respiratory depression, constipation and a strong sense of euphoria. There are opioid-like substances endogenously produced by the body. Naturally occurring peptides, called enkephalins, have opioid-like activities but are not derived from opium and exert opioid-like effects by interacting with opioid receptors on cell membranes. Yet, animals do contain the same morphine precursors and metabolites as opium poppy and are able to synthesize endogenous morphine alkaloid. Experimental and clinical studies show that opioids, at doses comparable to those of endogenous opioids, can activate pronociceptive systems, leading to pain hypersensitivity and short-term tolerance, a phenomenon encountered in postoperative pain management by acute opioid administration. Whether endogenous opioids play a role in the acute pain necessary to the survival of the individual, remains an open question. PMID:26811699

  20. The pharmacological basis of opioids.

    PubMed

    Ghelardini, Carla; Di Cesare Mannelli, Lorenzo; Bianchi, Enrica

    2015-01-01

    An opioid is a chemical that binds to opioid receptors, which are widely distributed in the central and peripheral nervous system and gastrointestinal tract. The different effects elicited by activation of these receptors are due to their specific neuronal and extraneuronal distribution. The painkiller effect of opioids is induced by the synergy of the two events, namely reduction of pain threshold and emotional detachment from pain. The opioid effects transcending analgesia include sedation, respiratory depression, constipation and a strong sense of euphoria. There are opioid-like substances endogenously produced by the body. Naturally occurring peptides, called enkephalins, have opioid-like activities but are not derived from opium and exert opioid-like effects by interacting with opioid receptors on cell membranes. Yet, animals do contain the same morphine precursors and metabolites as opium poppy and are able to synthesize endogenous morphine alkaloid. Experimental and clinical studies show that opioids, at doses comparable to those of endogenous opioids, can activate pronociceptive systems, leading to pain hypersensitivity and short-term tolerance, a phenomenon encountered in postoperative pain management by acute opioid administration. Whether endogenous opioids play a role in the acute pain necessary to the survival of the individual, remains an open question. PMID:26811699

  1. Cell death sensitization of leukemia cells by opioid receptor activation

    PubMed Central

    Friesen, Claudia; Roscher, Mareike; Hormann, Inis; Fichtner, Iduna; Alt, Andreas; Hilger, Ralf A.; Debatin, Klaus-Michael; Miltner, Erich

    2013-01-01

    Cyclic AMP (cAMP) regulates a number of cellular processes and modulates cell death induction. cAMP levels are altered upon stimulation of specific G-protein-coupled receptors inhibiting or activating adenylyl cyclases. Opioid receptor stimulation can activate inhibitory Gi-proteins which in turn block adenylyl cyclase activity reducing cAMP. Opioids such as D,L-methadone induce cell death in leukemia cells. However, the mechanism how opioids trigger apoptosis and activate caspases in leukemia cells is not understood. In this study, we demonstrate that downregulation of cAMP induced by opioid receptor activation using the opioid D,L-methadone kills and sensitizes leukemia cells for doxorubicin treatment. Enhancing cAMP levels by blocking opioid-receptor signaling strongly reduced D,L-methadone-induced apoptosis, caspase activation and doxorubicin-sensitivity. Induction of cell death in leukemia cells by activation of opioid receptors using the opioid D,L-methadone depends on critical levels of opioid receptor expression on the cell surface. Doxorubicin increased opioid receptor expression in leukemia cells. In addition, the opioid D,L-methadone increased doxorubicin uptake and decreased doxorubicin efflux in leukemia cells, suggesting that the opioid D,L-methadone as well as doxorubicin mutually increase their cytotoxic potential. Furthermore, we found that opioid receptor activation using D,L-methadone alone or in addition to doxorubicin inhibits tumor growth significantly in vivo. These results demonstrate that opioid receptor activation via triggering the downregulation of cAMP induces apoptosis, activates caspases and sensitizes leukemia cells for doxorubicin treatment. Hence, opioid receptor activation seems to be a promising strategy to improve anticancer therapies. PMID:23633472

  2. Downregulation of the endogenous opioid peptides in the dorsal striatum of human alcoholics

    PubMed Central

    Sarkisyan, Daniil; Hussain, Muhammad Z.; Watanabe, Hiroyuki; Kononenko, Olga; Bazov, Igor; Zhou, Xingwu; Yamskova, Olga; Krishtal, Oleg; Karpyak, Victor M.; Yakovleva, Tatiana; Bakalkin, Georgy

    2015-01-01

    The endogenous opioid peptides dynorphins and enkephalins may be involved in brain-area specific synaptic adaptations relevant for different stages of an addiction cycle. We compared the levels of prodynorphin (PDYN) and proenkephalin (PENK) mRNAs (by qRT-PCR), and dynorphins and enkephalins (by radioimmunoassay) in the caudate nucleus and putamen between alcoholics and control subjects. We also evaluated whether PDYN promoter variant rs1997794 associated with alcoholism affects PDYN expression. Postmortem specimens obtained from 24 alcoholics and 26 controls were included in final statistical analysis. PDYN mRNA and Met-enkephalin-Arg-Phe, a marker of PENK were downregulated in the caudate of alcoholics, while PDYN mRNA and Leu-enkephalin-Arg, a marker of PDYN were decreased in the putamen of alcoholics carrying high risk rs1997794 C allele. Downregulation of opioid peptides in the dorsal striatum may contribute to development of alcoholism including changes in goal directed behavior and formation of a compulsive habit in alcoholics. PMID:26029055

  3. Now or Later? An fMRI study of the effects of endogenous opioid blockade on a decision-making network.

    PubMed

    Boettiger, Charlotte A; Kelley, Elizabeth A; Mitchell, Jennifer M; D'Esposito, Mark; Fields, Howard L

    2009-09-01

    Previously, we found that distinct brain areas predict individual selection bias in decisions between small immediate ("Now") and larger delayed rewards ("Later"). Furthermore, such selection bias can be manipulated by endogenous opioid blockade. To test whether blocking endogenous opioids with naltrexone (NTX) alters brain activity during decision-making in areas predicting individual bias, we compared fMRI BOLD signal correlated with Now versus Later decision-making after acute administration of NTX (50 mg) or placebo. We tested abstinent alcoholics and control subjects in a double-blind two-session design. We defined regions of interest (ROIs) centered on activation peaks predicting Now versus Later selection bias. NTX administration significantly increased BOLD signal during decision-making in the right lateral orbital gyrus ROI, an area where enhanced activity during decision-making predicts Later bias. Exploratory analyses identified additional loci where BOLD signal during decision-making was enhanced (left orbitofrontal cortex, left inferior temporal gyrus, and cerebellum) or reduced (right superior temporal pole) by NTX. Additional analyses identified sites, including the right lateral orbital gyrus, in which NTX effects on BOLD signal predicted NTX effects on selection bias. These data agree with opioid receptor expression in human frontal and temporal cortices, and suggest possible mechanisms of NTX's therapeutic effects. PMID:19258022

  4. Now or Later? An fMRI study of the effects of endogenous opioid blockade on a decision-making network

    PubMed Central

    Boettiger, Charlotte A.; Kelley, Elizabeth A.; Mitchell, Jennifer M.; D’Esposito, Mark; Fields, Howard L.

    2009-01-01

    Previously, we found that distinct brain areas predict individual selection bias in decisions between small immediate (“Now”) and larger delayed rewards (“Later”). Furthermore, such selection bias can be manipulated by endogenous opioid blockade. To test whether blocking endogenous opioids with Naltrexone (NTX) alters brain activity during decision-making in areas predicting individual bias, we compared fMRI BOLD signal correlated with Now versus Later decision-making after acute administration of NTX (50 mg) or placebo. We tested abstinent alcoholics and control subjects in a double-blind two-session design. We defined regions of interest (ROI) centered on activation peaks predicting Now versus Later selection bias. NTX administration significantly increased BOLD signal during decision-making in the right lateral orbital gyrus ROI, an area where enhanced activity during decision-making predicts Later bias. Exploratory analyses identified additional loci where BOLD signal during decision-making was enhanced (left orbitofrontal cortex, left inferior temporal gyrus, and cerebellum) or reduced (right superior temporal pole) by NTX. Additional analyses identified sites, including the right lateral orbital gyrus, in which NTX effects on BOLD signal predicted NTX effects on selection bias. These data agree with opioid receptor expression in human frontal and temporal cortices, and suggest possible mechanisms of NTX’s therapeutic effects. PMID:19258022

  5. Endogenous opioids mediate the sexual inhibition but not the drug hypersensitivity induced by sexual satiation in male rats.

    PubMed

    Garduño-Gutiérrez, René; Guadarrama-Bazante, Lorena; León-Olea, Martha; Rodríguez-Manzo, Gabriela

    2013-06-01

    Ejaculation promotes endogenous opioid release. Copulation to exhaustion produces several enduring behavioral and physiological changes, among which a long-lasting sexual behavior inhibition and generalized drug hypersensitivity are the most conspicuous. Because copulation to exhaustion involves multiple successive ejaculations, in this work we hypothesized that the endogenous opioids released by multiple ejaculations during the copulation to exhaustion process might mediate the abovementioned sexual satiation-induced changes. To test this hypothesis, sexually experienced male rats were injected with the opioid receptor antagonist naltrexone before copulation to exhaustion and were tested for sexual behavior or drug hypersensitivity 24 h later. The latter was assessed by the appearance of the flat body posture sign of the serotonergic syndrome, in response to doses of the 5-hydroxytryptamine-1A (5-HT1A) receptor agonist 8-hydroxy-2-di-n-propylamino-tetralin (8-OH-DPAT), lower than those normally inducing this sign. The effect of administering naltrexone to already sexually exhausted animals (i.e., 24 h after the sexual satiation process) on both responses was also tested. Results showed that endogenous opioids mediate the establishment and maintenance of the long-lasting sexual behavior inhibition but not the drug hypersensitivity (to 8-OH-DPAT) characteristic of sexually exhausted male rats. It is concluded that although both phenomena appear as a consequence of copulation to satiation and follow a same time course of recovery, they are produced by distinct mechanisms. PMID:23544597

  6. Single housing during early adolescence causes time-, area- and peptide-specific alterations in endogenous opioids of rat brain

    PubMed Central

    Granholm, L; Roman, E; Nylander, I

    2015-01-01

    BACKGROUND AND PURPOSE A number of experimental procedures require single housing to assess individual behaviour and physiological responses to pharmacological treatments. The endogenous opioids are closely linked to social interaction, especially early in life, and disturbance in the social environment may affect opioid peptides and thereby confound experimental outcome. The aim of the present study was to examine time-dependent effects of single housing on opioid peptides in rats. EXPERIMENTAL APPROACH Early adolescent Sprague Dawley rats (post-natal day 22) were subjected to either prolonged (7 days) or short (30 min) single housing. Several brain regions were dissected and immunoreactive levels of Met-enkephalin-Arg6Phe7 (MEAP), dynorphin B and nociception/orphanin FQ, as well as serum corticosterone were measured using RIA. KEY RESULTS Prolonged single housing reduced immunoreactive MEAP in hypothalamus, cortical regions, amygdala, substantia nigra and periaqueductal grey. Short single housing resulted in an acute stress response as indicated by high levels of corticosterone, accompanied by elevated immunoreactive nociceptin/orphanin FQ in medial prefrontal cortex, nucleus accumbens and amygdala. Neither short nor prolonged single housing affected dynorphin B. CONCLUSIONS AND IMPLICATIONS Disruption in social environmental conditions of rats, through single housing during early adolescence, resulted in time-, area- and peptide-specific alterations in endogenous opioids in the brain. These results provide further evidence for an association between early life social environment and opioids. Furthermore, the results have implications for experimental design; in any pharmacological study involving opioid peptides, it is important to distinguish between effects induced by housing and treatment. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http

  7. Endogenous opiates and behavior: 2014.

    PubMed

    Bodnar, Richard J

    2016-01-01

    This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular

  8. Nicotine-specific and non-specific effects of cigarette smoking on endogenous opioid mechanisms.

    PubMed

    Nuechterlein, Emily B; Ni, Lisong; Domino, Edward F; Zubieta, Jon-Kar

    2016-08-01

    This study investigates differences in μ-opioid receptor mediated neurotransmission in healthy controls and overnight-abstinent smokers, and potential effects of the OPRM1 A118G genotype. It also examines the effects of smoking denicotinized (DN) and average nicotine (N) cigarettes on the μ-opioid system. Positron emission tomography with (11)C-carfentanil was used to determine regional brain μ-opioid receptor (MOR) availability (non-displaceable binding potential, BPND) in a sample of 19 male smokers and 22 nonsmoking control subjects. Nonsmokers showed greater MOR BPND than overnight abstinent smokers in the basal ganglia and thalamus. BPND in the basal ganglia was negatively correlated with baseline craving levels and Fagerström scores. Interactions between group and genotype were seen in the nucleus accumbens bilaterally and the amygdala, with G-allele carriers demonstrating lower BPND in these regions, but only among smokers. After smoking the DN cigarette, smokers showed evidence of MOR activation in the thalamus and nucleus accumbens. No additional activation was observed after the N cigarette, with a mean effect of increases in MOR BPND (i.e., deactivation) with respect to the DN cigarette effects in the thalamus and left amygdala. Changes in MOR BPND were related to both Fagerström scores and changes in craving. This study showed that overnight-abstinent smokers have lower concentrations of available MORs than controls, an effect that was related to both craving and the severity of addiction. It also suggests that nicotine non-specific elements of the smoking experience have an important role in regulating MOR-mediated neurotransmission, and in turn modulating withdrawal-induced craving ratings. PMID:27095017

  9. Deficits in neuronal cytochrome P450 activity attenuate opioid analgesia but not opioid side effects.

    PubMed

    Hough, Lindsay B; Nalwalk, Julia W; Cleary, Rachel A; Phillips, James G; Fang, Cheng; Yang, Weizhu; Ding, Xinxin

    2014-10-01

    Morphine-like analgesics act on µ opioid receptors in the CNS to produce highly effective pain relief, but the same class of receptors also mediates non-therapeutic side effects. The analgesic properties of morphine were recently shown to require the activity of a brain neuronal cytochrome P450 epoxygenase, but the significance of this pathway for opioid side effects is unknown. Here we show that brain P450 activity is not required for three of morphine׳s major side effects (respiratory depression, constipation, and locomotor stimulation). Following systemic or intracerebroventricular administration of morphine, transgenic mice with brain neuron - specific reductions in P450 activity showed highly attenuated analgesic responses as compared with wild-type (control) mice. However, brain P450-deficient mice showed normal morphine-induced side effects (respiratory depression, locomotor stimulation, and inhibition of intestinal motility). Pretreatment of control mice with the P450 inhibitor CC12 similarly reduced the analgesia, but not these side effects of morphine. Because activation of brain µ opioid receptors produces both opioid analgesia and opioid side effects, dissociation of the mechanisms for the therapeutic and therapy-limiting effects of opioids has important consequences for the development of analgesics with reduced side effects and/or limited addiction liability. PMID:25062792

  10. Endogenous opiates and behavior: 2004.

    PubMed

    Bodnar, Richard J; Klein, Gad E

    2005-12-01

    This paper is the 27th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over 30 years of research. It summarizes papers published during 2004 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses. PMID:16039752

  11. Endogenous opiates and behavior: 2013.

    PubMed

    Bodnar, Richard J

    2014-12-01

    This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses. PMID:25263178

  12. Endogenous opiates and behavior: 2007.

    PubMed

    Bodnar, Richard J

    2008-12-01

    This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses. PMID:18851999

  13. Endogenous opioids regulate glucocorticoid-dependent stress-coping strategies in mice.

    PubMed

    Szklarczyk, Klaudia; Korostynski, Michal; Golda, Slawomir; Piechota, Marcin; Ficek, Joanna; Przewlocki, Ryszard

    2016-08-25

    Coping skills are essential in determining the outcomes of aversive life events. Our research was aimed to elucidate the molecular underpinnings of different coping styles in two inbred mouse strains, C57BL/6J and SWR/J. We compared the influence of a preceding stressor (0.5h of restraint) on behavioral and gene expression profiles between these two strains. The C57BL/6J strain exhibited increased conditioned fear and high immobility (passive coping). Oppositely, the SWR/J mice demonstrated low freezing and immobility, low post-restraint anxiety and considerable struggling during the forced swim test (active coping). Gene profiling in the amygdala revealed transcriptional patterns that were related to the differential stress reactivity, such as the activation of glucocorticoid-dependent genes specifically in the C57BL/6J mice. Post-restraint blood sampling for corticosterone levels confirmed the association of hypothalamic-pituitary-adrenal (HPA) activation with a passive coping style. Pharmacological tools were used to modulate the stress-coping strategies. The blockade of opioid receptors (ORs) before the aversive event caused transcriptional and neuroendocrine changes in the SWR/J mice that were characteristic of the passive coping strategy. We found that treatment with a glucocorticoid receptor (GR) agonist (dexamethasone (DEX), 4mg/kg) impaired the consolidation of fear memory in the C57BL/6J mice and that this effect was reversed by OR blockade (naltrexone (NTX), 2mg/kg). In parallel, a glucocorticoid receptor antagonist (mifepristone (MIF), 20mg/kg) reversed the effect of morphine (20mg/kg) on conditioned fear in the C57BL/6J mice. Our results suggest that in mice, stress-coping strategies are determined by opioid-dependent mechanisms that modulate activity of the HPA axis. PMID:27235740

  14. Anger regulation style, anger arousal and acute pain sensitivity: evidence for an endogenous opioid “triggering” model

    PubMed Central

    Burns, John W.; Bruehl, Stephen; Chont, Melissa

    2014-01-01

    Findings suggest that greater tendency to express anger is associated with greater sensitivity to acute pain via endogenous opioid system dysfunction, but past studies have not addressed the role of anger arousal. We used a 2 × 2 factorial design with Drug Condition (placebo or opioid blockade with naltrexone) crossed with Task Order (anger-induction/pain-induction or pain-induction/anger-induction), and with continuous Anger-out Subscale scores. Drug × Task Order × Anger-out Subscale interactions were tested for pain intensity during a 4-min ischemic pain task performed by 146 healthy people. A significant Drug × Task Order × Anger-out Subscale interaction was dissected to reveal different patterns of pain intensity changes during the pain task for high anger-out participants who underwent pain-induction prior to anger-induction compared to those high in anger-out in the opposite order. Namely, when angered prior to pain, high anger-out participants appeared to exhibit low pain intensity under placebo that was not shown by high anger-out participants who received naltrexone. Results hint that people with a pronounced tendency to express anger may suffer from inadequate opioid function under simple pain-induction, but may experience analgesic benefit to some extent from the opioid triggering properties of strong anger arousal. PMID:23624641

  15. Plasma IL-12 levels are suppressed in vivo by stress and surgery through endogenous release of glucocorticoids and prostaglandins but not catecholamines or opioids.

    PubMed

    Shaashua, Lee; Rosenne, Ella; Neeman, Elad; Sorski, Liat; Sominsky, Luba; Matzner, Pini; Page, Gayle G; Ben-Eliyahu, Shamgar

    2014-04-01

    IL-12 is a prominent Th1 differentiator and leukocyte activator. Ample studies showed suppression of IL-12 production by numerous stress factors, including prostaglandins, catecholamines, glucocorticoids, and opioids, but did so in vitro and in the context of artificial leukocyte activation, not simulating the in vivo setting. In a recent study we reported in vivo suppression of plasma IL-12 levels by behavioral stress and surgery. The current study aims to elucidate neuroendocrine mechanisms underlying this phenomenon in naïve F344 rats. To this end, both adrenalectomy and administration of specific antagonists were used, targeting the aforementioned stress factors. The results indicated that corticosterone and prostaglandins are prominent mediators of the IL-12-suppressing effects of stress and surgery, apparently through directly suppressing leukocyte IL-12 production. Following surgery, endogenous prostaglandins exerted their effects mainly through elevating corticosterone levels. Importantly, stress-induced release of epinephrine or opioids had no impact on plasma IL-12 levels, while pharmacological administration of epinephrine reduced plasma IL-12 levels by elevating corticosterone levels. Last, a whole blood in vitro study indicated that prostaglandins and corticosterone, but not epinephrine, suppressed IL-12 production in non-stimulated leukocytes, and only corticosterone did so in the context of CpG-C-induced IL-12 production. Overall, the findings reiterate the notion that results from in vitro or pharmacological in vivo studies cannot indicate the effects of endogenously released stress hormones under stress/surgery conditions. Herein, corticosterone and prostaglandins, but not catecholamines or opioids, were key mediators of the suppressive effect of stress and surgery on in vivo plasma IL-12 levels in otherwise naïve animals. PMID:24636497

  16. Plasma IL-12 levels are suppressed in vivo by stress and surgery through endogenous release of glucocorticoids and prostaglandins but not catecholamines or opioids

    PubMed Central

    Shaashua, Lee; Rosenne, Ella; Neeman, Elad; Sorski, Liat; Sominsky, Luba; Matzner, Pini; Page, Gayle G.; Ben-Eliyahu, Shamgar

    2014-01-01

    IL-12 is a prominent Th1 differentiator and leukocyte activator. Ample studies showed suppression of IL-12 production by numerous stress factors, including prostaglandins, catecholamines, glucocorticoids, and opioids, but did so in vitro and in the context of artificial leukocyte activation, not simulating the in vivo setting. In a recent study we reported in vivo suppression of plasma IL-12 levels by behavioral stress and surgery. The current study aims to elucidate neuroendocrine mechanisms underlying this phenomenon in naïve F344 rats. To this end, both adrenalectomy and administration of specific antagonists were used, targeting the aforementioned stress factors. The results indicated that corticosterone and prostaglandins are prominent mediators of the IL-12-suppressing effects of stress and surgery, apparently through directly suppressing leukocyte IL-12 production. Following surgery, endogenous prostaglandins exerted their effects mainly through elevating corticosterone levels. Importantly, stress-induced release of epinephrine or opioids had no impact on plasma IL-12 levels, while pharmacological administration of epinephrine reduced plasma IL-12 levels by elevating corticosterone levels. Last, a whole blood in vitro study indicated that prostaglandins and corticosterone, but not epinephrine, suppressed IL-12 production in non-stimulated leukocytes, and only corticosterone did so in the context of CpG-C-induced IL-12 production. Overall, the findings reiterate the notion that results from in vitro or pharmacological in vivo studies cannot indicate the effects of endogenously released stress hormones under stress/surgery conditions. Herein, corticosterone and prostaglandins, but not catecholamines or opioids, were key mediators of the suppressive effect of stress and surgery on in vivo plasma IL-12 levels in otherwise naïve animals. PMID:24636497

  17. Delta Opioid activation of the Mitogen-activated protein kinase cascade does not require transphosphorylation of Receptor Tyrosine Kinases

    PubMed Central

    Kramer, H Kenneth; Onoprishvili, Irma; Andria, Matthew L; Hanna, Kayane; Sheinkman, Karina; Haddad, Lisa B; Simon, Eric J

    2002-01-01

    Background In this study, we investigated the mechanism(s) by which delta opioids induce their potent activation of extracellular signal-regulated protein kinases (ERKs) in different cell lines expressing the cloned δ-opioid receptor (δ-OR). While it has been known for some time that OR stimulation leads to the phosphorylation of both ERK isoforms, the exact progression of events has remained elusive. Results Our results indicate that the transphosphorylation of an endogenous epidermal growth factor receptor (EGFR) in the human embryonic kidney (HEK-293) cell line does not occur when co-expressed δ-ORs are stimulated by the δ-opioid agonist, D-Ser-Leu-enkephalin-Thr (DSLET). Moreover, neither pre-incubation of cultures with the selective EGFR antagonist, AG1478, nor down-regulation of the EGFR to a point where EGF could no longer activate ERKs had an inhibitory effect on ERK activation by DSLET. These results appear to rule out any structural or catalytic role for the EGFR in the δ-opioid-mediated MAPK cascade. To confirm these results, we used C6 glioma cells, a cell line devoid of the EGFR. In δ-OR-expressing C6 glioma cells, opioids produce a robust phosphorylation of ERK 1 and 2, whereas EGF has no stimulatory effect. Furthermore, antagonists to the RTKs that are endogenously expressed in C6 glioma cells (insulin receptor (IR) and platelet-derived growth factor receptor (PDGFR)) were unable to reduce opioid-mediated ERK activation. Conclusion Taken together, these data suggest that the transactivation of resident RTKs does not appear to be required for OR-mediated ERK phosphorylation and that the tyrosine-phosphorylated δ-OR, itself, is likely to act as its own signalling scaffold. PMID:11897012

  18. A genetic polymorphism of the endogenous opioid dynorphin modulates monetary reward anticipation in the corticostriatal loop.

    PubMed

    Votinov, Mikhail; Pripfl, Juergen; Windischberger, Christian; Kalcher, Klaudius; Zimprich, Alexander; Zimprich, Fritz; Moser, Ewald; Lamm, Claus; Sailer, Uta

    2014-01-01

    The dynorphin/κ-opioid receptor (KOP-R) system has been shown to play a role in different types of behavior regulation, including reward-related behavior and drug craving. It has been shown that alleles with 3 or 4 repeats (HH genotype) of the variable nucleotide tandem repeat (68-bp VNTR) functional polymorphism of the prodynorphin (PDYN) gene are associated with higher levels of dynorphin peptides than alleles with 1 or 2 repeats (LL genotype). We used fMRI on N = 71 prescreened healthy participants to investigate the effect of this polymorphism on cerebral activation in the limbic-corticostriatal loop during reward anticipation. Individuals with the HH genotype showed higher activation than those with the LL genotype in the medial orbitofrontal cortex (mOFC) when anticipating a possible monetary reward. In addition, the HH genotype showed stronger functional coupling (as assessed by effective connectivity analyses) of mOFC with VMPFC, subgenual anterior cingulate cortex, and ventral striatum during reward anticipation. This hints at a larger sensitivity for upcoming rewards in individuals with the HH genotype, resulting in a higher motivation to attain these rewards. These findings provide first evidence in humans that the PDYN polymorphism modulates neural processes associated with the anticipation of rewards, which ultimately may help to explain differences between genotypes with respect to addiction and drug abuse. PMID:24587148

  19. Structural Requirements for CNS Active Opioid Glycopeptides.

    PubMed

    Lefever, Mark; Li, Yingxue; Anglin, Bobbi; Muthu, Dhanasekaran; Giuvelis, Denise; Lowery, John J; Knapp, Brian I; Bidlack, Jean M; Bilsky, Edward J; Polt, Robin

    2015-08-13

    Glycopeptides related to β-endorphin penetrate the blood-brain barrier (BBB) of mice to produce antinociception. Two series of glycopeptides were assessed for opioid receptor binding affinity. Attempts to alter the mu-selectivity of [D-Ala(2),N-MePhe(4),Gly-ol(5)]enkephalin (DAMGO)-related glycopeptides by altering the charged residues of the amphipathic helical address were unsuccessful. A series of pan-agonists was evaluated for antinociceptive activity (55 °C tail flick) in mice. A flexible linker was required to maintain antinociceptive activity. Circular dichroism (CD) in H2O, trifluoroethanol (TFE), and SDS micelles confirmed the importance of the amphipathic helices (11s → 11sG → 11) for antinociception. The glycosylated analogues showed only nascent helices and random coil conformations in H2O. Chemical shift indices (CSI) and nuclear Overhauser effects (NOE) with 600 MHz NMR and CD confirmed helical structures in micelles, which were rationalized by molecular dynamics calculations. Antinociceptive studies with mice confirm that these glycosylated endorphin analogues are potential drug candidates that penetrate the BBB to produce potent central effects. PMID:26125201

  20. Kappa Opioid Receptor-Induced Aversion Requires p38 MAPK Activation in VTA Dopamine Neurons

    PubMed Central

    Ehrich, Jonathan M.; Messinger, Daniel I.; Knakal, Cerise R.; Kuhar, Jamie R.; Schattauer, Selena S.; Bruchas, Michael R.; Zweifel, Larry S.; Kieffer, Brigitte L.; Phillips, Paul E.M.

    2015-01-01

    The endogenous dynorphin-κ opioid receptor (KOR) system encodes the dysphoric component of the stress response and controls the risk of depression-like and addiction behaviors; however, the molecular and neural circuit mechanisms are not understood. In this study, we report that KOR activation of p38α MAPK in ventral tegmental (VTA) dopaminergic neurons was required for conditioned place aversion (CPA) in mice. Conditional genetic deletion of floxed KOR or floxed p38α MAPK by Cre recombinase expression in dopaminergic neurons blocked place aversion to the KOR agonist U50,488. Selective viral rescue by wild-type KOR expression in dopaminergic neurons of KOR−/− mice restored U50,488-CPA, whereas expression of a mutated form of KOR that could not initiate p38α MAPK activation did not. Surprisingly, while p38α MAPK inactivation blocked U50,488-CPA, p38α MAPK was not required for KOR inhibition of evoked dopamine release measured by fast scan cyclic voltammetry in the nucleus accumbens. In contrast, KOR activation acutely inhibited VTA dopaminergic neuron firing, and repeated exposure attenuated the opioid response. This adaptation to repeated exposure was blocked by conditional deletion of p38α MAPK, which also blocked KOR-induced tyrosine phosphorylation of the inwardly rectifying potassium channel (GIRK) subunit Kir3.1 in VTA dopaminergic neurons. Consistent with the reduced response, GIRK phosphorylation at this amino terminal tyrosine residue (Y12) enhances channel deactivation. Thus, contrary to prevailing expectations, these results suggest that κ opioid-induced aversion requires regulation of VTA dopaminergic neuron somatic excitability through a p38α MAPK effect on GIRK deactivation kinetics rather than by presynaptically inhibiting dopamine release. SIGNIFICANCE STATEMENT Kappa opioid receptor (KOR) agonists have the potential to be effective, nonaddictive analgesics, but their therapeutic utility is greatly limited by adverse effects on mood

  1. Avoiding Opioids and Their Harmful Side Effects in the Postoperative Patient: Exogenous Opioids, Endogenous Endorphins, Wellness, Mood, and Their Relation to Postoperative Pain.

    PubMed

    Stephan, Bradley C; Parsa, Fereydoun D

    2016-03-01

    Prescribed opioids are routinely used for many postoperative patients. However, these medications have daunting adverse effects on the body's innate pain management system - the action of the beta-endorphins. The prescribed opioids not only severely impair the function of the mu-opioid receptors, but also inhibit the release of beta-endorphin. This is unfortunate, because beta-endorphin appears to be a much more potent agonist of the mu-opioid receptor than opioids. In addition, beta-endorphin indirectly elevates dopamine, a neurotransmitter related to feelings of euphoria. Therefore, by prescribing opioids, practitioners may inadvertently prolong and increase the overall intensity of the postoperative patients' pain as well as herald anhedonia. This article highlights the relationships between prescribed (exogenous) opioids, beta-endorphins, mu-opioid receptors, wellness, mood, and postoperative pain. The role of patient education, opioid alternatives, and additional recommendations regarding pain control in the postoperative patient are also discussed. PMID:27011886

  2. Avoiding Opioids and Their Harmful Side Effects in the Postoperative Patient: Exogenous Opioids, Endogenous Endorphins, Wellness, Mood, and Their Relation to Postoperative Pain

    PubMed Central

    Parsa, Fereydoun D

    2016-01-01

    Prescribed opioids are routinely used for many postoperative patients. However, these medications have daunting adverse effects on the body's innate pain management system - the action of the beta-endorphins. The prescribed opioids not only severely impair the function of the mu-opioid receptors, but also inhibit the release of beta-endorphin. This is unfortunate, because beta-endorphin appears to be a much more potent agonist of the mu-opioid receptor than opioids. In addition, beta-endorphin indirectly elevates dopamine, a neurotransmitter related to feelings of euphoria. Therefore, by prescribing opioids, practitioners may inadvertently prolong and increase the overall intensity of the postoperative patients' pain as well as herald anhedonia. This article highlights the relationships between prescribed (exogenous) opioids, beta-endorphins, mu-opioid receptors, wellness, mood, and postoperative pain. The role of patient education, opioid alternatives, and additional recommendations regarding pain control in the postoperative patient are also discussed. PMID:27011886

  3. Propagation of conformational changes during μ-opioid receptor activation

    PubMed Central

    Sounier, Rémy; Mas, Camille; Steyaert, Jan; Laeremans, Toon; Manglik, Aashish; Huang, Weijiao; Kobilka, Brian; Déméné, Héléne; Granier, Sébastien

    2016-01-01

    μ-Opioid receptors (μOR) are G protein coupled receptors (GPCRs) that are activated by a structurally diverse spectrum of natural and synthetic agonists including endogenous endorphin peptides, morphine and methadone. The recent structures of the μOR in inactive1 and agonist-induced active states (companion article) provide snapshots of the receptor at the beginning and end of a signaling event, but little is known about the dynamic sequence of events that span these two states. Here we report the use of solution-state NMR to examine the process of μOR activation. We obtained spectra of the μOR in the absence of ligand, and in the presence of the high-affinity agonist BU72 alone, or with BU72 and a G protein mimetic nanobody. Our results show that conformational changes in transmembrane segments (TM) 5 and 6, which are required for the full engagement of a G protein, are almost completely dependent on the presence of both the agonist and the G protein mimetic nanobody revealing a weak allosteric coupling between the agonist binding pocket and the G protein coupling interface (TM5 and TM6) similar to what has been observed for the β2-adrenergic receptor2. Unexpectedly, in the presence of agonist alone, we observe larger spectral changes involving intracellular loop 1 (ICL1) and helix 8 (H8), when compared to changes in TM5 and TM6. These results suggest that one or both of these domains may play a role in the initial interaction with the G protein, and that TM5 and TM6 are only engaged later in the process of complex formation. The initial interactions between the G protein and ICL1 and/or H8 may play a role in G protein coupling specificity as has been suggested for other family A GPCRs. PMID:26245377

  4. Asymmetry of the Endogenous Opioid System in the Human Anterior Cingulate: a Putative Molecular Basis for Lateralization of Emotions and Pain

    PubMed Central

    Watanabe, Hiroyuki; Fitting, Sylvia; Hussain, Muhammad Z.; Kononenko, Olga; Iatsyshyna, Anna; Yoshitake, Takashi; Kehr, Jan; Alkass, Kanar; Druid, Henrik; Wadensten, Henrik; Andren, Per E.; Nylander, Ingrid; Wedell, Douglas H.; Krishtal, Oleg; Hauser, Kurt F.; Nyberg, Fred; Karpyak, Victor M.; Yakovleva, Tatjana; Bakalkin, Georgy

    2015-01-01

    Lateralization of the processing of positive and negative emotions and pain suggests an asymmetric distribution of the neurotransmitter systems regulating these functions between the left and right brain hemispheres. By virtue of their ability to selectively mediate euphoria, dysphoria, and pain, the μ-, δ-, and κ-opioid receptors and their endogenous ligands may subserve these lateralized functions. We addressed this hypothesis by comparing the levels of the opioid receptors and peptides in the left and right anterior cingulate cortex (ACC), a key area for emotion and pain processing. Opioid mRNAs and peptides and 5 “classical” neurotransmitters were analyzed in postmortem tissues from 20 human subjects. Leu-enkephalin-Arg (LER) and Met-enkephalin-Arg-Phe, preferential δ-/μ- and κ-/μ-opioid agonists, demonstrated marked lateralization to the left and right ACC, respectively. Dynorphin B (Dyn B) strongly correlated with LER in the left, but not in the right ACC suggesting different mechanisms of the conversion of this κ-opioid agonist to δ-/μ-opioid ligand in the 2 hemispheres; in the right ACC, Dyn B may be cleaved by PACE4, a proprotein convertase regulating left–right asymmetry formation. These findings suggest that region-specific lateralization of neuronal networks expressing opioid peptides underlies in part lateralization of higher functions, including positive and negative emotions and pain in the human brain. PMID:23960211

  5. Strategies to Improve Bioavailability and In Vivo Efficacy of the Endogenous Opioid Peptides Endomorphin-1 and Endomorphin-2.

    PubMed

    De Marco, Rossella; Janecka, Anna

    2015-01-01

    Morphine and the other alkaloids found in the opium poppy plant still represent the preferred therapeutic tools to treat severe pain in first aid protocols, as well as chronic pain. The use of the opiate alkaloids is accompanied by several unwanted side effects; additionally, some forms of pain are resistant to standard treatments (e.g. neuropathic pain from cancer). For these reasons, there is currently renewed interest in the design and assay of modified versions of the potent endogenous opioid peptides endomorphin-1 and endomorphin-2. This review presents a selection of the strategies directed at preparing highly stable peptidomimetics of the endomorphins, and of the strategies aimed at improving central nervous system bioavailability, for which increased in vivo antinociceptive efficacy was clearly demonstrated. PMID:26279081

  6. [Endogenous opioid system in the realization of the analgesic effect of alpha-tocopherol in reference to algomenorrhea].

    PubMed

    Kryzhanovskiĭ, G N; Bakuleva, L P; Luzina, N L; Vinogradov, V A; Iarygin, K N

    1988-02-01

    Beta-endorphin-like immunoreactivity was studied in 7 patients with algomenorrhea during pain attack and 15 minutes after alpha-tocopherol administration with a therapeutic aim (till the analgetic effect was reached). There was an increase in beta-endorphin-like immunoreactivity after alpha-tocopherol administration. Naloxone administration to 9 patients with algomenorrhea of various etiology resumed the pain. The effect of alpha-tocopherol application for pain relief depended on the pathogenesis of algomenorrhea. At the same time naloxone administration failed to resume the pain in patients, in whom alpha-tocopherol had a strong analgetic effect. It is assumed that the endogenous opioid system participates in alpha-tocopherol effect on pain relief in patients with algomenorrhea. PMID:2964879

  7. Studies on the synthesis and opioid agonistic activities of mitragynine-related indole alkaloids: discovery of opioid agonists structurally different from other opioid ligands.

    PubMed

    Takayama, Hiromitsu; Ishikawa, Hayato; Kurihara, Mika; Kitajima, Mariko; Aimi, Norio; Ponglux, Dhavadee; Koyama, Fumi; Matsumoto, Kenjiro; Moriyama, Tomoyuki; Yamamoto, Leonard T; Watanabe, Kazuo; Murayama, Toshihiko; Horie, Syunji

    2002-04-25

    Mitragynine (1) is a major alkaloidal component in the Thai traditional medicinal herb, Mitragyna speciosa, and has been proven to exhibit analgesic activity mediated by opioid receptors. By utilizing this natural product as a lead compound, synthesis of some derivatives, evaluations of the structure-activity relationship, and surveys of the intrinsic activities and potencies on opioid receptors were performed with guinea pig ileum. The affinities of some compounds for mu-, delta-, and kappa-receptors were determined in a receptor binding assay. The essential structural moieties in the Corynanthe type indole alkaloids for inducing the opioid agonistic activity were also clarified. The oxidative derivatives of mitragynine, i.e., mitragynine pseudoindoxyl (2) and 7-hydroxymitragynine (12), were found as opioid agonists with higher potency than morphine in the experiment with guinea pig ileum. In addition, 2 induced an analgesic activity in the tail flick test in mice. PMID:11960505

  8. Antitussive activity of Withania somnifera and opioid receptors.

    PubMed

    Nosálová, Gabriela; Sivová, Veronika; Ray, Bimalendu; Fraňová, Soňa; Ondrejka, Igor; Flešková, Dana

    2015-01-01

    Arabinogalactan is a polysaccharide isolated from the roots of the medicinal plant Withania somnifera L. It contains 65% arabinose and 18% galactose. The aim of the present study was to evaluate the antitussive activity of arabinogalactan in conscious, healthy adult guinea pigs and the role of the opioid pathway in the antitussive action. A polysaccharide extract was given orally in a dose of 50 mg/kg. Cough was induced by an aerosol of citric acid in a concentration 0.3 mol/L, generated by a jet nebulizer into a plethysmographic chamber. The intensity of cough response was defined as the number of cough efforts counted during a 3-min exposure to the aerosol. The major finding was that arabinogalactan clearly suppressed the cough reflex; the suppression was comparable with that of codeine that was taken as a reference drug. The involvement of the opioid system was tested with the use of a blood-brain barrier penetrable, naloxone hydrochloride, and non-penetrable, naloxone methiodide, to distinguish between the central and peripheral mu-opioid receptor pathways. Both opioid antagonists acted to reverse the arabinogalactan-induced cough suppression; the reversion was total over time with the latter antagonist. We failed to confirm the presence of a bronchodilating effect of the polysaccharide, which could be involved in its antitussive action. We conclude that the polysaccharide arabinogalactan from Withania somnifera has a distinct antitussive activity consisting of cough suppression and that this action involves the mu-opioid receptor pathways. PMID:25252908

  9. [Opioid receptors and their selective ligands].

    PubMed

    Piestrzeniewicz, Mariola Katarzyna; Fichna, Jakub; Michna, Jakub; Janecka, Anna

    2006-01-01

    Opioid receptors (micro, delta, and kappa) belong to a large family of G protein-coupled receptors and play an important physiological role. Stimulation of these receptors triggers analgesic effects and affects the function of gastrointestinal tract. The discovery of opioid peptides, which are endogenous ligands of opioid receptors, including delta-selective enkephalins, kappa-selective dynorphins, and micro-selective endomorphins, initiated their structure-activity relationship studies. For the last 30 years, hundreds of analogs of opioid peptides have been synthesized in an effort to obtain the compounds more active, selective, and resistant to biodegradation than the endogenous ligands. Different unnatural amino acids, as well as cyclisation procedures, leading to conformationaly restricted analogs, were employed. All these modifications resulted in obtaining very selective agonists and antagonists with high affinity at micro-, dlta-, and kappa-opioid receptors, which are extremely useful tools in further studies on the pharmacology of opioid receptors in a mammalian organism. PMID:17201067

  10. Synthesis and opioid activity of novel 6-ketolevorphanol derivatives.

    PubMed

    Gyulai, Zsuzsanna; Udvardy, Antal; Cs Bényei, Attila; Fichna, Jakub; Gach, Katarzyna; Storr, Martin; Tóth, Géza; Antus, Sándor; Berényi, Sándor; Janecka, Anna; Sipos, Attila

    2013-02-01

    Novel 6-ketolevorphanol analogs with diverse substitution patterns at ring C were synthesized and their binding affinities at the μ,δ and κ opioid receptors were investigated. The in vitro activity of the new analogs was then evaluated in the functional assay based on the electrically-stimulated contractions of the mouse ileum. It was shown that analogs with Δ7,8 bond had no significant potency at any of the opioid receptor types. In contrast, analogs with the saturated ring C were either potent κ agonist or antagonist depending on the absence or presence of the hydroxyl group in position 14. PMID:22741803

  11. Orally active opioid compounds from a non-poppy source.

    PubMed

    Raffa, Robert B; Beckett, Jaclyn R; Brahmbhatt, Vivek N; Ebinger, Theresa M; Fabian, Chrisjon A; Nixon, Justin R; Orlando, Steven T; Rana, Chintan A; Tejani, Ali H; Tomazic, Robert J

    2013-06-27

    The basic science and clinical use of morphine and other "opioid" drugs are based almost exclusively on the extracts or analogues of compounds isolated from a single source, the opium poppy (Papaver somniferum). However, it now appears that biological diversity has evolved an alternative source. Specifically, at least two alkaloids isolated from the plant Mitragyna speciosa, mitragynine ((E)-2-[(2S,3S)-3-ethyl-8-methoxy-1,2,3,4,6,7,12,12b-octahydroindolo[3,2-h]quinolizin-2-yl]-3-methoxyprop-2-enoic acid methyl ester; 9-methoxy coryantheidine; MG) and 7-hydroxymitragynine (7-OH-MG), and several synthetic analogues of these natural products display centrally mediated (supraspinal and spinal) antinociceptive (analgesic) activity in various pain models. Several characteristics of these compounds suggest a classic "opioid" mechanism of action: nanomolar affinity for opioid receptors, competitive interaction with the opioid receptor antagonist naloxone, and two-way analgesic cross-tolerance with morphine. However, other characteristics of the compounds suggest novelty, particularly chemical structure and possible greater separation from side effects. We review the chemical and pharmacological properties of these compounds. PMID:23517479

  12. Sensitization to the behavioural effects of cocaine: alterations in tyrosine hydroxylase or endogenous opioid mRNAs are not necessarily involved.

    PubMed

    Alvarez Fischer, D; Schäfer, M K; Ferger, B; Gross, S; Westermann, R; Weihe, E; Kuschinsky, K

    2001-03-01

    After repeated administration of cocaine at intervals, sensitization phenomena can be observed, so that its behavioural effects are enhanced. Since this phenomenon is long-lasting, it was of interest to study which persistent alterations in the activity of dopaminergic neurones or of endogenous opioid systems downstream of dopaminergic synapses in the basal ganglia are involved in the sensitization. Cocaine (10 mg/kg i.p.) was administered to rats on days 1, 3, 5 and 7 and saline on days 2, 4 and 6 ("repeated cocaine"), or saline was injected on days 1-6 and cocaine on day 7 ("acute cocaine"), or saline was injected on days 1-7 ("saline group"). The "repeated cocaine" schedule led to a significant sensitization to the locomotor activation produced by cocaine on day 7 or on day 17, 10 days after the end of sensitization protocol. Microdialysis in the nucleus accumbens which was performed after administration of cocaine (10 mg/kg i.p.) on day 7, or after an administration of the same dose 10 days after the last administration of cocaine, respectively, revealed significant acute increases of extracellular dopamine to about 200% of basal values. These increases were similar in "acute cocaine" and in "repeated cocaine" animals both after 7 days and after 17 days. For in situ hybridization studies, rats were sacrificed on day 7, 4.5 h after the last cocaine or saline administration. The mRNA for tyrosine hydroxylase (TH) in substantia nigra + ventral tegmental area was significantly elevated to about 140% of saline controls both in the "repeated cocaine" and the "acute cocaine" group as compared with the "saline group". In contrast, there were no differences between the three groups in the mRNAs of preprodynorphin or preproenkephalin levels measured in the nucleus accumbens (core and shell). These results suggest that sensitization phenomena to cocaine are not necessarily connected with alterations in the dopaminergic activity in the mesolimbic system or in the

  13. Endogenous Opioid-Masked Latent Pain Sensitization: Studies from Mouse to Human

    PubMed Central

    Dahl, Jørgen B.; Werner, Marianne; Taylor, Bradley K.; Werner, Mads U.

    2015-01-01

    Following the resolution of a severe inflammatory injury in rodents, administration of mu-opioid receptor inverse agonists leads to reinstatement of pain hypersensitivity. The mechanisms underlying this form of latent pain sensitization (LS) likely contribute to the development of chronic pain, but LS has not yet been demonstrated in humans. Using a C57BL/6 mouse model of cutaneous mild heat injury (MHI) we demonstrated a dose-dependent reinstatement of pain sensitization, assessed as primary (P < 0.001) and secondary hyperalgesia (P < 0.001) by naloxone (0.3–10 mg/kg), 168 hrs after the induction of MHI. Forward-translating the dose data to a human MHI model (n = 12) we could show that LS does indeed occur after naloxone 2 mg/kg, 168 hrs after a MHI. Our previous unsuccessful efforts to demonstrate unmasking of LS in humans are thus likely explained by an insufficient naloxone dose (0.021 mg/kg). However, while LS was consistently demonstrated in 21/24 mice, LS was only seen in 4/12 subjects. This difference is likely due to selection bias since the C57BL/6 mouse strain exhibits markedly enhanced pain sensitivity in assays of acute thermal nociception. Future exploratory studies in humans should prioritize inclusion of “high-sensitizers” prone to develop LS and use post-surgical models to elucidate markers of vulnerability to chronic postsurgical pain. Trial Registration EudraCT 2012-005663-27 PMID:26305798

  14. How Active Are Porcine Endogenous Retroviruses (PERVs)?

    PubMed Central

    Denner, Joachim

    2016-01-01

    Porcine endogenous retroviruses (PERVs) represent a risk factor if porcine cells, tissues, or organs were to be transplanted into human recipients to alleviate the shortage of human transplants; a procedure called xenotransplantation. In contrast to human endogenous retroviruses (HERVs), which are mostly defective and not replication-competent, PERVs are released from normal pig cells and are infectious. PERV-A and PERV-B are polytropic viruses infecting cells of several species, among them humans; whereas PERV-C is an ecotropic virus infecting only pig cells. Virus infection was shown in co-culture experiments, but also in vivo, in the pig, leading to de novo integration of proviruses in certain organs. This was shown by measurement of the copy number per cell, finding different numbers in different organs. In addition, recombinations between PERV-A and PERV-C were observed and the recombinant PERV-A/C were found to be integrated in cells of different organs, but not in the germ line of the animals. Here, the evidence for such in vivo activities of PERVs, including expression as mRNA, protein and virus particles, de novo infection and recombination, will be summarised. These activities make screening of pigs for provirus number and PERV expression level difficult, especially when only blood or ear biopsies are available for analysis. Highly sensitive methods to measure the copy number and the expression level will be required when selecting pigs with low copy number and low expression of PERV as well as when inactivating PERVs using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease (CRISPR/Cas) technology. PMID:27527207

  15. Identification of endogenous opioid receptor components in rat brain using a monoclonal antibody

    SciTech Connect

    Bero, L.A.; Roy, S.; Lee, N.M.

    1988-11-01

    A monoclonal antibody generated against the tertiary structure of a partially purified opioid binding protein was used to probe the structure of the dynorphin and beta-endorphin receptors. The Fab fragment 3B4F11 inhibited completely the binding of 125I-beta-endorphin and (3H)dynorphin to rat brain P2 membranes with IC50 values of 26 ng/ml and 40 ng/ml, respectively. To explore further the interaction of 3B4F11 with the beta-endorphin receptor, the effect of the Fab fragment on 125I-beta-endorphin cross-linking to rat brain membranes was examined. 125I-beta-endorphin was covalently bound to three major species of approximate molecular weights 108,000, 73,000, and 49,000. The delta-selective ligand D-Pen2, D-pen5enkephalin was least effective at inhibiting the cross-linking of beta-endorphin, whereas the micro-selective ligand Tyr-D-Ala-Gly-NMe-Phe-Gly-ol and kappa-selective ligand U50488 inhibited beta-endorphin cross-linking to the 108,000 and 73,000 Da species. Both 3B4F11 and beta-endorphin prevented the covalent binding of 125I-beta-endorphin to all three labeled species. These findings suggest that micro and kappa receptor types might have some structural similarities, whereas the delta receptor type might differ in molecular size. In addition, the micro, kappa, and delta ligands might have different primary sequences, whereas their tertiary structures might share regions of molecular homology with all three receptor constituents labeled by 125I-beta-endorphin. 3B4F11 will be a valuable tool for the purification and isolation of the several components of the beta-endorphin receptor complex.

  16. Dynorphin activation of kappa opioid receptor reduces neuronal excitability in the paraventricular nucleus of mouse thalamus.

    PubMed

    Chen, Zhiheng; Tang, Yamei; Tao, Huai; Li, Cunyan; Zhang, Xianghui; Liu, Yong

    2015-10-01

    It has been reported that kappa opioid receptor (KOR) is expressed in the paraventricular nucleus of thalamus (PVT), a brain region associated with arousal, drug reward and stress. Although intra-PVT infusion of KOR agonist was found to inhibit drug-seeking behavior, it is still unclear whether endogenous KOR agonists directly regulate PVT neuron activity. Here, we investigated the effect of the endogenous KOR agonist dynorphin-A (Dyn-A) on the excitability of mouse PVT neurons at different developmental ages. We found Dyn-A strongly inhibited PVT neurons through a direct postsynaptic hyperpolarization. Under voltage-clamp configuration, Dyn-A evoked an obvious outward current in majority of neurons tested in anterior PVT (aPVT) but only in minority of neurons in posterior PVT (pPVT). The Dyn-A current was abolished by KOR antagonist nor-BNI, Ba(2+) and non-hydrolyzable GDP analogue GDP-β-s, indicating that Dyn-A activates KOR and opens G-protein-coupled inwardly rectifying potassium channels in PVT neurons. More interestingly, by comparing Dyn-A currents in aPVT neurons of mice at various ages, we found Dyn-A evoked significant larger current in aPVT neurons from mice around prepuberty and early puberty stage. In addition, KOR activation by Dyn-A didn't produce obvious desensitization, while mu opioid receptor (MOR) activation induced obvious desensitization of mu receptor itself and also heterologous desensitization of KOR in PVT neurons. Together, our findings indicate that Dyn-A activates KOR and inhibits aPVT neurons in mice at various ages especially around puberty, suggesting a possible role of KOR in regulating aPVT-related brain function including stress response and drug-seeking behavior during adolescence. PMID:26056031

  17. Cannabidiol and endogenous opioid peptide-mediated mechanisms modulate antinociception induced by transcutaneous electrostimulation of the peripheral nervous system.

    PubMed

    Gonçalves, Thais Cristina Teixeira; Londe, Anna Karla; Albano, Rafael Isaac Pires; de Araújo Júnior, Artur Teixeira; de Aguiar Azeredo, Mariana; Biagioni, Audrey Francisco; Vasconcellos, Thiago Henrique Ferreira; Dos Reis Ferreira, Célio Marcos; Teixeira, Dulcinéa Gonçalves; de Souza Crippa, José Alexandre; Vieira, Débora; Coimbra, Norberto Cysne

    2014-12-15

    Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacological therapy for the treatment of pain. The present work investigated the effect of cannabidiol, naloxone and diazepam in combination with 10 Hz and 150 Hz TENS. Male Wistar rats were submitted to the tail-flick test (baseline), and each rodent received an acute administration (intraperitoneal) of naloxone (3.0mg/kg), diazepam (1.5mg/kg) or cannabidiol (0.75 mg/kg, 1.5mg/kg, 3.0mg/kg, 4.5mg/kg, 6.0mg/kg and 12.0mg/kg); 10 min after the acute administration, 10 Hz or 150 Hz TENS or a sham procedure was performed for 30 min. Subsequently, tail-flick measures were recorded over a 90-min period, at 5-min intervals. 10 Hz TENS increased the nociceptive threshold during the 90-min period. This antinociceptive effect was reversed by naloxone pre-treatment, was not altered by diazepam pre-treatment and was abolished by cannabidiol pre-treatment (1.5mg/kg). Moreover, 150 Hz TENS increased tail-flick latencies by 35 min post-treatment, which was partially inhibited by naloxone pre-treatment and totally inhibited by cannabidiol (1.5mg/kg). These data suggest the involvement of the endogenous opioid system and the cannabinoid-mediated neuromodulation of the antinociception induced by transcutaneous electrostimulation at 10 Hz and 150 Hz TENS. PMID:25282545

  18. Endogenous opioid regulation of stress-induced oxytocin release within the hypothalamic paraventricular nucleus is reversed in late pregnancy: a microdialysis study.

    PubMed

    Wigger, A; Neumann, I D

    2002-01-01

    Oxytocin secretion into blood in response to swim stress is differentially regulated by endogenous opioids in virgin and pregnant rats. Here, the influence of endogenous opioids on oxytocin release within the hypothalamic paraventricular and supraoptic nuclei was investigated using microdialysis in virgin and pregnant (day 19-21) rats. Rats fitted with a U-shaped microdialysis probe 3 days before testing were injected with naloxone (5 mg/kg body weight, s.c.) or vehicle (sterile saline) and, 3 min later, were forced to swim (10 min at 19 degrees C). Within the paraventricular nucleus, basal and stimulated oxytocin release did not significantly differ between vehicle-treated virgin and pregnant rats. After naloxone, local oxytocin release in response to swimming was lowered in virgin rats (P<0.01), whereas it was further increased in pregnant rats (P<0.01). Within the supraoptic nucleus, basal oxytocin release was significantly lower in pregnant compared to virgin rats (P<0.01). Forced swimming induced a similar rise in intranuclear oxytocin release in both vehicle-treated virgin and pregnant rats, but peak levels were still higher in the virgin controls. In contrast to the paraventricular nucleus, naloxone did not alter swim-induced oxytocin release within the supraoptic nucleus either in virgin or pregnant rats. Vasopressin release in the paraventricular nucleus was also increased by forced swimming but there was no effect of pregnancy or naloxone on it. In summary, in pregnancy, basal and stress-induced oxytocin release within the paraventricular nucleus was not changed, whereas it was blunted within the supraoptic nucleus. Further, within the paraventricular nucleus the excitatory effect of endogenous opioids on local oxytocin release seen in virgins was switched into an inhibitory action in pregnancy. In contrast, endogenous opioids were evidently not involved in the regulation of swim-induced oxytocin release within the supraoptic nucleus either in virgin or

  19. Endogenous pacemaker activity of rat tumour somatotrophs

    PubMed Central

    Kwiecien, Renata; Robert, Christophe; Cannon, Robert; Vigues, Stephan; Arnoux, Annie; Kordon, Claude; Hammond, Constance

    1998-01-01

    Cells derived from a rat pituitary tumour (GC cell line) that continuously release growth hormone behave as endogenous pacemakers. In simultaneous patch clamp recordings and cytosolic Ca2+ concentration ([Ca2+]i) imaging, they displayed rhythmic action potentials (44.7 ± 2.7 mV, 178 ± 40 ms, 0.30 ± 0.04 Hz) and concomitant [Ca2+]i transients (374 ± 57 nM, 1.0 ± 0.2 s, 0.27 ± 0.03 Hz). Action potentials and [Ca2+]i transients were reversibly blocked by removal of external Ca2+, addition of nifedipine (1 μM) or Ni2+ (40 μM), but were insensitive to TTX (1 μM). An L-type Ca2+ current activated at -33.6 ± 0.4 mV (holding potential (Vh), −40 mV), peaked at -1.8 ± 1.3 mV, was reduced by nifedipine and enhanced by S-(+)-SDZ 202 791. A T/R-type Ca2+ current activated at -41.7 ± 2.7 mV (Vh, -80 or -60 mV), peaked at -9.2 ± 3.0 mV, was reduced by low concentrations of Ni2+ (40 μM) or Cd2+ (10 μM) and was toxin resistant. Parallel experiments revealed the expression of the class E calcium channel α1-subunit mRNA. The K+ channel blockers TEA (25 mM) and charybdotoxin (10–100 nM) enhanced spike amplitude and/or duration. Apamin (100 nM) also strongly reduced the after-spike hyperpolarization. The outward K+ tail current evoked by a depolarizing step that mimicked an action potential reversed at −69.8 ± 0.3 mV, presented two components, lasted 2–3 s and was totally blocked by Cd2+ (400 μM). The slow pacemaker depolarization (3.5 ± 0.4 s) that separated consecutive spikes corresponded to a 2- to 3-fold increase in membrane resistance, was strongly Na+ sensitive but TTX insensitive. Computer simulations showed that pacemaker activity can be reproduced by a minimum of six currents: an L-type Ca2+ current underlies the rising phase of action potentials that are repolarized by a delayed rectifier and Ca2+-activated K+ currents. In between spikes, the decay of Ca2+-activated K+ currents and a persistent inward cationic current depolarize the membrane

  20. Behavioural activation system sensitivity is associated with cerebral μ-opioid receptor availability.

    PubMed

    Karjalainen, Tomi; Tuominen, Lauri; Manninen, Sandra; Kalliokoski, Kari K; Nuutila, Pirjo; Jääskeläinen, Iiro P; Hari, Riitta; Sams, Mikko; Nummenmaa, Lauri

    2016-08-01

    The reinforcement-sensitivity theory proposes that behavioural activation and inhibition systems (BAS and BIS, respectively) guide approach and avoidance behaviour in potentially rewarding and punishing situations. Their baseline activity presumably explains individual differences in behavioural dispositions when a person encounters signals of reward and harm. Yet, neurochemical bases of BAS and BIS have remained poorly understood. Here we used in vivo positron emission tomography with a µ-opioid receptor (MOR) specific ligand [(11)C]carfentanil to test whether individual differences in MOR availability would be associated with BAS or BIS. We scanned 49 healthy subjects and measured their BAS and BIS sensitivities using the BIS/BAS scales. BAS but not BIS sensitivity was positively associated with MOR availability in frontal cortex, amygdala, ventral striatum, brainstem, cingulate cortex and insula. Strongest associations were observed for the BAS subscale 'Fun Seeking'. Our results suggest that endogenous opioid system underlies BAS, and that differences in MOR availability could explain inter-individual differences in reward seeking behaviour. PMID:27053768

  1. Acute and chronic fentanyl administration causes hyperalgesia independently of opioid receptor activity in mice.

    PubMed

    Waxman, Amanda R; Arout, Caroline; Caldwell, Megan; Dahan, Albert; Kest, Benjamin

    2009-10-01

    Although mu-receptor opioids are clinically important analgesics, they can also paradoxically cause hyperalgesia independently of opioid receptor activity, presumably via the action of neuroexcitatory glucoronide metabolites. However, it is unknown whether the commonly used mu-receptor opioid analgesic fentanyl, which is not subject to glucuronidation, can also induce hyperalgesia independently of opioid receptor activity. Thus, here we examined whether fentanyl increases nociception on the tail-withdrawal test in CD-1 mice concurrently treated with the opioid receptor antagonist naltrexone or in opioid receptor triple knock-out mice lacking mu, delta, and kappa opioid receptors. For both groups, an acute fentanyl bolus dose (0.25mg/kg, s.c.) and continuous fentanyl infusion (cumulative daily dose: 10mg/kg) did not cause analgesia at any time. Instead, fentanyl significantly decreased withdrawal latencies relative to pre-drug values for the next 15-60 min and for six days, respectively. MK-801 blocked and reversed hyperalgesia caused by the acute injection and continuous infusion of fentanyl, respectively, in naltrexone-treated CD-1 mice, indicating the contribution of NMDA receptors to fentanyl hyperalgesia. These data show that the synthetic opioid fentanyl causes hyperalgesia independently of prior or concurrent opioid receptor activity or analgesia. Since the biotransformation of fentanyl does not yield any known pronociceptive metabolites, these data challenge assumptions regarding the role of neuroexcitatory metabolites in opioid-induced hyperalgesia. PMID:19559072

  2. Kappa opioid receptor activation alleviates experimental autoimmune encephalomyelitis and promotes oligodendrocyte-mediated remyelination

    PubMed Central

    Du, Changsheng; Duan, Yanhui; Wei, Wei; Cai, Yingying; Chai, Hui; Lv, Jie; Du, Xiling; Zhu, Jian; Xie, Xin

    2016-01-01

    Multiple sclerosis (MS) is characterized by autoimmune damage to the central nervous system. All the current drugs for MS target the immune system. Although effective in reducing new lesions, they have limited effects in preventing the progression of disability. Promoting oligodendrocyte-mediated remyelination and recovery of neurons are the new directions of MS therapy. The endogenous opioid system, consisting of MOR, DOR, KOR and their ligands, has been suggested to participate in the pathogenesis of MS. However, the exact receptor and mechanism remain elusive. Here we show that genetic deletion of KOR exacerbates experimental autoimmune encephalomyelitis, whereas activating KOR with agonists alleviates the symptoms. KOR does not affect immune cell differentiation and function. Instead, it promotes oligodendrocyte differentiation and myelination both in vitro and in vivo. Our study suggests that targeting KOR might be an intriguing way to develop new MS therapies that may complement the existing immunosuppressive approaches. PMID:27040771

  3. Kappa opioid receptor activation alleviates experimental autoimmune encephalomyelitis and promotes oligodendrocyte-mediated remyelination.

    PubMed

    Du, Changsheng; Duan, Yanhui; Wei, Wei; Cai, Yingying; Chai, Hui; Lv, Jie; Du, Xiling; Zhu, Jian; Xie, Xin

    2016-01-01

    Multiple sclerosis (MS) is characterized by autoimmune damage to the central nervous system. All the current drugs for MS target the immune system. Although effective in reducing new lesions, they have limited effects in preventing the progression of disability. Promoting oligodendrocyte-mediated remyelination and recovery of neurons are the new directions of MS therapy. The endogenous opioid system, consisting of MOR, DOR, KOR and their ligands, has been suggested to participate in the pathogenesis of MS. However, the exact receptor and mechanism remain elusive. Here we show that genetic deletion of KOR exacerbates experimental autoimmune encephalomyelitis, whereas activating KOR with agonists alleviates the symptoms. KOR does not affect immune cell differentiation and function. Instead, it promotes oligodendrocyte differentiation and myelination both in vitro and in vivo. Our study suggests that targeting KOR might be an intriguing way to develop new MS therapies that may complement the existing immunosuppressive approaches. PMID:27040771

  4. Endogenous opiates and behavior: 2012.

    PubMed

    Bodnar, Richard J

    2013-12-01

    This paper is the thirty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2012 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:24126281

  5. Endogenous opiates and behavior: 2009.

    PubMed

    Bodnar, Richard J

    2010-12-01

    This paper is the 32nd consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2009 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:20875476

  6. Endogenous opiates and behavior: 2005.

    PubMed

    Bodnar, Richard J; Klein, Gad E

    2006-12-01

    This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17). PMID:16973239

  7. Endogenous opiates and behavior: 2008.

    PubMed

    Bodnar, Richard J

    2009-12-01

    This paper is the 31st consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2008 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:19793543

  8. Endogenous opiates and behavior: 2010.

    PubMed

    Bodnar, Richard J

    2011-12-01

    This paper is the thirty-third consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2010 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17). PMID:21983105

  9. Endogenous opiates and behavior: 2006.

    PubMed

    Bodnar, Richard J

    2007-12-01

    This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:17949854

  10. Endogenous opiates and behavior: 2011.

    PubMed

    Bodnar, Richard J

    2012-12-01

    This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17). PMID:23041439

  11. Endogenous opiates and behavior: 2002.

    PubMed

    Bodnar, Richard J; Hadjimarkou, Maria M

    2003-08-01

    This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:14612197

  12. Endogenous opiates and behavior: 2003.

    PubMed

    Bodnar, Richard J; Klein, Gad E

    2004-12-01

    This paper is the 26th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2003 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:15572211

  13. Endogenous Opiates and Behavior: 2006

    PubMed Central

    Bodnar, Richard J.

    2009-01-01

    This paper is the twenty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning thirty years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:17949854

  14. The effects of ibudilast, a glial activation inhibitor, on opioid withdrawal symptoms in opioid-dependent volunteers.

    PubMed

    Cooper, Ziva D; Johnson, Kirk W; Pavlicova, Martina; Glass, Andrew; Vosburg, Suzanne K; Sullivan, Maria A; Manubay, Jeanne M; Martinez, Diana M; Jones, Jermaine D; Saccone, Phillip A; Comer, Sandra D

    2016-07-01

    Glial activation is hypothesized to contribute directly to opioid withdrawal. This study investigated the dose-dependent effects of a glial cell modulator, ibudilast, on withdrawal symptoms in opioid-dependent volunteers after abrupt discontinuation of morphine administration. Non-treatment-seeking heroin-dependent volunteers (n = 31) completed the in-patient, double-blind, placebo-controlled, within-subject and between-group study. Volunteers were maintained on morphine (30 mg, QID) for 14 days and placebo (0 mg, QID) for the last 7 days of the 3-week study. Volunteers also received placebo (0 mg, PO, BID) capsules on days 1-7. On days 8-21, volunteers were randomized to receive ibudilast (20 or 40 mg, PO, BID) or placebo capsules. Subjective and clinical ratings of withdrawal symptoms were completed daily using daily using the Subjective Opioid Withdrawal Scale (SOWS) and Clinical Opioid Withdrawal Scale (COWS). Medication side effects were also monitored. Relative to the first 2 weeks, all groups exhibited withdrawal during the third week as assessed by the SOWS and COWS (P ≤ 0.0001). Although overall SOWS scores did not differ between groups, exploratory analyses pooling the two ibudilast groups demonstrated that they had lower ratings of withdrawal symptoms on SOWS items ('anxious,' 'perspiring,' 'restless,' 'stomach cramps') during detoxification relative to the placebo group. Ibudilast was well tolerated; no serious adverse events occurred during the study. Pharmacological modulation of glial activity with ibudilast decreased some subjective ratings of opioid withdrawal symptoms. These exploratory findings are the first to demonstrate the potential clinical utility of glial modulators for treating opioid withdrawal in humans. PMID:25975386

  15. PPARγ Activation Attenuates Opioid Consumption and Modulates Mesolimbic Dopamine Transmission

    PubMed Central

    de Guglielmo, Giordano; Melis, Miriam; De Luca, Maria Antonietta; Kallupi, Marsida; Li, Hong Wu; Niswender, Kevin; Giordano, Antonio; Senzacqua, Martina; Somaini, Lorenzo; Cippitelli, Andrea; Gaitanaris, George; Demopulos, Gregory; Damadzic, Ruslan; Tapocik, Jenica; Heilig, Markus; Ciccocioppo, Roberto

    2015-01-01

    PPARγ is one of the three isoforms identified for the peroxisome proliferator-activated receptors (PPARs) and is the receptor for the thiazolidinedione class of anti-diabetic medications including pioglitazone. PPARγ has been long studied for its role in adipogenesis and glucose metabolism, but the discovery of the localization in ventral tegmental area (VTA) neurons opens new vistas for a potential role in the regulation of reward processing and motivated behavior in drug addiction. Here, we demonstrate that activation of PPARγ by pioglitazone reduces the motivation for heroin and attenuates its rewarding properties. These effects are associated with a marked reduction of heroin-induced increase in phosphorylation of DARPP-32 protein in the nucleus accumbens (NAc) and with a marked and selective reduction of acute heroin-induced elevation of extracellular dopamine (DA) levels in the NAc shell, as measured by in vivo microdialysis. Through ex vivo electrophysiology in acute midbrain slices, we also show that stimulation of PPARγ attenuates opioid-induced excitation of VTA DA neurons via reduction of presynaptic GABA release from the rostromedial tegmental nucleus (RMTg). Consistent with this finding, site-specific microinjection of pioglitazone into the RMTg but not into the VTA reduced heroin taking. Our data illustrate that activation of PPARγ may represent a new pharmacotherapeutic option for the treatment of opioid addiction. PMID:25311134

  16. Mu-opioid receptor activation in the medial shell of nucleus accumbens promotes alcohol consumption, self-administration and cue-induced reinstatement.

    PubMed

    Richard, Jocelyn M; Fields, Howard L

    2016-09-01

    Endogenous opioid signaling in ventral cortico-striatal-pallidal circuitry is implicated in elevated alcohol consumption and relapse to alcohol seeking. Mu-opioid receptor activation in the medial shell of the nucleus accumbens (NAc), a region implicated in multiple aspects of reward processing, elevates alcohol consumption while NAc opioid antagonists reduce it. However, the precise nature of the increases in alcohol consumption, and the effects of mu-opioid agonists on alcohol seeking and relapse are not clear. Here, we tested the effects of the mu-opioid agonist [D-Ala(2), N-MePhe(4), Gly-ol]-enkephalin (DAMGO) in rat NAc shell on lick microstructure in a free-drinking test, alcohol seeking during operant self-administration, extinction learning and expression, and cue-reinforced reinstatement of alcohol seeking. DAMGO enhanced the number, but not the size of drinking bouts. DAMGO also enhanced operant alcohol self-administration and cue-induced reinstatement, but did not affect extinction learning or elicit reinstatement in the absence of cues. Our results suggest that mu-opioid agonism in NAc shell elevates alcohol consumption, seeking and conditioned reinforcement primarily by enhancing the incentive motivational properties of alcohol and alcohol-paired cues, rather than by modulating palatability, satiety, or reinforcement. PMID:27089981

  17. Opioid receptors in the gastrointestinal tract

    PubMed Central

    Holzer, Peter

    2011-01-01

    Opium is arguably one of the oldest herbal medicines, being used as analgesic, sedative and antidiarrheal drug for thousands of years. These effects mirror the actions of the endogenous opioid system and are mediated by the principal μ-, κ- and δ-opioid receptors. In the gut, met-enkephalin, leu-enkephalin, β-endorphin and dynorphin occur in both neurons and endocrine cells. When released, opioid peptides activate opioid receptors on the enteric circuitry controlling motility and secretion. As a result, inhibition of gastric emptying, increase in sphincter tone, induction of stationary motor patterns and blockade of peristalsis ensue. Together with inhibition of ion and fluid secretion, these effects cause constipation, one of the most frequent and troublesome adverse reactions of opioid analgesic therapy. Although laxatives are most frequently used to ameliorate opioid-induced bowel dysfunction, their efficacy is unsatisfactory. Specific antagonism of peripheral opioid receptors is a more rational approach. This goal is addressed by the use of opioid receptor antagonists with limited absorption such as oral prolonged-release naloxone and opioid receptor antagonists that do not penetrate the blood-brain barrier such as methylnaltrexone and alvimopan. Preliminary evidence indicates that peripherally restricted opioid receptor antagonists may act as prokinetic drugs in their own right. PMID:19345246

  18. Characterization of opioid peptides and opioid receptors in the brain of jerboa (Jaculus orientalis), a hibernating rodent.

    PubMed

    Bourhim, N; Kabine, M; Elkebbaj, M S

    1997-01-01

    The present study was undertaken to investigate the biochemical characteristics of the opioid receptors and opioid peptides in the jerboa (Jaculus orientalis) brain, a subdesert rodent of Morocco. We have demonstrated the presence of delta, mu, and kappa sites in the jerboa brain. The endogenous opioid peptides methionine-enkephalin, beta-endorphin, and dynorphin were evaluated in different physiological states of the animal (active and hibernating). The circulating methionine-enkephalin in different states of the animal (active, hibernating, exposure to cold conditions, and fasting) was evaluated in the plasma. Our results indicate that the hibernating state the opioid receptors level decreased, whereas the concentration of opioid peptides increased. These findings suggest that both opioid receptors and opioid peptides could be involved in the adaptation of the jerboa to survive under thermal stress. PMID:9365806

  19. Stimulatory effects of opioid neuropeptides on locomotory activity and conformational changes in invertebrate and human immunocytes: evidence for a subtype of delta receptor.

    PubMed

    Stefano, G B; Cadet, P; Scharrer, B

    1989-08-01

    The presence of opioid neuropeptides was shown to stimulate conformational changes and locomotory activity in immunocytes of two representatives of invertebrates as well as in human leukocytes. Cells were examined by use of phase-contrast and Nomarski optics coupled with a Zeiss Axiophot microscope, and of the Zeiss Videoplan/Vidas Image Analysis system. Immunocompetent blood cells, activated by exogenous opioids or stressful stimuli presumed to engage endogenous opioids, showed flattening, elongation, and formation of pseudopodia. In the mollusc Mytilus edulis, ameboid movements resulted in the formation of cell clusters, an activity not observed in untreated controls, or in immunocytes simultaneously exposed to opioid and naloxone. Tests with nine immunoreactive substances revealed immunocyte stimulation by delta, mu-, kappa-, and epsilon(?)-selective ligands. One of these, [D-Ala2,D-Met5]enkephalinamide (DAMA), active at a concentration of 10 pM, proved to be considerably more effective than the rest. The high pharmacological potency of DAMA, observed in both human and invertebrate immunocytes, sets this opioid apart from the closely related [D-Ala2,D-Leu5]enkephalin, a discrepancy not occurring in the mammalian nervous system. This suggests a specific function for [Met]enkephalin in immunoregulation, mediated perhaps by a special subtype of delta receptor. PMID:2548205

  20. Imaging endogenous opioid peptide release with [11C]carfentanil and [3H]diprenorphine: influence of agonist-induced internalization

    PubMed Central

    Quelch, Darren R; Katsouri, Loukia; Nutt, David J; Parker, Christine A; Tyacke, Robin J

    2014-01-01

    Understanding the cellular processes underpinning the changes in binding observed during positron emission tomography neurotransmitter release studies may aid translation of these methodologies to other neurotransmitter systems. We compared the sensitivities of opioid receptor radioligands, carfentanil, and diprenorphine, to amphetamine-induced endogenous opioid peptide (EOP) release and methadone administration in the rat. We also investigated whether agonist-induced internalization was involved in reductions in observed binding using subcellular fractionation and confocal microscopy. After radioligand administration, significant reductions in [11C]carfentanil, but not [3H]diprenorphine, uptake were observed after methadone and amphetamine pretreatment. Subcellular fractionation and in vitro radioligand binding studies showed that amphetamine pretreatment only decreased total [11C]carfentanil binding. In vitro saturation binding studies conducted in buffers representative of the internalization pathway suggested that μ-receptors are significantly less able to bind the radioligands in endosomal compared with extracellular compartments. Finally, a significant increase in μ-receptor-early endosome co-localization in the hypothalamus was observed after amphetamine and methadone treatment using double-labeling confocal microscopy, with no changes in δ- or κ-receptor co-localization. These data indicate carfentanil may be superior to diprenorphine when imaging EOP release in vivo, and that alterations in the ability to bind internalized receptors may be a predictor of ligand sensitivity to endogenous neurotransmitter release. PMID:25005876

  1. Endogenous Methanol Regulates Mammalian Gene Activity

    PubMed Central

    Komarova, Tatiana V.; Petrunia, Igor V.; Shindyapina, Anastasia V.; Silachev, Denis N.; Sheshukova, Ekaterina V.; Kiryanov, Gleb I.; Dorokhov, Yuri L.

    2014-01-01

    We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH) converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP) and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis. PMID:24587296

  2. Expression and Localization of Opioid Receptors in Male Germ Cells and the Implication for Mouse Spermatogenesis

    PubMed Central

    Gianzo, Marta; Urizar-Arenaza, Itziar; Casis, Luis; Irazusta, Jon; Subirán, Nerea

    2016-01-01

    The presence of endogenous opioid peptides in different testicular cell types has been extensively characterized and provides evidence for the participation of the opioid system in the regulation of testicular function. However, the exact role of the opioid system during the spermatogenesis has remained controversial since the presence of the mu-, delta- and kappa-opioid receptors in spermatogenic cells was yet to be demonstrated. Through a combination of quantitative real-time PCR, immunofluorescence, immunohistochemistry and flow cytometry approaches, we report for the first time the presence of active mu-, delta- and kappa-opioid receptors in mouse male germ cells. They show an exposition time-dependent response to opioid agonist, hence suggesting their active involvement in spermatogenesis. Our results contribute to understanding the role of the opioid receptors in the spermatogenesis and could help to develop new strategies to employ the opioid system as a biochemical tool for the diagnosis and treatment of male infertility. PMID:27031701

  3. Quantitative conformationally sampled pharmacophore for delta opioid ligands: reevaluation of hydrophobic moieties essential for biological activity.

    PubMed

    Bernard, Denzil; Coop, Andrew; MacKerell, Alexander D

    2007-04-19

    Recent studies have indicated several therapeutic applications for delta opioid agonists and antagonists. To exploit the therapeutic potential of delta opioids developing a structural basis for the activity of ligands at the delta opioid receptor is essential. The conformationally sampled pharmacophore (CSP) method (Bernard et al. J. Am. Chem. Soc. 2003, 125, 3103-3107) is extended here to obtain quantitative models of delta opioid ligand efficacy and affinity. Quantification is performed via overlap integrals of the conformational space sampled by ligands with respect to a reference compound. Iterative refinement of the CSP model identified hydrophobic groups other than the traditional phenylalanine residues as important for efficacy and affinity in DSLET and ICI 174 864. The obtained models for a structurally diverse set of peptidic and nonpeptidic delta opioid ligands offer good predictions with R2 values>0.9, and the predicted efficacy for a set of test compounds was consistent with the experimental values. PMID:17367120

  4. Endogenous adenosine A3 receptor activation selectively alleviates persistent pain states

    PubMed Central

    Little, Joshua W.; Ford, Amanda; Symons-Liguori, Ashley M.; Chen, Zhoumou; Janes, Kali; Doyle, Timothy; Xie, Jennifer; Luongo, Livio; Tosh, Dillip K.; Maione, Sabatino; Bannister, Kirsty; Dickenson, Anthony H.; Vanderah, Todd W.; Porreca, Frank; Jacobson, Kenneth A.

    2015-01-01

    Chronic pain is a global burden that promotes disability and unnecessary suffering. To date, efficacious treatment of chronic pain has not been achieved. Thus, new therapeutic targets are needed. Here, we demonstrate that increasing endogenous adenosine levels through selective adenosine kinase inhibition produces powerful analgesic effects in rodent models of experimental neuropathic pain through the A3 adenosine receptor (A3AR, now known as ADORA3) signalling pathway. Similar results were obtained by the administration of a novel and highly selective A3AR agonist. These effects were prevented by blockade of spinal and supraspinal A3AR, lost in A3AR knock-out mice, and independent of opioid and endocannabinoid mechanisms. A3AR activation also relieved non-evoked spontaneous pain behaviours without promoting analgesic tolerance or inherent reward. Further examination revealed that A3AR activation reduced spinal cord pain processing by decreasing the excitability of spinal wide dynamic range neurons and producing supraspinal inhibition of spinal nociception through activation of serotonergic and noradrenergic bulbospinal circuits. Critically, engaging the A3AR mechanism did not alter nociceptive thresholds in non-neuropathy animals and therefore produced selective alleviation of persistent neuropathic pain states. These studies reveal A3AR activation by adenosine as an endogenous anti-nociceptive pathway and support the development of A3AR agonists as novel therapeutics to treat chronic pain. PMID:25414036

  5. Characterization of kappa opioid receptor mediated, dynorphin-stimulated [35S]GTPγS binding in mouse striatum for the evaluation of selective KOR ligands in an endogenous setting.

    PubMed

    Zhou, Lei; Stahl, Edward L; Lovell, Kimberly M; Frankowski, Kevin J; Prisinzano, Thomas E; Aubé, Jeffrey; Bohn, Laura M

    2015-12-01

    Differential modulation of kappa opioid receptor (KOR) signaling has been a proposed strategy for developing therapies for drug addiction and depression by either activating or blocking this receptor. Hence, there have been significant efforts to generate ligands with diverse pharmacological properties including partial agonists, antagonists, allosteric modulators as well as ligands that selectively activate some pathways while not engaging others (biased agonists). It is becoming increasingly evident that G protein coupled receptor signaling events are context dependent and that what may occur in cell based assays may not be fully indicative of signaling events that occur in the naturally occurring environment. As new ligands are developed, it is important to assess their signaling capacity in relevant endogenous systems in comparison to the performance of endogenous agonists. Since KOR is considered the cognate receptor for dynorphin peptides we have evaluated the selectivity profiles of dynorphin peptides in wild-type (WT), KOR knockout (KOR-KO), and mu opioid receptor knockout (MOR-KO) mice using [35S]GTPγS binding assay in striatal membrane preparations. We find that while the small molecule KOR agonist U69,593, is very selective for KOR, dynorphin peptides promiscuously stimulate G protein signaling in striatum. Furthermore, our studies demonstrate that norBNI and 5'GNTI are highly nonselective antagonists as they maintain full potency and efficacy against dynorphin signaling in the absence of KOR. Characterization of a new KOR antagonist, which may be more selective than NorBNI and 5'GNTI, is presented using this approach. PMID:26160155

  6. Opioid activity in behavioral and heart rate responses of tethered pigs to acute stress.

    PubMed

    Loijens, L W S; Janssens, C J J G; Schouten, W G P; Wiegant, V M

    2002-04-15

    In a longitudinal experiment, effects of long-term tether housing on heart rate and behavioral responses to an acute stressor (a 15-min challenge with a nosesling) were investigated in pigs. The animals were challenged during loose housing and again after 10-11 weeks of tether housing. To detect possible changes in endogenous opioid systems modifying these responses, the pigs were pretreated with the opioid receptor antagonist naloxone (0.5 mg/kg body weight, iv). In response to the nosesling challenge, the animals showed pronounced resistance behavior and a sharp rise in heart rate. Following this initial phase of resistance, the heart rate dropped to prechallenge levels or below this line, and the pigs seemed to become sedated. Pretreatment with naloxone increased the heart rate response in animals that were long-term tether housed (n=12). No such effect was found in the control group (n=5) that was loose-housed during the entire experiment, indicating that the impact of endogenous opioid systems mitigating heart rate responses to acute stress had increased as a result of long-term tether housing. Changes in the effect of naloxone on the behavioral response were not found. Adaptive changes in opioid systems may prevent excessive physiological reactions to acute stress and, thus, may serve as a coping mechanism. PMID:12020727

  7. Structural insights into μ-opioid receptor activation

    PubMed Central

    Huang, Weijiao; Manglik, Aashish; Venkatakrishnan, A. J.; Laeremans, Toon; Feinberg, Evan N.; Sanborn, Adrian L.; Kato, Hideaki E.; Livingston, Kathryn E.; Thorsen, Thor S.; Kling, Ralf; Granier, Sébastien; Gmeiner, Peter; Husbands, Stephen M.; Traynor, John R.; Weis, William I.; Steyaert, Jan; Dror, Ron O.; Kobilka, Brian K.

    2015-01-01

    Summary Activation of the μ-opioid receptor (μOR) is responsible for the efficacy of the most effective analgesics. To understand the structural basis for μOR activation, we obtained a 2.1 Å X-ray crystal structure of the μOR bound to the morphinan agonist BU72 and stabilized by a G protein-mimetic camelid-antibody fragment. The BU72-stabilized changes in the μOR binding pocket are subtle and differ from those observed for agonist-bound structures of the β2 adrenergic receptor (β2AR) and the M2 muscarinic receptor (M2R). Comparison with active β2AR reveals a common rearrangement in the packing of three conserved amino acids in the core of the μOR, and molecular dynamics simulations illustrate how the ligand-binding pocket is conformationally linked to this conserved triad. Additionally, an extensive polar network between the ligand-binding pocket and the cytoplasmic domains appears to play a similar role in signal propagation for all three GPCRs. PMID:26245379

  8. Maturational alterations in constitutive activity of medial prefrontal cortex kappa-opioid receptors in Wistar rats.

    PubMed

    Sirohi, Sunil; Walker, Brendan M

    2015-11-01

    Opioid receptors can display spontaneous agonist-independent G-protein signaling (basal signaling/constitutive activity). While constitutive κ-opioid receptor (KOR) activity has been documented in vitro, it remains unknown if KORs are constitutively active in native systems. Using [(35) S] guanosine 5'-O-[gamma-thio] triphosphate coupling assay that measures receptor functional state, we identified the presence of medial prefrontal cortex KOR constitutive activity in young rats that declined with age. Furthermore, basal signaling showed an age-related decline and was insensitive to neutral opioid antagonist challenge. Collectively, the present data are first to demonstrate age-dependent alterations in the medial prefrontal cortex KOR constitutive activity in rats and changes in the constitutive activity of KORs can differentially impact KOR ligand efficacy. These data provide novel insights into the functional properties of the KOR system and warrant further consideration of KOR constitutive activity in normal and pathophysiological behavior. Opioid receptors exhibit agonist-independent constitutive activity; however, kappa-opioid receptor (KOR) constitutive activity has not been demonstrated in native systems. Our results confirm KOR constitutive activity in the medial prefrontal cortex (mPFC) that declines with age. With the ability to presynaptically inhibit multiple neurotransmitter systems in the mPFC, maturational or patho-logical alterations in constitutive activity could disrupt corticofugal glutamatergic pyramidal projection neurons mediating executive function. Regulation of KOR constitutive activity could serve as a therapeutic target to treat compromised executive function. PMID:26257334

  9. Endogenous opioids contribute to insensitivity to pain in humans and mice lacking sodium channel Nav1.7.

    PubMed

    Minett, Michael S; Pereira, Vanessa; Sikandar, Shafaq; Matsuyama, Ayako; Lolignier, Stéphane; Kanellopoulos, Alexandros H; Mancini, Flavia; Iannetti, Gian D; Bogdanov, Yury D; Santana-Varela, Sonia; Millet, Queensta; Baskozos, Giorgios; MacAllister, Raymond; Cox, James J; Zhao, Jing; Wood, John N

    2015-01-01

    Loss-of-function mutations in the SCN9A gene encoding voltage-gated sodium channel Nav1.7 cause congenital insensitivity to pain in humans and mice. Surprisingly, many potent selective antagonists of Nav1.7 are weak analgesics. We investigated whether Nav1.7, as well as contributing to electrical signalling, may have additional functions. Here we report that Nav1.7 deletion has profound effects on gene expression, leading to an upregulation of enkephalin precursor Penk mRNA and met-enkephalin protein in sensory neurons. In contrast, Nav1.8-null mutant sensory neurons show no upregulated Penk mRNA expression. Application of the opioid antagonist naloxone potentiates noxious peripheral input into the spinal cord and dramatically reduces analgesia in both female and male Nav1.7-null mutant mice, as well as in a human Nav1.7-null mutant. These data suggest that Nav1.7 channel blockers alone may not replicate the analgesic phenotype of null mutant humans and mice, but may be potentiated with exogenous opioids. PMID:26634308

  10. Enhanced nocturnal melatonin secretion in women with functional secondary amenorrhea: relationship to opioid system and endogenous estrogen levels.

    PubMed

    Okatani, Y; Sagara, Y

    1995-01-01

    The purpose of this study was to evaluate the role of the opioid system and the estrogen environment in the nocturnal secretion of melatonin in women with secondary amenorrhea (SA). Nocturnal melatonin concentrations in patients with SA were significantly higher than in normal women (p < 0.01 vs. women with normal menstrual cycles). There were significant negative correlations between cumulative melatonin levels (between 8 p.m. and 8 a.m.) and serum estradiol-17 beta (r = -0.561, p < 0.01) and between peak serum melatonin values and serum estradiol-17 beta concentrations (r = -0.608, p < 0.01) in SA. Intravenous administration of a conjugated estrogen (Premarin 20 mg) significantly suppressed nocturnal melatonin secretion (p < 0.05), but a continuous intravenous infusion of naloxone (1.6 mg/h from 8 p.m. to 6 a.m.), an opiate antagonist, did not affect nocturnal melatonin secretion in SA. Our findings suggest that elevated nocturnal melatonin secretion may be related to low estrogen levels, but that it is not mediated by the opioid system. PMID:7782049

  11. Endogenous opioids contribute to insensitivity to pain in humans and mice lacking sodium channel Nav1.7

    PubMed Central

    Minett, Michael S.; Pereira, Vanessa; Sikandar, Shafaq; Matsuyama, Ayako; Lolignier, Stéphane; Kanellopoulos, Alexandros H.; Mancini, Flavia; Iannetti, Gian D.; Bogdanov, Yury D.; Santana-Varela, Sonia; Millet, Queensta; Baskozos, Giorgios; MacAllister, Raymond; Cox, James J.; Zhao, Jing; Wood, John N.

    2015-01-01

    Loss-of-function mutations in the SCN9A gene encoding voltage-gated sodium channel Nav1.7 cause congenital insensitivity to pain in humans and mice. Surprisingly, many potent selective antagonists of Nav1.7 are weak analgesics. We investigated whether Nav1.7, as well as contributing to electrical signalling, may have additional functions. Here we report that Nav1.7 deletion has profound effects on gene expression, leading to an upregulation of enkephalin precursor Penk mRNA and met-enkephalin protein in sensory neurons. In contrast, Nav1.8-null mutant sensory neurons show no upregulated Penk mRNA expression. Application of the opioid antagonist naloxone potentiates noxious peripheral input into the spinal cord and dramatically reduces analgesia in both female and male Nav1.7-null mutant mice, as well as in a human Nav1.7-null mutant. These data suggest that Nav1.7 channel blockers alone may not replicate the analgesic phenotype of null mutant humans and mice, but may be potentiated with exogenous opioids. PMID:26634308

  12. Mu-opioids activate phospholipase C in SH-SY5Y human neuroblastoma cells via calcium-channel opening.

    PubMed

    Smart, D; Smith, G; Lambert, D G

    1995-01-15

    We have recently reported that, in SH-SY5Y cells, mu-opioid receptor occupancy activates phospholipase C via a pertussis toxin-sensitive G-protein. In the present study we have further characterized the mechanisms involved in this process. Fentanyl (0.1 microM) caused a monophasic increase in inositol 1,4,5-trisphosphate mass formation, with a peak (20.5 +/- 3.6 pmol/mg of protein) at 15 s. Incubation in Ca(2+)-free buffer abolished this response, while Ca2+ replacement 1 min later restored the stimulation of inositol 1,4,5-trisphosphate formation (20.1 +/- 0.6 pmol/mg of protein). In addition, nifedipine (1 nM-0.1 mM), an L-type Ca(2+)-channel antagonist, caused a dose-dependent inhibition of inositol 1,4,5-trisphosphate formation, with an IC50 of 60.3 +/- 1.1 nM. Elevation of endogenous beta/gamma subunits by selective activation of delta-opioid and alpha 2 adrenoceptors failed to stimulate phospholipase C. Fentanyl also caused a dose-dependent (EC50 of 16.2 +/- 1.0 nM), additive enhancement of carbachol-induced inositol 1,4,5-trisphosphate formation. In summary, we have demonstrated that in SH-SY5Y cells activation of the mu-opioid receptor allows Ca2+ influx to activate phospholipase C. However, the possible role of this mechanism in the process of analgesia remains to be elucidated. PMID:7832776

  13. Opioid peptides mediate the suppressive effect of stress on natural killer cell cytotoxicity.

    PubMed

    Shavit, Y; Lewis, J W; Terman, G W; Gale, R P; Liebeskind, J C

    1984-01-13

    The cytotoxic activity of natural killer cells was investigated in rats subjected to one of two inescapable footshock stress paradigms, both of which induce analgesia, but only one via activation of opioid mechanisms. Splenic natural killer cell activity was suppressed by the opioid, but not the nonopioid, form of stress. This suppression was blocked by the opioid antagonist naltrexone. Similar suppression of natural killer activity was induced by high doses of morphine. These results suggest that endogenous opioid peptides mediate the suppressive effect of certain forms of stress on natural killer cell cytotoxicity. PMID:6691146

  14. [Dmt1]DALDA analogues with enhanced μ opioid agonist potency and with a mixed μ/κ opioid activity profile

    PubMed Central

    Bai, Longxiang; Li, Ziyuan; Chen, Jiajia; Chung, Nga N.; Wilkes, Brian C.; Li, Tingyou; Schiller, Peter W.

    2014-01-01

    Analogues of [Dmt1]DALDA (H-Dmt-D-Arg-Phe-Lys-NH2; Dmt = 2′,6′-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity, were prepared by replacing Phe3 with various 2′,6′-dialkylated Phe analogues, including 2′,6′-dimethylphenylalanine (Dmp), 2′4′,6′-trimethylphenylalanine (Tmp), 2′-isopropyl-6′-methylphenylalanine (Imp) and 2′-ethyl-6′-methylphenylalanine (Emp), or with the bulky amino acids 3′-(1-naphthyl)alanine (1-Nal), 3′-(2-naphthyl)alanine (2-Nal) or Trp. Several compounds showed significantly increased μ agonist potency, retained μ receptor selectivity and are of interest as drug candidates for neuropathic pain treatment. Surprisingly, the Dmp3-, Imp3-, Emp3- and 1-Nal3-containing analogues showed much increased κ receptor binding affinity and had mixed μ/κ properties. In these cases, molecular dynamics studies indicated conformational preorganization of the unbound peptide ligands due to rotational restriction around the Cβ-Cγ bond of the Xxx3 residue, in correlation with the observed κ receptor binding enhancement. Compounds with a mixed μ/κ opioid activity profile are known to have therapeutic potential for treatment of cocaine abuse. PMID:24602401

  15. Sustained Suppression of Hyperalgesia during Latent Sensitization by μ-, δ-, and κ-opioid receptors and α2A Adrenergic Receptors: Role of Constitutive Activity

    PubMed Central

    Walwyn, Wendy M.; Chen, Wenling; Kim, Hyeyoung; Minasyan, Ani; Ennes, Helena S.; McRoberts, James A.

    2016-01-01

    sensitization is a phenomenon studied in rodents that has many key features of chronic pain: it is initiated by a variety of noxious stimuli, has indefinite duration, and pain appears in episodes that can be triggered by stress. Here, we show that, during latent sensitization, there is a sustained state of pain hypersensitivity that is continuously suppressed by the activation of μ-, δ-, and κ-opioid receptors and by adrenergic α2A receptors in the spinal cord. Furthermore, we show that the activation of μ-opioid receptors is not due to the release of endogenous opioids, but rather to its ligand-independent constitutive activity. PMID:26740662

  16. Effects of opioid peptides on thermoregulation

    SciTech Connect

    Clark, W.G.

    1981-11-01

    In a given species, injected opioid peptides usually cause changes in temperature similar to those caused by nonpeptide opioids. The main effect in those species most studied, the cat, rat, and mouse, is an increase in the level about which body temperature is regulated; there is a coordinated change in the activity of thermoregulatory effectors such that hyperthermia is produced in both hot and cold environments. Larger doses may depress thermoregulation, thereby causing body temperature to decrease in the cold. Elicitation of different patterns of response over a range of environmental temperatures and studies with naloxone and naltrexone indicate that stimulation of a number of different receptors by both peptide and nonpeptide opioids can evoke thermoregulatory responses. ..beta..-Endorphin is readily antagonized by naloxone whereas methionine-enkephalin can act on naloxone-insensitive receptors. Moreover, synthetic peptide analogs do not necessarily evoke the same response as does the related endogenous peptide. The lack of effect of naloxone on body temperature of subjects housed at usual laboratory temperature or on pyrogen-induced increases in body temperature indicates that an action of endogenous peptides on naloxone-sensitive receptors plays little, if any, role in normal thermoregulation or in fever. However, there is some evidence that such an action may be involved in responses to restraint or ambient temperature-induced stress. Further evaluation of possible physiological roles of endogenous opioid peptides will be facilitated when specific antagonists at other types of opioid receptors become available.

  17. Shadows across mu-Star? Constitutively active mu-opioid receptors revisited.

    PubMed

    Connor, Mark

    2009-04-01

    Constitutively active mu-opioid receptors (mu* receptors) are reported to be formed following prolonged agonist treatment of cells or whole animals. mu* receptors signal in the absence of activating ligand and a blockade of mu* activation of G-proteins by naloxone and naltrexone has been suggested to underlie the profound withdrawal syndrome precipitated by these antagonists in vivo. In this issue of the Journal, Divin et al. examined whether treatment of C6 glioma cells with mu-opioid receptor agonists produced constitutively active mu-opioid receptors or other commonly reported adaptations to prolonged agonist treatment. Adenylyl cyclase superactivation was readily apparent following agonist treatment but there was no evidence of the formation of constitutively active mu-opioid receptors. This result challenges the notion that prolonged agonist exposure inevitably produces mu* receptors, and is consistent with many studies of adaptations in neurons produced by chronic agonist treatment. The investigators provide no explanation of their failure to see mu* receptors in C6 cells, but this is perhaps understandable because the molecular nature of mu* receptors remains elusive, and the precise mechanisms that lead to their formation are unknown. Without knowing exactly what mu* receptors are, how they are formed and how they signal, understanding their role in cellular adaptations to prolonged opioid treatment will remain impossible. Studies such as this should refocus attention on establishing the molecular mechanisms that underlie that phenomenon of mu* receptors. PMID:19368530

  18. Opioid treatment of experimental pain activates nuclear factor-κB

    PubMed Central

    Compton, Peggy; Griffis, Charles; Breen, Elizabeth Crabb; Torrington, Matthew; Sadakane, Ryan; Tefera, Eshetu; Irwin, Michael R.

    2015-01-01

    Objective To determine the independent and combined effects of pain and opioids on the activation of an early marker of inflammation, nuclear factor-κB (NF-κB). Design NF-κB activation was compared within-subjects following four randomly ordered experimental sessions of opioid-only (intravenous fentanyl 1 μg/kg), pain-only (cold-pressor), opioid + pain, and a resting condition. Setting University General Clinical Research Center. Participants Twenty-one (11 female) healthy controls. Interventions Following exposure to treatment (fentanyl administration and/or cold-pressor pain), blood samples for NF-kB analysis were obtained. Main outcome measures Intracellular levels of activated NF-κB, in unstimulated and stimulated peripheral blood mononuclear cells at 15 and 30 minutes. Results Neither pain nor opioid administration alone effected NF-κB levels in cell populations; however, the combination of treatments induced significant increases of NF-κB in stimulated peripheral blood mononuclear cell, lymphocytes, and monocytes. Conclusions The combination of acute pain with opioids, as occurs in clinical situations, activates a key transcription factor involved in proinflammatory responses. PMID:25901477

  19. Activation of endogenous neural stem cells for multiple sclerosis therapy.

    PubMed

    Michailidou, Iliana; de Vries, Helga E; Hol, Elly M; van Strien, Miriam E

    2014-01-01

    Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system, leading to severe neurological deficits. Current MS treatment regimens, consist of immunomodulatory agents aiming to reduce the rate of relapses. However, these agents are usually insufficient to treat chronic neurological disability. A promising perspective for future therapy of MS is the regeneration of lesions with replacement of the damaged oligodendrocytes or neurons. Therapies targeting to the enhancement of endogenous remyelination, aim to promote the activation of either the parenchymal oligodendrocyte progenitor cells or the subventricular zone-derived neural stem cells (NSCs). Less studied but highly potent, is the strategy of neuronal regeneration with endogenous NSCs that although being linked to numerous limitations, is anticipated to ameliorate cognitive disability in MS. Focusing on the forebrain, this review highlights the role of NSCs in the regeneration of MS lesions. PMID:25653584

  20. Activation of endogenous neural stem cells for multiple sclerosis therapy

    PubMed Central

    Michailidou, Iliana; de Vries, Helga E.; Hol, Elly M.; van Strien, Miriam E.

    2015-01-01

    Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system, leading to severe neurological deficits. Current MS treatment regimens, consist of immunomodulatory agents aiming to reduce the rate of relapses. However, these agents are usually insufficient to treat chronic neurological disability. A promising perspective for future therapy of MS is the regeneration of lesions with replacement of the damaged oligodendrocytes or neurons. Therapies targeting to the enhancement of endogenous remyelination, aim to promote the activation of either the parenchymal oligodendrocyte progenitor cells or the subventricular zone-derived neural stem cells (NSCs). Less studied but highly potent, is the strategy of neuronal regeneration with endogenous NSCs that although being linked to numerous limitations, is anticipated to ameliorate cognitive disability in MS. Focusing on the forebrain, this review highlights the role of NSCs in the regeneration of MS lesions. PMID:25653584

  1. Drawing a fine line on endogenous retroelement activity

    PubMed Central

    Castro-Diaz, Nathaly; Friedli, Marc; Trono, Didier

    2015-01-01

    Endogenous retroelements (EREs) are essential motors of evolution yet require careful control to prevent genomic catastrophes, notably during the vulnerable phases of epigenetic reprogramming that occur immediately after fertilization and in germ cells. Accordingly, a variety of mechanisms restrict these mobile genetic units. Previous studies have revealed the importance of KRAB-containing zinc finger proteins (KRAB-ZFPs) and their cofactor, KAP1, in the early embryonic silencing of endogenous retroviruses and so-called SVAs, but the implication of this transcriptional repression system in the control of LINE-1, the only known active autonomous retrotransposon in the human genome, was thought to be marginal. Two recent studies straighten the record by revealing that the KRAB/KAP system is key to the control of L1 in embryonic stem (ES) cells, and go further in demonstrating that DNA methylation and KRAB/KAP1-induced repression contribute to this process in an evolutionally dynamic fashion. These results shed light on the delicate equilibrium between higher vertebrates and endogenous retroelements, which are not just genetic invaders calling for strict control but rather a constantly renewed and nicely exploitable source of evolutionary potential. PMID:26442176

  2. Antinociceptive action of isolated mitragynine from Mitragyna Speciosa through activation of opioid receptor system.

    PubMed

    Shamima, Abdul Rahman; Fakurazi, Sharida; Hidayat, Mohamad Taufik; Hairuszah, Ithnin; Moklas, Mohamad Aris Mohd; Arulselvan, Palanisamy

    2012-01-01

    Cannabinoids and opioids systems share numerous pharmacological properties and antinociception is one of them. Previous findings have shown that mitragynine (MG), a major indole alkaloid found in Mitragyna speciosa (MS) can exert its antinociceptive effects through the opioids system. In the present study, the action of MG was investigated as the antinociceptive agent acting on Cannabinoid receptor type 1 (CB1) and effects on the opioids receptor. The latency time was recorded until the mice showed pain responses such as shaking, licking or jumping and the duration of latency was measured for 2 h at every 15 min interval by hot plate analysis. To investigate the beneficial effects of MG as antinociceptive agent, it was administered intraperitoneally 15 min prior to pain induction with a single dosage (3, 10, 15, 30, and 35 mg/kg b.wt). In this investigation, 35 mg/kg of MG showed significant increase in the latency time and this dosage was used in the antagonist receptor study. The treated groups were administered with AM251 (cannabinoid receptor-1 antagonist), naloxone (non-selective opioid antagonist), naltrindole (δ-opioid antagonist) naloxonazine (μ(1)-receptor antagonist) and norbinaltorpimine (κ-opioid antagonist) respectively, prior to administration of MG (35 mg/kg). The results showed that the antinociceptive effect of MG was not antagonized by AM251; naloxone and naltrindole were effectively blocked; and norbinaltorpimine partially blocked the antinociceptive effect of MG. Naloxonazine did inhibit the effect of MG, but it was not statistically significant. These results demonstrate that CB1 does not directly have a role in the antinociceptive action of MG where the effect was observed with the activation of opioid receptor. PMID:23109863

  3. Antinociceptive Action of Isolated Mitragynine from Mitragyna Speciosa through Activation of Opioid Receptor System

    PubMed Central

    Shamima, Abdul Rahman; Fakurazi, Sharida; Hidayat, Mohamad Taufik; Hairuszah, Ithnin; Moklas, Mohamad Aris Mohd; Arulselvan, Palanisamy

    2012-01-01

    Cannabinoids and opioids systems share numerous pharmacological properties and antinociception is one of them. Previous findings have shown that mitragynine (MG), a major indole alkaloid found in Mitragyna speciosa (MS) can exert its antinociceptive effects through the opioids system. In the present study, the action of MG was investigated as the antinociceptive agent acting on Cannabinoid receptor type 1 (CB1) and effects on the opioids receptor. The latency time was recorded until the mice showed pain responses such as shaking, licking or jumping and the duration of latency was measured for 2 h at every 15 min interval by hot plate analysis. To investigate the beneficial effects of MG as antinociceptive agent, it was administered intraperitoneally 15 min prior to pain induction with a single dosage (3, 10, 15, 30, and 35 mg/kg b.wt). In this investigation, 35 mg/kg of MG showed significant increase in the latency time and this dosage was used in the antagonist receptor study. The treated groups were administered with AM251 (cannabinoid receptor-1 antagonist), naloxone (non-selective opioid antagonist), naltrindole (δ-opioid antagonist) naloxonazine (μ1-receptor antagonist) and norbinaltorpimine (κ-opioid antagonist) respectively, prior to administration of MG (35 mg/kg). The results showed that the antinociceptive effect of MG was not antagonized by AM251; naloxone and naltrindole were effectively blocked; and norbinaltorpimine partially blocked the antinociceptive effect of MG. Naloxonazine did inhibit the effect of MG, but it was not statistically significant. These results demonstrate that CB1 does not directly have a role in the antinociceptive action of MG where the effect was observed with the activation of opioid receptor. PMID:23109863

  4. Opioid receptor activation triggering downregulation of cAMP improves effectiveness of anti-cancer drugs in treatment of glioblastoma

    PubMed Central

    Friesen, Claudia; Hormann, Inis; Roscher, Mareike; Fichtner, Iduna; Alt, Andreas; Hilger, Ralf; Debatin, Klaus-Michael; Miltner, Erich

    2014-01-01

    Glioblastoma are the most frequent and malignant human brain tumors, having a very poor prognosis. The enhanced radio- and chemoresistance of glioblastoma and the glioblastoma stem cells might be the main reason why conventional therapies fail. The second messenger cyclic AMP (cAMP) controls cell proliferation, differentiation, and apoptosis. Downregulation of cAMP sensitizes tumor cells for anti-cancer treatment. Opioid receptor agonists triggering opioid receptors can activate inhibitory Gi proteins, which, in turn, block adenylyl cyclase activity reducing cAMP. In this study, we show that downregulation of cAMP by opioid receptor activation improves the effectiveness of anti-cancer drugs in treatment of glioblastoma. The µ-opioid receptor agonist D,L-methadone sensitizes glioblastoma as well as the untreatable glioblastoma stem cells for doxorubicin-induced apoptosis and activation of apoptosis pathways by reversing deficient caspase activation and deficient downregulation of XIAP and Bcl-xL, playing critical roles in glioblastomas’ resistance. Blocking opioid receptors using the opioid receptor antagonist naloxone or increasing intracellular cAMP by 3-isobutyl-1-methylxanthine (IBMX) strongly reduced opioid receptor agonist-induced sensitization for doxorubicin. In addition, the opioid receptor agonist D,L-methadone increased doxorubicin uptake and decreased doxorubicin efflux, whereas doxorubicin increased opioid receptor expression in glioblastomas. Furthermore, opioid receptor activation using D,L-methadone inhibited tumor growth significantly in vivo. Our findings suggest that opioid receptor activation triggering downregulation of cAMP is a promising strategy to inhibit tumor growth and to improve the effectiveness of anti-cancer drugs in treatment of glioblastoma and in killing glioblastoma stem cells. PMID:24626197

  5. Opioid-mediated regulation of A11 diencephalospinal dopamine neurons: pharmacological evidence of activation by morphine

    PubMed Central

    Pappas, Samuel S.; Kennedy, Tom; Goudreau, John L.; Lookingland, Keith J.

    2011-01-01

    Dopamine (DA) neurons of the A11 diencephalospinal system represent the sole source of DA innervation to the spinal cord in mice, serving neuromodulatory roles in the processing of nociceptive input and movement. These neurons originate in the dorsocaudal diencephalon and project axons unilaterally throughout the rostrocaudal extent of the spinal cord, terminating predominantly in the dorsal horn. The density of A11 DA axon terminals in the lumbar region is greater in males compared to females, while in both sexes the activity of neurons terminating in the thoracic spinal cord is greater than those terminating in the lumbar region. The present study was designed to test the hypothesis that A11 DA neurons are activated by opioids. To test this hypothesis, male and female mice were systemically treated with agonists or antagonists acting at the μ-opioid receptor, and spinal cord concentrations of DA and its metabolite DOPAC were determined in the thoracic and lumbar spinal cord using high performance liquid chromatography coupled with electrochemical detection. Systemic administration of the μ-opioid agonist morphine led to a dose- and time-dependent increase in spinal cord DOPAC/DA ratio (an estimate of DA neuronal activity) in both male and female mice, with greater changes occurring in the lumbar segment. Blockade of opioid receptors with the opioid antagonist naloxone reversed the stimulatory effects of morphine on A11 DA neurons in both male and female mice, but had little to no effect on the activity of these neurons when administered alone. Present findings are consistent with the conclusion that spinal cord- projecting axon terminals of A11 DA neurons are activated by opioids in both male and female mice, most likely through a disinhibitory mechanism. PMID:21605572

  6. Human neuromelanin: an endogenous microglial activator for dopaminergic neuron death

    PubMed Central

    Zhang, Wei; Zecca, Luigi; Wilson, Belinda; Ren, RW; Wang, Yong-jun; Wang, Xiao-min; Hong, Jau-Shyong

    2013-01-01

    Substantial evidence indicates that neuroinflammation caused by over-activation of microglial in the substantia nigra is critical in the pathogenesis of dopaminergic neurodegeneration in Parkinson’s disease (PD). Increasing data demonstrates that environmental factors such as rotenone, paraquat play pivotal roles in the death of dopaminergic neurons. Here, potential role and mechanism of neuromelanin (NM), a major endogenous component in dopaminergic neurons of the substantia nigra, on microglial activation and associated dopaminergic neurotoxicity were investigated. Using multiple well-established primary mesencephalic cultures, we tested whether human NM (HNM) could activate microglia, thereby provoking dopaminergic neurodegeneration. The results demonstrated that in primary mesencephalic neuron-glia cultures, HNM caused dopaminergic neuronal damage characterized by the decreased dopamine uptake and reduced numbers and shorted dendrites of dopaminergic neurons. HNM-induced degeneration was relatively selective to dopaminergic neurons since the other types of neurons determined by either gamma-aminobutyric acid uptake and total neuronal numbers after staining showed smaller decrease. We demonstrated that HNM produced modest dopaminergic neurotoxicity in neuron-enriched cultures; in contrast, much greater neurotoxicity was observed in the presence of microglia. HNM-induced microglial activation was shown by morphological changes and production of proinflammatory and neurotoxic factors. These results suggest that HNM, once released from damaged dopaminergic neurons, can be an potent endogenous activator involved in the reactivation of microglia, which may mediate disease progression. Thus, inhibition of reactive microglia can be a useful strategy for PD therapy. PMID:23276965

  7. κ-Opioid receptor participates of NSAIDs peripheral antinociception.

    PubMed

    Silva, Lívia Caroline Resende; Castor, Marina Gomes Miranda E; Navarro, Larissa Caldeira; Romero, Thiago Roberto Lima; Duarte, Igor Dimitri Gama

    2016-05-27

    NSAIDs represent some of the most widely prescribed drugs for relief of short-term fever, pain and inflammation. The participation of the opioid system in the peripheral is poorly understood. The aim of this study was evaluate the role of opioid system in the peripheral antinociception by diclofenac and dipyrone. To test this hypothesis, opioid receptor antagonists were evaluated using the rat paw pressure test, in which pain sensitivity is increased by intraplantar injection of prostaglandin E2 (PGE2, 2μg). Diclofenac (20μg/paw) and Dipyrone (40μg/paw) administered locally into the right paw elicited an antinociceptive effect. It was used naloxone (50μg/paw), a non-selective opioid receptor antagonist, which antagonized peripheral antinociception induced by diclofenac and dipyrone. Selectively, it was evaluated the μ-, δ- and κ-opioid receptor antagonists, respectively, clocinnamox (40μg/paw), naltrindole (50μg/paw) and nor-binaltorphimine (20, 40 and 80μg/paw). Our data indicated that only the κ-opioid antagonist was capable to reverse the peripheral antinociception by NSAIDs. The present results provide evidence that the opioid system participated in the diclofenac and dipyrone-induced peripheral antinociception by indirect activation of κ-opioid receptor probable by release of endogenous opioids such as dynorphins. PMID:27091501

  8. Opiate-induced constipation related to activation of small intestine opioid μ2-receptors

    PubMed Central

    Chen, Wency; Chung, Hsien-Hui; Cheng, Juei-Tang

    2012-01-01

    AIM: To investigate the role of opioid μ-receptor subtype in opiate-induced constipation (OIC). METHODS: The effect of loperamide on intestinal transit was investigated in mice. Ileum strips were isolated from 12-wk-old male BALB/c mice for identification of isometric tension. The ileum strips were precontracted with 1 μmol/L acetylcholine (ACh). Then, decrease in muscle tone (relaxation) was characterized after cumulative administration of 0.1-10 μmol/L loperamide into the organ bath, for a concentration-dependent study. Specific blockers or antagonists were used for pretreatment to compare the changes in loperamide-induced relaxation. RESULTS: In addition to the delay in intestinal transit, loperamide produced a marked relaxation in isolated ileum precontracted with ACh, in a dose-dependent manner. This relaxation was abolished by cyprodime, a selective opioid μ-receptor antagonist, but not modified by naloxonazine at a dose sufficient to block opioid μ-1 receptors. Also, treatment with opioid μ-1 receptor agonist failed to modify the muscle tone. Moreover, the relaxation by loperamide was attenuated by glibenclamide at a dose sufficient to block ATP-sensitive K+ (KATP) channels, and by protein kinase A (PKA) inhibitor, but was enhanced by an inhibitor of phosphodiesterase for cyclic adenosine monophosphate (cAMP). CONCLUSION: Loperamide induces intestinal relaxation by activation of opioid μ-2 receptors via the cAMP-PKA pathway to open KATP channels, relates to OIC. PMID:22493554

  9. Muscle pain perception and sympathetic nerve activity to exercise during opioid modulation

    NASA Technical Reports Server (NTRS)

    Cook, D. B.; O'Connor, P. J.; Ray, C. A.

    2000-01-01

    The purpose of this experiment was to examine the effects of the endogenous opioid system on forearm muscle pain and muscle sympathetic nerve activity (MSNA) during dynamic fatiguing exercise. Twelve college-age men (24 +/- 4 yr) performed graded (1-min stages; 30 contractions/min) handgrip to fatigue 1 h after the ingestion of either 60 mg codeine, 50 mg naltrexone, or placebo. Pain (0-10 scale) and exertion (0-10 and 6-20 scales) intensities were measured during the last 15 s of each minute of exercise and every 15 s during recovery. MSNA was measured continuously from the peroneal nerve in the left leg. Pain threshold occurred earlier [1.8 +/- 1, 2. 2 +/- 1, 2.2 +/- 1 J: codeine, naltrexone, and placebo, respectively] and was associated with a lower rating of perceived exertion (RPE) (2.7 +/- 2, 3.6 +/- 2, 3.8 +/- 2: codeine, naltrexone, and placebo, respectively) in the codeine condition compared with either the naltrexone or placebo conditions. There were no main effects (i.e., drugs) or interaction (i.e., drugs x time) for either forearm muscle pain or RPE during exercise [pain: F (2, 22) = 0.69, P = 0.51]. There was no effect of drug on MSNA, heart rate, or blood pressure during baseline, exercise, or recovery. Peak exercise MSNA responses were 21 +/- 1, 21 +/- 2.0, and 21 +/- 2.0 bursts/30 s for codeine, naltrexone, and placebo conditions, respectively. Peak mean arterial pressure responses were 135 +/- 4, 131 +/- 3, and 132 +/- 4 mmHg for codeine, naltrexone, and placebo conditions, respectively. It is concluded that neither 60 mg codeine nor 50 mg naltrexone has an effect on forearm muscle pain, exertion, or MSNA during high- intensity handgrip to fatigue.

  10. Stereochemical influences upon the opioid ligand activities of 4-alkyl-4-arylpiperidine derivatives.

    PubMed

    Casy, A F; Dewar, G H; al Deeb, O A

    1989-01-01

    The synthesis and stereochemistry (configuration and preferred solute conformation) of some 4-alkyl (methyl, n-propyl, isobutyl)-4-(3-hydroxy-phenyl)-1-methylpiperidines and corresponding 3-methyl diastereoisomeric pairs are reported, together with their in vivo and in vitro activities as opioid ligands. All potent agonists exhibit a preference for axial 4-aryl chair conformations when protonated, and stereochemical analogies with rigid opioids of the benzomorphan class are discussed. Antagonist properties are found in compounds with preference for equatorial 4-aryl chairs, notably the cis 3,4-dimethyl derivative. PMID:2561991

  11. Prostatic relaxation induced by loperamide is mediated through activation of opioid μ-2 receptors in vitro

    PubMed Central

    LU, CHIH-CHENG; CHUNG, HSIEN-HUI; CHENG, JUEI-TANG

    2011-01-01

    The merit of opioid μ-receptor activation in the improvement of benign prostatic hyperplasia (BPH) remains obscure. In the present study, we used loperamide to identify the subtype of opioid μ-receptors involved in prostatic relaxation and investigate the possible mechanism of this relaxation. Prostate strips were isolated from 12-week-old male Wistar rats for identification of isometric tension. The prostate strips were precontracted with either 1 μmol/l phenylephrine or 50 mmol/l KCl. The decrease in muscle tone (relaxation) was then characterized after cumulative administration of loperamide (0.1 to 10 μmol/l) into the organ bath for the concentration-dependent study. Pretreatment with specific blockers or antagonists was carried out to compare the changes in loperamide-induced relaxation. Loperamide produced a marked relaxation in the isolated prostates precontracted with phenylephrine or KCl in a dose-dependent manner. This relaxation was abolished by cyprodime, a selective opioid μ-receptor antagonist, but was not modified by naloxonazine at a dose sufficient to block the opioid μ-1 receptors. Treatment with an agonist for opioid μ-1 receptors also failed to modify the muscle tone. Moreover, the relaxation by loperamide was attenuated by glibenclamide at a dose sufficient to block ATP-sensitive K+ channels. In addition, this action of loperamide was abolished by protein kinase A (PKA) inhibitor and enhanced by the inhibitor of phosphodiesterase for cyclic AMP (cAMP). Our results suggest that loperamide induces prostatic relaxation through activation of opioid μ-2 receptors via the cAMP-PKA pathway to open ATP-sensitive K+ channels. PMID:22977498

  12. Opioid-induced preconditioning: recent advances and future perspectives.

    PubMed

    Peart, Jason N; Gross, Eric R; Gross, Garrett J

    2005-01-01

    Opioids, named by Acheson for compounds with morphine-like actions despite chemically distinct structures, have received much research interest, particularly for their central nervous system (CNS) actions involved in pain management, resulting in thousands of scientific papers focusing on their effects on the CNS and other organ systems. A more recent area which may have great clinical importance concerns the role of opioids, either endogenous or exogenous compounds, in limiting the pathogenesis of ischemia-reperfusion injury in heart and brain. The role of endogenous opioids in hibernation provides tantalizing evidence for the protective potential of opioids against ischemia or hypoxia. Mammalian hibernation, a distinct energy-conserving state, is associated with depletion of energy stores, intracellular acidosis and hypoxia, similar to those which occur during ischemia. However, despite the potentially detrimental cellular state induced with hibernation, the myocardium remains resilient for many months. What accounts for the hypoxia-tolerant state is of great interest. During hibernation, circulating levels of opioid peptides are increased dramatically, and indeed, are considered a "trigger" of hibernation. Furthermore, administration of opioid antagonists can effectively reverse hibernation in mammals. Therefore, it is not surprising that activation of opioid receptors has been demonstrated to preserve cellular status following a hypoxic insult, such as ischemia-reperfusion in many model systems including the intestine [Zhang, Y., Wu, Y.X., Hao, Y.B., Dun, Y. Yang, S.P., 2001. Role of endogenous opioid peptides in protection of ischemic preconditioning in rat small intestine. Life Sci. 68, 1013-1019], skeletal muscle [Addison, P.D., Neligan, P.C., Ashrafpour, H., Khan, A., Zhong, A., Moses, M., Forrest, C.R., Pang, C.Y., 2003. Noninvasive remote ischemic preconditioning for global protection of skeletal muscle against infarction. Am. J. Physiol. Heart Circ

  13. Opioids inhibit visceral afferent activation of catecholamine neurons in the solitary tract nucleus.

    PubMed

    Cui, R J; Roberts, B L; Zhao, H; Andresen, M C; Appleyard, S M

    2012-10-11

    Brainstem A2/C2 catecholamine (CA) neurons within the solitary tract nucleus (NTS) influence many homeostatic functions, including food intake, stress, respiratory and cardiovascular reflexes. They also play a role in both opioid reward and withdrawal. Injections of opioids into the NTS modulate many autonomic functions influenced by catecholamine neurons including food intake and cardiac function. We recently showed that NTS-CA neurons are directly activated by incoming visceral afferent inputs. Here we determined whether opioid agonists modulate afferent activation of NTS-CA neurons using transgenic mice with EGFP expressed under the control of the tyrosine hydroxylase promoter (TH-EGFP) to identify catecholamine neurons. The opioid agonist Met-enkephalin (Met-Enk) significantly attenuated solitary tract-evoked excitatory postsynaptic currents (ST-EPSCs) in NTS TH-EGFP neurons by 80%, an effect reversed by wash or the mu opioid receptor-specific antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP). Met-Enk had a significantly greater effect to inhibit afferent inputs onto TH-EGFP-positive neurons than EGFP-negative neurons, which were only inhibited by 50%. The mu agonist, DAMGO, also inhibited the ST-EPSC in TH-EGFP neurons in a dose-dependent manner. In contrast, neither the delta agonist DPDPE, nor the kappa agonist, U69,593, consistently inhibited the ST-EPSC amplitude. Met-Enk and DAMGO increased the paired pulse ratio, decreased the frequency, but not amplitude, of mini-EPSCs and had no effect on holding current, input resistance or current-voltage relationships in TH-EGFP neurons, suggesting a presynaptic mechanism of action on afferent terminals. Met-Enk significantly reduced both the basal firing rate of NTS TH-EGFP neurons and the ability of afferent stimulation to evoke an action potential. These results suggest that opioids inhibit NTS-CA neurons by reducing an excitatory afferent drive onto these neurons through presynaptic inhibition of

  14. Touch Perception Altered by Chronic Pain and by Opioid Blockade.

    PubMed

    Case, Laura K; Čeko, Marta; Gracely, John L; Richards, Emily A; Olausson, Håkan; Bushnell, M Catherine

    2016-01-01

    Touch plays a significant role in human social behavior and social communication, and its rewarding nature has been suggested to involve opioids. Opioid blockade in monkeys leads to increased solicitation and receipt of grooming, suggesting heightened enjoyment of touch. We sought to study the role of endogenous opioids in perception of affective touch in healthy adults and in patients with fibromyalgia, a chronic pain condition shown to involve reduced opioid receptor availability. The pleasantness of touch has been linked to the activation of C-tactile fibers, which respond maximally to slow gentle touch and correlate with ratings of pleasantness. We administered naloxone to patients and healthy controls to directly observe the consequences of µ-opioid blockade on the perceived pleasantness and intensity of touch. We found that at baseline chronic pain patients showed a blunted distinction between slow and fast brushing for both intensity and pleasantness, suggesting reduced C-tactile touch processing. In addition, we found a differential effect of opioid blockade on touch perception in healthy subjects and pain patients. In healthy individuals, opioid blockade showed a trend toward increased ratings of touch pleasantness, while in chronic pain patients it significantly decreased ratings of touch intensity. Further, in healthy individuals, naloxone-induced increase in touch pleasantness was associated with naloxone-induced decreased preference for slow touch, suggesting a possible effect of opioid levels on processing of C-tactile fiber input. These findings suggest a role for endogenous opioids in touch processing, and provide further evidence for altered opioid functioning in chronic pain patients. PMID:27022625

  15. The Useage of Opioids and their Adverse Effects in Gastrointestinal Practice: A Review

    PubMed Central

    Khansari, MahmoudReza; Sohrabi, MasourReza; Zamani, Farhad

    2013-01-01

    Opium is one of the oldest herbal medicines currently used as an analgesic, sedative and antidiarrheal treatment. The effects of opium are principally mediated by the μ-, κ- and δ-opioid receptors. Opioid substances consist of all natural and synthetic alkaloids that are derived from opium. Most of their effects on gastrointestinal motility and secretion result from suppression of neural activity. Inhibition of gastric emptying, increase in sphincter tone, changes in motor patterns, and blockage of peristalsis result from opioid use. Common adverse effects of opioid administration include sedation, dizziness, nausea, vomiting, constipation, dependency and tolerance, and respiratory depression. The most common adverse effect of opioid use is constipation. Although stool softeners are frequently used to decrease opioid-induced bowel dysfunction, however they are not efficacious. Possibly, the use of specific opioid receptor antagonists is a more suitable approach. Opioid antagonists, both central and peripheral, could affect gastrointestinal function and visceromotor sensitivity, which suggests an important role for endogenous opioid peptides in the control of gastrointestinal physiology. Underlying diseases or medications known to influence the central nervous system (CNS) often accelerate the opioid’s adverse effects. However, changing the opioid and/or route of administration could also decrease their adverse effects. Appropriate patient selection, patient education and discussion regarding potential adverse effects may assist physicians in maximizing the effectiveness of opioids, while reducing the number and severity of adverse effects. PMID:24829664

  16. Displacement of /sup 3/H-EKC binding by opioids in rat kidney: A correlate to diuretic activity

    SciTech Connect

    Slizgi, G.R.; Ludens, J.H.

    1985-06-10

    Multiple opioid binding sites have been documented in brain tissue. In this study the authors report on the presence of binding sites for that opioid ethylketocyclazocine (EKC) in a membrane fraction of rat kidney. Binding appeared to be selective in the opioids varied markedly in their capacities to displace /sup 3/ -EKC. Correlating with the capacity of an opioid to displace /sup 3/H-EKC was the ability to produce diuresis. Although the studies cannot assign a particular physiological or pharmacological role for the renal EKC binding sites, binding studies of this nature may, nonetheless, be a means by which diuretic activity of opioids can be predicted. 15 references, 2 figures, 1 table.

  17. [THE INFLUENCE OF OPIOID PEPTIDES ON LIPID PEROXIDATION AND ANTIOXIDANT ENZYME ACTIVITY IN RATS AFTER SWIMMING STRESS].

    PubMed

    Solin, A V; Lyashev, Yu D

    2015-08-01

    It was established in experiments on rats, that injection of opioid peptides DAGO (a selective igonist of opioid mu-receptors), DSLET (a selective agonist of opioid delta-receptors) or dynorpiin A (1-13) (a selective agonist of opioid kappa-receptors) decreased the stress-induced activatin of lipid peroxidation in liver tissue and plasma. A selective agonist of opioid mu-receptors) AGO manifested the most expressed activity. The using of investigating peptides caused the increase of superoxiddismutase activity in liver tissue. The reinforcement of catalase activity was )bserved in DSLET or dynorphin A (1-13). DAGO decreased its activity. The peptide effects of lifferent directions oncatalase activity in plasma were established. These effects can be explained y the stress-limiting action of peptides in entire organism, the peculiarities of opioid receptors spreading in liver tissue and by the influence of preceded load with non-complete oxidized sub stances after intensive swimming on the opioid receptor affinity. PMID:26591588

  18. Activation of G protein by opioid receptors: role of receptor number and G-protein concentration.

    PubMed

    Remmers, A E; Clark, M J; Alt, A; Medzihradsky, F; Woods, J H; Traynor, J R

    2000-05-19

    The collision-coupling model for receptor-G-protein interaction predicts that the rate of G-protein activation is dependent on receptor density, but not G-protein levels. C6 cells expressing mu- or delta-opioid receptors, or SH-SY5Y cells, were treated with beta-funaltrexamine (mu) or naltrindole-5'-isothiocyanate (delta) to decrease receptor number. The time course of full or partial agonist-stimulated ¿35SGTPgammaS binding did not vary in C6 cell membranes containing <1-25 pmol/mg mu-opioid receptor, or 1. 4-4.3 pmol/mg delta-opioid receptor, or in SHSY5Y cells containing 0. 16-0.39 pmol/mg receptor. The association of ¿35SGTPgammaS binding was faster in membranes from C6mu cells than from C6delta cells. A 10-fold reduction in functional G-protein, following pertussis toxin treatment, lowered the maximal level of ¿35SGTPgammaS binding but not the association rate. These data indicate a compartmentalization of opioid receptors and G protein at the cell membrane. PMID:10822058

  19. delta-Opioid receptors exhibit high efficiency when activating trimeric G proteins in membrane domains.

    PubMed

    Bourova, Lenka; Kostrnova, Alexandra; Hejnova, Lucie; Moravcova, Zuzana; Moon, Hyo-Eun; Novotny, Jiri; Milligan, Graeme; Svoboda, Petr

    2003-04-01

    Low-density membrane fragments (domains) were separated from the bulk of plasma membranes of human embryonic kidney (HEK)293 cells expressing a delta-opioid (DOP) receptor-Gi1alpha fusion protein by drastic homogenization and flotation on equilibrium sucrose density gradients. The functional activity of trimeric G proteins and capacity of the DOP receptor to stimulate both the fusion protein-linked Gi1alpha and endogenous pertussis-toxin sensitive G proteins was measured as d-Ala2, d-Leu5-enkephalin stimulated high-affinity GTPase or guanosine-5'-[gamma-35S]triphosphate ([35S]GTPgammaS) binding. The maximum d-Ala2-d-Leu5 enkephalin (DADLE)-stimulated GTPase was two times higher in low-density membrane fragments than in bulk of plasma membranes; 58 and 27 pmol/mg/min, respectively. The same difference was obtained for [35S]GTPgammaS binding. Contrarily, the low-density domains contained no more than half the DOP receptor binding sites (Bmax = 6.6 pmol/mg versus 13.6 pmol/mg). Thus, when corrected for expression levels of the receptor, low-density domains exhibited four times higher agonist-stimulated GTPase and [35S]GTPgammaS binding than the bulk plasma membranes. The regulator of G protein signaling RGS1, enhanced further the G protein functional activity but did not remove the difference between domain-bound and plasma membrane pools of G protein. The potency of the agonist in functional studies and the affinity of specific [3H]DADLE binding to the receptor were, however, the same in both types of membranes - EC50 = 4.5 +/- 0.1 x 10(-8) and 3.2 +/- 1.4 x 10(-8) m for GTPase; Kd = 1.2 +/- 0.1 and 1.3 +/- 0.1 nm for [3H]DADLE radioligand binding assay. Similar results were obtained when sodium bicarbonate was used for alkaline isolation of membrane domains. By contrast, detergent-insensitive membrane domains isolated following treatment of cells with Triton X100 exhibited no DADLE-stimulated GTPase or GTPgammaS binding. Functional coupling between the DOP receptor

  20. Effect of Iboga Alkaloids on µ-Opioid Receptor-Coupled G Protein Activation

    PubMed Central

    Antonio, Tamara; Childers, Steven R.; Rothman, Richard B.; Dersch, Christina M.; King, Christine; Kuehne, Martin; Bornmann, William G.; Eshleman, Amy J.; Janowsky, Aaron; Simon, Eric R.; Reith, Maarten E. A.; Alper, Kenneth

    2013-01-01

    Objective The iboga alkaloids are a class of small molecules defined structurally on the basis of a common ibogamine skeleton, some of which modify opioid withdrawal and drug self-administration in humans and preclinical models. These compounds may represent an innovative approach to neurobiological investigation and development of addiction pharmacotherapy. In particular, the use of the prototypic iboga alkaloid ibogaine for opioid detoxification in humans raises the question of whether its effect is mediated by an opioid agonist action, or if it represents alternative and possibly novel mechanism of action. The aim of this study was to independently replicate and extend evidence regarding the activation of μ-opioid receptor (MOR)-related G proteins by iboga alkaloids. Methods Ibogaine, its major metabolite noribogaine, and 18-methoxycoronaridine (18-MC), a synthetic congener, were evaluated by agonist-stimulated guanosine-5´-O-(γ-thio)-triphosphate ([35S]GTPγS) binding in cells overexpressing the recombinant MOR, in rat thalamic membranes, and autoradiography in rat brain slices. Results And Significance In rat thalamic membranes ibogaine, noribogaine and 18-MC were MOR antagonists with functional Ke values ranging from 3 uM (ibogaine) to 13 uM (noribogaine and 18MC). Noribogaine and 18-MC did not stimulate [35S]GTPγS binding in Chinese hamster ovary cells expressing human or rat MORs, and had only limited partial agonist effects in human embryonic kidney cells expressing mouse MORs. Ibogaine did not did not stimulate [35S]GTPγS binding in any MOR expressing cells. Noribogaine did not stimulate [35S]GTPγS binding in brain slices using autoradiography. An MOR agonist action does not appear to account for the effect of these iboga alkaloids on opioid withdrawal. Taken together with existing evidence that their mechanism of action also differs from that of other non-opioids with clinical effects on opioid tolerance and withdrawal, these findings suggest a

  1. Opioid control of gonadotrophin secretion in humans.

    PubMed

    Genazzani, A R; Genazzani, A D; Volpogni, C; Pianazzi, F; Li, G A; Surico, N; Petraglia, F

    1993-11-01

    Hypothalamus-pituitary-axis (HPA) is constantly under the modulatory effect of many substances, such as neurotransmitters, neuromodulators and steroid hormones. Recently, the involvement of endogenous opioid peptides (EOP) in the control of the neuroendocrine mechanism modulating gonadotrophin secretion has been supported by several authors. It has been demonstrated that acute morphine administration decreases luteinizing hormone (LH) plasma levels and this is due to an inhibitory modulation on gonadotrophin releasing hormone discharge from the hypothalamic neurons. EOP are usually increased by stressful situations. In stress-induced amenorrhoea, the presence of low LH plasma levels and an abnormal LH pulsatile secretion has been related to an increased opioid activity, thus supporting the integrative role of opioids between hormonal and neuronal afferences of brain. PMID:8276950

  2. Mu-opioid receptors modulate the stability of dendritic spines.

    PubMed

    Liao, Dezhi; Lin, Hang; Law, Ping Yee; Loh, Horace H

    2005-02-01

    Opioids classically regulate the excitability of neurons by suppressing synaptic GABA release from inhibitory neurons. Here, we report a role for opioids in modulating excitatory synaptic transmission. By activating ubiquitously clustered mu-opioid receptor (MOR) in excitatory synapses, morphine caused collapse of preexisting dendritic spines and decreased synaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. Meanwhile, the opioid antagonist naloxone increased the density of spines. Chronic treatment with morphine decreased the density of dendritic spines even in the presence of Tetrodotoxin, a sodium channel blocker, indicating that the morphine's effect was not caused by altered activity in neural network through suppression of GABA release. The effect of morphine on dendritic spines was absent in transgenic mice lacking MORs and was blocked by CTOP (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-ThrNH2), a mu-receptor antagonist. These data together with others suggest that endogenous opioids and/or constitutive activity of MORs participate in maintaining normal morphology and function of spines, challenging the classical model of opioids. Abnormal alteration of spines may occur in drug addiction when opioid receptors are overactivated by exogenous opiates. PMID:15659552

  3. Hydrogen Sulfide Is an Endogenous Potentiator of T Cell Activation*

    PubMed Central

    Miller, Thomas W.; Wang, Evelyn A.; Gould, Serge; Stein, Erica V.; Kaur, Sukhbir; Lim, Langston; Amarnath, Shoba; Fowler, Daniel H.; Roberts, David D.

    2012-01-01

    H2S is an endogenous signaling molecule that may act via protein sulfhydrylation to regulate various physiological functions. H2S is also a byproduct of dietary sulfate metabolism by gut bacteria. Inflammatory bowel diseases such as ulcerative colitis are associated with an increase in the colonization of the intestine by sulfate reducing bacteria along with an increase in H2S production. Consistent with its increased production, H2S is implicated as a mediator of ulcerative colitis both in its genesis or maintenance. As T cells are well established mediators of inflammatory bowel disease, we investigated the effect of H2S exposure on T cell activation. Using primary mouse T lymphocytes (CD3+), OT-II CD4+ T cells, and the human Jurkat T cell line, we show that physiological levels of H2S potentiate TCR-induced activation. Nanomolar levels of H2S (50–500 nm) enhance T cell activation assessed by CD69 expression, interleukin-2 expression, and CD25 levels. Exposure of T cells to H2S dose-dependently enhances TCR-stimulated proliferation with a maximum at 300 nm (30% increase, p < 0.01). Furthermore, activation increases the capacity of T cells to make H2S via increased expression of cystathionine γ-lyase and cystathionine β-synthase. Disrupting this response by silencing these H2S producing enzymes impairs T cell activation, and proliferation and can be rescued by the addition of 300 nm H2S. Thus, H2S represents a novel autocrine immunomodulatory molecule in T cells. PMID:22167178

  4. tirant, a newly discovered active endogenous retrovirus in Drosophila simulans.

    PubMed

    Akkouche, Abdou; Rebollo, Rita; Burlet, Nelly; Esnault, Caroline; Martinez, Sonia; Viginier, Barbara; Terzian, Christophe; Vieira, Cristina; Fablet, Marie

    2012-04-01

    Endogenous retroviruses have the ability to become permanently integrated into the genomes of their host, and they are generally transmitted vertically from parent to progeny. With the exception of gypsy, few endogenous retroviruses have been identified in insects. In this study, we describe the tirant endogenous retrovirus in a subset of Drosophila simulans natural populations. By focusing on the envelope gene, we show that the entire retroviral cycle (transcription, translation, and retrotransposition) can be completed for tirant within one population of this species. PMID:22278247

  5. tirant, a Newly Discovered Active Endogenous Retrovirus in Drosophila simulans

    PubMed Central

    Akkouche, Abdou; Rebollo, Rita; Burlet, Nelly; Esnault, Caroline; Martinez, Sonia; Viginier, Barbara; Terzian, Christophe; Vieira, Cristina

    2012-01-01

    Endogenous retroviruses have the ability to become permanently integrated into the genomes of their host, and they are generally transmitted vertically from parent to progeny. With the exception of gypsy, few endogenous retroviruses have been identified in insects. In this study, we describe the tirant endogenous retrovirus in a subset of Drosophila simulans natural populations. By focusing on the envelope gene, we show that the entire retroviral cycle (transcription, translation, and retrotransposition) can be completed for tirant within one population of this species. PMID:22278247

  6. Opioid intoxication

    MedlinePlus

    Intoxication - opioids ... In the United States, the most commonly abused opioids are heroin and methadone. People who become addicted ... of these drugs. Also, the use of prescription opioids for nonmedical reasons is an extensive and growing ...

  7. Opioid intoxication

    MedlinePlus

    ... use of opioid-based drugs. These include morphine, heroin, oxycodone, and synthetic (man-made) opioid narcotics. Prescription ... United States, the most commonly abused opioids are heroin and methadone. People who become addicted to these ...

  8. Endogenous opiates and behavior: 2001.

    PubMed

    Bodnar, Richard J; Hadjimarkou, Maria M

    2002-12-01

    This paper is the twenty-fourth installment of the annual review of research concerning the opiate system. It summarizes papers published during 2001 that studied the behavioral effects of the opiate peptides and antagonists. The particular topics covered this year include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology(Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17). PMID:12535711

  9. Activation of peripheral opioid receptors has no effect on heart rate variability.

    PubMed

    Ellidokuz, Ender; Kaya, Dayimi; Uslan, Ihsan; Celik, Ataç; Esen, Ali Metin; Barutça, Irfan

    2008-06-01

    Opioid receptors involved in regulating the motility of the gastrointestinal tract have been localized in both contractile and neuronal tissues. Trimebutine, a peripheral opioid receptor agonist, modulates gastrointestinal motor activity in both directions and also may act on cardiac tissue. This study investigated the effects of trimebutine in clinical doses on cardiac autonomic functions with heart rate variability. The effect of trimebutine on cardiac autonomic outflows was evaluated in 11 healthy subjects. Trimebutine (200 mg) or placebo was administered orally at random in a double-blind, cross-over manner. Continuous electrocardiography recordings were obtained before and after drug administration during three states: rest, controlled breathing, and a hand grip exercise. Heart rate variability analysis showed that there was no significant difference between subjects administered with placebo or trimebutine throughout rest, controlled breathing, or the hand grip exercise. We concluded that trimebutine, in clinical doses, has no significant effect on cardiac autonomic functions. PMID:18449593

  10. The physiology of opiate hedonic effects and the role of opioids in motivated behavior.

    PubMed

    Carr, K D

    1984-01-01

    The topics discussed in this article are the neural mechanisms of opiate hedonic effects and the role of endogenous opioids in regulating motivational-affective responses of the organism. First, research on the mechanisms of opiate hedonic effects is briefly reviewed; evidence is discussed which suggests the existence of separate neural substrates for the mediation of opiate analgesia, amelioration of aversive emotion, and reward. In the remainder of the article, recent work of our laboratory is summarized which concerns the role of endogenous opioids in regulating feeding and reward elicited by electrical stimulation in the lateral hypothalamus; evidence is presented which indicates that opioid activity associated with the state of food motivation potentiates reward processes. In addition, evidence is discussed which suggests that this opioid activity may concurrently diminish the organism's emotional responsiveness to competing aversive stimuli. The relevance of this area of research to human opiate abuse is discussed. PMID:6388274

  11. A role for kappa-, but not mu-opioid, receptor activation in acute food deprivation-induced reinstatement of heroin seeking in rats.

    PubMed

    Sedki, Firas; Eigenmann, Karine; Gelinas, Jessica; Schouela, Nicholas; Courchesne, Shannon; Shalev, Uri

    2015-05-01

    Stress is considered to be one of the major triggers to drug relapse, even after prolonged periods of abstinence. In rats, the activation of stress-related brain systems, including corticotropin-releasing factor and norepinephrine, is critical for stress-induced reinstatement of extinguished drug seeking, an animal model for drug relapse. In addition, there are strong indications that activation of the endogenous opioid system is important for the effects of stress on drug seeking. More specifically, activation of the dynorphin/kappa opioid receptor (KOR) system is critically involved in the reinstatement of cocaine seeking following exposure to stressors, such as footshock, forced swimming or social stress. However, studies on the role of the dynorphin/KOR system in stress-induced reinstatement of heroin seeking are scarce. Here, rats were trained to self-administer heroin (0.1 mg/kg/infusion) for 10 days. Drug seeking was then extinguished and the rats were tested for acute (21 hours) food deprivation-induced reinstatement of heroin seeking. In two separate experiments, rats were injected with the mu-opioid receptor (MOR) antagonist, naltrexone (0.0, 1.0, 10.0 mg/kg; s.c.) or the KOR antagonist, norBNI (0.0, 1.0, 10.0 mg/kg; i.p.) before the reinstatement test. Naltrexone treatment did not affect stress-induced reinstatement. In contrast, treatment with norBNI dose-dependently attenuated food deprivation-induced reinstatement of heroin seeking. These results support the hypothesis that activation of KOR, but not MOR, is critically involved in stress-induced reinstatement of drug seeking. PMID:24725195

  12. Glycodermorphins: opioid peptides with potent and prolonged analgesic activity and enhanced blood-brain barrier penetration.

    PubMed

    Negri, L; Lattanzi, R; Tabacco, F; Scolaro, B; Rocchi, R

    1998-08-01

    1. In order to improve the in vivo stability of the opioid peptide dermorphin we synthesized O-betaglucosylated analogs ([Ser7-O-betaGlc]dermorphin and [Ser7-O-betaGlc(Ac)4]-dermorphin) and C-alphagalactosylated analogs ([Ala7-C-alphaGal]dermorphin and [Ala7-C-alphaGal(Ac)4]-dermorphin). 2. O- and C-glycosylation of dermorphin halved the peptide affinity for brain mu-opioid receptors and the biological potency in guinea-pig ileum assay (GPI). Despite their lower opioid receptor affinity, when administered intracerebroventricularly (i.c.v., 8-40 pmol) and subcutaneously (s.c., 0.5-3 micromol kg(-1)) in rats, glycosylated analogs were two times more potent than dermorphin in reducing the nociceptive response to radiant heat. Acetylation of sugar hydroxyl groups reduces 5-10 times both biological activity on GPI and mu-receptor affinity, whereas the antinociceptive potency was equal to (i.c.v.) or only two-three times lower (s.c.) than dermorphin potency. 3. Blood-Brain Barrier Permeability Index (BBB-PI) of the glycodermorphins was significantly higher than that of dermorphin, indicating a facilitated entry into the brain: O-beta-linked glucoconiugates are expected to enter CNS by the glucose transporter GLUT-1 of the endothelial barrier. However the calculated BBB-PI for the C-alphagalactoside was about two times higher than that of the O-betaglucoside, excluding the implication of GLUT-1 that is known to be selective for O-beta-links and preferring for the exose glucose. 4. The enhanced brain permeability with the subsequent decrease in peripheral dosage of these opioid peptides did not result in lowering constipation. PMID:9723966

  13. Can Neural Activity Propagate by Endogenous Electrical Field?

    PubMed

    Qiu, Chen; Shivacharan, Rajat S; Zhang, Mingming; Durand, Dominique M

    2015-12-01

    It is widely accepted that synaptic transmissions and gap junctions are the major governing mechanisms for signal traveling in the neural system. Yet, a group of neural waves, either physiological or pathological, share the same speed of ∼0.1 m/s without synaptic transmission or gap junctions, and this speed is not consistent with axonal conduction or ionic diffusion. The only explanation left is an electrical field effect. We tested the hypothesis that endogenous electric fields are sufficient to explain the propagation with in silico and in vitro experiments. Simulation results show that field effects alone can indeed mediate propagation across layers of neurons with speeds of 0.12 ± 0.09 m/s with pathological kinetics, and 0.11 ± 0.03 m/s with physiologic kinetics, both generating weak field amplitudes of ∼2-6 mV/mm. Further, the model predicted that propagation speed values are inversely proportional to the cell-to-cell distances, but do not significantly change with extracellular resistivity, membrane capacitance, or membrane resistance. In vitro recordings in mice hippocampi produced similar speeds (0.10 ± 0.03 m/s) and field amplitudes (2.5-5 mV/mm), and by applying a blocking field, the propagation speed was greatly reduced. Finally, osmolarity experiments confirmed the model's prediction that cell-to-cell distance inversely affects propagation speed. Together, these results show that despite their weak amplitude, electric fields can be solely responsible for spike propagation at ∼0.1 m/s. This phenomenon could be important to explain the slow propagation of epileptic activity and other normal propagations at similar speeds. PMID:26631463

  14. Curcumin Attenuates Opioid Tolerance and Dependence by Inhibiting Ca2+/Calmodulin-Dependent Protein Kinase II α Activity

    PubMed Central

    Hu, Xiaoyu; Huang, Fang; Szymusiak, Magdalena

    2015-01-01

    Chronic use of opioid analgesics has been hindered by the development of opioid addiction and tolerance. We have reported that curcumin, a natural flavonoid from the rhizome of Curcuma longa, attenuated opioid tolerance, although the underlying mechanism remains unclear. In this study, we tested the hypothesis that curcumin may inhibit Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα), a protein kinase that has been previously proposed to be critical for opioid tolerance and dependence. In this study, we used state-of-the-art polymeric formulation technology to produce poly(lactic-co-glycolic acid) (PLGA)-curcumin nanoparticles (nanocurcumin) to overcome the drug’s poor solubility and bioavailability, which has made it extremely difficult for studying in vivo pharmacological actions of curcumin. We found that PLGA-curcumin nanoparticles reduced the dose requirement by 11- to 33-fold. Pretreatment with PLGA-curcumin (by mouth) prevented the development of opioid tolerance and dependence in a dose-dependent manner, with ED50 values of 3.9 and 3.2 mg/kg, respectively. PLGA-curcumin dose-dependently attenuated already-established opioid tolerance (ED50 = 12.6 mg/kg p.o.) and dependence (ED50 = 3.1 mg/kg p.o.). Curcumin or PLGA-curcumin did not produce antinociception by itself or affect morphine (1–10 mg/kg) antinociception. Moreover, we found that the behavioral effects of curcumin on opioid tolerance and dependence correlated with its inhibition of morphine-induced CaMKIIα activation in the brain. These results suggest that curcumin may attenuate opioid tolerance and dependence by suppressing CaMKIIα activity. PMID:25515789

  15. Activity profiles of dalargin and its analogues in μ-, δ- and κ-opioid receptor selective bioassays

    PubMed Central

    Pencheva, Nevena; Pospišek, Jan; Hauzerova, Linda; Barth, Tomislav; Milanov, Peter

    1999-01-01

    To elucidate the structural features ensuring action of [D-Ala2, Leu5]-enkephalyl-Arg (dalargin), a series of dalargin analogues were tested for their effectiveness in depressing electrically-evoked contractions of the guinea-pig myenteric plexus-longitudinal muscle preparations (μ- and κ-opioid receptors) and the vasa deferentia of the hamster (δ-opioid receptors), mouse (μ-, δ- and κ-opioid receptors), rat (similar to μ-opioid receptors) and rabbit (κ-opioid receptors). The naloxone KB values in the myenteric plexus were also obtained.[L-Ala2]-dalargin was 19 times less potent than dalargin, and its pharmacological activity was peptidase-sensitive. The ratio of δ-activity to μ-activity for [L-Ala2]-dalargin was 6.78, and KB was 7.9 nM. This emphasizes the role that D-configuration of Ala2 plays in determining the active folding of dalargin molecule as well as in conferring resistance to peptidases.[Met5]-dalargin was equipotent to dalargin in the myenteric plexus, but was more potent in the vasa deferentia of hamster and mouse (KB=5.5 nM). Leu5 and the interdependence of Leu5 and D-Ala2 are of importance for the selectivity of dalargin for μ-opioid receptors.Dalarginamide was more potent and selective for μ-opioid receptors than dalargin, whilst dalarginethylamide, though equipotent to dalarginamide in the myenteric plexus, was more potent at δ-opioid receptors (KB=5.0 nM). [D-Phe4]-dalarginamide and N-Me-[D-Phe4]-dalarginamide were inactive indicating the contribution of L-configuration of Phe4 to the pharmacological potency of dalargin.N-Me-[L-Phe4]-dalarginamide possessed the highest potency and selectivity for μ-opioid receptors (the ratio of δ-activity to μ-activity was 0.00053; KB=2.6 nM). The CONH2 terminus combined with the N-methylation of L-Phe4 increased the potency and selectivity of dalargin for μ-opioid receptors. PMID:10516634

  16. Activity profiles of dalargin and its analogues in mu-, delta- and kappa-opioid receptor selective bioassays.

    PubMed

    Pencheva, N; Pospisek, J; Hauzerova, L; Barth, T; Milanov, P

    1999-10-01

    1. To elucidate the structural features ensuring action of [D-Ala2, Leu5]-enkephalyl-Arg (dalargin), a series of dalargin analogues were tested for their effectiveness in depressing electrically-evoked contractions of the guinea-pig myenteric plexus-longitudinal muscle preparations (mu- and kappa-opioid receptors) and the vasa deferentia of the hamster (delta-opioid receptors), mouse (mu-, delta- and kappa-opioid receptors), rat (similar to mu-opioid receptors) and rabbit (kappa-opioid receptors). The naloxone KB values in the myenteric plexus were also obtained. 2. [L-Ala2]-dalargin was 19 times less potent than dalargin, and its pharmacological activity was peptidase-sensitive. The ratio of delta-activity to mu-activity for [L-Ala2]-dalargin was 6.78, and KB was 7.9 nM. This emphasizes the role that D-configuration of Ala2 plays in determining the active folding of dalargin molecule as well as in conferring resistance to peptidases. 3. [Met5]-dalargin was equipotent to dalargin in the myenteric plexus, but was more potent in the vasa deferentia of hamster and mouse (KB=5.5 nM). Leu5 and the interdependence of Leu5 and D-Ala2 are of importance for the selectivity of dalargin for mu-opioid receptors. 4. Dalarginamide was more potent and selective for mu-opioid receptors than dalargin, whilst dalarginethylamide, though equipotent to dalarginamide in the myenteric plexus, was more potent at delta-opioid receptors (KB=5.0 nM). [D-Phe4]-dalarginamide and N-Me-[D-Phe4]-dalarginamide were inactive indicating the contribution of L-configuration of Phe4 to the pharmacological potency of dalargin. 5. N-Me-[L-Phe4]-dalarginamide possessed the highest potency and selectivity for mu-opioid receptors (the ratio of delta-activity to mu-activity was 0.00053; KB=2.6 nM). The CONH2 terminus combined with the N-methylation of L-Phe4 increased the potency and selectivity of dalargin for mu-opioid receptors. PMID:10516634

  17. Mitragyna speciosa, a psychoactive tree from Southeast Asia with opioid activity.

    PubMed

    Adkins, Jessica E; Boyer, Edward W; McCurdy, Christopher R

    2011-01-01

    Mitragyna speciosa Korth. (Rubiaceae) is a tree that is commonly found in Southeast Asia. Leaves from this tree have been traditionally been used for both their stimulant properties as well as an opium substitute. The tree/leaves are currently illegal in four countries, but is currently legal and widely available in the United States. To date over 40 compounds have been isolated from the leaves. The major alkaloid found within the crude extract, mitragynine, has been the subject of many pharmacological studies. In addition to the pharmacological studies, two total syntheses of mitragynine have been published as well as general structure-activity relationships (SARs) with respect to opioid activity. PMID:21050173

  18. Endogenous protease activity in byproducts of pink salmon (Oncorhynchus gorbuscha)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrolysate production is a low-cost method of preservation that could be employed to decrease the amount of fish byproducts discarded by Alaska’s salmon industry. However, endogenous enzymes within salmon vary with spawning maturity, and must be controlled in the raw material to ensure a consistent...

  19. Can Neural Activity Propagate by Endogenous Electrical Field?

    PubMed Central

    Qiu, Chen; Shivacharan, Rajat S.; Zhang, Mingming

    2015-01-01

    It is widely accepted that synaptic transmissions and gap junctions are the major governing mechanisms for signal traveling in the neural system. Yet, a group of neural waves, either physiological or pathological, share the same speed of ∼0.1 m/s without synaptic transmission or gap junctions, and this speed is not consistent with axonal conduction or ionic diffusion. The only explanation left is an electrical field effect. We tested the hypothesis that endogenous electric fields are sufficient to explain the propagation with in silico and in vitro experiments. Simulation results show that field effects alone can indeed mediate propagation across layers of neurons with speeds of 0.12 ± 0.09 m/s with pathological kinetics, and 0.11 ± 0.03 m/s with physiologic kinetics, both generating weak field amplitudes of ∼2–6 mV/mm. Further, the model predicted that propagation speed values are inversely proportional to the cell-to-cell distances, but do not significantly change with extracellular resistivity, membrane capacitance, or membrane resistance. In vitro recordings in mice hippocampi produced similar speeds (0.10 ± 0.03 m/s) and field amplitudes (2.5–5 mV/mm), and by applying a blocking field, the propagation speed was greatly reduced. Finally, osmolarity experiments confirmed the model's prediction that cell-to-cell distance inversely affects propagation speed. Together, these results show that despite their weak amplitude, electric fields can be solely responsible for spike propagation at ∼0.1 m/s. This phenomenon could be important to explain the slow propagation of epileptic activity and other normal propagations at similar speeds. SIGNIFICANCE STATEMENT Neural activity (waves or spikes) can propagate using well documented mechanisms such as synaptic transmission, gap junctions, or diffusion. However, the purpose of this paper is to provide an explanation for experimental data showing that neural signals can propagate by means other than synaptic

  20. Neuroimmune Interaction in the Regulation of Peripheral Opioid-Mediated Analgesia in Inflammation

    PubMed Central

    Hua, Susan

    2016-01-01

    Peripheral immune cell-mediated analgesia in inflammation is an important endogenous mechanism of pain control. Opioid receptors localized on peripheral sensory nerve terminals are activated by endogenous opioid peptides released from immune cells to produce significant analgesia. Following transendothelial migration of opioid-containing leukocytes into peripheral sites of inflammation, opioid peptides are released into a harsh milieu associated with an increase in temperature, low pH, and high proteolytic activity. Together, this microenvironment has been suggested to increase the activity of opioid peptide metabolism. Therefore, the proximity of immune cells and nerve fibers may be essential to produce adequate analgesic effects. Close associations between opioid-containing immune cells and peripheral nerve terminals have been observed. However, it is not yet determined whether these immune cells actually form synaptic-like contacts with peripheral sensory terminals and/or whether they secrete opioids in a paracrine manner. This review will provide novel insight into the peripheral mechanisms of immune-derived analgesia in inflammation, in particular, the importance of direct interactions between immune cells and the peripheral nervous system. PMID:27532001

  1. Neuroimmune Interaction in the Regulation of Peripheral Opioid-Mediated Analgesia in Inflammation.

    PubMed

    Hua, Susan

    2016-01-01

    Peripheral immune cell-mediated analgesia in inflammation is an important endogenous mechanism of pain control. Opioid receptors localized on peripheral sensory nerve terminals are activated by endogenous opioid peptides released from immune cells to produce significant analgesia. Following transendothelial migration of opioid-containing leukocytes into peripheral sites of inflammation, opioid peptides are released into a harsh milieu associated with an increase in temperature, low pH, and high proteolytic activity. Together, this microenvironment has been suggested to increase the activity of opioid peptide metabolism. Therefore, the proximity of immune cells and nerve fibers may be essential to produce adequate analgesic effects. Close associations between opioid-containing immune cells and peripheral nerve terminals have been observed. However, it is not yet determined whether these immune cells actually form synaptic-like contacts with peripheral sensory terminals and/or whether they secrete opioids in a paracrine manner. This review will provide novel insight into the peripheral mechanisms of immune-derived analgesia in inflammation, in particular, the importance of direct interactions between immune cells and the peripheral nervous system. PMID:27532001

  2. Involvement of nitric oxide in the inhibition of bone cancer-induced hyperalgesia through the activation of peripheral opioid receptors in mice.

    PubMed

    Menéndez, Luis; Juárez, Lucía; García, Verónica; Hidalgo, Agustín; Baamonde, Ana

    2007-07-01

    Experiments were designed to elucidate the involvement of nitric oxide (NO) in the antihyperalgesic effect induced by the activation of peripheral mu-opioid receptors on osteosarcoma-induced thermal hyperalgesia in mice. Since this pathway has previously been shown to be involved in the antihyperalgesic effect induced by some drugs--including opiates--on inflammatory pain, experiments were also performed in inflamed mice. The intraplantar administration of loperamide (15 microg) abolishes the thermal hyperalgesia that appears 4 weeks after the intratibial inoculation of NCTC 2472 cells in C3H/HeJ mice. The blockade of this effect by coadministering a peripheral opioid receptor antagonist (naloxone methiodide), a nitric oxide synthase (NOS) inhibitor (L-NMMA), a soluble guanylyl cyclase inhibitor (ODQ), a PKG inhibitor (KT-5823) or a K(+)(ATP)-channel blocker (glibenclamide) shows the involvement of a NO/cGMP/K(+)(ATP)-channel pathway. Accordingly the administration of loperamide produced, in osteosarcoma-bearing mice, an increase in the concentrations of NO metabolites, nitrites and nitrates, extracted from paws. The selective inhibitor of eNOS L-NIO, but not the inhibitors of nNOS (N-omega-propyl-L-arginine) or iNOS (1400w), blocked the effect of loperamide on osteosarcoma-induced hyperalgesia and also the endogenous opioid peripheral hypoalgesia that appears during the initial stages of the development of this osteosarcoma. Although this pathway also participates in the inhibitory effect of loperamide on the thermal hyperalgesia induced by administration of complete Freund's adjuvant, only selective inhibitors of nNOS or iNOS antagonized this effect. Our results demonstrate that the activation of a NO/cGMP/K(+)(ATP)-channel triggered by eNOS participates in the peripheral antihyperalgesic of loperamide on osteosarcoma-induced thermal hyperalgesia. PMID:17543351

  3. Purification to homogeneity of an active opioid receptor from rat brain by affinity chromatography.

    PubMed

    Loukas, S; Mercouris, M; Panetsos, F; Zioudrou, C

    1994-05-10

    Active opioid binding proteins were solubilized from rat brain membranes in high yield with sodium deoxycholate in the presence of NaCl. Purification of opioid binding proteins was accomplished by opioid antagonist affinity chromatography. Chromatography using the delta-opioid antagonist N,N-diallyl-Tyr-D-Leu-Gly-Tyr-Leu attached to omega-aminododecyl-agarose (Affi-G) (procedure A) yielded a partially purified protein that binds selectively the delta-opioid agonist [3H]Tyr-D-Ser-Gly-Phe-Leu-Thr ([3H]DSLET), with a Kd of 19 +/- 3 nM and a Bmax of 5.1 +/- 0.4 nmol/mg of protein. Subsequently, Lens culinaris agglutinin-Sepharose 4B chromatography of the Affi-G eluate resulted in isolation of an electrophoretically homogeneous protein of 58 kDa that binds selectively [3H]DSLET with a Kd of 21 +/- 3 nM and a Bmax of 16.5 +/- 1.0 nmol/mg of protein. Chromatography using the nonselective antagonist 6-aminonaloxone coupled to 6-aminohexanoic acid-Sepharose 4B (Affi-NAL) (procedure B) resulted in isolation of a protein that binds selectively [3H]DSLET with a Kd of 32 +/- 2 nM and a Bmax of 12.4 +/- 0.5 nmol/mg of protein, and NaDodSO4/PAGE revealed a major band of apparent molecular mass 58 kDa. Polyclonal antibodies (Anti-R IgG) raised against the Affi-NAL protein inhibit the specific [3H]DSLET binding to the Affi-NAL eluate and to the solubilized membranes. Moreover, the Anti-R IgG inhibits the specific binding of radiolabeled Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol (DAMGO; mu-agonist), DSLET (delta-agonist), and naloxone to homogenates of rat brain membranes with equal potency. Furthermore, immunoaffinity chromatography of solubilized membranes resulted in the retention of a major protein of apparent molecular mass 58 kDa. In addition, immunoblotting of solubilized membranes and purified proteins from the Affi-G and Affi-NAL matrices revealed that the Anti-R IgG interacts with a protein of 58 kDa. PMID:8183950

  4. Role of the mu opioid receptor in opioid modulation of immune function

    PubMed Central

    Ninković, Jana; Roy, Sabita

    2014-01-01

    SUMMARY Endogenous opioids are synthesized in vivo in order to modulate pain mechanisms and inflammatory pathways. Endogenous and exogenous opioids mediate analgesia in response to painful stimuli by binding to opioid receptors on neuronal cells. However, wide distribution of opioid receptors on tissues and organ systems outside the CNS, such as the cells of the immune system, indicate that opioids are capable of exerting additional effects in the periphery, such as immunomodulation. The increased prevalence of infections in opioid abusers based epidemiological studies further highlights the immunosuppressive effects of opioids. In spite of their many debilitating side effects, prescription opioids remain a gold standard for treatment of chronic pain. Therefore, given the prevalence of opioid use and abuse, opioid mediated immune suppression presents a serious concern in our society today. It is imperative to understand the mechanisms by which exogenous opioids modulate immune processes. In this review we will discuss the role of opioid receptors and their ligands in mediating immune suppressive functions. We will summarize recent studies on direct and indirect opioid modulation of the cells of the immune system as well as the role of opioids in exacerbation of certain disease states. PMID:22170499

  5. Brain P450 Epoxygenase Activity is Required for the Antinociceptive Effects of Improgan, a Non-Opioid Analgesic

    PubMed Central

    Hough, Lindsay B.; Nalwalk, Julia W.; Yang, Jun; Conroy, Jennie L.; VanAlstine, Melissa A.; Yang, Weizhu; Gargano, Joseph; Shan, Zhixing; Zhang, Shao-Zhong; Wentland, Mark P; Phillips, James G.; Knapp, Brian I.; Bidlack, Jean M.; Zuiderveld, Obbe P.; Leurs, Rob; Ding, Xinxin

    2011-01-01

    The search for the mechanism of action of improgan (a non-opioid analgesic) led to the recent discovery of CC12, a compound which blocks improgan antinociception. Since CC12 is a cytochrome P450 inhibitor, and brain P450 mechanisms were recently shown to be required in opioid analgesic signaling, pharmacological and transgenic studies were performed in rodents to test the hypothesis that improgan antinociception requires brain P450 epoxygenase activity. Intracerebroventricular (icv) administration of the P450 inhibitors miconazole and fluconazole, and the arachidonic acid (AA) epoxygenase inhibitor N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH) potently inhibited improgan antinociception in rats at doses which were inactive alone. MW06-25, a new P450 inhibitor which combines chemical features of CC12 and miconazole, also potently blocked improgan antinociception. Although miconazole and CC12 were weakly active at opioid and histamine H3 receptors, MW06-25 showed no activity at these sites, yet retained potent P450-inhibiting properties. The P450 hypothesis was also tested in Cprlow mice, a viable knock-in model with dramatically reduced brain P450 activity. Improgan (145 nmol, icv) antinociception was reduced by 37-59% in Cprlow mice, as compared with control mice. Moreover, CC12 pretreatment (200 nmol, icv) abolished improgan action (70-91%) in control mice, but had no significant effect in Cprlow mice. Thus, improgan’s activation of bulbospinal non-opioid analgesic circuits requires brain P450 epoxygenase activity. A model is proposed in which 1) improgan activates an unknown receptor to trigger downstream P450 activity, and 2) brainstem epoxygenase activity is a point of convergence for opioid and non-opioid analgesic signaling. PMID:21316152

  6. Relative Timing Between Kappa Opioid Receptor Activation and Cocaine Determines the Impact on Reward and Dopamine Release.

    PubMed

    Chartoff, Elena H; Ebner, Shayla R; Sparrow, Angela; Potter, David; Baker, Phillip M; Ragozzino, Michael E; Roitman, Mitchell F

    2016-03-01

    Negative affective states can increase the rewarding value of drugs of abuse and promote drug taking. Chronic cocaine exposure increases levels of the neuropeptide dynorphin, an endogenous ligand at kappa opioid receptors (KOR) that suppresses dopamine release in the nucleus accumbens (NAc) and elicits negative affective states upon drug withdrawal. However, there is evidence that the effects of KOR activation on affective state are biphasic: immediate aversive effects are followed by delayed increases in reward. The impact of KOR-induced affective states on reward-related effects of cocaine over time is not known. We hypothesize that the initial aversive effects of KOR activation increase, whereas the delayed rewarding effects decrease, the net effects of cocaine on reward and dopamine release. We treated rats with cocaine at various times (15 min to 48 h) after administration of the selective KOR agonist salvinorin A (salvA). Using intracranial self-stimulation and fast scan cyclic voltammetry, we found that cocaine-induced increases in brain stimulation reward and evoked dopamine release in the NAc core were potentiated when cocaine was administered within 1 h of salvA, but attenuated when administered 24 h after salvA. Quantitative real-time PCR was used to show that KOR and prodynorphin mRNA levels were decreased in the NAc, whereas tyrosine hydroxylase and dopamine transporter mRNA levels and tissue dopamine content were increased in the ventral tegmental area 24 h post-salvA. These findings raise the possibility that KOR activation-as occurs upon withdrawal from chronic cocaine-modulates vulnerability to cocaine in a time-dependent manner. PMID:26239494

  7. Activation of kappa-opioid receptor as a method for prevention of ischemic and reperfusion arrhythmias: role of protein kinase C and K(ATP) channels.

    PubMed

    Lishmanov, A Yu; Maslov, L N; Lasukova, T V; Crawford, D; Wong, T M

    2007-02-01

    Intravenous pretreatment with kappa-opioid receptor antagonist (-)-U-50,488 (1 mg/kg) improved heart resistance to the arrhythmogenic effect of coronary occlusion and reperfusion. Selective kappa1-opioid receptor antagonist norbinaltorphimine and nonselective blocker of peripheral opioid receptors methylnaloxone abolished this antiarrhythmic effect. Preliminary blockade of protein kinase C with chelerythrine or inhibition of ATP-dependent K+ channels (K(ATP) channels) with glybenclamide abolished the antiarrhythmic effect of kappa-opioid receptor activation. Selective inhibitor of sarcolemmal K(ATP) channels did not modulate the kappa-opioid receptor-mediated increase in cardiac electrical stability. Our results suggest that protein kinase C and mitochondrial K(ATP) channels play an important role in the antiarrhythmic effect associated with activation of peripheral kappa-opioid receptors. PMID:17970197

  8. Harnessing endogenous growth factor activity modulates stem cell behavior

    PubMed Central

    Hudalla, Gregory A.; Kouris, Nicholas A.; Koepsel, Justin T.; Ogle, Brenda M.; Murphy, William L.

    2014-01-01

    The influence of specific serum-borne biomolecules (e.g. heparin) on growth factor-dependent cell behavior is often difficult to elucidate in traditional cell culture due to the random, non-specific nature of biomolecule adsorption from serum. We hypothesized that chemically well-defined cell culture substrates could be used to study the influence of sequestered heparin on human mesenchymal stem cell (hMSC) behavior. Specifically, we used bio-inert self-assembled monolayers (SAMs) chemically modified with a bioinspired heparin-binding peptide (termed “HEPpep”) and an integrin-binding peptide (RGDSP) as stem cell culture substrates. Our results demonstrate that purified heparin binds to HEPpep SAMs in a dose-dependent manner, and serum-borne heparin binds specifically and in a dose-dependent manner to HEPpep SAMs. These heparin-sequestering SAMs enhance hMSC proliferation by amplifying endogenous fibroblast growth factor (FGF) signaling, and enhance hMSC osteogenic differentiation by amplifying endogenous bone morphogenetic protein (BMP) signaling. The effects of heparin-sequestering are similar to the effects of supraphysiologic concentrations of recombinant FGF-2. hMSC phenotype is maintained over multiple population doublings on heparin-sequestering substrates in growth medium, while hMSC osteogenic differentiation is enhanced in a bone morphogenetic protein-dependent manner on the same substrates during culture in osteogenic induction medium. Together, these observations demonstrate that the influence of the substrate on stem cell phenotype is sensitive to the culture medium formulation. Our results also demonstrate that enhanced hMSC proliferation can be spatially localized by patterning the location of HEPpep on the substrate. Importantly, the use of chemically well-defined SAMs in this study eliminated the confounding factor of random, non-specific biomolecule adsorption, and identified serum-borne heparin as a key mediator of hMSC response to endogenous

  9. Touch Perception Altered by Chronic Pain and by Opioid Blockade1,2,3

    PubMed Central

    Gracely, John L.; Richards, Emily A.; Olausson, Håkan

    2016-01-01

    Abstract Touch plays a significant role in human social behavior and social communication, and its rewarding nature has been suggested to involve opioids. Opioid blockade in monkeys leads to increased solicitation and receipt of grooming, suggesting heightened enjoyment of touch. We sought to study the role of endogenous opioids in perception of affective touch in healthy adults and in patients with fibromyalgia, a chronic pain condition shown to involve reduced opioid receptor availability. The pleasantness of touch has been linked to the activation of C-tactile fibers, which respond maximally to slow gentle touch and correlate with ratings of pleasantness. We administered naloxone to patients and healthy controls to directly observe the consequences of µ-opioid blockade on the perceived pleasantness and intensity of touch. We found that at baseline chronic pain patients showed a blunted distinction between slow and fast brushing for both intensity and pleasantness, suggesting reduced C-tactile touch processing. In addition, we found a differential effect of opioid blockade on touch perception in healthy subjects and pain patients. In healthy individuals, opioid blockade showed a trend toward increased ratings of touch pleasantness, while in chronic pain patients it significantly decreased ratings of touch intensity. Further, in healthy individuals, naloxone-induced increase in touch pleasantness was associated with naloxone-induced decreased preference for slow touch, suggesting a possible effect of opioid levels on processing of C-tactile fiber input. These findings suggest a role for endogenous opioids in touch processing, and provide further evidence for altered opioid functioning in chronic pain patients. PMID:27022625

  10. Spatiotemporal control of opioid signaling and behavior

    PubMed Central

    Siuda, Edward R.; Copits, Bryan A.; Schmidt, Martin J.; Baird, Madison A.; Al-Hasani, Ream; Planer, William J.; Funderburk, Samuel C.; McCall, Jordan G.; Gereau, Robert W.; Bruchas, Michael R.

    2015-01-01

    Summary Optogenetics is now a widely accepted tool for spatiotemporal manipulation of neuronal activity. However, a majority of optogenetic approaches use binary on/off control schemes. Here we extend the optogenetic toolset by developing a neuromodulatory approach using a rationale-based design to generate a Gi-coupled, optically-sensitive, mu-opioid-like receptor, we term opto-MOR. We demonstrate that opto-MOR engages canonical mu-opioid signaling through inhibition of adenylyl cyclase, activation of MAPK and G protein-gated inward rectifying potassium (GIRK) channels, and internalizes with similar kinetics as the mu-opioid receptor. To assess in vivo utility we expressed a Cre-dependent viral opto-MOR in RMTg/VTA GABAergic neurons, which led to a real-time place preference. In contrast, expression of opto-MOR in GABAergic neurons of the ventral pallidum hedonic cold spot, led to real-time place aversion. This tool has generalizable application for spatiotemporal control of opioid signaling and, furthermore, can be used broadly for mimicking endogenous neuronal inhibition pathways. PMID:25937173

  11. Activation of κ-opioid receptor exerts the glucose-homeostatic effect in streptozotocin-induced diabetic mice.

    PubMed

    Shang, Yulong; Guo, Fan; Li, Juan; Fan, Rong; Ma, Xinliang; Wang, Yuemin; Feng, Na; Yin, Yue; Jia, Min; Zhang, Shumiao; Zhou, Jingjun; Wang, Hongbing; Pei, Jianming

    2015-02-01

    Opioid and its receptors play important roles in glucose homeostasis. However, few reports were available for the study of κ-opioid receptor in glucose regulation. In our study, we found that the blood glucose of diabetic mice dropped significantly following the treatment with U50,488H (a selective κ-opioid receptor agonist). This phenomenon was time-dependent and associated with the coincident alteration of Glut4 translocation in the skeleton muscles. U50,488H increased the serum adiponectin, but not serum insulin in diabetic mice. U50,488H increased the AdipoR1 expression at both mRNA and protein levels. It also promoted AMPK phosphorylation and Glut4 translocation. All these effects were abolished by nor-BNI (a selective κ-opioid receptor antagonist). These findings suggest that activation of κ-opioid receptor reduces hyperglycemia in streptozotocin-induced diabetic mice. This effect is associated with the translocation of Glut4 and might be relevant to increased adiponectin, AdipoR1, and AMPK phosphorylation. PMID:25186835

  12. Opioid modulation of taste hedonics within the ventral striatum.

    PubMed

    Kelley, A E; Bakshi, V P; Haber, S N; Steininger, T L; Will, M J; Zhang, M

    2002-07-01

    There is a long-standing interest in the role of endogenous opioid peptides in feeding behavior and, in particular, in the modulation of food reward and palatability. Since drugs such as heroin, morphine, alcohol, and cannabinoids, interact with this system, there may be important common neural substrates between food and drug reward with regard to the brain's opioid systems. In this paper, we review the proposed functional role of opioid neurotransmission and mu opiate receptors within the nucleus accumbens and surrounding ventral striatum. Opioid compounds, particularly those selective for the mu receptor, induce a potent increase in food intake, sucrose, salt, saccharin, and ethanol intake. We have explored this phenomenon with regard to macronutrient selection, regional specificity, role of output structures, Fos mapping, analysis of motivational state, and enkephalin gene expression. We hypothesize that opioid-mediated mechanisms within ventral striatal medium spiny neurons mediate the affective or hedonic response to food ('liking' or food 'pleasure'). A further refinement of this hypothesis is that activation of ventral striatal opioids specifically encodes positive affect induced by tasty and/or calorically dense foods (such as sugar and fat), and promotes behaviors associated with this enhanced palatability. It is proposed that this brain mechanism was beneficial in evolutionary development for ensuring the consumption of relatively scarce, high-energy food sources. However, in modern times, with unlimited supplies of high-calorie food, it has contributed to the present epidemic of obesity. PMID:12117573

  13. Enhanced efficacy (intrinsic activity) of cyclic opioid peptide analogs at the. mu. -receptor

    SciTech Connect

    Schiller, P.W.; Lemieux, C.; Nguyen, T.M.D.; Maziak, L.A.

    1986-05-01

    Side-chain to end group cyclized enkephalin analogs (e.g. H-Tyr-cyclo(-D-Lys-Gly-Phe-Leu-) and cyclic opioid peptide analogs obtained through covalent linkage of two side-chains (e.g. H-Tyr-D-Cys-Gly-Phe-Cys-NH/sub 2/ or H-Tyr-D-Lys-Gly-Phe-Glu-NH/sub 3/) were tested in the ..mu..-receptor-representative guinea pig ileum (GPI) bioassay and in a binding assay based on displacement of the ..mu..-ligand (/sup 3/H)DAGO from rat brain membranes. The cyclic analogs were 5 to 70 times more potent in the GPI assay than in the binding assay, whereas linear analogs showed equal potency in the two assays. These results suggest that the efficacy (intrinsic activity) of cyclic opioid peptide analogs at the ..mu..-receptor is increased as a consequence of the conformation constraint imposed through ring closure. This effect was most pronounced in analogs containing a long hydrophobic sidechain as part of the ring structure in the 2-position of the peptide sequence. Further experimental evidence ruled out the possibilities that these potency discrepancies may be due to differences in enzymatic degradation, dissimilar exposure of the receptors in their lipid environment or interaction with different receptor types in the two assay systems. It can be hypothesized that the semi-rigid cyclic analogs may induce a more productive conformational change in the receptor protein than the linear peptides.

  14. Collybolide is a novel biased agonist of κ-opioid receptors with potent antipruritic activity.

    PubMed

    Gupta, Achla; Gomes, Ivone; Bobeck, Erin N; Fakira, Amanda K; Massaro, Nicholas P; Sharma, Indrajeet; Cavé, Adrien; Hamm, Heidi E; Parello, Joseph; Devi, Lakshmi A

    2016-05-24

    Among the opioid receptors, the κ-opioid receptor (κOR) has been gaining considerable attention as a potential therapeutic target for the treatment of complex CNS disorders including depression, visceral pain, and cocaine addiction. With an interest in discovering novel ligands targeting κOR, we searched natural products for unusual scaffolds and identified collybolide (Colly), a nonnitrogenous sesquiterpene from the mushroom Collybia maculata. This compound has a furyl-δ-lactone core similar to that of Salvinorin A (Sal A), another natural product from the plant Salvia divinorum Characterization of the molecular pharmacological properties reveals that Colly, like Sal A, is a highly potent and selective κOR agonist. However, the two compounds differ in certain signaling and behavioral properties. Colly exhibits 10- to 50-fold higher potency in activating the mitogen-activated protein kinase pathway compared with Sal A. Taken with the fact that the two compounds are equipotent for inhibiting adenylyl cyclase activity, these results suggest that Colly behaves as a biased agonist of κOR. Behavioral studies also support the biased agonistic activity of Colly in that it exhibits ∼10-fold higher potency in blocking non-histamine-mediated itch compared with Sal A, and this difference is not seen in pain attenuation by these two compounds. These results represent a rare example of functional selectivity by two natural products that act on the same receptor. The biased agonistic activity, along with an easily modifiable structure compared with Sal A, makes Colly an ideal candidate for the development of novel therapeutics targeting κOR with reduced side effects. PMID:27162327

  15. Dynorphin A (1-13) Neurotoxicity In Vitro: Opioid and Non-Opioid Mechanisms in Mouse Spinal Cord Neurons

    PubMed Central

    Hauser, Kurt F.; Foldes, Jane K.; Turbek, Carol S.

    2016-01-01

    Dynorphin A is an endogenous opioid peptide that preferentially activates κ opioid receptors and is antinociceptive at physiological concentrations. Levels of dynorphin A and a major metabolite, dynorphin A (1-13), increase significantly following spinal cord trauma and reportedly contribute to neurodegeneration associated with secondary injury. Interestingly, both κ opioid and N-methyl-D-aspartate (NMDA) receptor antagonists can modulate dynorphin toxicity, suggesting that dynorphin is acting (directly or indirectly) through κ opioid and/or NMDA receptor (NMDAR) types. Despite these findings, few studies have systematically explored dynorphin toxicity at the cellular level in defined populations of neurons co-expressing κ opioid and NMDA receptors. To address this question, we isolated populations of neurons enriched in both κ opioid and NMDA receptors from embryonic mouse spinal cord and examined the effects of dynorphin A (1-13) on intracellular calcium concentration ([Ca2+]i) and neuronal survival in vitro. Time-lapse photography was used to repeatedly follow the same neurons before and during experimental treatments. At micromolar concentrations, dynorphin A (1-13) elevated [Ca2+]i and caused a significant loss of neurons. The excitotoxic effects were prevented by MK-801 (Dizocilpine) (10 μM), 2-amino-5-phosphopentanoic acid (AP-5) (100 μM), or 7-chlorokynurenic acid (100 μM)— suggesting that dynorphin A (1-13) was acting (directly or indirectly) through NMDA receptors. In contrast, co-treatment with (−)-naloxone (3 μM), or the more selective κ opioid receptor antagonist nor-binaltorphimine (3 μM), exacerbated dynorphin A (1-13)-induced neuronal loss; however, cell losses were not enhanced by the inactive stereoisomer (+)-naloxone (3 μM). Neuronal losses were not seen with exposure to the opioid antagonists alone (10 μM). Thus, opioid receptor blockade significantly increased toxicity, but only in the presence of excitotoxic levels of

  16. Exploring pharmacological activities and signaling of morphinans substituted in position 6 as potent agonists interacting with the μ opioid receptor

    PubMed Central

    2014-01-01

    Background Opioid analgesics are the most effective drugs for the treatment of moderate to severe pain. However, they also produce several adverse effects that can complicate pain management. The μ opioid (MOP) receptor, a G protein-coupled receptor, is recognized as the opioid receptor type which primarily mediates the pharmacological actions of clinically used opioid agonists. The morphinan class of analgesics including morphine and oxycodone are of main importance as therapeutically valuable drugs. Though the natural alkaloid morphine contains a C-6-hydroxyl group and the semisynthetic derivative oxycodone has a 6-carbonyl function, chemical approaches have uncovered that functionalizing position 6 gives rise to a range of diverse activities. Hence, position 6 of N-methylmorphinans is one of the most manipulated sites, and is established to play a key role in ligand binding at the MOP receptor, efficacy, signaling, and analgesic potency. We have earlier reported on a chemically innovative modification in oxycodone resulting in novel morphinans with 6-acrylonitrile incorporated substructures. Results This study describes in vitro and in vivo pharmacological activities and signaling of new morphinans substituted in position 6 with acrylonitrile and amido functions as potent agonists and antinociceptive agents interacting with MOP receptors. We show that the presence of a 6-cyano group in N-methylmorphinans has a strong influence on the binding to the opioid receptors and post-receptor signaling. One 6-cyano-N-methylmorphinan of the series was identified as the highest affinity and most selective MOP agonist, and very potent in stimulating G protein coupling and intracellular calcium release through the MOP receptor. In vivo, this MOP agonist showed to be greatly effective against thermal and chemical nociception in mice with marked increased antinociceptive potency than the lead molecule oxycodone. Conclusion Development of such novel chemotypes by targeting

  17. Nociceptin/Orphanin FQ Receptor Structure, Signaling, Ligands, Functions, and Interactions with Opioid Systems.

    PubMed

    Toll, Lawrence; Bruchas, Michael R; Calo', Girolamo; Cox, Brian M; Zaveri, Nurulain T

    2016-04-01

    The NOP receptor (nociceptin/orphanin FQ opioid peptide receptor) is the most recently discovered member of the opioid receptor family and, together with its endogenous ligand, N/OFQ, make up the fourth members of the opioid receptor and opioid peptide family. Because of its more recent discovery, an understanding of the cellular and behavioral actions induced by NOP receptor activation are less well developed than for the other members of the opioid receptor family. All of these factors are important because NOP receptor activation has a clear modulatory role on mu opioid receptor-mediated actions and thereby affects opioid analgesia, tolerance development, and reward. In addition to opioid modulatory actions, NOP receptor activation has important effects on motor function and other physiologic processes. This review discusses how NOP pharmacology intersects, contrasts, and interacts with the mu opioid receptor in terms of tertiary structure and mechanism of receptor activation; location of receptors in the central nervous system; mechanisms of desensitization and downregulation; cellular actions; intracellular signal transduction pathways; and behavioral actions with respect to analgesia, tolerance, dependence, and reward. This is followed by a discussion of the agonists and antagonists that have most contributed to our current knowledge. Because NOP receptors are highly expressed in brain and spinal cord and NOP receptor activation sometimes synergizes with mu receptor-mediated actions and sometimes opposes them, an understanding of NOP receptor pharmacology in the context of these interactions with the opioid receptors will be crucial to the development of novel therapeutics that engage the NOP receptor. PMID:26956246

  18. Antithrombotic and Antioxidant Activity of Amaranth Hydrolysate Obtained by Activation of an Endogenous Protease.

    PubMed

    Sabbione, Ana Clara; Ibañez, Sabrina M; Martínez, E Nora; Añón, María Cristina; Scilingo, Adriana A

    2016-06-01

    Ingestion of diets with antithrombotic and antioxidant components offer a convenient and effective way to prevent and reduce the incidence of cardiovascular diseases. The aim of the present work was to obtain an amaranth hydrolysate by the activation of an endogenous aspartic protease, to establish adequate experimental conditions, and to evaluate its antithrombotic and antioxidant activity in order to assess its potential application as an ingredient in functional foods. The results obtained not only confirmed the presence of an endogenous protease in the amaranth isolate, but also allowed us to select an adequate incubation conditions (pH 2, 40 °C, 16 h). The hydrolysate obtained (degree of hydrolysis 5.3 ± 0.4 %) showed potential antithrombotic activity (IC50 = 5.9 ± 0.1 mg soluble protein/mL) and had more antioxidant activity than the isolate, indicating that the activation of the protease released bioactive peptides from amaranth proteins. Decreasing the pH is a simple and cheap process and is another way to obtain potential functional ingredients with bioactive compounds. PMID:27023251

  19. Opioid Analgesics.

    PubMed

    Jamison, Robert N; Mao, Jianren

    2015-07-01

    Chronic pain is an international health issue of immense importance that is influenced by both physical and psychological factors. Opioids are useful in treating chronic pain but have accompanying complications. It is important for clinicians to understand the basics of opioid pharmacology, the benefits and adverse effects of opioids, and related problematic issues of tolerance, dependence, and opioid-induced hyperalgesia. In this article, the role of psychiatric comorbidity and the use of validated assessment tools to identify individuals who are at the greatest risk for opioid misuse are discussed. Additionally, interventional treatment strategies for patients with chronic pain who are at risk for opioid misuse are presented. Specific behavioral interventions designed to improve adherence with prescription opioids among persons treated for chronic pain, such as frequent monitoring, periodic urine screens, opioid therapy agreements, opioid checklists, and motivational counseling, are also reviewed. Use of state-sponsored prescription drug monitoring programs is also encouraged. Areas requiring additional investigation are identified, and the future role of abuse-deterrent opioids and innovative technology in addressing issues of opioid therapy and pain are presented. PMID:26141334

  20. Regulation of plasma motilin by opioids in the dog.

    PubMed

    Poitras, P; Boivin, M; Lahaie, R G; Trudel, L

    1989-07-01

    In the first part of this study, we compared the effects of morphine and trimebutine, two opioid receptor agonists, on small intestinal motility and plasma motilin in dogs. Morphine (100 micrograms/kg iv for 10 min) induced first a typical vomiting myoelectric profile followed subsequently by a migrating electrical activity mimicking phase III of the migrating myoelectric complex; trimebutine (5 mg/kg iv for 10 min) initiated only a migrating phase III-like activity. Despite their different initial contractile effects, both agents induced a significant and similar rise in plasma motilin that preceded the beginning of the premature phase III. In the second portion of the study, naloxone, an opioid receptor antagonist, was infused to verify the influence of endogenous opiates on plasma motilin and on the migrating motor complex. Naloxone (2 mg/kg, then 0.5 mg.kg-1.h-1 iv) delayed significantly the cyclic recurrence of plasma motilin peak increases and of the phase IIIs. In some animals, where naloxone abolished the phase IIIs, the amplitude of the motilin peak increases was significantly diminished. These results suggest 1) that opioid administration increases plasma levels of motilin by a mechanism that is independent of the intestinal contractile activity, and 2) that endogenous opioids could be physiological inducers of plasma motilin increases in the conscious dog. PMID:2546442

  1. Pharmacological properties of novel cyclic pentapeptides with µ-opioid receptor agonist activity.

    PubMed

    Perlikowska, Renata; Piekielna, Justyna; Fichna, Jakub; do-Rego, Jean Claude; Toth, Geza; Janecki, Tomasz; Janecka, Anna

    2014-03-01

    In our previous paper we have reported the synthesis and biological activity of a cyclic analog, Tyr-c(D-Lys- Phe-Phe-Asp)-NH2, based on endomorphin-2 (EM-2) structure. This analog displayed high affinity for the µ-opioid receptor, was much more stable than EM-2 in rat brain homogenate and showed remarkable antinociceptive activity after intracerebroventricular (i.c.v.) injection. Even more importantly, the cyclic analog elicited weak analgesia also after peripheral administration, giving evidence that it was able to cross, at least to some extent, the blood-brain barrier (BBB). Here we describe further modifications of this analog aimed at enhancing brain delivery by increasing lipophilicity. Two new cyclic pentapeptides, Tyr-c(D-Lys-D-1-Nal-Phe-Asp)-NH2 and Tyr-c(D-Lys-D-2-Nal-Phe-Asp)-NH2 (where 1-Nal=1- naphthyl-3-alanine, 2-Nal=2-naphthyl-3-alanine) were synthesized and evaluated in biological assays. Both analogs showed high µ-opioid receptor affinity and agonist activity and were stable in the rat brain homogenates. Unfortunately, the increase of lipophilicity was achieved at the expense of water solubility. The analog with D-2-Nal residue showed strong analgesic effect when given i.c.v. but could not be tested after intravenous (i.v.) administration where higher concentrations of the compound are required. However, this analog showed inhibitory effect on gastrointestinal (GI) motility in vivo, providing an interesting approach to the development of peripherally restricted agents that could be useful for studying gastrointestinal disorders in animal models. PMID:23628088

  2. Opioid receptors and their ligands in the musculoskeletal system and relevance for pain control.

    PubMed

    Spetea, Mariana

    2013-01-01

    Interest in opioid drugs like morphine, as the oldest and most potent pain-killing agents known, has been maintained through the years. One of the most frequent chronic pain sensations people experience is associated with pathological conditions of the musculoskeletal system. Chronic musculoskeletal pain is a major health problem, and an adequate management requires understanding of both peripheral and central components, with more attention drawn to the former. Intense experimental and clinical research activities resulted in important knowledge on the mechanisms and functions of the endogenous opioid system located in the periphery. This review describes the occurrence and distribution of endogenous opioids and their receptors in the musculoskeletal system, and their role in pain control in musculoskeletal disorders, such as rheumatoid arthritis and osteoarthritis. Using different techniques, including immunohistochemistry, electron microscopy or radioimmunoassay, expression of enkephalins, dynorphin, β-endorphin, and endomorphins was demonstrated in musculoskeletal tissues of animals and humans. Localization of opioid peptides was found in synovial membrane, periosteum, bone and bone marrow, loose connective tissue, the paratenon and musculotendinous junction of the achilles tendon. Animal and human studies have also demonstrated expression of µ, δ and κ opioid receptor proteins in musculoskeletal tissues using radioligand binding assays, autoradiography, electrophysiology, immunohistochemistry and Western blotting. Opioid receptor gene expression was reported based on polymerase chain reaction and in situ hybridization techniques. Combining morphological and quantitative approaches, important evidence that the musculoskeletal apparatus is equipped with a peripheral opioid system is provided. Demonstration of the occurrence of an endogenous opioid system in bone and joint tissues represents an essential step for defining novel pharmacological strategies to

  3. Seizures, refractory status epilepticus, and depolarization block as endogenous brain activities

    NASA Astrophysics Data System (ADS)

    El Houssaini, Kenza; Ivanov, Anton I.; Bernard, Christophe; Jirsa, Viktor K.

    2015-01-01

    Epilepsy, refractory status epilepticus, and depolarization block are pathological brain activities whose mechanisms are poorly understood. Using a generic mathematical model of seizure activity, we show that these activities coexist under certain conditions spanning the range of possible brain activities. We perform a detailed bifurcation analysis and predict strategies to escape from some of the pathological states. Experimental results using rodent data provide support of the model, highlighting the concept that these pathological activities belong to the endogenous repertoire of brain activities.

  4. Opportunistic activation of TRP receptors by endogenous lipids: Exploiting lipidomics to understand TRP receptor cellular communication

    PubMed Central

    Bradshaw, Heather B.; Raboune, Siham; Hollis, Jennifer L.

    2012-01-01

    Transient receptor potential channels (TRPs) form a large family of ubiquitous non-selective cation channels that function as cellular sensors and in many cases regulate intracellular calcium. Identification of the endogenous ligands that activate these TRP receptors is still under intense investigation with the majority of these channels still remaining “orphans”. That these channels respond to a variety of external stimuli (e.g. plant-derived lipids, changes in temperature, and changes in pH) provides a framework for their abilities as cellular sensors, however, the mechanism of direct activation is still under much debate and research. In the cases where endogenous ligands (predominately lipids) have shown direct activation of a channel, multiple ligands have been shown to activate the same channel suggesting that these receptors are “promiscuous” in nature. Lipidomics of a growing class of endogenous lipids, N-acyl amides, the most famous of which is N-arachidonoyl ethanolamine (the endogenous cannabinoid, Anandamide) is providing a novel set of ligands that have been shown to activate some members of the TRP family and have the potential to deorphanize many more. Here it is argued that activation of TRPV receptors, a subset of the larger family of TRPs, by multiple endogenous lipids that are structurally analogous is a model system to drive our understanding that many TRP receptors are not promiscuous, but are more characteristically “opportunistic” in nature; exploiting the structural similarity and biosynthesis of a narrow range of analogous endogenous lipids. In addition, this manuscript will compare the activation properties of TRPC5 to the activity profile of an “orphan” lipid, N-palmitoyl glycine; further demonstrating that lipidomics aimed at expanding our knowledge of the family of N-acyl amides has the potential to provide novel avenues of research for TRP receptors. PMID:23178153

  5. The opioid receptors as targets for drug abuse medication

    PubMed Central

    Noble, Florence; Lenoir, Magalie; Marie, Nicolas

    2015-01-01

    The endogenous opioid system is largely expressed in the brain, and both endogenous opioid peptides and receptors are present in areas associated with reward and motivation. It is well known that this endogenous system plays a key role in many aspects of addictive behaviours. The present review summarizes the modifications of the opioid system induced by chronic treatment with drugs of abuse reported in preclinical and clinical studies, as well as the action of opioid antagonists and agonists on the reinforcing effects of drugs of abuse, with therapeutic perspectives. We have focused on the effects of chronic psychostimulants, alcohol and nicotine exposure. Taken together, the changes in both opioid peptides and opioid receptors in different brain structures following acute or chronic exposure to these drugs of abuse clearly identify the opioid system as a potential target for the development of effective pharmacotherapy for the treatment of addiction and the prevention of relapse. PMID:25988826

  6. The opioid receptors as targets for drug abuse medication.

    PubMed

    Noble, Florence; Lenoir, Magalie; Marie, Nicolas

    2015-08-01

    The endogenous opioid system is largely expressed in the brain, and both endogenous opioid peptides and receptors are present in areas associated with reward and motivation. It is well known that this endogenous system plays a key role in many aspects of addictive behaviours. The present review summarizes the modifications of the opioid system induced by chronic treatment with drugs of abuse reported in preclinical and clinical studies, as well as the action of opioid antagonists and agonists on the reinforcing effects of drugs of abuse, with therapeutic perspectives. We have focused on the effects of chronic psychostimulants, alcohol and nicotine exposure. Taken together, the changes in both opioid peptides and opioid receptors in different brain structures following acute or chronic exposure to these drugs of abuse clearly identify the opioid system as a potential target for the development of effective pharmacotherapy for the treatment of addiction and the prevention of relapse. PMID:25988826

  7. Role of opioid ligands in the irritable bowel syndrome.

    PubMed

    Corazziari, E

    1999-03-01

    Endogenous opioid peptides - enkephalins, beta-endorphin and dynorphins - are located in specific sites of the brain, the spinal cord, the autonomic ganglia and the enteric nervous system. Endogenous opioids participate in the regulation of nervous visceral afference and sensitivity as well as of several visceral motor function induced by the central nervous system and through the enteroenteric and the myoenteric reflexes. Their final effect on gut physiology is the net and harmonically balanced result of their binding to mu, delta and kappa opioid receptor subtypes. Exogenous opioid receptor ligands with different affinities for the opioid receptor subtypes have been effectively used to modify and normalize altered gut functions. The mu receptor agonists - morphine and, to a greater extent, the meperidine congeners diphenoxylate and loperamide - have been shown to slow gastrointestinal transit by their effects on the circular and longitudinal muscle of the intestine. Diphenoxylate and, more efficiently, loperamide, for the lack of any effect on the central nervous system, have been usefully employed in the treatment of diarrhea in irritable bowel syndrome (IBS) patients. Unlike the mu receptor agonists morphine and loperamide, which invariably stimulate colonic motility, trimebutine, which has almost equal affinity for mu, delta and kappa receptors, has no effect on normal colonic activity but reduces the abnormal increase in postprandial motor activity in IBS patients and accelerates slow large bowel transit in constipated patients. Opioid ligands can be usefully employed to normalize altered visceral sensitivity in IBS patients. The kappa receptor agonist fedotozine exerts its antinociceptive effect by acting on peripheral nerve endings of sensory vagal and nonvagal afferent pathways. Fedotozine has been shown to increase the threshold of perception to colonic distension in experimental conditions and to affect favourably symptoms of IBS in clinical trials. PMID

  8. N-METHYL-d-ASPARTATE RECEPTORS AND LARGE CONDUCTANCE CALCIUM-SENSITIVE POTASSIUM CHANNELS INHIBIT THE RELEASE OF OPIOID PEPTIDES THAT INDUCE μ-OPIOID RECEPTOR INTERNALIZATION IN THE RAT SPINAL CORD

    PubMed Central

    SONG, B.; MARVIZÓN, J. C. G.

    2006-01-01

    Endogenous opioids in the spinal cord play an important role in nociception, but the mechanisms that control their release are poorly understood. To simultaneously detect all opioids able to activate the μ-opioid receptor, we measured μ-opioid receptor internalization in rat spinal cord slices stimulated electrically or chemically to evoke opioid release. Electrical stimulation of the dorsal horn in the presence of peptidase inhibitors produced μ-opioid receptor internalization in half of the μ-opioid receptor neurons. This internalization was rapidly abolished by N-methyl-d-aspartate (IC50=2 μM), and N-methyl-d-aspartate antagonists prevented this effect. μ-Opioid receptor internalization evoked by high K+ or veratridine was also inhibited by N-methyl-d-aspartate receptor activation. N-methyl-d-aspartate did not affect μ-opioid receptor internalization induced by exogenous endomorphins, confirming that the effect of N-methyl-d-aspartate was on opioid release. We hypothesized that this inhibition was mediated by large conductance Ca2+-sensitive K+ channels BK(Ca2+). Indeed, inhibition by N-methyl-d-aspartate was prevented by tetraethylammonium and by the selective BK(Ca2+) blockers paxilline, penitrem A and verruculogen. Paxilline did not increase μ-opioid receptor internalization in the absence of N-methyl-d-aspartate, indicating that it does not produce an increase in opioid release unrelated to the inhibition by N-methyl-d-aspartate. The BK(Ca2+) involved appears to be a subtype with slow association kinetics for iberiotoxin, which was effective only with long incubations. The BK(Ca2+) opener NS-1619 also inhibited the evoked μ-opioid receptor internalization, and iberiotoxin prevented this effect. We concluded that Ca2+ influx through N-methyl-d-aspartate receptors causes the opening of BK(Ca2+) and hyperpolarization in opioid-containing dorsal horn neurons, resulting in the inhibition of opioid release. Since μ-opioid receptors in the dorsal horn

  9. N-methyl-D-aspartate receptors and large conductance calcium-sensitive potassium channels inhibit the release of opioid peptides that induce mu-opioid receptor internalization in the rat spinal cord.

    PubMed

    Song, B; Marvizón, J C G

    2005-01-01

    Endogenous opioids in the spinal cord play an important role in nociception, but the mechanisms that control their release are poorly understood. To simultaneously detect all opioids able to activate the mu-opioid receptor, we measured mu-opioid receptor internalization in rat spinal cord slices stimulated electrically or chemically to evoke opioid release. Electrical stimulation of the dorsal horn in the presence of peptidase inhibitors produced mu-opioid receptor internalization in half of the mu-opioid receptor neurons. This internalization was rapidly abolished by N-methyl-D-aspartate (IC50=2 microM), and N-methyl-D-aspartate antagonists prevented this effect. mu-Opioid receptor internalization evoked by high K+ or veratridine was also inhibited by N-methyl-D-aspartate receptor activation. N-methyl-D-aspartate did not affect mu-opioid receptor internalization induced by exogenous endomorphins, confirming that the effect of N-methyl-D-aspartate was on opioid release. We hypothesized that this inhibition was mediated by large conductance Ca2+-sensitive K+ channels BK(Ca2+). Indeed, inhibition by N-methyl-D-aspartate was prevented by tetraethylammonium and by the selective BK(Ca2+) blockers paxilline, penitrem A and verruculogen. Paxilline did not increase mu-opioid receptor internalization in the absence of N-methyl-D-aspartate, indicating that it does not produce an increase in opioid release unrelated to the inhibition by N-methyl-d-aspartate. The BK(Ca2+) involved appears to be a subtype with slow association kinetics for iberiotoxin, which was effective only with long incubations. The BK(Ca2+) opener NS-1619 also inhibited the evoked mu-opioid receptor internalization, and iberiotoxin prevented this effect. We concluded that Ca2+ influx through N-methyl-D-aspartate receptors causes the opening of BK(Ca2+) and hyperpolarization in opioid-containing dorsal horn neurons, resulting in the inhibition of opioid release. Since mu-opioid receptors in the dorsal horn

  10. Buprenorphine for opioid addiction

    PubMed Central

    Ling, Walter; Mooney, Larissa; Torrington, Matthew

    2014-01-01

    SUMMARY Buprenorphine is a partial opioid agonist of the µ-receptor, and is used as a daily dose sublingual tablet or filmstrip for managing opioid addiction. In the USA, the Drug Addiction Treatment Act of 2000 made buprenorphine the only opioid medication for opioid addiction that can be prescribed in an office-based setting. Owing to its high affinity for the µ-receptor, buprenorphine inhibits the reinforcing effect of exogenous opioids. The ceiling effect of buprenorphine's µ-agonist activity reduces the potential for drug overdose and confers low toxicity even at high doses. Buprenorphine pharmacotherapy has proven to be a treatment approach that supports recovery from addiction while reducing or curtailing the use of opioids. This article examines buprenorphine pharmacotherapy for opioid addiction, focusing on the situation in the USA, and is based on a review of pertinent literature, and the authors’ research and clinical experience. The references in this paper were chosen according to the authors’ judgment of quality and relevance, and with respect to their familiarity and involvement in related research. PMID:24654720

  11. Sexual activity, endogenous reproductive hormones and ovulation in premenopausal women.

    PubMed

    Prasad, Ankita; Mumford, Sunni L; Buck Louis, Germaine M; Ahrens, Katherine A; Sjaarda, Lindsey A; Schliep, Karen C; Perkins, Neil J; Kissell, Kerri A; Wactawski-Wende, Jean; Schisterman, Enrique F

    2014-07-01

    We investigated whether sexual activity was associated with reproductive function in the BioCycle Study, a prospective cohort study that followed 259 regularly menstruating women aged 18 to 44years for one (n=9) or two (n=250) menstrual cycles in 2005-2007. Women were not attempting pregnancy nor using hormonal contraceptives. History of ever having been sexually active was assessed at baseline and frequency of sexual activity, defined as vaginal-penile intercourse, was self-reported daily throughout the study. Serum concentrations of estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and testosterone were measured up to 8times/cycle. Sporadic anovulation was identified using peak progesterone concentration. Linear mixed models were used to estimate associations between sexual activity and reproductive hormone concentrations and generalized linear models were used to estimate associations with sporadic anovulation. Models were adjusted for age, race, body mass index, perceived stress, and alcohol consumption and accounted for repeated measures within women. Elevated concentrations of estrogen (+14.6%, P<.01), luteal progesterone (+41.0%, P<.01) and mid-cycle LH (+23.4%, P<.01), but not FSH (P=.33) or testosterone (P=.37), were observed in sexually active women compared with sexually inactive women (no prior and no study-period sexual activity); sexually active women had lower odds of sporadic anovulation (adjusted odds ratio=0.34, 95% confidence interval: 0.16-0.73). Among sexually active women, frequency of sexual activity was not associated with hormones or sporadic anovulation (all P>.23). Findings from our study suggest that ever having been sexually active is associated with improved reproductive function, even after controlling for factors such as age. PMID:24954690

  12. SHARPIN is an endogenous inhibitor of beta1-integrin activation

    PubMed Central

    Rantala, Juha K.; Pouwels, Jeroen; Pellinen, Teijo; Veltel, Stefan; Laasola, Petra; Potter, Christopher S.; Duffy, Ted; Sundberg, John P.; Kallioniemi, Olli; Askari, Janet A.; Humphries, Martin; Parsons, Maddy; Salmi, Marko; Ivaska, Johanna

    2012-01-01

    Regulated activation of integrins is critical for cell adhesion, motility and tissue homeostasis. Talin and Kindlins activate β1-integrins, but the counteracting inhibiting mechanisms are poorly defined. Here we identified SHARPIN as an important inactivator of β1-integrins in an RNAi-screen. SHARPIN inhibited β1-integrin functions in human cancer cells and primary leukocytes. Fibroblasts, leukocytes and keratinocytes from SHARPIN-deficient mice exhibited increased β1-integrin activity which was fully rescued by re-expression of SHARPIN. SHARPIN directly bound to a conserved cytoplasmic region of integrin α-subunits and inhibited recruitment of Talin and Kindlin to the integrin. Therefore, SHARPIN inhibits the critical switching of β1-integrins from inactive to active conformations. PMID:21947080

  13. The diverse clinical uses of opioid receptor drugs.

    PubMed

    Howland, Robert H

    2010-05-01

    Opioid receptors are widely distributed throughout the nervous system. In addition to their central role in brain pathways mediating pain, endogenous opioid peptides function as neuromodulators and opioid systems are involved in many physiological functions. Opioid receptor drugs, including methadone (Dolophine), buprenorphine (Buprenex, Subutex), naltrexone (Revia), naloxone (Narcan), and buprenorphine/naloxone (Suboxone), are the focus of this article. This class of drugs is likely to be further developed for the treatment of addictions and mood disorders. PMID:20415289

  14. 3D modeling, ligand binding and activation studies of the cloned mouse delta, mu; and kappa opioid receptors.

    PubMed

    Filizola, M; Laakkonen, L; Loew, G H

    1999-11-01

    Refined 3D models of the transmembrane domains of the cloned delta, mu and kappa opioid receptors belonging to the superfamily of G-protein coupled receptors (GPCRs) were constructed from a multiple sequence alignment using the alpha carbon template of rhodopsin recently reported. Other key steps in the procedure were relaxation of the 3D helix bundle by unconstrained energy optimization and assessment of the stability of the structure by performing unconstrained molecular dynamics simulations of the energy optimized structure. The results were stable ligand-free models of the TM domains of the three opioid receptors. The ligand-free delta receptor was then used to develop a systematic and reliable procedure to identify and assess putative binding sites that would be suitable for similar investigation of the other two receptors and GPCRs in general. To this end, a non-selective, 'universal' antagonist, naltrexone, and agonist, etorphine, were used as probes. These ligands were first docked in all sites of the model delta opioid receptor which were sterically accessible and to which the protonated amine of the ligands could be anchored to a complementary proton-accepting residue. Using these criteria, nine ligand-receptor complexes with different binding pockets were identified and refined by energy minimization. The properties of all these possible ligand-substrate complexes were then examined for consistency with known experimental results of mutations in both opioid and other GPCRs. Using this procedure, the lowest energy agonist-receptor and antagonist-receptor complexes consistent with these experimental results were identified. These complexes were then used to probe the mechanism of receptor activation by identifying differences in receptor conformation between the agonist and the antagonist complex during unconstrained dynamics simulation. The results lent support to a possible activation mechanism of the mouse delta opioid receptor similar to that recently

  15. Transglutaminase from Streptomyces mobaraensis is activated by an endogenous metalloprotease.

    PubMed

    Zotzel, J; Keller, P; Fuchsbauer, H-L

    2003-08-01

    Streptomyces mobaraensis secretes a Ca2+-independent transglutaminase (TGase) that is activated by removing an N-terminal peptide from a precursor protein during submerged culture in a complex medium [Pasternack, R., Dorsch, S., Otterbach, J. T., Robenek, I. R., Wolf, S. & Fuchsbauer, H.-L. (1998) Eur. J. Biochem. 257, 570-576]. However, an activating protease could not be identified, probably because of the presence of a 14-kDa protein (P14) belonging to the Streptomyces subtilisin inhibitor family. In contrast, if the microorganism was allowed to grow on a minimal medium, several soluble proteases were extracted, among them the TGase-activating protease (TAMEP). TAMEP was purified by sequential chromatography on DEAE- and Arg-Sepharose and used to determine the cleavage site of TGase. It was clearly shown that the peptide bond between Phe(-4) and Ser(-5) was hydrolyzed, indicating that at least one additional peptidase is necessary to complete TGase processing, even if TAMEP cleavage was sufficient to obtain total activity. Sequence analysis from the N-terminus of TAMEP revealed the close relationship to a zinc endo-protease from S. griseus. The S. griseus protease differs from other members of the M4 protease family, such as thermolysin, in that it may be inhibited by the Streptomyces subtilisin inhibitor. P14 likewise inhibits TAMEP in approximately equimolar concentrations, suggesting its important role in regulating TGase activity. PMID:12869197

  16. Endogenous Sequential Cortical Activity Evoked by Visual Stimuli

    PubMed Central

    Miller, Jae-eun Kang; Hamm, Jordan P.; Jackson, Jesse; Yuste, Rafael

    2015-01-01

    Although the functional properties of individual neurons in primary visual cortex have been studied intensely, little is known about how neuronal groups could encode changing visual stimuli using temporal activity patterns. To explore this, we used in vivo two-photon calcium imaging to record the activity of neuronal populations in primary visual cortex of awake mice in the presence and absence of visual stimulation. Multidimensional analysis of the network activity allowed us to identify neuronal ensembles defined as groups of cells firing in synchrony. These synchronous groups of neurons were themselves activated in sequential temporal patterns, which repeated at much higher proportions than chance and were triggered by specific visual stimuli such as natural visual scenes. Interestingly, sequential patterns were also present in recordings of spontaneous activity without any sensory stimulation and were accompanied by precise firing sequences at the single-cell level. Moreover, intrinsic dynamics could be used to predict the occurrence of future neuronal ensembles. Our data demonstrate that visual stimuli recruit similar sequential patterns to the ones observed spontaneously, consistent with the hypothesis that already existing Hebbian cell assemblies firing in predefined temporal sequences could be the microcircuit substrate that encodes visual percepts changing in time. PMID:26063915

  17. Targeting the opioid growth factor: opioid growth factor receptor axis for treatment of human ovarian cancer.

    PubMed

    Zagon, Ian S; Donahue, Renee; McLaughlin, Patricia J

    2013-05-01

    The opioid growth factor (OGF) - opioid growth factor receptor (OGFr) axis is a biological pathway that is present in human ovarian cancer cells and tissues. OGF, chemically termed [Met(5)]-enkephalin, is an endogenous opioid peptide that interfaces with OGFr to delay cells moving through the cell cycle by upregulation of cyclin-dependent inhibitory kinase pathways. OGF inhibitory activity is dose dependent, receptor mediated, reversible, protein and RNA dependent, but not related to apoptosis or necrosis. The OGF-OGFr axis can be targeted for treatment of human ovarian cancer by (i) administration of exogenous OGF, (ii) genetic manipulation to over-express OGFr and (iii) use of low dosages of naltrexone, an opioid antagonist, which stimulates production of OGF and OGFr for subsequent interaction following blockade of the receptor. The OGF-OGFr axis may be a feasible target for treatment of cancer of the ovary (i) in a prophylactic fashion, (ii) following cytoreduction or (iii) in conjunction with standard chemotherapy for additive effectiveness. In summary, preclinical data support the transition of these novel therapies for treatment of human ovarian cancer from the bench to bedside to provide additional targets for treatment of this devastating disease. PMID:23856908

  18. Methadone, monoamine oxidase, and depression: opioid distribution and acute effects on enzyme activity

    SciTech Connect

    Kaufmann, C.A.; Kreek, M.J.; Raghunath, J.; Arns, P.

    1983-09-01

    Narcotic withdrawal is often accompanied by an atypical depression which responds to resumption of narcotics. It was hypothesized that methadone might exert its antidepressant effects through monoamine oxidase (MAO) inhibition. The current study examined /sub 3/H-methadone distribution in rat brain and effects on regional MAO activity with acute doses (2.5 mg/kg) which approximate those found during chronic methadone maintenance in man. Limbic areas (amygdala, basomedial hypothalamus, caudate-putamen, hippocampus, preoptic nucleus), as well as pituitary and liver were assayed for MAO activity and methadone concentration. MAO activities did not differ significantly in acute methadone or saline-treated cage-mates at 1 or 24 hr. The concentrations of methadone at 1 hr ranged between 17 and 223 ng/100 mg wet wt tissue in the preoptic nucleus and pituitary, respectively. No significant correlation was found between change in MAO activity (MAO methadone/MAO saline) and methadone concentration in any region at 1 or 24 hr. This study does not support the hypothesis that methadone acts as an antidepressant through MAO inhibition, at least not following acute administration of this exogenous opioid.

  19. GIRK Channels Modulate Opioid-Induced Motor Activity in a Cell Type- and Subunit-Dependent Manner

    PubMed Central

    Kotecki, Lydia; Hearing, Matthew; McCall, Nora M.; Marron Fernandez de Velasco, Ezequiel; Pravetoni, Marco; Arora, Devinder; Victoria, Nicole C.; Munoz, Michaelanne B.; Xia, Zhilian; Slesinger, Paul A.; Weaver, C. David

    2015-01-01

    G-protein-gated inwardly rectifying K+ (GIRK/Kir3) channel activation underlies key physiological effects of opioids, including analgesia and dependence. GIRK channel activation has also been implicated in the opioid-induced inhibition of midbrain GABA neurons and consequent disinhibition of dopamine (DA) neurons in the ventral tegmental area (VTA). Drug-induced disinhibition of VTA DA neurons has been linked to reward-related behaviors and underlies opioid-induced motor activation. Here, we demonstrate that mouse VTA GABA neurons express a GIRK channel formed by GIRK1 and GIRK2 subunits. Nevertheless, neither constitutive genetic ablation of Girk1 or Girk2, nor the selective ablation of GIRK channels in GABA neurons, diminished morphine-induced motor activity in mice. Moreover, direct activation of GIRK channels in midbrain GABA neurons did not enhance motor activity. In contrast, genetic manipulations that selectively enhanced or suppressed GIRK channel function in midbrain DA neurons correlated with decreased and increased sensitivity, respectively, to the motor-stimulatory effect of systemic morphine. Collectively, these data support the contention that the unique GIRK channel subtype in VTA DA neurons, the GIRK2/GIRK3 heteromer, regulates the sensitivity of the mouse mesolimbic DA system to drugs with addictive potential. PMID:25948263

  20. The evolution of vertebrate opioid receptors

    PubMed Central

    Stevens, Craig W.

    2011-01-01

    The proteins that mediate the analgesic and other effects of opioid drugs and endogenous opioid peptides are known as opioid receptors. Opioid receptors consist of a family of four closely-related proteins belonging to the large superfamily of G-protein coupled receptors. The three types of opioid receptors shown unequivocally to mediate analgesia in animal models are the mu (MOR), delta (DOR), and kappa (KOR) opioid receptor proteins. The role of the fourth member of the opioid receptor family, the nociceptin or orphanin FQ receptor (ORL), is not as clear as hyperalgesia, analgesia, and no effect was reported after administration of ORL agonists. There are now cDNA sequences for all four types of opioid receptors that are expressed in the brain of six species from three different classes of vertebrates. This review presents a comparative analysis of vertebrate opioid receptors using bioinformatics and data from recent human genome studies. Results indicate that opioid receptors arose by gene duplication, that there is a vector of opioid receptor divergence, and that MOR shows evidence of rapid evolution. PMID:19273128

  1. Dual allosteric modulation of opioid antinociceptive potency by α2A-adrenoceptors.

    PubMed

    Chabot-Doré, Anne-Julie; Millecamps, Magali; Naso, Lina; Devost, Dominic; Trieu, Phan; Piltonen, Marjo; Diatchenko, Luda; Fairbanks, Carolyn A; Wilcox, George L; Hébert, Terence E; Stone, Laura S

    2015-12-01

    Opioid and α2-adrenoceptor (AR) agonists are analgesic when administered in the spinal cord and show a clinically beneficial synergistic interaction when co-administered. However, α2-AR antagonists can also inhibit opioid antinociception, suggesting a complex interaction between the two systems. The α2A-AR subtype is necessary for spinal adrenergic analgesia and synergy with opioids for most agonist combinations. Therefore, we investigated whether spinal opioid antinociception and opioid-adrenergic synergy were under allosteric control of the α2A-AR. Drugs were administered intrathecally in wild type (WT) and α2A-knock-out (KO) mice and antinociception was measured using the hot water tail immersion or substance P behavioral assays. The α2A-AR agonist clonidine was less effective in α2A-KO mice in both assays. The absence of the α2A-AR resulted in 10-70-fold increases in the antinociceptive potency of the opioid agonists morphine and DeltII. In contrast, neither morphine nor DeltII synergized with clonidine in α2A-KO mice, indicating that the α2AAR has both positive and negative modulatory effects on opioid antinociception. Depletion of descending adrenergic terminals with 6-OHDA resulted in a significant decrease in morphine efficacy in WT but not in α2A-KO mice, suggesting that endogenous norepinephrine acts through the α2A-AR to facilitate morphine antinociception. Based on these findings, we propose a model whereby ligand-occupied versus ligand-free α2A-AR produce distinct patterns of modulation of opioid receptor activation. In this model, agonist-occupied α2A-ARs potentiate opioid analgesia, while non-occupied α2A-ARs inhibit opioid analgesia. Exploiting such interactions between the two receptors could lead to the development of better pharmacological treatments for pain management. PMID:26254859

  2. Structure-Activity Relationships of the Peptide Kappa Opioid Receptor Antagonist Zyklophin.

    PubMed

    Joshi, Anand A; Murray, Thomas F; Aldrich, Jane V

    2015-11-25

    The dynorphin (Dyn) A analogue zyklophin ([N-benzyl-Tyr(1)-cyclo(d-Asp(5),Dap(8))]dynorphin A(1-11)NH2) is a kappa opioid receptor (KOR)-selective antagonist in vitro, is active in vivo, and antagonizes KOR in the CNS after systemic administration. Hence, we synthesized zyklophin analogues to explore the structure-activity relationships of this peptide. The synthesis of selected analogues required modification to introduce the N-terminal amino acid due to poor solubility and/or to avoid epimerization of this residue. Among the N-terminal modifications, the N-phenethyl and N-cyclopropylmethyl substitutions resulted in analogues with the highest KOR affinities. Pharmacological results for the alanine-substituted analogues indicated that Phe(4) and Arg(6), but interestingly not the Tyr(1) phenol, are important for zyklophin's KOR affinity and that Arg(7) was important for KOR antagonist activity. In the GTPγS assay, while all of the cyclic analogues exhibited negligible KOR efficacy, the N-cyclopropylmethyl-Tyr(1) and N-benzyl-Phe(1) analogues were 28- and 11-fold more potent KOR antagonists, respectively, than zyklophin. PMID:26491810

  3. A light-inducible CRISPR/Cas9 system for control of endogenous gene activation

    PubMed Central

    Polstein, Lauren R.; Gersbach, Charles A.

    2015-01-01

    Optogenetic systems enable precise spatial and temporal control of cell behavior. We engineered a light-activated CRISPR/Cas9 effector (LACE) system that induces transcription of endogenous genes in the presence of blue light. This was accomplished by fusing the light-inducible heterodimerizing proteins CRY2 and CIB1 to a transactivation domain and the catalytically inactive dCas9, respectively. The versatile LACE system can be easily directed to new DNA sequences for the dynamic regulation of endogenous genes. PMID:25664691

  4. Reduced endogenous Ca2+ buffering speeds active zone Ca2+ signaling.

    PubMed

    Delvendahl, Igor; Jablonski, Lukasz; Baade, Carolin; Matveev, Victor; Neher, Erwin; Hallermann, Stefan

    2015-06-01

    Fast synchronous neurotransmitter release at the presynaptic active zone is triggered by local Ca(2+) signals, which are confined in their spatiotemporal extent by endogenous Ca(2+) buffers. However, it remains elusive how rapid and reliable Ca(2+) signaling can be sustained during repetitive release. Here, we established quantitative two-photon Ca(2+) imaging in cerebellar mossy fiber boutons, which fire at exceptionally high rates. We show that endogenous fixed buffers have a surprisingly low Ca(2+)-binding ratio (∼ 15) and low affinity, whereas mobile buffers have high affinity. Experimentally constrained modeling revealed that the low endogenous buffering promotes fast clearance of Ca(2+) from the active zone during repetitive firing. Measuring Ca(2+) signals at different distances from active zones with ultra-high-resolution confirmed our model predictions. Our results lead to the concept that reduced Ca(2+) buffering enables fast active zone Ca(2+) signaling, suggesting that the strength of endogenous Ca(2+) buffering limits the rate of synchronous synaptic transmission. PMID:26015575

  5. Reduced endogenous Ca2+ buffering speeds active zone Ca2+ signaling

    PubMed Central

    Delvendahl, Igor; Jablonski, Lukasz; Baade, Carolin; Matveev, Victor; Neher, Erwin; Hallermann, Stefan

    2015-01-01

    Fast synchronous neurotransmitter release at the presynaptic active zone is triggered by local Ca2+ signals, which are confined in their spatiotemporal extent by endogenous Ca2+ buffers. However, it remains elusive how rapid and reliable Ca2+ signaling can be sustained during repetitive release. Here, we established quantitative two-photon Ca2+ imaging in cerebellar mossy fiber boutons, which fire at exceptionally high rates. We show that endogenous fixed buffers have a surprisingly low Ca2+-binding ratio (∼15) and low affinity, whereas mobile buffers have high affinity. Experimentally constrained modeling revealed that the low endogenous buffering promotes fast clearance of Ca2+ from the active zone during repetitive firing. Measuring Ca2+ signals at different distances from active zones with ultra-high-resolution confirmed our model predictions. Our results lead to the concept that reduced Ca2+ buffering enables fast active zone Ca2+ signaling, suggesting that the strength of endogenous Ca2+ buffering limits the rate of synchronous synaptic transmission. PMID:26015575

  6. Endogenous heparan sulfate and heparin modulate bone morphogenetic protein-4 signaling and activity.

    PubMed

    Khan, Shaukat A; Nelson, Matthew S; Pan, Chendong; Gaffney, Patrick M; Gupta, Pankaj

    2008-06-01

    Bone morphogenetic proteins (BMPs) and their endogenous antagonists are important for brain and bone development and tumor initiation and progression. Heparan sulfate (HS) proteoglycans (HSPG) modulate the activities of BMPs and their antagonists. How glycosaminoglycans (GAGs) influence BMP activity in various malignancies and in inherited abnormalities of GAG metabolism, and the structural features of GAGs essential for modulation of BMP signaling, remain incompletely defined. We examined whether chemically modified soluble heparins, the endogenous HS in malignant cells and the HS accumulated in Hurler syndrome cells influence BMP-4 signaling and activity. We show that both exogenous (soluble) and endogenous GAGs modulate BMP-4 signaling and activity, and that this effect is dependent on specific sulfate residues of GAGs. Our studies suggest that endogenous sulfated GAGs promote the proliferation and impair differentiation of malignant human cells, providing the rationale for investigating whether pharmacological agents that inhibit GAG synthesis or function might reverse this effect. Our demonstration of impairment of BMP-4 signaling by GAGs in multipotent stem cells in human Hurler syndrome identifies a mechanism that might contribute to the progressive neurological and skeletal abnormalities in Hurler syndrome and related mucopolysaccharidoses. PMID:18385288

  7. Endogenous KCNE Subunits Govern Kv2.1 K+ Channel Activation Kinetics in Xenopus Oocyte Studies

    PubMed Central

    Gordon, Earl; Roepke, Torsten K.; Abbott, Geoffrey W.

    2006-01-01

    Kv2.1 is a voltage-gated potassium (Kv) channel that generates delayed rectifier currents in mammalian heart and brain. The biophysical properties of Kv2.1 and other ion channels have been characterized by functional expression in heterologous systems, and most commonly in Xenopus laevis oocytes. A number of previous oocyte-based studies of mammalian potassium channels have revealed expression-level-dependent changes in channel properties, leading to the suggestion that endogenous oocyte factors regulate channel gating. Here, we show that endogenous oocyte potassium channel KCNE ancillary subunits xMinK and xMiRP2 slow the activation of oocyte-expressed mammalian Kv2.1 channels two-to-fourfold. This produces a sigmoidal relationship between Kv2.1 current density and activation rate in oocyte-based two-electrode voltage clamp studies. The effect of endogenous xMiRP2 and xMinK on Kv2.1 activation is diluted at high Kv2.1 expression levels, or by RNAi knockdown of either endogenous subunit. RNAi knockdown of both xMiRP2 and xMinK eliminates the correlation between Kv2.1 expression level and activation kinetics. The data demonstrate a molecular basis for expression-level-dependent changes in Kv channel gating observed in heterologous expression studies. PMID:16326911

  8. Antinociceptive effect of 7-hydroxymitragynine in mice: Discovery of an orally active opioid analgesic from the Thai medicinal herb Mitragyna speciosa.

    PubMed

    Matsumoto, Kenjiro; Horie, Syunji; Ishikawa, Hayato; Takayama, Hiromitsu; Aimi, Norio; Ponglux, Dhavadee; Watanabe, Kazuo

    2004-03-12

    Mitragynine is an indole alkaloid isolated from the Thai medicinal plant Mitragyna speciosa. We previously reported the morphine-like action of mitragynine and its related compounds in the in vitro assays. In the present study, we investigated the opioid effects of 7-hydroxymitragynine, which is isolated as its novel constituent, on contraction of isolated ileum, binding of the specific ligands to opioid receptors and nociceptive stimuli in mice. In guinea-pig ileum, 7-hydroxymitragynine inhibited electrically induced contraction through the opioid receptors. Receptor-binding assays revealed that 7-hydroxymitragynine has a higher affinity for micro-opioid receptors relative to the other opioid receptors. Administration of 7-hydroxymitragynine (2.5-10 mg/kg, s.c.) induced dose-dependent antinociceptive effects in tail-flick and hot-plate tests in mice. Its effect was more potent than that of morphine in both tests. When orally administered, 7-hydroxymitragynine (5-10 mg/kg) showed potent antinociceptive activities in tail-flick and hot-plate tests. In contrast, only weak antinociception was observed in the case of oral administration of morphine at a dose of 20 mg/kg. It was found that 7-hydroxymitragynine is a novel opioid agonist that is structurally different from the other opioid agonists, and has potent analgesic activity when orally administered. PMID:14969718

  9. Identification of short-acting κ-opioid receptor antagonists with anxiolytic-like activity.

    PubMed

    Peters, Matthew F; Zacco, Anna; Gordon, John; Maciag, Carla M; Litwin, Linda C; Thompson, Carolann; Schroeder, Patricia; Sygowski, Linda A; Piser, Timothy M; Brugel, Todd A

    2011-07-01

    The κ-opioid receptor plays a central role in mediating the response to stressful life events. Inhibiting κ-opioid receptor signaling is proposed as a mechanism for treating stress-related conditions such as depression and anxiety. Preclinical testing consistently confirms that disruption of κ-opioid signaling is efficacious in animal models of mood disorders. However, concerns about the feasibility of developing antagonists into drugs stem from an unusual pharmacodynamic property of prototypic κ-opioid receptor-selective antagonists; they inhibit receptor signaling for weeks to months after a single dose. Several fundamental questions include - is it possible to identify short-acting antagonists; is long-lasting inhibition necessary for efficacy; and is it safe to develop long-acting antagonists in the clinic. Here, we test representative compounds (AZ-ECPC, AZ-MTAB, and LY-DMPF) from three new chemical series of κ-opioid receptor ligands for long-lasting inhibition. Each compound dose-dependently reversed κ-opioid agonist-induced diuresis. However, unlike the prototypic antagonist, nBNI, which fully inhibited evoked diuresis for at least four weeks, the new compounds showed no inhibition after one week. The two compounds with greater potency and selectivity were tested in prenatally-stressed rats on the elevated plus maze, an exploration-based model of anxiety. Spontaneous exploration of open arms in the elevated plus maze was suppressed by prenatal stress and restored with both compounds. These findings indicate that persistent inhibition is not an inherent property of κ-opioid-selective antagonists and that post-stress dosing with transient inhibitors can be effective in a mood disorder model. This further supports κ-opioid receptor as a promising target for developing novel psychiatric medications. PMID:21539838

  10. Activation of μ opioid receptors in the LPBN facilitates sodium intake in rats.

    PubMed

    Pavan, Carolina G; Roncari, Camila F; Barbosa, Silas P; De Paula, Patrícia M; Colombari, Débora S A; De Luca, Laurival A; Colombari, Eduardo; Menani, José V

    2015-07-15

    Important inhibitory mechanisms for the control of water and sodium intake are present in the lateral parabrachial nucleus (LPBN). Opioid receptors are expressed by LPBN neurons and injections of β-endorphin (nonspecific opioid receptor agonist) in this area induce 0.3M NaCl and water intake in satiated rats. In the present study, we investigated the effects of the injections of endomorphin-1 (μ opioid receptor agonist) alone or combined with the blockade of μ, κ or δ opioid receptors into the LPBN on 0.3M NaCl and water intake induced by subcutaneous injections of the diuretic furosemide (FURO) combined with low dose of the angiotensin converting enzyme inhibitor captopril (CAP). Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. Bilateral injections of endomorphin-1 (0.1, 0.25, 0.5, 1.0, 2.0 and 4.0nmol/0.2μl) into the LPBN increased 0.3M NaCl and water intake induced by FURO+CAP. The previous blockade of μ opioid receptor with CTAP (1.0nmol/0.2μl) into the LPBN reduced the effect of endomorphin-1 on FURO+CAP-induced 0.3M NaCl. GNTI (κ opioid receptor antagonist; 2.0nmol/0.2μl) and naltrindole (δ opioid receptor antagonist; 2.0nmol/0.2μl) injected into the LPBN did not change the effects of endomorphin-1 on FURO+CAP-induced 0.3M NaCl. The results suggest that μ opioid receptors in the LPBN are involved in the control of sodium intake. PMID:25827924

  11. Asymmetric synthesis and in vitro and in vivo activity of tetrahydroquinolines featuring a diverse set of polar substitutions at the 6 position as mixed-efficacy μ opioid receptor/δ opioid receptor ligands.

    PubMed

    Bender, Aaron M; Griggs, Nicholas W; Anand, Jessica P; Traynor, John R; Jutkiewicz, Emily M; Mosberg, Henry I

    2015-08-19

    We previously reported a small series of mixed-efficacy μ opioid receptor (MOR) agonist/δ opioid receptor (DOR) antagonist peptidomimetics featuring a tetrahydroquinoline scaffold and showed the promise of this series as effective analgesics after intraperitoneal administration in mice. We report here an expanded structure-activity relationship study of the pendant region of these compounds and focus in particular on the incorporation of heteroatoms into this side chain. These analogues provide new insight into the binding requirements for this scaffold at MOR, DOR, and the κ opioid receptor (KOR), and several of them (10j, 10k, 10m, and 10n) significantly improve upon the overall MOR agonist/DOR antagonist profile of our previous compounds. In vivo data for 10j, 10k, 10m, and 10n are also reported and show the antinociceptive potency and duration of action of compounds 10j and 10m to be comparable to those of morphine. PMID:25938166

  12. [Variable magnetic field of 8 Hz corrects the opioid system activity in mollusks behind the ferromagnetic screening].

    PubMed

    Temur'iants, N A; Kostiuk, A S

    2014-01-01

    The three phases of mollusk nociception alteration as a result of extended ferromagnetic screening combined with exposure to a variable magnetic field of 8 Hz correlated with phase changes in the opioid system activity (OSA) deduced from the naloxone action on the thermal avoidance response. On phase I, OSA inactivation was inhibited and, consequently, hyperalgesia progression was expedited. On phase II, OSA rose so that naloxone annulled completely the antinociceptive effect produced by the ferromagnetic screening. On phase III, OSA declined progressively, as naloxone merely reduced the antinociceptive effect because of apparently, growing OSA tolerance to the ferromagnetic screening. Phase I was absent when mollusks were exposed to the ferromagnetic screening and variable magnetic field; however, OSA changes on phases II and III were present. It was concluded that the variable magnetic field of 8 Hz can be used for correcting changes in the opioid system activity in mollusks behind the ferromagnetic screening. PMID:25163338

  13. The opioid receptors of the rat periaqueductal gray

    SciTech Connect

    Fedynyshyn, J.P.

    1989-01-01

    The opioid binding characteristics of the rat (PAG) and the signal transduction mechanisms of the opioid receptors were examined with in vitro radioligand binding, GTPase, adenylyl cyclase, and inositol phosphate assays. The nonselective ligand {sup 3}H-ethylketocyclazocine (EKC), the {mu} and {delta} selective ligand {sup 3}H-(D-Ala{sup 2}, D-Leu{sup 5}) enkephalin (DADLE), the {mu} selective ligand {sup 3}H-(D-Ala{sup 2}, N-methyl Phe{sup 4}, Glyol{sup 5}) enkephalin (DAGO), and the {delta} selective ligand {sup 3}H-(D-Pen{sup 2}, D-Pen{sup 5}) enkephalin (DPDPE) were separately used as tracer ligands to label opioid binding sites in rat PAG enriched P{sub 2} membrane in competition with unlabeled DADLE, DAGO, DPDPE, or the {kappa} selective ligand trans-3,4-dichloro-N-(2-(1-pyrrolidinyl)cyclohexyl)benzeneacetamide, methane sulfonate, hydrate (U50, 488H). Only {mu} selective high affinity opioid binding was observed. No high affinity {delta} or {kappa} selective binding was detected. {sup 3}H-DAGO was used as a tracer ligand to label {mu} selective high affinity opioid binding sites in PAG enriched P{sub 2} membrane in competition with unlabeled {beta}-endorphin, dynorphin A (1-17), BAM-18, methionine enkephalin, dynorphin A (1-8), and leucine enkephalin. Of these endogenous opioid peptides only those with previously reported high affinity {mu} type opioid binding activity competed with {sup 3}H-DAGO for binding sites in rat PAG enriched P{sub 2} membrane with affinities similar to that of unlabeled DAGO.

  14. Estrogen changes as a critical factor in modulation of central opioid tonus: possible correlations with post-menopausal migraine.

    PubMed

    Genazzani, A R; Petraglia, F; Volpe, A; Facchinetti, F

    1985-05-01

    The effects exerted by ovarian steroids on the modulation of opioid activity were investigated in post-menopausal migraine sufferers and in healthy controls. In order to evaluate central opioid tonus, plasma LH rise after naloxone injection was measured, bearing in mind the tonic inhibition of endogenous opioid on hypothalamic LH-RH. There was no response of plasma LH to naloxone in post-menopausal women or in patients submitted to ovariectomy in fertile life. When the subjects underwent a sequential estrogens + progestagens therapy, such a response was noted from the first month of treatment; progestagens alone were ineffective. The same phenomena were also evident in post-menopausal migraine sufferers. These data indicate that ovarian steroids modulate the activity of opiate receptors in both healthy women and migraine sufferers. Interestingly, replacement therapies through ovarian steroids restored the activity of central opioid tonus in patients affected by migraine. PMID:2990722

  15. BU08073 a buprenorphine analogue with partial agonist activity at μ-receptors in vitro but long-lasting opioid antagonist activity in vivo in mice

    PubMed Central

    Khroyan, T V; Wu, J; Polgar, W E; Cami-Kobeci, G; Fotaki, N; Husbands, S M; Toll, L

    2015-01-01

    BACKGROUND AND PURPOSE Buprenorphine is a potent analgesic with high affinity at μ, δ and κ and moderate affinity at nociceptin opioid (NOP) receptors. Nevertheless, NOP receptor activation modulates the in vivo activity of buprenorphine. Structure activity studies were conducted to design buprenorphine analogues with high affinity at each of these receptors and to characterize them in in vitro and in vivo assays. EXPERIMENTAL APPROACH Compounds were tested for binding affinity and functional activity using [35S]GTPγS binding at each receptor and a whole-cell fluorescent assay at μ receptors. BU08073 was evaluated for antinociceptive agonist and antagonist activity and for its effects on anxiety in mice. KEY RESULTS BU08073 bound with high affinity to all opioid receptors. It had virtually no efficacy at δ, κ and NOP receptors, whereas at μ receptors, BU08073 has similar efficacy as buprenorphine in both functional assays. Alone, BU08073 has anxiogenic activity and produces very little antinociception. However, BU08073 blocks morphine and U50,488-mediated antinociception. This blockade was not evident at 1 h post-treatment, but is present at 6 h and remains for up to 3–6 days. CONCLUSIONS AND IMPLICATIONS These studies provide structural requirements for synthesis of ‘universal’ opioid ligands. BU08073 had high affinity for all the opioid receptors, with moderate efficacy at μ receptors and reduced efficacy at NOP receptors, a profile suggesting potential analgesic activity. However, in vivo, BU08073 had long-lasting antagonist activity, indicating that its pharmacokinetics determined both the time course of its effects and what receptor-mediated effects were observed. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24903063

  16. An opioid growth factor regulates the replication of microorganisms.

    PubMed

    Zagon, I S; McLaughlin, P J

    1992-01-01

    An opioid growth factor (OGF), [Met5]-enkephalin, interacts with the zeta (zeta) opioid receptor to modulate development of eukaryotes. We have found that [Met5]-enkephalin, an endogenous opioid peptide serves to inhibit the growth of S. aureus. This effect on growth involves cell proliferative events and is under tonic control, since potent opioid antagonists accelerate cell replication. Both the OGF and zeta opioid receptor were associated with these microorganisms. Other opioid receptors (mu, delta and kappa) were not detected. OGF also controlled the growth of other bacteria: P. aeruginosa and S. marcesans. These results indicate that OGF and its receptor, known to be important in the regulation of mammalian development, also function in the growth of simple unicellular organisms. We suggest that the endogenous opioid system related to growth originated billions of years ago. PMID:1313136

  17. Ethanol Disinhibits Dorsolateral Striatal Medium Spiny Neurons Through Activation of A Presynaptic Delta Opioid Receptor.

    PubMed

    Patton, Mary H; Roberts, Bradley M; Lovinger, David M; Mathur, Brian N

    2016-06-01

    The dorsolateral striatum mediates habit formation, which is expedited by exposure to alcohol. Across species, alcohol exposure disinhibits the DLS by dampening GABAergic transmission onto this structure's principal medium spiny projection neurons (MSNs), providing a potential mechanistic basis for habitual alcohol drinking. However, the molecular and circuit components underlying this disinhibition remain unknown. To examine this, we used a combination of whole-cell patch-clamp recordings and optogenetics to demonstrate that ethanol potently depresses both MSN- and fast-spiking interneuron (FSI)-MSN GABAergic synaptic transmission in the DLS. Concentrating on the powerfully inhibitory FSI-MSN synapse, we further show that acute exposure of ethanol (50 mM) to striatal slices activates delta opioid receptors that reside on FSI axon terminals and negatively couple to adenylyl cyclase to induce a long-term depression of GABA release onto both direct and indirect pathway MSNs. These findings elucidate a mechanism through which ethanol may globally disinhibit the DLS. PMID:26758662

  18. Synergistic effect of decreased opioid activity and sleep deprivation on head-twitch response in mice.

    PubMed

    Ionov, Ilya D

    2010-07-01

    In schizophrenia, an opioidergic understimulation and a decreased sleep duration are found. The pathogenic significance of these factors is unknown. The present study assessed the influence of the combination of the factors on serotonergic 2A (5-HT(2A)) receptors that are possibly related to psychosis development. 2,5-dimethoxy-4-iodoamphetamine (DOI)-induced head-twitch response in mice was used as a model of 5-HT(2A) receptor functioning. Mice underwent sleep deprivation and/or a blockade of opioidergic receptors with naloxone. To evaluate the involvement of 5-HT(2A) receptor in effects observed, animals were pretreated with MDL 100,907, a potent and selective antagonist of 5-HT(2A) receptor. As was found, 4h of sleep deprivation followed by administration of naloxone significantly increases the frequency of head twitches, with sleep deprivation and naloxone being ineffective alone. The action of the "sleep deprivation-opioid understimulation" combination is antagonized completely by MDL 100,907. Thus, some schizophrenia-associated factors can synergistically enhance the activity of 5-HT(2A) receptors. These results suggest the above factors being pathogenically relevant in schizophrenia. PMID:20399224

  19. “Listening” and “talking” to neurons: Implications of immune activation for pain control and increasing the efficacy of opioids

    PubMed Central

    Watkins, Linda R.; Hutchinson, Mark R.; Milligan, Erin D.; Maier, Steven F.

    2008-01-01

    It is recently become clear that activated immune cells and immune-like glial cells can dramatically alter neuronal function. By increasing neuronal excitability, these non-neuronal cells are now implicated in the creation and maintenance of pathological pain, such as occurs in response to peripheral nerve injury. Such effects are exerted at multiple sites along the pain pathway, including at peripheral nerves, dorsal root ganglia, and spinal cord. In addition, activated glial cells are now recognized as disrupting the pain suppressive effects of opioid drugs and contributing to opioid tolerance and opioid dependence/withdrawal. While this review focuses on regulation of pain and opioid actions, such immune-neuronal interactions are broad in their implications. Such changes in neuronal function would be expected to occur wherever immune-derived substances come in close contact with neurons. PMID:17706291

  20. Activation of μ Opioid Receptors Modulates Inflammation in Acute Experimental Colitis

    PubMed Central

    Anselmi, L.; Huynh, J.; Duraffourd, C.; Jaramillo, I.; Vegezzi, G.; Saccani, F; Boschetti, E.; Brecha, N.C.; De Giorgio, R.; Sternini, C

    2015-01-01

    Background μ opioid receptors (μORs) are expressed by neurons and inflammatory cells and mediate immune response. We tested whether activation of peripheral μORs ameliorates the acute and delayed phase of colitis. Methods C57BL/6J mice were treated with 3% dextran sodium sulfate in water, 5 days (DSS) with or without the peripherally-acting μOR agonist, [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin (DAMGO) or with DAMGO+μOR antagonist at day 2–5, then euthanized. Other mice received DSS followed by water for 4 weeks, or DSS with DAMGO starting at day 2 of DSS for 2 or 3 weeks followed by water, then euthanized at 4 weeks. Disease activity index (DAI), histological damage, and myeloperoxidase assay (MPO), as index of neutrophil infiltration, were evaluated. Cytokines and μOR mRNAs were measured with RT-PCR, and nuclear factor-kB (NF-kB), the antiapoptotic factor Bcl-xL, and caspase 3 and 7 with Western blot. Key Results DSS induced acute colitis with elevated DAI, tissue damage, apoptosis and increased MPO, cytokines, μOR mRNA and NF-kB. DAMGO significantly reduced DAI, inflammatory indexes, cytokines, and caspases, and NF-kB, and upregulated Bcl-xL, effects prevented by μOR antagonist. In DSS mice plus 4 weeks of water, DAI, NF-kB and μOR were normal, whereas MPO, histological damage and cytokines were still elevated; DAMGO did not reduce inflammation, and did not upregulate Bcl-xL. Conclusions & Inferences μOR activation ameliorated the acute but not the delayed phase of DSS colitis by reducing cytokines, likely through activation of the antiapoptotic factor, Bcl-xL, and suppression of NF- kB, a potentiator of inflammation. PMID:25690069

  1. Endometriosis Is Associated With a Shift in MU Opioid and NMDA Receptor Expression in the Brain Periaqueductal Gray.

    PubMed

    Torres-Reverón, Annelyn; Palermo, Karylane; Hernández-López, Anixa; Hernández, Siomara; Cruz, Myrella L; Thompson, Kenira J; Flores, Idhaliz; Appleyard, Caroline B

    2016-09-01

    Studies have examined how endometriosis interacts with the nervous system, but little attention has been paid to opioidergic systems, which are relevant to pain signaling. We used the autotransplantation rat model of endometriosis and allowed to progress for 60 days. The brain was collected and examined for changes in endogenous opioid peptides, mu opioid receptors (MORs), and the N-methyl-d-aspartate subunit receptor (NR1) in the periaqueductal gray (PAG), since both of these receptors can regulate PAG activity. No changes in endogenous opioid peptides in met- and leu-enkephalin or β-endorphin levels were observed within the PAG. However, MOR immunoreactivity was significantly decreased in the ventral PAG in the endometriosis group. Endometriosis reduced by 20% the number of neuronal profiles expressing MOR and reduced by 40% the NR1 profiles. Our results suggest that endometriosis is associated with subtle variations in opioidergic and glutamatergic activity within the PAG, which may have implications for pain processing. PMID:27089914

  2. Characteristics and Functional Roles of Opioids Originally Present in Vivo.

    PubMed

    Ozaki, Masanobu

    2016-01-01

    The characteristics and functional roles of opioids originally present in vivo (endogenous opioids) in guinea-pig ileum were investigated. The release of endogenous opioids was determined by the inhibitory twitch response evoked by 0.1 Hz stimulation after 10 Hz stimulation (post-tetanic twitch inhibition). The effects of peptidase inhibitors increased the post-tetanic twitch inhibition, prevented by β-funaltrexamine and nor-binaltorphimine, which are selective μ- and κ-opioid receptor subtype antagonists, respectively. Dopamine receptor antagonists (haloperidol, sultopride and domperidone) increased the post-tetanic twitch inhibition. These results suggest that dopamine receptors are involved in modulation of the ileal opioid system, so as to diminish endogenous opioid release by tetanic stimulation, and dopamine antagonists increase the opioid action, that might depend more on the increased release of endogenous opioids. The post-tetanic twitch inhibition was inhibited by adrenalectomy, and showed the supersensitivity of the opioid receptors, resulting from a decrease of endogenous opioids by adrenalectomy. These findings suggest that the increase in morphine-analgesia by adrenalectomy was due to this process. In the presence of naloxone, an opioid antagonist, an increase in basal tension after tetanic stimulation (10 Hz stimulation) (post-tetanic contraction) was observed, and was blocked by spantide, a substance P antagonist, and indomethacin, a prostaglandins-biosynthesis inhibitor. This contraction increased with morphine or peptidase inhibitor exposure, depending on the length of time the ileum was exposed to the morphine or peptidase inhibitor. Post-tetanic contraction might be a useful indicator of the formation of physical dependence to morphine or endogenous opioids in the ileum. PMID:27040344

  3. Comparing analgesia and μ-opioid receptor internalization produced by intrathecal enkephalin

    PubMed Central

    Chen, Wenling; Song, Bingbing; Lao, Lijun; Pérez, Orlando A.; Kim, Woojae; Marvizón, Juan Carlos G.

    2007-01-01

    Summary Opioid receptors in the spinal cord produce strong analgesia, but the mechanisms controlling their activation by endogenous opioids remain unclear. We have previously shown in spinal cord slices that peptidases preclude μ-opioid receptor (MOR) internalization by opioids. Our present goals were to investigate whether enkephalin-induced analgesia is also precluded by peptidases, and whether it is mediated by MORs or δ-opioid receptors (DORs). Tail-flick analgesia and MOR internalization were measured in rats injected intrathecally with Leu-enkephalin and peptidase inhibitors. Without peptidase inhibitors, Leu-enkephalin produced neither analgesia nor MOR internalization at doses up to 100 nmol, whereas with peptidase inhibitors it produced analgesia at 0.3 nmol and MOR internalization at 1 nmol. Leu-enkephalin was ten times more potent to produce analgesia than to produce MOR internalization, suggesting that DORs were involved. Selective MOR or DOR antagonists completely blocked the analgesia elicited by 0.3 nmol Leu-enkephalin (a dose that produced little MOR internalization), indicating that it involved these two receptors, possibly by an additive or synergistic interaction. The selective MOR agonist endomorphin-2 produced analgesia even in the presence of a DOR antagonist, but at doses substantially higher than Leu-enkephalin. Unlike Leu-enkephalin, endomorphin-2 had the same potencies to induce analgesia and MOR internalization. We concluded that low doses of enkephalins produce analgesia by activating both MORs and DORs. Analgesia can also be produced exclusively by MORs at higher agonist doses. Since peptidases prevent the activation of spinal opioid receptors by enkephalins, the coincident release of opioids and endogenous peptidase inhibitors may be required for analgesia. PMID:17845806

  4. Mu Opioid Receptor Binding Correlates with Nicotine Dependence and Reward in Smokers

    PubMed Central

    Brasic, James R.; Contoreggi, Carlo; Cascella, Nicola; Mackowick, Kristen M.; Taylor, Richard; Rousset, Olivier; Willis, William; Huestis, Marilyn A.; Concheiro, Marta; Wand, Gary; Wong, Dean F.; Volkow, Nora D.

    2014-01-01

    The rewarding effects of nicotine are associated with activation of nicotine receptors. However, there is increasing evidence that the endogenous opioid system is involved in nicotine's rewarding effects. We employed PET imaging with [11C]carfentanil to test the hypotheses that acute cigarette smoking increases release of endogenous opioids in the human brain and that smokers have an upregulation of mu opioid receptors (MORs) when compared to nonsmokers. We found no significant changes in binding potential (BPND) of [11C]carfentanil between the placebo and the active cigarette sessions, nor did we observe differences in MOR binding between smokers and nonsmokers. Interestingly, we showed that in smokers MOR availability in bilateral superior temporal cortices during the placebo condition was negatively correlated with scores on the Fagerström Test for Nicotine Dependence (FTND). Also in smokers, smoking-induced decreases in [11C]carfentanil binding in frontal cortical regions were associated with self-reports of cigarette liking and wanting. Although we did not show differences between smokers and nonsmokers, the negative correlation with FTND corroborates the role of MORs in superior temporal cortices in nicotine addiction and provides preliminary evidence of a role of endogenous opioid signaling in frontal cortex in nicotine reward. PMID:25493427

  5. Activation and Allosteric Modulation of Human μ Opioid Receptor in Molecular Dynamics.

    PubMed

    Bartuzi, Damian; Kaczor, Agnieszka A; Matosiuk, Dariusz

    2015-11-23

    Allosteric protein modulation has gained increasing attention in drug design. Its application as a mechanism of action could bring forth safer and more effective medicines. Targeting opioid receptors with allosteric modulators can result in better treatment of pain, depression, and respiratory and immune disorders. In this work we use recent reports on negative modulators of μ opioid receptor as a starting point for identification of allosteric sites and mechanisms of opioid receptor modulation using homology modeling and docking and molecular dynamics studies. An allosteric binding site description is presented. Results suggest a shared binding region for lipophilic allosteric ligands, reveal possible differences in the modulation mechanism between cannabinoids and salvinorin A, and show ambiguous properties of the latter. Also, they emphasize the importance of native-like environment in molecular dynamics simulations and uncover relationships between modulator and orthosteric ligand binding and receptor behavior. Relationships between ligands, transmission switch, and hydrophobic lock are analyzed. PMID:26517559

  6. Pharmacological Investigations of N-Substituent Variation in Morphine and Oxymorphone: Opioid Receptor Binding, Signaling and Antinociceptive Activity

    PubMed Central

    Ben Haddou, Tanila; Béni, Szabolcs; Hosztafi, Sándor; Malfacini, Davide; Calo, Girolamo; Schmidhammer, Helmut; Spetea, Mariana

    2014-01-01

    Morphine and structurally related derivatives are highly effective analgesics, and the mainstay in the medical management of moderate to severe pain. Pharmacological actions of opioid analgesics are primarily mediated through agonism at the µ opioid peptide (MOP) receptor, a G protein-coupled receptor. Position 17 in morphine has been one of the most manipulated sites on the scaffold and intensive research has focused on replacements of the 17-methyl group with other substituents. Structural variations at the N-17 of the morphinan skeleton led to a diversity of molecules appraised as valuable and potential therapeutics and important research probes. Discovery of therapeutically useful morphine-like drugs has also targeted the C-6 hydroxyl group, with oxymorphone as one of the clinically relevant opioid analgesics, where a carbonyl instead of a hydroxyl group is present at position 6. Herein, we describe the effect of N-substituent variation in morphine and oxymorphone on in vitro and in vivo biological properties and the emerging structure-activity relationships. We show that the presence of a N-phenethyl group in position 17 is highly favorable in terms of improved affinity and selectivity at the MOP receptor, potent agonism and antinociceptive efficacy. The N-phenethyl derivatives of morphine and oxymorphone were very potent in stimulating G protein coupling and intracellular calcium release through the MOP receptor. In vivo, they were highly effective against acute thermal nociception in mice with marked increased antinociceptive potency compared to the lead molecules. It was also demonstrated that a carbonyl group at position 6 is preferable to a hydroxyl function in these N-phenethyl derivatives, enhancing MOP receptor affinity and agonist potency in vitro and in vivo. These results expand the understanding of the impact of different moieties at the morphinan nitrogen on ligand-receptor interaction, molecular mode of action and signaling, and may be

  7. Regional differences in mu and kappa opioid receptor G-protein activation in brain in male and female prairie voles.

    PubMed

    Martin, T J; Sexton, T; Kim, S A; Severino, A L; Peters, C M; Young, L J; Childers, S R

    2015-12-17

    Prairie voles are unusual mammals in that, like humans, they are capable of forming socially monogamous pair bonds, display biparental care, and engage in alloparental behaviors. Both mu and kappa opioid receptors are involved in behaviors that either establish and maintain, or result from pair bond formation in these animals. Mu and kappa opioid receptors both utilize inhibitory G-proteins in signal transduction mechanisms, however the efficacy by which these receptor subtypes stimulate G-protein signaling across the prairie vole neuraxis is not known. Utilizing [(35)S]GTPγS autoradiography, we characterized the efficacy of G-protein stimulation in coronal sections throughout male and female prairie vole brains by [D-Ala2,NMe-Phe4,Gly-ol5]-enkephalin (DAMGO) and U50,488H, selective mu and kappa opioid agonists, respectively. DAMGO stimulation was highest in the forebrain, similar to that found with other rodent species. U-50,488H produced greater stimulation in prairie voles than is typically seen in mice and rats, particularly in select forebrain areas. DAMGO produced higher stimulation in the core versus the shell of the nucleus accumbens (NAc) in females, while the distribution of U-50,488H stimulation was the opposite. There were no gender differences for U50,488H stimulation of G-protein activity across the regions examined, while DAMGO stimulation was greater in sections from females compared to those from males for NAc core, entopeduncular nucleus, and hippocampus. These data suggest that the kappa opioid system may be more sensitive to manipulation in prairie voles compared to mice and rats, and that female prairie voles may be more sensitive to mu agonists in select brain regions than males. PMID:26523979

  8. Alterations of estrous activity in the ewe by circadian-based manipulation of the endogenous pacemaker.

    PubMed

    Guerin, M V; Matthews, C D

    1998-02-01

    The timing of reproductive activity in the seasonal breeding Romney Marsh ewe depends on the measurement of photoperiodic time. In this experiment, artificial light and dark signals are provided in a measured sequence at an inappropriate time of year to induce breeding out of phase with environmental photoperiod. The endogenous circadian responses and reproductive effects are documented. One group (Group A, control) of 6 Romney Marsh ewes was held in natural photoperiod throughout the experiment. For 8 weeks centered about the winter solstice (Stage 1), an additional 18 animals (Groups B, C, and D) were exposed to an artificial earlier dawn. Measurements of endogenous melatonin performed under acutely extended darkness confirmed a phase advance of the endogenous circadian pacemaker of the suprachiasmatic nucleus compared to control animals. In Stage 2, to the summer solstice (21 December), Group B animals were returned to natural photoperiod, Group C animals were subjected to an earlier artificial dusk, and Group D animals were subjected to an artificial delayed dawn. Melatonin measurements during Stage 2 confirmed that onset and offset times for Group C were earlier and that onset and offset times for Group D were delayed compared to corresponding times for Group B animals. Ovarian activity was monitored throughout. During Stage 2, Groups C and D commenced reproductive activity in mid-spring, and this continued until the experimental conditions changed. Groups A and B commenced reproductive activity at the normal timing in the subsequent autumn. Although not exclusive, these results are consistent with a coincidence model to explain the timing of seasonal breeding in this species with a dusk-located phase of the endogenous pacemaker sensitive to both light and melatonin. The temporal relationship between circadian alterations and the environmental photoperiod warrants further investigation as an explanation for seasonal breeding. PMID:9486844

  9. Brain opioid and nociceptin receptors are involved in regulation of bombesin-induced activation of central sympatho-adrenomedullary outflow in the rat.

    PubMed

    Yawata, Toshio; Higashi, Youichirou; Shimizu, Takahiro; Shimizu, Shogo; Nakamura, Kumiko; Taniuchi, Keisuke; Ueba, Tetsuya; Saito, Motoaki

    2016-01-01

    Previously, we reported that central administration of bombesin, a stress-related peptide, elevated plasma levels of catecholamines (noradrenaline and adrenaline) in the rat. The sympatho-adrenomedullary system, which is an important component of stress responses, can be regulated by the central opioid system. In the present study, therefore, we examined the roles of brain opioid receptor subtypes (µ, δ, and κ) and nociceptin receptors, originally identified as opioid-like orphan receptors, in the bombesin-induced activation of central sympatho-adrenomedullary outflow using anesthetized male Wistar rats. Intracerebroventricularly (i.c.v.) administered bombesin-(1 nmol/animal) induced elevation of plasma catecholamines was significantly potentiated by pretreatment with naloxone (300 and 1000 µg/animal, i.c.v.), a non-selective antagonist for µ-, δ-, and κ-opioid receptors. Pretreatment with cyprodime (100 µg/animal, i.c.v.), a selective antagonist for µ-opioid receptors, also potentiated the bombesin-induced responses. In contrast, pretreatment with naltrindole (100 µg/animal, i.c.v.) or nor-binaltorphimine (100 µg/animal, i.c.v.), a selective antagonist for δ- or κ-opioid receptors, significantly reduced the elevation of bombesin-induced catecholamines. In addition, pretreatment with JTC-801 (30 and 100 µg/animal, i.c.v.) or J-113397 (100 µg/animal, i.c.v.), which are selective antagonists for nociceptin receptors, also reduced the bombesin-induced responses. These results suggest that brain µ-opioid receptors play a suppressive role and that brain δ-, κ-opioid, and nociceptin receptors play a facilitative role in the bombesin-induced elevation of plasma catecholamines in the rat. Thus, in the brain, these receptors could play differential roles in regulating the activation of central sympatho-adrenomedullary outflow. PMID:26427671

  10. δ-Opioid Receptor Activation and MicroRNA Expression of the Rat Cortex in Hypoxia

    PubMed Central

    He, Xiaozhou; Moore, Meredith L.; Kang, Xuezhi; Chao, Dongman; Wang, Rong; Kim, Dong H.; Xia, Ying

    2012-01-01

    Prolonged hypoxic/ischemic stress may cause cortical injury and clinically manifest as a neurological disability. Activation of the δ-opioid receptor (DOR) may induce cortical protection against hypoxic/ischemic insults. However, the mechanisms underlying DOR protection are not clearly understood. We have recently found that DOR activation modulates the expression of microRNAs (miRNAs) in the kidney exposed to hypoxia, suggesting that DOR protection may involve a miRNA mechanism. To determine if the miRNAs expressed in the cortex mediated DOR neuroprotection, we examined 19 miRNAs that were previously identified as hypoxia- and DOR-regulated miRNAs in the kidney, in the rat cortex treated with UFP-512, a potent and specific DOR agonist under hypoxic condition. Of the 19 miRNAs tested, 17 were significantly altered by hypoxia and/or DOR activation with the direction and amplitude varying depending on hypoxic duration and times of DOR treatment. Expression of several miRNAs such as miR-29b, -101b, -298, 324-3p, -347 and 466b was significantly depressed after 24 hours of hypoxia. Similar changes were seen in normoxic condition 24 hours after DOR activation with one-time treatment of UFP-512. In contrast, some miRNAs were more tolerant to hypoxic stress and showed significant reduction only with 5-day (e.g., miR-31 and -186) or 10-day (e.g., miR-29a, let-7f and -511) exposures. In addition, these miRNAs had differential responses to DOR activation. Other miRNAs like miRs-363* and -370 responded only to the combined exposure to hypoxia and DOR treatment, with a notable reduction of >70% in the 5-day group. These data suggest that cortical miRNAs are highly yet differentially sensitive to hypoxia. DOR activation can modify, enhance or resolve the changes in miRNAs that target HIF, ion transport, axonal guidance, free radical signaling, apoptosis and many other functions. PMID:23272113

  11. μ-Opioid receptor activation and noradrenaline transport inhibition by tapentadol in rat single locus coeruleus neurons

    PubMed Central

    Sadeghi, Mahsa; Tzschentke, Thomas M; Christie, MacDonald J

    2015-01-01

    BACKGROUND AND PURPOSE Tapentadol is a novel analgesic that combines moderate μ-opioid receptor agonism and noradrenaline reuptake inhibition in a single molecule. Both mechanisms of action are involved in producing analgesia; however, the potency and efficacy of tapentadol in individual neurons has not been characterized. EXPERIMENTAL APPROACH Whole-cell patch-clamp recordings of G-protein-coupled inwardly rectifying K+ (KIR3.x) currents were made from rat locus coeruleus neurons in brain slices to investigate the potency and relative efficacy of tapentadol and compare its intrinsic activity with other clinically used opioids. KEY RESULTS Tapentadol showed agonist activity at μ receptors and was approximately six times less potent than morphine with respect to KIR3.x current modulation. The intrinsic activity of tapentadol was lower than [Met]enkephalin, morphine and oxycodone, but higher than buprenorphine and pentazocine. Tapentadol inhibited the noradrenaline transporter (NAT) with potency similar to that at μ receptors. The interaction between these two mechanisms of action was additive in individual LC neurons. CONCLUSIONS AND IMPLICATIONS Tapentadol displays similar potency for both µ receptor activation and NAT inhibition in functioning neurons. The intrinsic activity of tapentadol at the μ receptor lies between that of buprenorphine and oxycodone, potentially explaining the favourable profile of side effects, related to μ receptors. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24372103

  12. Rice genomes recorded ancient pararetrovirus activities: Virus genealogy and multiple origins of endogenization during rice speciation.

    PubMed

    Chen, Sunlu; Liu, Ruifang; Koyanagi, Kanako O; Kishima, Yuji

    2014-12-01

    Viral fossils in rice genomes are a best entity to understand ancient pararetrovirus activities through host plant history because of our advanced knowledge of the genomes and evolutionary history with rice and its related species. Here, we explored organization, geographic origins and genealogy of rice pararetroviruses, which were turned into endogenous rice tungro bacilliform virus-like (eRTBVL) sequences. About 300 eRTBVL sequences from three representative rice genomes were clearly classified into six families. Most of the endogenization events of the eRTBVLs were initiated before differentiation of the rice progenitor (> 160,000 years ago). We successfully followed the genealogy of old relic viruses during rice speciation, and inferred the geographical origins for these viruses. Possible virus genomic sequences were explained mostly by recombinations between different virus families. Interestingly, we discovered that only a few recombination events among the numerous occasions had determined the virus genealogy. PMID:25461539

  13. Endogenous antioxidant activities in relation to concurrent vitamins A, C, and E intake in dementia.

    PubMed

    Tabet, Naji; Mantle, David; Walker, Zuzana; Orrell, Martin

    2002-03-01

    Previous reports on the activities of essential endogenous antioxidants such as superoxide dismutase, catalase, and glutathione in dementia patients have not included a simultaneous quantitative assessment of dietary antioxidant intake. This is important because the reported differences in endogenous antioxidant levels among dementia patients may have reflected variations in the total antioxidants' intake. In this study we measured the levels of antioxidant vitamins A, C, and E in the diet of 81 dementia patients and controls at the same time as assessing blood levels of three endogenous antioxidants. Results showed a significant decrease in the intake of vitamins C (p < .001) and E (p < .01) in patients with severe Alzheimer's disease (AD) when compared to controls. Patients with mild/moderate AD differed from controls only in the intake of vitamin C (p < .01). The blood levels of catalase but not superoxide dismutase and glutathione were significantly decreased in the patients with severe AD when compared to controls (p < .01), patients with mild/moderate AD (p < .0 1), and patients with dementia with Lewy bodies (p < .05). The blood catalase levels of dementia patients, as a whole, were significantly and positively associated with the intake of vitamins A (p < .05), C (p < .01), and E (p < .05). The results indicated that dietary intake of vitamins A, C, and E may influence blood levels of catalase possibly through their antioxidant effects on free radicals. The data underscore the importance of concurrent quantitative assessment of nutritional intake when measuring endogenous antioxidant activities and support a role for antioxidant supplementation in the treatment of dementia disorders. PMID:12094909

  14. Positive allosteric modulators of the μ-opioid receptor: a novel approach for future pain medications

    PubMed Central

    Burford, N T; Traynor, J R; Alt, A

    2015-01-01

    Morphine and other agonists of the μ-opioid receptor are used clinically for acute and chronic pain relief and are considered to be the gold standard for pain medication. However, these opioids also have significant side effects, which are also mediated via activation of the μ-opioid receptor. Since the latter half of the twentieth century, researchers have sought to tease apart the mechanisms underlying analgesia, tolerance and dependence, with the hope of designing drugs with fewer side effects. These efforts have revolved around the design of orthosteric agonists with differing pharmacokinetic properties and/or selectivity profiles for the different opioid receptor types. Recently, μ-opioid receptor-positive allosteric modulators (μ-PAMs) were identified, which bind to a (allosteric) site on the μ-opioid receptor separate from the orthosteric site that binds an endogenous agonist. These allosteric modulators have little or no detectable functional activity when bound to the receptor in the absence of orthosteric agonist, but can potentiate the activity of bound orthosteric agonist, seen as an increase in apparent potency and/or efficacy of the orthosteric agonist. In this review, we describe the potential advantages that a μ-PAM approach might bring to the design of novel therapeutics for pain that may lack the side effects currently associated with opioid therapy. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24460691

  15. The role of δ-opioid receptors in learning and memory underlying the development of addiction

    PubMed Central

    Klenowski, Paul; Morgan, Michael; Bartlett, Selena E

    2015-01-01

    Opioids are important endogenous ligands that exist in both invertebrates and vertebrates and signal by activation of opioid receptors to produce analgesia and reward or pleasure. The μ-opioid receptor is the best known of the opioid receptors and mediates the acute analgesic effects of opiates, while the δ-opioid receptor (DOR) has been less well studied and has been linked to effects that follow from chronic use of opiates such as stress, inflammation and anxiety. Recently, DORs have been shown to play an essential role in emotions and increasing evidence points to a role in learning actions and outcomes. The process of learning and memory in addiction has been proposed to involve strengthening of specific brain circuits when a drug is paired with a context or environment. The DOR is highly expressed in the hippocampus, amygdala, striatum and other basal ganglia structures known to participate in learning and memory. In this review, we will focus on the role of the DOR and its potential role in learning and memory underlying the development of addiction. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24641428

  16. Quantitative Signaling and Structure-Activity Analyses Demonstrate Functional Selectivity at the Nociceptin/Orphanin FQ Opioid Receptor.

    PubMed

    Chang, Steven D; Mascarella, S Wayne; Spangler, Skylar M; Gurevich, Vsevolod V; Navarro, Hernan A; Carroll, F Ivy; Bruchas, Michael R

    2015-09-01

    Comprehensive studies that consolidate selective ligands, quantitative comparisons of G protein versus arrestin-2/3 coupling, together with structure-activity relationship models for G protein-coupled receptor (GPCR) systems are less commonly employed. Here we examine biased signaling at the nociceptin/orphanin FQ opioid receptor (NOPR), the most recently identified member of the opioid receptor family. Using real-time, live-cell assays, we identified the signaling profiles of several NOPR-selective ligands in upstream GPCR signaling (G protein and arrestin pathways) to determine their relative transduction coefficients and signaling bias. Complementing this analysis, we designed novel ligands on the basis of NOPR antagonist J-113,397 [(±)-1-[(3R*,4R*)-1-(cyclooctylmethyl)-3-(hydroxymethyl)-4-piperidinyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one] to explore structure-activity relationships. Our study shows that NOPR is capable of biased signaling, and further, the NOPR selective ligands MCOPPB [1-[1-(1-methylcyclooctyl)-4-piperidinyl]-2-(3R)-3-piperidinyl-1H-benzimidazole trihydrochloride] and NNC 63-0532 [8-(1-naphthalenylmethyl)-4-oxo-1-phenyl-1,3,8-triazaspiro[4.5]decane-3-acetic acid, methyl ester] are G protein-biased agonists. Additionally, minor structural modification of J-113,397 can dramatically shift signaling from antagonist to partial agonist activity. We explore these findings with in silico modeling of binding poses. This work is the first to demonstrate functional selectivity and identification of biased ligands at the nociceptin opioid receptor. PMID:26134494

  17. Activation of SPS from darkened spinach leaves by an endogenous protein phosphatase

    SciTech Connect

    Huber, S.C.; Huber, J.L. )

    1990-05-01

    Sucrose-phosphate synthase from darkened spinach leaves has a low activation state but can undergo a time-dependent activation in desalted leaf extracts that is inhibited by Pi, molybdate, okadaic acid and vanadate, but stimulated by fluoride. SPS labeled in vivo with ({sup 32}P)Pi in excised leaves in the dark loses incorporated {sup 32}P with time when extracts are incubated at 25{degree}C. This loss is largely prevented by vanadate, suggesting that an endogenous protein phosphatase can use SPS as substrate. Changes in phosphorylation state are closely paralleled by changes in SPS activation state. The spontaneous activation achieved in the extracts can be reversed by addition of 2 mM MgATP. Feeding okadaic acid to darkened leaves prevents light activation of SPS suggesting that the endogenous protein phosphatase is similar to the type-1 enzyme of animal tissues. Overall, the results are consistent with the notion that light activation of SPS involves dephosphorylation of inhibitory phosphorylation site(s). Regulation of the protein phosphatase by Pi may be of physiological significance.

  18. A Homogeneous Cell-Based Assay for Measurement of Endogenous PON1 Activity

    PubMed Central

    Ahmad, Syed; Carter, Jade J.; Scott, John E.

    2010-01-01

    PON1 is a high density lipoprotein-associated enzyme that plays an important role in organophosphate detoxification and prevention of atherosclerosis. Thus, there is significant interest in identifying nutritional and pharmacological enhancers of PON1 activity. In order to identify such compounds, we developed a rapid homogeneous assay to detect endogenous cell-associated PON1 activity. PON1 activity was measured by the simple addition of fluorigenic PON1 substrate DEPFMU to live Huh7 cells in media and monitoring change in fluorescence. A specific PON1 inhibitor, 2-hydroxyquinoline, was used to confirm that the observed activity was due to PON1. The assay was optimized and characterized with regard to time course, substrate and sodium chloride concentration, number of cells and tolerance to DMSO and serum. Aspirin, quercetin and simvastatin are compounds reported to increase PON1 expression. Consistent with the literature and western blot data, these compounds enhanced PON1 activity in this assay with comparable efficacies and potencies. A known toxic compound did not increase assay signal. This assay method also detected PON1 activity in normal hepatocytes. Thus, a novel, homogenous assay for detection of endogenous PON1 expression has been developed and is amenable to high throughput screening for the identification of small molecules that enhance PON1 expression. PMID:20096260

  19. Opioids in Preclinical and Clinical Trials

    NASA Astrophysics Data System (ADS)

    Nagase, Hiroshi; Fujii, Hideaki

    Since 1952, when Gates determined the stereo structure of morphine, numerous groups have focused on discovering a nonnarcotic opioid drug [1]. Although several natural, semisynthetic, and synthetic opioid ligands (alkaloids and peptides) have been developed in clinical studies, very few were nonnarcotic opioid drugs [2]. One of the most important studies in the opioid field appeared in 1976, when Martin and colleagues [3] established types of opioid receptors (these are now classified into μ, δ, and κ types). Later, Portoghese discovered a highly selective μ type opioid receptor antagonist, β-funaltrexamine [4]. This led to the finding that the μ type opioid receptor was correlated to drug dependence [5]. Consequently, δ, and particularly κ, opioid agonists were expected to lead to ideal opioid drugs. Moreover, opioid antagonists were evaluated for the treatment of symptoms related to undesirable opioid system activation. In this chapter, we provide a short survey of opioid ligands in development and describe the discovery of the two most promising drugs, TRK-851 [6] and TRK-820 (nalfurafine hydrochloride) [7].

  20. Identification of Small Activating RNAs that Enhance Endogenous OCT4 Expression in Human Mesenchymal Stem Cells

    PubMed Central

    Wang, Ji; Huang, Vera; Ye, Lin; Bárcena, Alicia; Lin, Guiting; Lue, Tom F.

    2015-01-01

    Ectopic overexpression of transcription factors has been used to reprogram cell fate. For example, virus-mediated overexpression of four transcription factors OCT4, SOX2, MYC, and KLF4, known as Yamanaka factors, can convert somatic cells to induced pluripotent stem (iPS) cells. However, gene-specific switch-on of endogenous gene production without the use of foreign DNA remains a challenge. The small RNA machinery that comprised small RNAs and Argonaute proteins is known to silence gene expression, but can be repurposed to activate gene expression when directed to gene promoters, a phenomenon known as RNA activation or RNAa. By screening of dsRNAs targeting OCT4 promoter, we identified a small activating RNA (saRNA) that activated OCT4 expression in several types of human mesenchymal stem cells (MSCs). We found that saRNA-induced OCT4 activation can be further enhanced by a histone deacetylase inhibitor, valproic acid. Furthermore, introducing OCT4 saRNA in combination with viruses encoding the remaining three Yamanaka factors (SOX2, MYC, and KLF4) into MSCs led to the derivation of partially reprogrammed iPS cells. Findings from this study suggest that, with further optimization, RNAa can be a powerful tool to reprogram cell fate by inducing the expression of endogenous genes. PMID:25232932

  1. Acute opioid administration induces hypothalamic-pituitary-adrenal activation and is mediated by genetic variation in interleukin (Il)1B.

    PubMed

    Kershaw, Stephanie G; Della Vedova, Chris B; Majumder, Irina; Ward, Michael B; Farquharson, Aaron L; Williamson, Paul A; White, Jason M

    2015-11-01

    There is a complex relationship between drug dependence and stress, with alcohol and other drugs of abuse both relieving stress and potentially inducing physiological stress responses in the user. Opioid drugs have been shown to modulate hypothalamic-pituitary-adrenal (HPA) activity in animal models and individual response to this modulation may play a role in continuation of drug use. Healthy young Caucasian adults were administered a single dose of immediate release oxycodone (20mg, n=30) or assigned to a control group (n=19) that was not administered the drug. At 0, 1, 2, 4 and 6h post-administration, blood and saliva samples were collected along with assessment of pupil diameter. The HPA response was determined by measurement of salivary cortisol through a commercially available enzyme-linked immunosorbent assay (ELISA). The results were compared to genotype at the -511 and -31 positions in the interleukin1B (IL1B) gene. No difference in cortisol production was initially observed between the two groups, however, when participants were separated based on their genotype for two single nucleotide polymorphisms in the promoter of the IL1B gene, which have been shown to occur at a higher frequency in opioid-dependent populations, individuals carrying the -511T and -31 C alleles (-511 C/T, -31 C/T or -511 T/T, -31 C/C) had a significantly (p<0.05) higher cortisol levels compared to individuals homozygous for the -511 C and -31T alleles. These results suggest that individuals carrying the -511T and -31 C alleles experience HPA activation in response to opioid administration and therefore may be less likely to undertake subsequent self-administration. PMID:26363312

  2. The crystal structure of a bimorphinan with highly selective kappa opioid receptor antagonist activity

    NASA Astrophysics Data System (ADS)

    Urbańczyk-Lipkowska, Zofia; Etter, Margaret C.; Lipkowski, Andrzej W.; Portoghese, Philip S.

    1987-07-01

    The crystal structure of the dihydrobromide heptahydrate of nor-binaltorphimine (17, 17'-bis(cyclopropylmethyl)-6,6',7,7'-tetrahydro-4,5α: 4',5'α-diepoxy-6,6'-imino[7,7' bimorphinan]-3,3',14,14'-tetraol)is presented. This structure is the first reported structure of a rigid bivalent opioid ligand. Two morphinan pharmacophores are connected by a rigid spacer, the pyrrole ring. The nor-binaltorphimine structure itself shows unique, high selectivity as a kappa opioid receptor antagonist. Crystal data: P3 2, Z = 3, a = b = 20.223 (4), c = 9.541(7) Å, α = β = 90°, γ = 120°; R = 0.079 (1765 reflections, Fobs > 1σ( F)).

  3. Synthesis of mixed MOR/KOR efficacy cyclic opioid peptide analogs with antinociceptive activity after systemic administration.

    PubMed

    Perlikowska, Renata; Piekielna, Justyna; Gentilucci, Luca; De Marco, Rossella; Cerlesi, Maria Camilla; Calo, Girolamo; Artali, Roberto; Tömböly, Csaba; Kluczyk, Alicja; Janecka, Anna

    2016-02-15

    Cyclic pentapeptide Tyr-c[D-Lys-Phe-Phe-Asp]NH2, based on the structure of endomorphin-2 (EM-2), which shows high affinity to the μ-opioid receptor (MOR) and a very strong antinociceptive activity in mice was used as a parent compound for the structure-activity relationship studies. In this report we synthesized analogs of a general sequence Dmt-c[D-Lys-Xaa-Yaa-Asp]NH2, with D-1- or D-2-naphthyl-3-alanine (D-1-Nal or D-2-Nal) in positions 3 or 4. In our earlier papers we have indicated that replacing a phenylalanine residue by the more extended aromatic system of naphthylalanines may result in increased bioactivities of linear analogs. The data obtained here showed that only cyclopeptides modified in position 4 retained the sub-nanomolar MOR and nanomolar κ-opioid receptor (KOR) affinity, similar but not better than that of a parent cyclopeptide. In the in vivo mouse hot-plate test, the most potent analog, Dmt-c[D-Lys-Phe-D-1-Nal-Asp]NH2, exhibited higher than EM-2 but slightly lower than the cyclic parent peptide antinociceptive activity after peripheral (ip) and also central administration (icv). Conformational analyses in a biomimetic environment and molecular docking studies disclosed the structural determinants responsible for the different pharmacological profiles of position 3- versus position 4-modified analogs. PMID:26785295

  4. Toll-like Receptor 9 Can be Activated by Endogenous Mitochondrial DNA to Induce Podocyte Apoptosis

    PubMed Central

    Bao, Wenduona; Xia, Hong; Liang, Yaojun; Ye, Yuting; Lu, Yuqiu; Xu, Xiaodong; Duan, Aiping; He, Jing; Chen, Zhaohong; Wu, Yan; Wang, Xia; Zheng, Chunxia; Liu, Zhihong; Shi, Shaolin

    2016-01-01

    Toll-like receptor 9 (TLR9) senses bacterial DNA characteristic of unmethylated CpG motifs to induce innate immune response. TLR9 is de novo expressed in podocytes of some patients with glomerular diseases, but its role in podocyte injury remains undetermined. Since TLR9 activates p38 MAPK and NFkB that are known to mediate podocyte apoptosis, we hypothesized that TLR9 induces podocyte apoptosis in glomerular diseases. We treated immortalized podocytes with puromycin aminonucleosides (PAN) and observed podocyte apoptosis, accompanied by TLR9 upregulation. Prevention of TLR9 upregulation by siRNA significantly attenuated NFκB p65 or p38 activity and apoptosis, demonstrating that TLR9 mediates podocyte apoptosis. We next showed that endogenous mitochondrial DNA (mtDNA), whose CpG motifs are also unmethylated, is the ligand for TLR9, because PAN induced mtDNA accumulation in endolysosomes where TLR9 is localized, overexpression of endolysosomal DNase 2 attenuated PAN-induced p38 or p65 activity and podocyte apoptosis, and DNase 2 silencing was sufficient to activate p38 or p65 and induce apoptosis. In PAN-treated rats, TLR9 was upregulated in the podocytes, accompanied by increase of apoptosis markers. Thus, de novo expressed TLR9 may utilize endogenous mtDNA as the ligand to facilitate podocyte apoptosis, a novel mechanism underlying podocyte injury in glomerular diseases. PMID:26934958

  5. Characterization of the endogenous protein kinase activity of the hepatitis B virus.

    PubMed

    Kann, M; Thomssen, R; Köchel, H G; Gerlich, W H

    1993-01-01

    During the assembly of the nucleocapsid of the hepatitis B virus a protein kinase, probably of cellular origin, is encapsidated. This enzyme phosphorylates serine residue(s) localized within the lumen of the particle. By using purified, liver-derived core particles, we characterized the protein kinase activity in the presence of different ions and inhibitors. Controls were performed with cAMP-dependent protein kinase (PKA) and protein kinase C (PKC) and recombinant core particles. We showed that the endogenous protein kinase of the core particles was not inhibited by H89, a specific inhibitor of PKA. Staurosporine, a selective inhibitor of PKC inhibited the endogenous kinase activity only within the first minutes of the reaction. In contrast, quercetine, a selective inhibitor of the protein kinase M (PKM) did not inhibit during the first minutes but inhibited efficiently during later phases of incubation. PKM represents an enzymatically active proteolytic fragment of PKC. These results suggest that PKC is encapsidated into human core particles and is converted to PKM during the in vitro reaction. This conclusion implies the association of a protease activity localized with the HBV nucleocapsid inside liver-derived core particles. PMID:8260877

  6. Unique spectrum of activity of prosimian TRIM5alpha against exogenous and endogenous retroviruses.

    PubMed

    Rahm, Nadia; Yap, Melvyn; Snoeck, Joke; Zoete, Vincent; Muñoz, Miguel; Radespiel, Ute; Zimmermann, Elke; Michielin, Olivier; Stoye, Jonathan P; Ciuffi, Angela; Telenti, Amalio

    2011-05-01

    Lentiviruses, the genus of retrovirus that includes HIV-1, rarely endogenize. Some lemurs uniquely possess an endogenous lentivirus called PSIV ("prosimian immunodeficiency virus"). Thus, lemurs provide the opportunity to study the activity of host defense factors, such as TRIM5α, in the setting of germ line invasion. We characterized the activities of TRIM5α proteins from two distant lemurs against exogenous retroviruses and a chimeric PSIV. TRIM5α from gray mouse lemur, which carries PSIV in its genome, exhibited the narrowest restriction activity. One allelic variant of gray mouse lemur TRIM5α restricted only N-tropic murine leukemia virus (N-MLV), while a second variant restricted N-MLV and, uniquely, B-tropic MLV (B-MLV); both variants poorly blocked PSIV. In contrast, TRIM5α from ring-tailed lemur, which does not contain PSIV in its genome, revealed one of the broadest antiviral activities reported to date against lentiviruses, including PSIV. Investigation into the antiviral specificity of ring-tailed lemur TRIM5α demonstrated a major contribution of a 32-amino-acid expansion in variable region 2 (v2) of the B30.2/SPRY domain to the breadth of restriction. Data on lemur TRIM5α and the prediction of ancestral simian sequences hint at an evolutionary scenario where antiretroviral specificity is prominently defined by the lineage-specific expansion of the variable loops of B30.2/SPRY. PMID:21345948

  7. GR94839, a kappa-opioid agonist with limited access to the central nervous system, has antinociceptive activity.

    PubMed Central

    Rogers, H.; Birch, P. J.; Harrison, S. M.; Palmer, E.; Manchee, G. R.; Judd, D. B.; Naylor, A.; Scopes, D. I.; Hayes, A. G.

    1992-01-01

    1. The pharmacological profile of GR94839, a kappa-opioid agonist with limited access to the central nervous system, has been investigated. Its antinociceptive activity has been compared with that of GR103545, a centrally-penetrating kappa-agonist and ICI204448, the previously described peripherally-selective kappa-agonist. 2. GR94839 was a potent agonist in the rabbit vas deferens in vitro assay for kappa-opioid receptors (IC50: 1.4 +/- 0.3 nM; n = 6), but had limited activity at mu- or delta-opioid receptors. 3. In the mouse abdominal constriction test, GR94839 was 238 fold more potent when given i.c.v. (ED50: 0.008 (0.004-0.029) mg kg-1; n = 18) than when s.c. (ED50: 1.9 (0.7-3.1) mg kg-1; n = 30). In comparison, GR103545 was equipotent when given i.c.v. or s.c. 4. After intravenous administration, the maximum plasma to brain concentration-ratio attained by GR94839 was 18 compared with 2 for GR85571, a structurally-related kappa-agonist that is centrally-penetrating. 5. GR94839 inhibited the 2nd phase of the rat formalin response at doses 7 fold lower than those required to inhibit the 1st phase (ED50 vs 1st phase: 10.2 (6.7-17.1) mg kg-1, s.c.; ED50 vs 2nd phase: 1.4 (1.0-1.8) mg kg-1, s.c.; n = 18). GR103545 was equipotent against the two phases. 6. Intraplantar administration of the opioid antagonists, norbinaltorphimine (100 micrograms) or naltrexone (1 microgram), reversed the antinociceptive effect of systemic GR94839 (3 mg kg-1, s.c.) against the 2nd phase of the formalin response and intraplantar injection of GR94839 (30-100 micrograms) selectively inhibited the 2nd phase.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1327387

  8. Endogenous and Uric Acid-Induced Activation of NLRP3 Inflammasome in Pregnant Women with Preeclampsia

    PubMed Central

    Matias, Mariana Leticia; Romão, Mariana; Weel, Ingrid Cristina; Ribeiro, Vanessa Rocha; Nunes, Priscila Rezeck; Borges, Vera Therezinha; Araújo, João Pessoa; Peraçoli, José Carlos; de Oliveira, Leandro; Peraçoli, Maria Terezinha

    2015-01-01

    Preeclampsia (PE) is a specific syndrome of pregnancy, characterized by hypertension and proteinuria. This pathology is associated with hyperuricemia and elevated serum levels of inflammatory cytokines. Uric acid crystals may activate an intracellular complex called inflammasome, which is important for processing and release of inflammatory cytokines. This study investigated the state of monocyte activation, both endogenous and stimulated with monosodium urate (MSU), by gene expression of NLRP1 and NLRP3 receptors as well as their association with inflammatory cytokines expression. Monocytes were obtained from peripheral blood of 23 preeclamptic pregnant women, 23 normotensive pregnant women (NT) and 23 healthy non-pregnant women (NP). Inflammasome activation was evaluated by the gene expression of NLRP1, NLRP3, caspase-1, IL-1β, IL-18 and TNF-α by RT-qPCR in unstimulated monocytes (endogenous expression), or after cell stimulation with MSU (stimulated expression). The concentration of cytokines was assessed by ELISA. In preeclamptic pregnant women, gene expression of NLRP1, NLRP3, caspase-1, IL-1β and TNF-α by monocytes stimulated or not with MSU was significantly higher than in NT and NP groups. Stimulation of monocytes from preeclamptic and non-pregnant women with MSU induced increased gene expression of NLRP3, caspase-1 and TNF-α in relation to the endogenous expression in these groups, while this was not observed in the NT group. The cytokine determination showed that monocytes from women with PE produced higher endogenous levels of IL-1β, IL-18 and TNF-α compared to the other groups, while the stimulus with MSU led to higher production of these cytokines in preeclamptic group than in the NT group. In conclusion, the results showed increased basal gene expression of NLRP1 and NLRP3 receptors in monocytes from PE group. These cells stimulation with MSU demonstrates that uric acid plays a role in NLRP3 inflammasome activation, suggesting the participation

  9. Endogenous and Uric Acid-Induced Activation of NLRP3 Inflammasome in Pregnant Women with Preeclampsia.

    PubMed

    Matias, Mariana Leticia; Romão, Mariana; Weel, Ingrid Cristina; Ribeiro, Vanessa Rocha; Nunes, Priscila Rezeck; Borges, Vera Therezinha; Araújo, João Pessoa; Peraçoli, José Carlos; de Oliveira, Leandro; Peraçoli, Maria Terezinha

    2015-01-01

    Preeclampsia (PE) is a specific syndrome of pregnancy, characterized by hypertension and proteinuria. This pathology is associated with hyperuricemia and elevated serum levels of inflammatory cytokines. Uric acid crystals may activate an intracellular complex called inflammasome, which is important for processing and release of inflammatory cytokines. This study investigated the state of monocyte activation, both endogenous and stimulated with monosodium urate (MSU), by gene expression of NLRP1 and NLRP3 receptors as well as their association with inflammatory cytokines expression. Monocytes were obtained from peripheral blood of 23 preeclamptic pregnant women, 23 normotensive pregnant women (NT) and 23 healthy non-pregnant women (NP). Inflammasome activation was evaluated by the gene expression of NLRP1, NLRP3, caspase-1, IL-1β, IL-18 and TNF-α by RT-qPCR in unstimulated monocytes (endogenous expression), or after cell stimulation with MSU (stimulated expression). The concentration of cytokines was assessed by ELISA. In preeclamptic pregnant women, gene expression of NLRP1, NLRP3, caspase-1, IL-1β and TNF-α by monocytes stimulated or not with MSU was significantly higher than in NT and NP groups. Stimulation of monocytes from preeclamptic and non-pregnant women with MSU induced increased gene expression of NLRP3, caspase-1 and TNF-α in relation to the endogenous expression in these groups, while this was not observed in the NT group. The cytokine determination showed that monocytes from women with PE produced higher endogenous levels of IL-1β, IL-18 and TNF-α compared to the other groups, while the stimulus with MSU led to higher production of these cytokines in preeclamptic group than in the NT group. In conclusion, the results showed increased basal gene expression of NLRP1 and NLRP3 receptors in monocytes from PE group. These cells stimulation with MSU demonstrates that uric acid plays a role in NLRP3 inflammasome activation, suggesting the participation

  10. Relaxation Training and Opioid Inhibition of Blood Pressure Response to Stress.

    ERIC Educational Resources Information Center

    McCubbin, James A.; And Others

    1996-01-01

    Sought to determine the role of endogenous opioid mechanisms in the circulatory effects of relaxation training. Subjects were 32 young men with mildly elevated casual arterial pressure. Assessed opioid mechanisms by examining the effects of opioid receptor blockade with naltrexone on acute cardiovascular reactivity to laboratory stress before and…

  11. Human Endogenous Retrovirus Protein Activates Innate Immunity and Promotes Experimental Allergic Encephalomyelitis in Mice

    PubMed Central

    Perron, Hervé; Dougier-Reynaud, Hei-Lanne; Lomparski, Christina; Popa, Iuliana; Firouzi, Reza; Bertrand, Jean-Baptiste; Marusic, Suzana; Portoukalian, Jacques; Jouvin-Marche, Evelyne; Villiers, Christian L.; Touraine, Jean-Louis; Marche, Patrice N.

    2013-01-01

    Multiple sclerosis (MS) is a complex multifactorial disease of the central nervous system (CNS) for which animal models have mainly addressed downstream immunopathology but not potential inducers of autoimmunity. In the absence of a pathogen known to cause neuroinflammation in MS, Mycobacterial lysate is commonly used in the form of complete Freund's adjuvant to induce autoimmunity to myelin proteins in Experimental Allergic Encephalomyelitis (EAE), an animal model for MS. The present study demonstrates that a protein from the human endogenous retrovirus HERV-W family (MSRV-Env) can be used instead of mycobacterial lysate to induce autoimmunity and EAE in mice injected with MOG, with typical anti-myelin response and CNS lesions normally seen in this model. MSRV-Env was shown to induce proinflammatory response in human macrophage cells through TLR4 activation pathway. The present results demonstrate a similar activation of murine dendritic cells and show the ability of MSRV-Env to trigger EAE in mice. In previous studies, MSRV-Env protein was reproducibly detected in MS brain lesions within microglia and perivascular macrophages. The present results are therefore likely to provide a model for MS, in which the upstream adjuvant triggering neuroinflammation is the one detected in MS active lesions. This model now allows pre-clinical studies with therapeutic agents targeting this endogenous retroviral protein in MS. PMID:24324591

  12. The Effect of Endogenous Adenosine on Neuronal Activity in Rats: An FDG PET Study.

    PubMed

    Parkinson, Fiona E; Paul, Soumen; Zhang, Dali; Mzengeza, Shadreck; Ko, Ji Hyun

    2016-07-01

    2-(18) F-fluorodeoxy-D-glucose (FDG) is a glucose analog that is taken up by cells and phosphorylated. The amount of FDG accumulated by cells is a measure of the rate of glycolysis, which reflects cellular activity. As the levels and actions of the neuromodulator adenosine are dynamically regulated by neuronal activity, this study was designed to test whether endogenous adenosine affects tissue accumulation of FDG as assessed by positron emission tomography (PET) or by postmortem analysis of tissue radioactivity. Rats were given an intraperitoneal injection of the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropyl-xanthine (DPCPX, 3 mg/kg), the adenosine kinase inhibitor ABT-702 (3 mg/kg), or vehicle 10 minutes prior to an intravenous injection of FDG (15.4 ± 0.7 MBq per rat). Rats were then subjected to a 15 minute static PET scan. Reconstructed images were normalized to FDG PET template for rats and standard uptake values (SUVs) were calculated. To examine the regional effect of active treatment compared to vehicle, statistical parametric mapping analysis was performed. Whole-brain FDG uptake was not affected by drug treatment. Significant regional hypometabolism was detected, particularly in cerebellum, of DPCPX- and ABT-702 treated rats, relative to vehicle-treated rats. Thus, endogenous adenosine can affect FDG accumulation although this effect is modest in quiescent rats. PMID:27082948

  13. Opioid receptors and cardioprotection – ‘opioidergic conditioning’ of the heart

    PubMed Central

    Headrick, John P; See Hoe, Louise E; Du Toit, Eugene F; Peart, Jason N

    2015-01-01

    Ischaemic heart disease (IHD) remains a major cause of morbidity/mortality globally, firmly established in Westernized or ‘developed’ countries and rising in prevalence in developing nations. Thus, cardioprotective therapies to limit myocardial damage with associated ischaemia–reperfusion (I–R), during infarction or surgical ischaemia, is a very important, although still elusive, clinical goal. The opioid receptor system, encompassing the δ (vas deferens), κ (ketocyclazocine) and μ (morphine) opioid receptors and their endogenous opioid ligands (endorphins, dynorphins, enkephalins), appears as a logical candidate for such exploitation. This regulatory system may orchestrate organism and organ responses to stress, induces mammalian hibernation and associated metabolic protection, triggers powerful adaptive stress resistance in response to ischaemia/hypoxia (preconditioning), and mediates cardiac benefit stemming from physical activity. In addition to direct myocardial actions, central opioid receptor signalling may also enhance the ability of the heart to withstand I–R injury. The δ- and κ-opioid receptors are strongly implicated in cardioprotection across models and species (including anti-infarct and anti-arrhythmic actions), with mixed evidence for μ opioid receptor-dependent protection in animal and human tissues. A small number of clinical trials have provided evidence of cardiac benefit from morphine or remifentanil in cardiopulmonary bypass or coronary angioplasty patients, although further trials of subtype-specific opioid receptor agonists are needed. The precise roles and utility of this GPCR family in healthy and diseased human myocardium, and in mediating central and peripheral survival responses, warrant further investigation, as do the putative negative influences of ageing, IHD co-morbidities, and relevant drugs on opioid receptor signalling and protective responses. PMID:25521834

  14. Specific induction of endogenous viral restriction factors using CRISPR/Cas-derived transcriptional activators

    PubMed Central

    Bogerd, Hal P.; Kornepati, Anand V. R.; Marshall, Joy B.; Kennedy, Edward M.; Cullen, Bryan R.

    2015-01-01

    Whereas several mammalian proteins can restrict the replication of HIV-1 and other viruses, these are often not expressed in relevant target cells. A potential method to inhibit viral replication might therefore be to use synthetic transcription factors to induce restriction factor expression. In particular, mutants of the RNA-guided DNA binding protein Cas9 that have lost their DNA cleavage activity could be used to recruit transcription activation domains to specific promoters. However, initial experiments revealed only weak activation unless multiple promoter-specific single guide RNAs (sgRNAs) were used. Recently, the recruitment of multiple transcription activation domains by a single sgRNA, modified to contain MS2-derived stem loops that recruit fusion proteins consisting of the MS2 coat protein linked to transcription activation domains, was reported to induce otherwise silent cellular genes. Here, we demonstrate that such “synergistic activation mediators” can induce the expression of two restriction factors, APOBEC3G (A3G) and APOBEC3B (A3B), in human cells that normally lack these proteins. We observed modest activation of endogenous A3G or A3B expression using single sgRNAs but high expression when two sgRNAs were used. Whereas the induced A3G and A3B proteins both blocked infection by an HIV-1 variant lacking a functional vif gene by inducing extensive dC-to-dU editing, only the induced A3B protein inhibited wild-type HIV-1. These data demonstrate that Cas9-derived transcriptional activators have the potential to be used for screens for endogenous genes that affect virus replication and raise the possibility that synthetic transcription factors might prove clinically useful if efficient delivery mechanisms could be developed. PMID:26668372

  15. Specific induction of endogenous viral restriction factors using CRISPR/Cas-derived transcriptional activators.

    PubMed

    Bogerd, Hal P; Kornepati, Anand V R; Marshall, Joy B; Kennedy, Edward M; Cullen, Bryan R

    2015-12-29

    Whereas several mammalian proteins can restrict the replication of HIV-1 and other viruses, these are often not expressed in relevant target cells. A potential method to inhibit viral replication might therefore be to use synthetic transcription factors to induce restriction factor expression. In particular, mutants of the RNA-guided DNA binding protein Cas9 that have lost their DNA cleavage activity could be used to recruit transcription activation domains to specific promoters. However, initial experiments revealed only weak activation unless multiple promoter-specific single guide RNAs (sgRNAs) were used. Recently, the recruitment of multiple transcription activation domains by a single sgRNA, modified to contain MS2-derived stem loops that recruit fusion proteins consisting of the MS2 coat protein linked to transcription activation domains, was reported to induce otherwise silent cellular genes. Here, we demonstrate that such "synergistic activation mediators" can induce the expression of two restriction factors, APOBEC3G (A3G) and APOBEC3B (A3B), in human cells that normally lack these proteins. We observed modest activation of endogenous A3G or A3B expression using single sgRNAs but high expression when two sgRNAs were used. Whereas the induced A3G and A3B proteins both blocked infection by an HIV-1 variant lacking a functional vif gene by inducing extensive dC-to-dU editing, only the induced A3B protein inhibited wild-type HIV-1. These data demonstrate that Cas9-derived transcriptional activators have the potential to be used for screens for endogenous genes that affect virus replication and raise the possibility that synthetic transcription factors might prove clinically useful if efficient delivery mechanisms could be developed. PMID:26668372

  16. Differential antinociceptive effects of spinal opioids on foot withdrawal responses evoked by C fibre or Aδ nociceptor activation

    PubMed Central

    Lu, Y; Pirec, V; Yeomans, D C

    1997-01-01

    Intrathecal application of μ, δ, and κ opioids attenuate responses on several tests of animal nociception. However, the potency of these opioids differ depending on which tests were used. One factor contributing to these discrepancies is that different types of noxious stimuli activate different sets of nociceptor types, which may be differentially sensitive to opiate inhibition. To examine this hypothesis, we used a recently developed behavioural test which allows for differential assessment of nociception evoked by the activation of myelinated (Aδ) and unmyelinated C thermonociceptors. Administration of a κ-selective agonist was ineffective on either type of response. δ1 drugs were slightly more potent on C fibre-mediated responses than on Aδ-mediated responses. Intrathecal μ and δ2 drugs were antinociceptive on both Aδ and C nociceptor-mediated responses. However, unlike the δ1 effects, the dose-response curves for μ and δ2 drugs were significantly more steep for Aδ than for C fibre-mediated responses, potentially indicating differences in the mechanisms by which the drugs act on these 2 response types. PMID:9249259

  17. A comparison of endogenous and microbial proteolytic activities during fast fermentation of silver carp inoculated with Lactobacillus plantarum.

    PubMed

    Yang, Fang; Xia, Wen-Shui; Zhang, Xiao-Wei; Xu, Yan-Shun; Jiang, Qi-Xing

    2016-09-15

    The study was aimed to investigate different roles of endogenous and Lactobacillus plantarum proteases during fast fermentation of silver carp. The results show that endogenous proteases could degrade both sarcoplasmic and myofibrillar proteins. In contrast, L. plantarum had low proteinase activities and could only hydrolyze sarcoplasmic peptides. This indicates that gel properties could be mainly affected by endogenous proteolysis while microbial proteolysis contributed to the production of smaller peptides and free amino acids which may be related to flavor and taste. Texture and free amino acid analyses verified these hypotheses. It shows that endogenous lysosomal proteases were the major contributors for the decrease of gel strength while L. plantarum proteolytic activities could lead to the increase of aspartic acid, glutamic acid, and alanine, which may result in umami and sweet taste; and also lead to a rise in some amino acids which were volatile compounds precursors. PMID:27080883

  18. Evidence for the involvement of opioid neuropeptides in the adherence and migration of immunocompetent invertebrate hemocytes.

    PubMed Central

    Stefano, G B; Leung, M K; Zhao, X H; Scharrer, B

    1989-01-01

    Evidence for the participation of opioid neuropeptides in immunoregulatory activities, especially cellular adherence and migration, has been obtained in representatives of two phyla of invertebrates, the mollusc Mytilus edulis and the insect Leucophaea maderae. The injection of a synthetic analog of [Met]enkephalin [( D-Ala2,Met5]enkephalinamide, DAMA; 10(-6) M) had a stimulatory, naloxone-reversible effect on the directed migration of immunocompetent hemocytes. Incubation of hemolymph in the presence of exogenous or endogenous opioid material significantly enhanced the adherence of hemocytes on albumin-coated slides as demonstrated by use of indirect Zeiss-Zonax reflectance computer analysis. Conversely, hemocyte adherence was markedly reduced by the addition of naloxone (10(-8) M) to the incubation medium, either alone or in combination with DAMA. The antagonistic effects of naloxone on the stimulatory activities of opioids indicate that, like those previously reported in mammals, they are receptor-mediated. The presence of an endogenous [Met]enkephalin-like material was demonstrated in cell-free hemolymph as well as sequestered hemocytes by use of high-pressure liquid chromatography and radioimmunoassay. These results demonstrate that the capacity of immunocytes to release and respond to opioid neuropeptide messengers is not restricted to mammalian organisms but was developed early in the course of evolution. Images PMID:2536172

  19. Involvement of the peripheral sensory and sympathetic nervous system in the vascular endothelial expression of ICAM-1 and the recruitment of opioid-containing immune cells to inhibit inflammatory pain.

    PubMed

    Mousa, Shaaban A; Shaqura, Mohammed; Brendl, Ute; Al-Khrasani, Mahmoud; Fürst, Susanna; Schäfer, Michael

    2010-11-01

    Endogenous opioids are known to be released within certain brain areas following stressful stimuli. Recently, it was shown that also leukocytes are a potential source of endogenously released opioid peptides following stress. They activate sensory neuron opioid receptors and result in the inhibition of local inflammatory pain. An important prerequisite for the recruitment of such leukocytes is the expression of intracellular adhesion molecule-1 (ICAM-1) in blood vessels of inflamed tissue. Here, we investigated the contribution of peripheral sensory and/or sympathetic nerves to the enhanced expression of ICAM-1 simultaneously with the increased recruitment of opioid peptide-containing leukocytes to promote the inhibition of inflammatory pain. Selective degeneration of either peripheral sensory or sympathetic nerve fibers by their respective neurotoxins, capsaicin or 6-hydroxydopamime, significantly reduced the subcutaneous immigration of β-endorphin- (END-) and met-enkephalin- (ENK-)-containing polymorphonuclear leukocytes (PMN) (in the early phase) and mononuclear cells (in the late phase) during painful Freund's complete adjuvant (FCA) rat hind paw inflammation. In contrast, this treatment did not alter the percentage of opioid peptide-containing leukocytes in the circulation. Calcitonin gene-related peptide- (CGRP-) and tyrosine hydroxylase- (TH-) immunoreactive (IR) nerve fibers were in close contact to ICAM-1 IR blood vessels within inflamed subcutaneous tissue. The selective degeneration of sensory or sympathetic nerve fibers attenuated the enhanced expression of vascular endothelial ICAM-1 after intraplantar (i.pl.) FCA and abolished endogenous opioid peptide-mediated peripheral analgesia. Our results suggest that, during localized inflammatory pain, peripheral sensory and sympathetic nerve fibers augment the expression of vascular endothelial ICAM-1 simultaneously with the increased recruitment of opioid peptide-containing leukocytes which consequently

  20. Endogenous cortisol level interacts with noradrenergic activation in the human amygdala.

    PubMed

    van Stegeren, Anda H; Wolf, Oliver T; Everaerd, Walter; Scheltens, Philip; Barkhof, Frederik; Rombouts, Serge A R B

    2007-01-01

    Animal studies show that high cortisol levels exert their effect on stressful task performance via modulation of the amygdala. Availability of noradrenaline in this brain region appears to be a critical prerequisite for this effect. This relationship between noradrenaline and cortisol is explained by an animal model where the amygdala constitutes a crucial region for this interaction. In humans this model has not been extensively tested so far. In a previously reported study human subjects (aged 20.93+/-2.38) were scanned using fMRI when watching sets of emotional and neutral pictures after taking the beta-adrenergic antagonist propranolol or placebo. Stimulus sets consisted of 92 pictures, divided in four emotional categories that ranged from neutral scenes of domestic objects (CAT1) to extremely negative scenes of mutilation or accidents (CAT4). Confrontation with arousing emotional pictures, accompanied by increased noradrenaline levels, evoked increased amygdala activation under placebo but not under betablocker condition. This new and additional analysis of this data set was carried out to determine the effect of differential endogenous cortisol levels on amygdala activation. Cortisol levels during scanning were determined using salivary samples and subjects were post hoc divided in a High (n=14) and Low cortisol group (n=14). When subjects were watching emotional stimuli, presumably associated with enhanced noradrenaline (NA) levels, amygdala activation was contrasted between the two cortisol groups. We hypothesized that emotional stimuli would elicit more amygdala activation in the High than in the Low cortisol group. Here we demonstrate indeed a significant interaction effect of the endogenous cortisol level with increasing activation in the amygdala under placebo but not under betablocker condition, thereby extending the rodent based model of a synergistic effect of the two stress hormones to the human. PMID:16884932

  1. Proglumide exhibits delta opioid agonist properties.

    PubMed

    Rezvani, A; Stokes, K B; Rhoads, D L; Way, E L

    1987-01-01

    Recently, it was reported that proglumide, a cholecystokinin (CCK) antagonist, potentiates the analgetic effects of morphine and endogenous opioid peptides and reverses morphine tolerance by antagonizing the CCK system in the central nervous system of the rat. In order to provide additional insight into the mode of action of this agent, we assessed the effect of proglumide in the isolated guinea pig ileum and the mouse, rat and rabbit vas deferens. Furthermore, we studied the in vitro binding affinity of this substance to mouse brain synaptosomes. Our results show that proglumide inhibits, dose dependently, the electrically stimulated twitches in the mouse vas deferens and guinea pig ileum, but not in the rat or rabbit vas deferens. The inhibitory action of proglumide on the mouse vas deferens, but not on the guinea pig ileum, is antagonized by naloxone and by the selective delta-antagonist, ICI 174,864, in a competitive fashion. Other CCK antagonists were found to be devoid of such activity on the mouse vas deferens. In vitro binding studies showed that proglumide displaces D-ala-D-[leucine]5-enkephalin (DADLE), a delta agonist, but not ethylketocyclazocine (EKC), a preferentially selective kappa agonist. The effect of proglumide appeared to be elicited presynaptically since it did not alter the norepinephrine-induced contractions of the mouse vas deferens. Our results suggest that proglumide might exert its opiate-like effects by activation of delta-opioid receptors. PMID:3030338

  2. Detection of an endogenous urinary biomarker associated with CYP2D6 activity using global metabolomics

    PubMed Central

    Tay-Sontheimer, Jessica; Shireman, Laura M; Beyer, Richard P; Senn, Taurence; Witten, Daniela; Pearce, Robin E; Gaedigk, Andrea; Fomban, Cletus L Gana; Lutz, Justin D; Isoherranen, Nina; Thummel, Kenneth E; Fiehn, Oliver; Leeder, J Steven; Lin, Yvonne S

    2015-01-01

    Aim We sought to discover endogenous urinary biomarkers of human CYP2D6 activity. Patients & methods Healthy pediatric subjects (n = 189) were phenotyped using dextromethorphan and randomized for candidate biomarker selection and validation. Global urinary metabolomics was performed using liquid chromatography quadrupole time-of-flight mass spectrometry. Candidate biomarkers were tested in adults receiving fluoxetine, a CYP2D6 inhibitor. Results A biomarker, M1 (m/z 444.3102) was correlated with CYP2D6 activity in both the pediatric training and validation sets. Poor metabolizers had undetectable levels of M1, whereas it was present in subjects with other phenotypes. In adult subjects, a 9.56-fold decrease in M1 abundance was observed during CYP2D6 inhibition. Conclusion Identification and validation of M1 may provide a noninvasive means of CYP2D6 phenotyping. PMID:25521354

  3. Pharmacological characterization of the activity of endogenous inotropic factor from porcine left ventricle.

    PubMed

    Chen, Q M; Chau, T; Agbanyo, M; Navaratnam, S; Khatter, J C; Bose, D

    1993-01-01

    We report some of the unique pharmacological properties of a semipurified endogenous inotropic factor (EIF) present in the extract of the porcine left ventricle. EIF produced the following effects: (a) increase in isometric contractile force developed by electrically driven canine right ventricular trabecula, reaching a maximum with 60-100 microliters/ml concentration; (b) inhibition of Na-pump activity in canine portal vein; (c) no digitalis-like cardiac toxicity, e.g., increased diastolic tension or spontaneous diastolic mechanical oscillatory activity, despite inhibition of the sodium pump; (d) a small increase in sarcoplasmic reticular Ca release from the heart but a large increase in transsarcolemmal Ca influx as seen in biphasic contractions, an action similar to that produced by digitalis-like substances; and (e) prolongation of the action potential duration and refractory period of the canine isolated trabeculae. This latter action may confer a unique antiarrhythmic property to EIF. PMID:7508042

  4. Trypsin-like proteinase and its endogenous inhibitor from Yersinia pseudotuberculosis. Biological activity.

    PubMed

    Burtseva, T I; Loenko, Y N

    1999-09-01

    A trypsin-like proteinase (YPTP) and its endogenous inhibitor (ITYP) were isolated from the culture filtrate of the pathogenic bacterium Yersinia pseudotuberculosis, and their biological activities were studied. YPTP was found to be highly toxic for random-bred white mice. Under in vitro conditions the proteolytic enzyme destroyed protective proteins of the immune system of the animals--IgG, IgA, and proteins of the complement system (CIq, C3, and C5)--and, consequently, was a pathogenetic factor in yersinioses. The inhibitor ITYP was shown to manifest antibacterial activity against virulent forms of Yersinia pseudotuberculosis, Escherichia coli, and Salmonella typhimurium. The ITYP preparation was harmless and nontoxic. PMID:10521713

  5. Transcriptional activity of human endogenous retrovirus in Albanian children with autism spectrum disorders.

    PubMed

    Balestrieri, Emanuela; Cipriani, Chiara; Matteucci, Claudia; Capodicasa, Natale; Pilika, Anita; Korca, Ina; Sorrentino, Roberta; Argaw-Denboba, Ayele; Bucci, Ilaria; Miele, Martino Tony; Coniglio, Antonella; Alessandrelli, Riccardo; Sinibaldi Vallebona, Paola

    2016-09-01

    Recent studies suggest that autism spectrum disorders (ASD) result from interactions between genetic and environmental factors, whose possible links could be represented by epigenetic mechanisms. Here, we investigated the transcriptional activity of three human endogenous retrovirus (HERV) families, in peripheral blood mononuclear cells (PBMCs) from Albanian ASD children, by quantitative real-time PCR. We aimed to confirm the different expression profile already found in Italian ASD children, and to highlight any social and family health condition emerging from information gathered through a questionnaire, to be included among environmental risk factors. The presence of increased HERV-H transcriptional activity in all autistic patients could be understood as a constant epigenetic imprinting of the disease, potentially useful for early diagnosis and for the development of effective novel therapeutic strategies. PMID:27602423

  6. Effects of loperamide and other opioid-related substances on the transcriptional regulation of the rat pro-opiomelanocortin gene in AtT20 cells.

    PubMed

    Nomura, A; Iwasaki, Y; Aoki, Y; Yamamori, E; Mutsuga, N; Yoshida, M; Asai, M; Oiso, Y; Saito, H

    2001-08-01

    Although opioid peptides are involved in the regulation of the hypothalamic-pituitary-adrenal axis, their role in pro-opiomelanocortin (POMC) gene expression at the pituitary level is not known. We therefore examined the effects of opioid receptor agonists, including recently discovered endogenous opioid peptides, on POMC gene expression using the AtT20PL cell line, a subclone of AtT20 in which the rat POMC 5'-promoter-luciferase fusion gene was stably incorporated. The endogenous mu-opioid receptor agonists endomorphin 1 and 2 had no effect on either basal or corticotropin-stimulating-hormone-induced POMC expression. This was also the case with the delta-agonist BUBUC, the kappa-agonist U50488H and the orphan receptor agonist orphanin FQ. In contrast, the synthetic mu-agonist loperamide significantly inhibited basal and yet enhanced cAMP-induced POMC expression. The inhibitory effect of loperamide was mimicked by the calmodulin antagonist W7 and antagonized by the calcium channel blocker nifedipine, whereas neither the inhibitory nor the enhancing effect of loperamide was influenced by the opioid antagonist naloxone. These results suggest that the synthetic mu-agonist loperamide has a modulatory effect on the 5'-promoter activity of the POMC gene. This effect does not seem to be mediated through the classical mu-opioid receptor but rather in part through a calcium/calmodulin-related mechanism. PMID:11474216

  7. Probing the structure-activity relationship of endogenous histone deacetylase complexes with immobilized peptide-inhibitors.

    PubMed

    Sindlinger, Julia; Bierlmeier, Jan; Geiger, Lydia-Christina; Kramer, Katharina; Finkemeier, Iris; Schwarzer, Dirk

    2016-05-01

    Histone deacetylases (HDACs) are key regulators of numerous cellular proteins by removing acetylation marks from modified lysine residues. Peptide-based HDAC probes containing α-aminosuberic acid ω-hydroxamate have been established as useful tools for investigating substrate selectivity and composition of endogenous HDAC complexes in cellular lysates. Here we report a structure-activity study of potential HDAC-probes containing derivatives of the hydroxamate moieties. While most of these probes did not recruit significant amounts of endogenous HDACs from cellular lysates, peptides containing Nε-acetyl-Nε-hydroxy-L-lysine served as HDAC probe. The recruitment efficiency varied between HDACs and was generally lower than that of α-aminosuberic acid ω-hydroxamate probes, but showed a similar global interaction profile. These findings indicate that Nε-acetyl-Nε-hydroxy-L-lysine might be a useful tool for investigations on HDAC complexes and the development of HDAC inhibitors. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. PMID:27071932

  8. [Nociceptin and the ORL1 receptor: pharmacology of a new opioid receptor].

    PubMed

    Grond, S; Meuser, T; Pietruck, C; Sablotzki, A

    2002-12-01

    Molecular biological investigations led to the discovery of the ORL1 receptor ( opioid receptor like-1 receptor) and its endogenous ligand nociceptin. Although its sequence and structure are closely related to traditional opioid receptors, the ORL1 receptor shows low binding affinities for selective opioid agonists and antagonists. On the other hand, the ORL1 ligand nociceptin does not bind to the three traditional opioid receptors. The activation of the G protein-coupled ORL1 receptor inhibits adenlylate cyclase activity, reduces the intracellular concentration of the second messenger cAMP and regulates ion channels. The supraspinal administration of nociceptin produces hyperalgesia. unlike opioids. Spinal intrathecal and peripheral administration of nociceptin causes hyperalgesia in low doses and analgesia in high doses. The physiological role and detailed mechanisms of these dose-dependent nociceptin effects in opposite directions are not yet known. In addition, nociceptin modulates other biological phenomena such as feeding, locomotion, gastrointestinal function,memory, cardiovascular function,immunity, renal function, anxiety,dependence and tolerance.Future research on the physiological and pathophysiological importance of the nociceptin/ORL1 receptor systems may provide a target for novel therapeutics. PMID:12486589

  9. {delta}-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    SciTech Connect

    Heiss, Anika; Ammer, Hermann; Eisinger, Daniela A.

    2009-07-15

    {delta}-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen{sup 2,5}]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G{sub i/o} proteins, because pre-treatment with pertussis toxin, but not over-expression of the G{sub q/11} scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the G{beta}{gamma} scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  10. Effect of delta opioid receptor activation on spatial cognition and neurogenesis in cerebral ischemic rats.

    PubMed

    Wang, Shu-Yan; Duan, Ya-Le; Zhao, Bing; Wang, Xiang-Rui; Zhao, Zheng; Zhang, Guang-Ming

    2016-05-01

    This study aimed to investigate whether a selective delta opioid receptor agonist, [D-Ala2, D-Leu5]-Enkephalin (DADLE), regulates neurogenesis in the hippocampus of ischemic rats. Using an intracerebral cannula, rats were subjected to cerebral ischemia using the standard four-vessel occlusion. DADLE (2.5nmol), DADLE (2.5nmol) with naltrindole (NAL) (2.5nmol), or vehicle was administered at the onset of reperfusion. Bromodeoxyuridine (BrdU, 100mg/kg, intraperitoneal) was used to label newly formed cells from days 1 to 7 after ischemia. Immunohistochemistry was used to evaluate cell proliferation and apoptosis and differentiation 7days 28 days, respectively, after ischemia. Morris water maze test was conducted to test spatial learning and memory 23-27 days after ischemia. We found that DADLE treatment improved performance in the Morris water maze test, promoted proliferation and differentiation of newly formed neurons, and inhibited differentiation into astrocytes in a rat model of cerebral ischemia. Furthermore, the protective effects of DADLE were significantly reversed by co-administration of NAL (P<0.05), a highly potent and selective delta opioid receptor antagonist. Our findings suggest that DADLE promotes spatial cognitive function recovery and regulates neurogenesis after ischemia, which may provide a promising therapeutic strategy for cerebral ischemia. PMID:27016387

  11. Blockade of opioid receptors in anterior cingulate cortex disrupts ethanol-seeking behavior in mice.

    PubMed

    Gremel, Christina M; Young, Emily A; Cunningham, Christopher L

    2011-06-01

    The anterior cingulate cortex (ACC) and opioid receptors have been suggested to play a role in attributing incentive motivational properties to drug-related cues. We examined whether blockade of ACC opioid receptors would reduce cue-induced ethanol-seeking behavior in mice. We show that intra-ACC opioid receptor blockade disrupted expression of an ethanol-induced conditioned place preference, suggesting that endogenous opioid modulation in the ACC may be critical for maintaining the cue's conditioned rewarding effects. PMID:21219940

  12. Extensive Post-translational Modification of Active and Inactivated Forms of Endogenous p53*

    PubMed Central

    DeHart, Caroline J.; Chahal, Jasdave S.; Flint, S. J.; Perlman, David H.

    2014-01-01

    The p53 tumor suppressor protein accumulates to very high concentrations in normal human fibroblasts infected by adenovirus type 5 mutants that cannot direct assembly of the viral E1B 55-kDa protein-containing E3 ubiquitin ligase that targets p53 for degradation. Despite high concentrations of nuclear p53, the p53 transcriptional program is not induced in these infected cells. We exploited this system to examine select post-translational modifications (PTMs) present on a transcriptionally inert population of endogenous human p53, as well as on p53 activated in response to etoposide treatment of normal human fibroblasts. These forms of p53 were purified from whole cell lysates by means of immunoaffinity chromatography and SDS-PAGE, and peptides derived from them were subjected to nano-ultra-high-performance LC-MS and MS/MS analyses on a high-resolution accurate-mass MS platform (data available via ProteomeXchange, PXD000464). We identified an unexpectedly large number of PTMs, comprising phosphorylation of Ser and Thr residues, methylation of Arg residues, and acetylation, ubiquitinylation, and methylation of Lys residues—for example, some 150 previously undescribed modifications of p53 isolated from infected cells. These modifications were distributed across all functional domains of both forms of the endogenous human p53 protein, as well as those of an orthologous population of p53 isolated from COS-1 cells. Despite the differences in activity, including greater in vitro sequence-specific DNA binding activity exhibited by p53 isolated from etoposide-treated cells, few differences were observed in the location, nature, or relative frequencies of PTMs on the two populations of human p53. Indeed, the wealth of PTMs that we have identified is consistent with a far greater degree of complex, combinatorial regulation of p53 by PTM than previously anticipated. PMID:24056736

  13. Expression of corticotropin-releasing factor in inflamed tissue is required for intrinsic peripheral opioid analgesia.

    PubMed Central

    Schafer, M; Mousa, S A; Zhang, Q; Carter, L; Stein, C

    1996-01-01

    Immune cell-derived opioid peptides can activate opioid receptors on peripheral sensory nerves to inhibit inflammatory pain. The intrinsic mechanisms triggering this neuroimmune interaction are unknown. This study investigates the involvement of endogenous corticotropin-releasing factor (CRF) and interleukin-1beta (IL-1). A specific stress paradigm, cold water swim (CWS), produces potent opioid receptor-specific antinociception in inflamed paws of rats. This effect is dose-dependently attenuated by intraplantar but not by intravenous alpha-helical CRF. IL-1 receptor antagonist is ineffective. Similarly, local injection of antiserum against CRF, but not to IL-1, dose-dependently reverses this effect. Intravenous anti-CRF is only inhibitory at 10(4)-fold higher concentrations and intravenous CRF does not produce analgesia. Pretreatment of inflamed paws with an 18-mer 3'-3'-end inverted CRF-antisense oligodeoxynucleotide abolishes CWS-induced antinociception. The same treatment significantly reduces the amount of CRF extracted from inflamed paws and the number of CRF-immunostained cells without affecting gross inflammatory signs. A mismatch oligodeoxynucleotide alters neither the CWS effect nor CRF immunoreactivity. These findings identify locally expressed CRF as the predominant agent to trigger opioid release within inflamed tissue. Endogenous IL-1, circulating CRF or antiinflammatory effects, are not involved. Thus, an intact immune system plays an essential role in pain control, which is important for the understanding of pain in immunosuppressed patients with cancer or AIDS. Images Fig. 4 PMID:8650225

  14. In-vivo detection of binary PKA network interactions upon activation of endogenous GPCRs

    PubMed Central

    Röck, Ruth; Bachmann, Verena; Bhang, Hyo-eun C; Malleshaiah, Mohan; Raffeiner, Philipp; Mayrhofer, Johanna E; Tschaikner, Philipp M; Bister, Klaus; Aanstad, Pia; Pomper, Martin G; Michnick, Stephen W; Stefan, Eduard

    2015-01-01

    Membrane receptor-sensed input signals affect and modulate intracellular protein-protein interactions (PPIs). Consequent changes occur to the compositions of protein complexes, protein localization and intermolecular binding affinities. Alterations of compartmentalized PPIs emanating from certain deregulated kinases are implicated in the manifestation of diseases such as cancer. Here we describe the application of a genetically encoded Protein-fragment Complementation Assay (PCA) based on the Renilla Luciferase (Rluc) enzyme to compare binary PPIs of the spatially and temporally controlled protein kinase A (PKA) network in diverse eukaryotic model systems. The simplicity and sensitivity of this cell-based reporter allows for real-time recordings of mutually exclusive PPIs of PKA upon activation of selected endogenous G protein-coupled receptors (GPCRs) in cancer cells, xenografts of mice, budding yeast, and zebrafish embryos. This extends the application spectrum of Rluc PCA for the quantification of PPI-based receptor-effector relationships in physiological and pathological model systems. PMID:26099953

  15. Endogenous changes in citokinin activity in systemically virus-infected plants.

    PubMed

    Pennazio, S; Roggero, P

    1998-10-01

    Viral diseases may alter cytokinin activity in plants, an effect associated with morphological and physiological changes. Experimental evidence indicates that the level of cytokinins may be both reduced or increased depending on different viral diseases. Circumstantial evidence suggests a change in virus-diseased plants showing specific alterations such as tumors and disorders in carbon partitioning and chlorophyll metabolism. The knowledge reached on cytokinin changes is not yet adequate to the importance of their role during viral pathogenesis. Furthermore, unclear results are available on the effect of cytokinins on virus replication. There is little information on how systemic virus infection alters cytokinin metabolism and no information on how this alteration can affect plant metabolism. Nevertheless, a possible control of some viral diseases by biomanipulation of plants to modify the endogenous levels of such hormone may be suggested, provided that higher levels of cytokinins do not increase the rate of virus replication. PMID:9812325

  16. Regulation of opioid receptors by cocaine.

    PubMed

    Unterwald, E M

    2001-06-01

    Cocaine is a widely abused psychostimulant. Its direct actions include inhibition of dopamine, serotonin, and norepinephrine reuptake into presynaptic nerve terminals, thereby potentiating the actions of these transmitters in the synapse. A variety of studies have demonstrated that cocaine can also have profound effects on the endogenous opioid system. Compelling evidence points to the importance of mu opioid receptors in human cocaine addiction and craving. Animal studies support these findings and demonstrate that chronic cocaine administration can result in alterations in opioid receptor expression and function as measured by changes in critical signal transduction pathways. This chapter reviews studies on the regulation of opioid receptors as the result of exposure to cocaine. PMID:11458541

  17. CRISPR-on system for the activation of the endogenous human INS gene.

    PubMed

    Giménez, C A; Ielpi, M; Mutto, A; Grosembacher, L; Argibay, P; Pereyra-Bonnet, F

    2016-06-01

    Advances in the field of epigenetics have allowed the design of new therapeutic strategies to address complex diseases such as type 1 diabetes (T1D). Clustered regularly interspaced short palindromic repeats (CRISPR)-on is a novel and powerful RNA-guided transcriptional activator system that can turn on specific gene expression; however, it remains unclear whether this system can be widely used or whether its use will be restricted depending on cell types, methylation promoter statuses or the capacity to modulate chromatin state. Our results revealed that the CRISPR-on system fused with transcriptional activators (dCas9-VP160) activated endogenous human INS, which is a silenced gene with a fully methylated promoter. Similarly, we observed a synergistic effect on gene activation when multiple single guide RNAs were used, and the transcriptional activation was maintained until day 21. Regarding the epigenetic profile, the targeted promoter gene did not exhibit alteration in its methylation status but rather exhibited altered levels of H3K9ac following treatment. Importantly, we showed that dCas9-VP160 acts on patients' cells in vitro, particularly the fibroblasts of patients with T1D. PMID:27052801

  18. [ROLE PHOSPHOINOSITID SIGNALING PATHWAY IN OPIOIDS CONTROL OF P2X3 RECEPTORS IN THE PRIMARY SENSORY NEURONS].

    PubMed

    Kulyk, V B; Chizhmakov, I V; Volkova, T M; Maximyuk, O P; Krishtal, O A

    2015-01-01

    Homomeric P2X3 receptors expressed in primary nociceptive neurons are crucial elements in the pain signal generation. In turn, opioid system regulates the intensity of this signal in both CNS and PNS. Here we describe the effects of opioids on P2X3 receptors in DRG neurons studied by using patch clamp technique. Activation of G-protein coupled opioid receptors by endogenous opioid Leu-enkephalin (Leu), resulted in the two opposite effects on P2X3 receptor-mediated currents (P2X3 currents). In particular, application of 1 µM Leu lead to the complete inhibition of P2X3 currents. However, after pretreatment of the neurons with a Gi/o-protein inhibitor pertussis toxin (PT), the same concentration of Leu caused facilitation of P2X3 currents. PLC inhibitor U-73122 at concentration of 1 µM completely eliminated both facilitating and inhibitory effects of Leu on P2X3 currents. Thus, opioid receptor agonists cause two oppositely directed effects on P2X3 receptors in DRG neurons of rats and both of them are mediated through PLC signaling pathway. Our results point to a possible molecular basis of the mechanism for the well-known transition inhibitory action of opioids (analgesia) to facilitating (hyperalgesia). PMID:26552301

  19. New Mechanism of Bone Cancer Pain: Tumor Tissue-Derived Endogenous Formaldehyde Induced Bone Cancer Pain via TRPV1 Activation.

    PubMed

    Wan, You

    2016-01-01

    In recent years, our serial investigations focused on the role of cancer cells-derived endogenous formaldehyde in bone cancer pain. We found that cancer cells produced formaldehyde through demethylation process by serine hydroxymethyltransferase (SHMT1 and SHMT2) and lysine-specific histone demethylase 1 (LSD1). When the cancer cells metastasized into bone marrow, the elevated endogenous formaldehyde induced bone cancer pain through activation on the transient receptor potential vanilloid subfamily member 1 (TRPV1) in the peripheral nerve fibers. More interestingly, TRPV1 expressions in the peripheral fibers were upregulated by the local insulin-like growth factor I (IGF-I) produced by the activated osteoblasts. In conclusion, tumor tissue-derived endogenous formaldehyde induced bone cancer pain via TRPV1 activation. PMID:26900062

  20. δ-Opioid Receptor Activation Modified MicroRNA Expression in the Rat Kidney under Prolonged Hypoxia

    PubMed Central

    He, Xiaozhou; Yang, Yilin; Zhi, Feng; Moore, Meredith L.; Kang, Xuezhi; Chao, Dongman; Wang, Rong; Balboni, Gianfranco; Salvadori, Severo; Kim, Dong H.; Xia, Ying

    2013-01-01

    Hypoxic/ischemic injury to kidney is a frequently encountered clinical problem with limited therapeutic options. Since microRNAs are differentially involved in hypoxic/ischemic events and δ-opioid receptor (DOR) activation is known to protect against hypoxic/ischemic injury, we speculated on the involvement of DOR activation in altering the microRNA (miRNA) expression in kidney under hypoxic condition. We selected 31 miRNAs based on microarray data for quantitative PCR analysis. Among them, 14 miRNAs were significantly altered after prolonged hypoxia, DOR activation or a combination of both. We found that 1) DOR activation alters miRNA expression profiles in normoxic conditions; 2) hypoxia differentially alters miRNA expression depending on the duration of hypoxia; and 3) DOR activation can modify hypoxia-induced changes in miRNA expression. For example, 10-day hypoxia reduced the level of miR-212 by over 70%, while DOR activation could mimic such reduction even in normoxic kidney. In contrast, the same stress increased miR-29a by >100%, which was reversed following DOR activation. These first data suggest that hypoxia comprehensively modifies the miRNA profile within the kidney, which can be mimicked or modified by DOR activation. Ascertaining the targeted pathways that regulate the diverse cellular and molecular functions of miRNA may provide new insights into potential therapies for hypoxic/ischemic injury of the kidney. PMID:23596515

  1. Immunoreactive opioid peptides in human breast cancer.

    PubMed Central

    Scopsi, L.; Balslev, E.; Brünner, N.; Poulsen, H. S.; Andersen, J.; Rank, F.; Larsson, L. I.

    1989-01-01

    Opioid peptides have a variety of actions on inter alia pituitary hormone secretion and the immune system. Release of endogenous opioids has been found to stimulate growth of experimental breast cancers and opiate receptor blockers have reduced the growth of chemically induced rat breast tumors. Opioid peptides may therefore play a role in human breast cancer. Invasive ductal carcinomas from 61 premenopausal women were immunocytochemically analyzed for the presence of opioid peptide immunoreactivity. Positive staining was unambiguously identified in 34 of the tumors (56%). In addition, a medullary carcinoma was positive. In a smaller series of tumors, opioid peptide immunoreactive cells were detected in both primary tumors and metastases. Positive tumor cells were usually few and scattered. Therefore, underestimates of their true frequency of occurrence are likely to have occurred, making accurate correlations with clinical behavior and estrogen receptor status difficult. No correlations with estrogen receptors were established for the unambiguously opioid peptide-positive tumors. Many of the positive tumors also stained with antibodies to gamma-endorphin and alpha-melanocyte-stimulating hormone, suggesting the presence of proopiomelanocortin-derived peptides in them. However, peptides derived from other opioid precursors also may be present in breast cancer. Images Figure 1 PMID:2464945

  2. Involvement of μ-opioid receptors in antinociceptive action of botulinum toxin type A.

    PubMed

    Drinovac, V; Bach-Rojecky, L; Matak, I; Lacković, Z

    2013-07-01

    Botulinum toxin A (BTX-A) is approved for treatment of chronic migraine and has been investigated in various other painful conditions. Recent evidence demonstrated retrograde axonal transport and suggested the involvement of CNS in antinociceptive effect of BTX-A. However, the mechanism of BTX-A central antinociceptive action is unknown. In this study we investigated the potential role of opioid receptors in BTX-A's antinociceptive activity. In formalin-induced inflammatory pain we assessed the effect of opioid antagonists on antinociceptive activity of BTX-A. Naltrexone was injected subcutaneously (0.02-2 mg/kg) or intrathecally (0.07 μg/10 μl-350 μg/10 μl), while selective μ-antagonist naloxonazine was administered intraperitoneally (5 mg/kg) prior to nociceptive testing. The influence of naltrexone (2 mg/kg s.c.) on BTX-A antinociceptive activity was examined additionally in an experimental neuropathy induced by partial sciatic nerve transection. To investigate the effects of naltrexone and BTX-A on neuronal activation in spinal cord, c-Fos expression was immunohistochemically examined in a model of formalin-induced pain. Antinociceptive effects of BTX-A in formalin and sciatic nerve transection-induced pain were prevented by non-selective opioid antagonist naltrexone. Similarly, BTX-A-induced pain reduction was abolished by low dose of intrathecal naltrexone and by selective μ-antagonist naloxonazine. BTX-A-induced decrease in dorsal horn c-Fos expression was prevented by naltrexone. Prevention of BTX-A effects on pain and c-Fos expression by opioid antagonists suggest that the central antinociceptive action of BTX-A might be associated with the activity of endogenous opioid system (involving μ-opioid receptor). These results provide first insights into the mechanism of BTX-A's central antinociceptive activity. PMID:23499661

  3. The HERV-K Human Endogenous Retrovirus Envelope Protein Antagonizes Tetherin Antiviral Activity

    PubMed Central

    Lemaître, Cécile; Harper, Francis; Pierron, Gérard

    2014-01-01

    ABSTRACT Endogenous retroviruses are the remnants of past retroviral infections that are scattered within mammalian genomes. In humans, most of these elements are old degenerate sequences that have lost their coding properties. The HERV-K(HML2) family is an exception: it recently amplified in the human genome and corresponds to the most active proviruses, with some intact open reading frames and the potential to encode viral particles. Here, using a reconstructed consensus element, we show that HERV-K(HML2) proviruses are able to inhibit Tetherin, a cellular restriction factor that is active against most enveloped viruses and acts by keeping the viral particles attached to the cell surface. More precisely, we identify the Envelope protein (Env) as the viral effector active against Tetherin. Through immunoprecipitation experiments, we show that the recognition of Tetherin is mediated by the surface subunit of Env. Similar to Ebola glycoprotein, HERV-K(HML2) Env does not mediate Tetherin degradation or cell surface removal; therefore, it uses a yet-undescribed mechanism to inactivate Tetherin. We also assessed all natural complete alleles of endogenous HERV-K(HML2) Env described to date for their ability to inhibit Tetherin and found that two of them (out of six) can block Tetherin restriction. However, due to their recent amplification, HERV-K(HML2) elements are extremely polymorphic in the human population, and it is likely that individuals will not all possess the same anti-Tetherin potential. Because of Tetherin's role as a restriction factor capable of inducing innate immune responses, this could have functional consequences for individual responses to infection. IMPORTANCE Tetherin, a cellular protein initially characterized for its role against HIV-1, has been proven to counteract numerous enveloped viruses. It blocks the release of viral particles from producer cells, keeping them tethered to the cell surface. Several viruses have developed strategies to

  4. Tetrahydroquinoline derivatives as opioid receptor antagonists.

    PubMed

    Zhang, Cunyu; Westaway, Susan M; Speake, Jason D; Bishop, Michael J; Goetz, Aaron S; Carballo, Luz Helena; Hu, Mike; Epperly, Andrea H

    2011-01-15

    Opioid receptors play an important role in both behavioral and homeostatic functions. We herein report tetrahydroquinoline derivatives as opioid receptor antagonists. SAR studies led to the identification of the potent antagonist 2v, endowed with 1.58nM (K(i)) functional activity against the μ opioid receptor. DMPK data suggest that novel tetrahydroquinoline analogs may be advantageous in peripheral applications. PMID:21193310

  5. Ligand-biased activation of extracellular signal-regulated kinase 1/2 leads to differences in opioid induced antinociception and tolerance.

    PubMed

    Bobeck, Erin N; Ingram, Susan L; Hermes, Sam M; Aicher, Sue A; Morgan, Michael M

    2016-02-01

    Opioids produce antinociception by activation of G protein signaling linked to the mu-opioid receptor (MOPr). However, opioid binding to the MOPr also activates β-arrestin signaling. Opioids such as DAMGO and fentanyl differ in their relative efficacy for activation of these signaling cascades, but the behavioral consequences of this differential signaling are not known. The purpose of this study was to evaluate the behavioral significance of G protein and internalization dependent signaling within ventrolateral periaqueductal gray (vlPAG). Antinociception induced by microinjecting DAMGO into the vlPAG was attenuated by blocking Gαi/o protein signaling with administration of pertussis toxin (PTX), preventing internalization with administration of dynamin dominant-negative inhibitory peptide (dyn-DN) or direct inhibition of ERK1/2 with administration of the MEK inhibitor, U0126. In contrast, the antinociceptive effect of microinjecting fentanyl into the vlPAG was not altered by administration of PTX or U0126, and was enhanced by administration of dyn-DN. Microinjection of DAMGO, but not fentanyl, into the vlPAG induced phosphorylation of ERK1/2, which was blocked by inhibiting receptor internalization with administration of dyn-DN, but not by inhibition of Gαi/o proteins. ERK1/2 inhibition also prevented the development and expression of tolerance to repeated DAMGO microinjections, but had no effect on fentanyl tolerance. These data reveal that ERK1/2 activation following MOPr internalization contributes to the antinociceptive effect of some (e.g., DAMGO), but not all opioids (e.g., fentanyl) despite the known similarities for these agonists to induce β-arrestin recruitment and internalization. PMID:26497105

  6. An endogenous ribonuclease inhibitor regulates the antimicrobial activity of ribonuclease 7 in the human urinary tract.

    PubMed

    Spencer, John D; Schwaderer, Andrew L; Eichler, Tad; Wang, Huanyu; Kline, Jennifer; Justice, Sheryl S; Cohen, Daniel M; Hains, David S

    2014-05-01

    Recent studies stress the importance of antimicrobial peptides in protecting the urinary tract from infection. Previously, we have shown that ribonuclease 7 (RNase 7) is a potent antimicrobial peptide that has a broad-spectrum antimicrobial activity against uropathogenic bacteria. The urothelium of the lower urinary tract and intercalated cells of the kidney produce RNase 7, but regulation of its antimicrobial activity has not been well defined. Here, we characterize the expression of an endogenous inhibitor, ribonuclease inhibitor (RI), in the urinary tract and evaluate its effect on the antimicrobial activity of RNase 7. Using RNA isolated from non-infected human bladder and kidney tissue, quantitative real-time polymerase chain reaction showed that RNH1, the gene encoding RI, is constitutively expressed throughout the urinary tract. With pyelonephritis, RNH1 expression and RI peptide production significantly decrease. Immunostaining localized RI production to the umbrella cells of the bladder and intercalated cells of the renal collecting tubule. In vitro assays showed that RI bound to RNase 7 and suppressed its antimicrobial activity by blocking its ability to bind the cell wall of uropathogenic bacteria. Thus, these results demonstrate a new immunomodulatory role for RI and identified a unique regulatory pathway that may affect how RNase 7 maintains urinary tract sterility. PMID:24107847

  7. An endogenous ribonuclease inhibitor regulates the antimicrobial activity of ribonuclease 7 in the human urinary tract

    PubMed Central

    Spencer, John David; Schwaderer, Andrew L.; Eichler, Tad; Wang, Huanyu; Kline, Jennifer; Justice, Sheryl S.; Cohen, Daniel M.; Hains, David S.

    2013-01-01

    Recent studies stress the importance of antimicrobial peptides in protecting the urinary tract from infection. Previously, we have shown that ribonuclease 7 (RNase 7) is a potent antimicrobial peptide that has broad-spectrum antimicrobial activity against uropathogenic bacteria. The urothelium of the lower urinary tract and intercalated cells of the kidney produce RNase 7 but regulation of its antimicrobial activity has not been well defined. Here we characterize the expression of an endogenous inhibitor, ribonuclease inhibitor (RI), in the urinary tract and evaluate its effect on RNase 7’s antimicrobial activity. Using RNA isolated from non-infected human bladder and kidney tissue, quantitative real-time PCR showed that RNH1, the gene encoding RI, is constitutively expressed throughout the urinary tract. With pyelonephritis, RNH1 expression and RI peptide production significantly decrease. Immunostaining localized RI production to the umbrella cells of the bladder and intercalated cells of the renal collecting tubule. In vitro assays showed that RI bound to RNase 7 and suppressed its antimicrobial activity by blocking its ability to bind the cell wall of uropathogenic bacteria. Thus, these results demonstrate a new immunomodulatory role for RI and identified a unique regulatory pathway that may affect how RNase 7 maintains urinary tract sterility. PMID:24107847

  8. Interactions of the opioid and cannabinoid systems in reward: Insights from knockout studies

    PubMed Central

    Befort, Katia

    2015-01-01

    The opioid system consists of three receptors, mu, delta, and kappa, which are activated by endogenous opioid peptides (enkephalins, endorphins, and dynorphins). The endogenous cannabinoid system comprises lipid neuromodulators (endocannabinoids), enzymes for their synthesis and their degradation and two well-characterized receptors, cannabinoid receptors CB1 and CB2. These systems play a major role in the control of pain as well as in mood regulation, reward processing and the development of addiction. Both opioid and cannabinoid receptors are coupled to G proteins and are expressed throughout the brain reinforcement circuitry. Extending classical pharmacology, research using genetically modified mice has provided important progress in the identification of the specific contribution of each component of these endogenous systems in vivo on reward process. This review will summarize available genetic tools and our present knowledge on the consequences of gene knockout on reinforced behaviors in both systems, with a focus on their potential interactions. A better understanding of opioid–cannabinoid interactions may provide novel strategies for therapies in addicted individuals. PMID:25698968

  9. Does the kappa opioid receptor system contribute to pain aversion?

    PubMed Central

    Cahill, Catherine M.; Taylor, Anna M. W.; Cook, Christopher; Ong, Edmund; Morón, Jose A.; Evans, Christopher J.

    2014-01-01

    The kappa opioid receptor (KOR) and the endogenous peptide-ligand dynorphin have received significant attention due the involvement in mediating a variety of behavioral and neurophysiological responses, including opposing the rewarding properties of drugs of abuse including opioids. Accumulating evidence indicates this system is involved in regulating states of motivation and emotion. Acute activation of the KOR produces an increase in motivational behavior to escape a threat, however, KOR activation associated with chronic stress leads to the expression of symptoms indicative of mood disorders. It is well accepted that KOR can produce analgesia and is engaged in chronic pain states including neuropathic pain. Spinal studies have revealed KOR-induced analgesia in reversing pain hypersensitivities associated with peripheral nerve injury. While systemic administration of KOR agonists attenuates nociceptive sensory transmission, this effect appears to be a stress-induced effect as anxiolytic agents, including delta opioid receptor agonists, mitigate KOR agonist-induced analgesia. Additionally, while the role of KOR and dynorphin in driving the dysphoric and aversive components of stress and drug withdrawal has been well characterized, how this system mediates the negative emotional states associated with chronic pain is relatively unexplored. This review provides evidence that dynorphin and the KOR system contribute to the negative affective component of pain and that this receptor system likely contributes to the high comorbidity of mood disorders associated with chronic neuropathic pain. PMID:25452729

  10. Retention of Endogenous Viable Cells Enhances the Anti-Inflammatory Activity of Cryopreserved Amnion

    PubMed Central

    Duan-Arnold, Yi; Gyurdieva, Alexandra; Johnson, Amy; Uveges, Thomas E.; Jacobstein, Douglas A.; Danilkovitch, Alla

    2015-01-01

    Objective: Human amniotic membrane (hAM) has been used to treat wounds for more than 100 years. However, widespread use of fresh hAM has been limited due to its short shelf life and safety concerns. To overcome these concerns, different preservation methods have been introduced. The majority of these methods result in devitalized hAM (dev-hAM). Recently, we developed a cryopreservation method that retains all hAM components intact (int-hAM), including viable endogenous cells. To understand the advantages of retaining viable cells in preserved hAM, we compared the anti-inflammatory properties of int-hAM and dev-hAM. Approach: The tissue composition of int-hAM and dev-hAM was compared with fresh hAM through histology and cell viability analysis. We also evaluated the ability of int-hAM and dev-hAM to regulate tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), and IL-10 release when co-cultured with immune cells; to produce prostaglandin E2 (PGE2) on TNF-α stimulation; and to inhibit proteases. Results: Int-hAM maintained the structural and cellular integrity of fresh hAM. Int-hAM had >80% cell viability post-thaw and remained viable for at least a week in culture. Viable cells were not detected in dev-hAM. Compared with dev-hAM, int-hAM showed significantly greater downregulation of TNF-α and IL-1α, upregulation of PGE2 and IL-10, and stronger inhibition of collagenase. Innovation and Conclusion: A new cryopreservation method has been developed to retain all native components of hAM. For the first time, we show that viable endogenous cells significantly augment the anti-inflammatory activity of cryopreserved hAM. PMID:26401419

  11. Prescription Opioids during Pregnancy

    MedlinePlus

    ... brand names ConZip®, Ryzolt®, Ultram®) The street drug heroin also is an opioid. What problems can opioids ... to buy them illegally. People often start using heroin after becoming addicted to prescription opioids. Sometimes opioids ...

  12. Molecular Physiology of Enteric Opioid Receptors

    PubMed Central

    Galligan, James J.; Akbarali, Hamid I.

    2015-01-01

    Opioid drugs have powerful antidiarrheal effects and many patients taking these drugs for chronic pain relief experience chronic constipation that can progress to opioid-induced bowel dysfunction. Three classes of opioid receptors are expressed by enteric neurons: μ-, δ-, and κ-opioid receptors (MOR, DOR, and KOR). MOR and DOR couple to inhibition of adenylate cylase and nerve terminal Ca2+ channels and activation of K+ channels. These effects reduce neuronal activity and neurotransmitter release. KOR couples to inhibition of Ca2+ channels and inhibition of neurotransmitter release. In the human gastrointestinal tract, MOR, DOR, and KOR link to inhibition of acetylcholine release from enteric interneurons and purine/nitric oxide release from inhibitory motorneurons. These actions inhibit propulsive motility. MOR and DOR also link to inhibition of submucosal secretomotor neurons, reducing active Cl− secretion and passive water movement into the colonic lumen. These effects account for the constipation caused by opioid receptor agonists. Tolerance develops to the analgesic effects of opioid receptor agonists but not to the constipating actions. This may be due to differential β-arrestin-2-dependent opioid receptor desensitization and internalization in enteric nerves in the colon compared with the small intestine and in neuronal pain pathways. Further studies of differential opioid receptor desensitization and tolerance in subsets of enteric neurons may identify new drugs or other treatment strategies of opioid-induced bowel dysfunction. PMID:25207608

  13. Molecular physiology of enteric opioid receptors.

    PubMed

    Galligan, James J; Akbarali, Hamid I

    2014-09-10

    Opioid drugs have powerful antidiarrheal effects and many patients taking these drugs for chronic pain relief experience chronic constipation that can progress to opioid-induced bowel dysfunction. Three classes of opioid receptors are expressed by enteric neurons: μ-, δ-, and κ-opioid receptors (MOR, DOR, and KOR). MOR and DOR couple to inhibition of adenylate cylase and nerve terminal Ca(2+) channels and activation of K(+) channels. These effects reduce neuronal activity and neurotransmitter release. KOR couples to inhibition of Ca(2+) channels and inhibition of neurotransmitter release. In the human gastrointestinal tract, MOR, DOR, and KOR link to inhibition of acetylcholine release from enteric interneurons and purine/nitric oxide release from inhibitory motorneurons. These actions inhibit propulsive motility. MOR and DOR also link to inhibition of submucosal secretomotor neurons, reducing active Cl(-) secretion and passive water movement into the colonic lumen. These effects account for the constipation caused by opioid receptor agonists. Tolerance develops to the analgesic effects of opioid receptor agonists but not to the constipating actions. This may be due to differential β-arrestin-2-dependent opioid receptor desensitization and internalization in enteric nerves in the colon compared with the small intestine and in neuronal pain pathways. Further studies of differential opioid receptor desensitization and tolerance in subsets of enteric neurons may identify new drugs or other treatment strategies of opioid-induced bowel dysfunction. PMID:25207608

  14. Detection of endogenous alkaline phosphatase activity in intact cells by flow cytometry using the fluorogenic ELF-97 phosphatase substrate

    NASA Technical Reports Server (NTRS)

    Telford, W. G.; Cox, W. G.; Stiner, D.; Singer, V. L.; Doty, S. B.

    1999-01-01

    BACKGROUND: The alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone (ELF((R))-97 for enzyme-labeled fluorescence) has been found useful for the histochemical detection of endogenous AP activity and AP-tagged proteins and oligonucleotide probes. In this study, we evaluated its effectiveness at detecting endogenous AP activity by flow cytometry. METHODS: The ELF-97 phosphatase substrate was used to detect endogenous AP activity in UMR-106 rat osteosarcoma cells and primary cultures of chick chondrocytes. Cells were labeled with the ELF-97 reagent and analyzed by flow cytometry using an argon ultraviolet (UV) laser. For comparison purposes, cells were also assayed for AP using a Fast Red Violet LB azo dye assay previously described for use in detecting AP activity by flow cytometry. RESULTS: The ELF-97 phosphatase substrate effectively detected endogenous AP activity in UMR-106 cells, with over 95% of the resulting fluorescent signal resulting from AP-specific activity (as determined by levamisole inhibition of AP activity). In contrast, less than 70% of the fluorescent signal from the Fast Red Violet LB (FRV) assay was AP-dependent, reflecting the high intrinsic fluorescence of the unreacted components. The ELF-97 phosphatase assay was also able to detect very low AP activity in chick chondrocytes that was undetectable by the azo dye method. CONCLUSIONS: The ELF-97 phosphatase assay was able to detect endogenous AP activity in fixed mammalian and avian cells by flow cytometry with superior sensitivity to previously described assays. This work also shows the applicability of ELF-97 to flow cytometry, supplementing its previously demonstrated histochemical applications. Copyright 1999 Wiley-Liss, Inc.

  15. Lamin A Is an Endogenous SIRT6 Activator and Promotes SIRT6-Mediated DNA Repair.

    PubMed

    Ghosh, Shrestha; Liu, Baohua; Wang, Yi; Hao, Quan; Zhou, Zhongjun

    2015-11-17

    The nuclear lamins are essential for various molecular events in the nucleus, such as chromatin organization, DNA replication, and provision of mechanical support. A specific point mutation in the LMNA gene creates a truncated prelamin A termed progerin, causing Hutchinson-Gilford progeria syndrome (HGPS). SIRT6 deficiency leads to defective genomic maintenance and accelerated aging similar to HGPS, suggesting a potential link between lamin A and SIRT6. Here, we report that lamin A is an endogenous activator of SIRT6 and facilitates chromatin localization of SIRT6 upon DNA damage. Lamin A promotes SIRT6-dependent DNA-PKcs (DNA-PK catalytic subunit) recruitment to chromatin, CtIP deacetylation, and PARP1 mono-ADP ribosylation in response to DNA damage. The presence of progerin jeopardizes SIRT6 activation and compromises SIRT6-mediated molecular events in response to DNA damage. These data reveal a critical role for lamin A in regulating SIRT6 activities, suggesting that defects in SIRT6 functions contribute to impaired DNA repair and accelerated aging in HGPS. PMID:26549451

  16. Endogeneous β-D: -xylosidase and α-L: -arabinofuranosidase activity in flax seed mucilage.

    PubMed

    Rasmussen, Louise E; Meyer, Anne S

    2010-12-01

    Flax seed mucilage (FM) contains a mixture of highly doubly substituted arabinoxylan as well as rhamnogalacturonan I with unusual side group substitutions. Treatment of FM with a GH11 Bacillus subtilis XynA endo 1,4-β-xylanase (BsX) gave limited formation of reducing ends but when BsX and FM were incubated together on different wheat arabinoxylan substrates and birchwood xylan, significant amounts of xylose were released. Moreover, arabinose was released from both water-extractable and water-unextractable wheat arabinoxylan. Since no xylose or arabinose was released by BsX addition alone on these substrates, nor without FM or BsX addition, the results indicate the presence of endogenous β-D: -xylosidase and α-L: -arabinofuranosidase activities in FM. FM also exhibited activity on both p-nitrophenyl α-L: -arabinofuranoside (pNPA) and p-nitrophenyl β-D: -xylopyranoside (pNPX). Based on K ( M ) values, the FM enzyme activities had a higher affinity for pNPX (K ( M ) 2 mM) than for pNPA (K ( M ) 20 mM). PMID:20703806

  17. Endogenous plasminogen activators mediate progressive intracerebral hemorrhage after traumatic brain injury in mice

    PubMed Central

    Hijazi, Nuha; Abu Fanne, Rami; Abramovitch, Rinat; Yarovoi, Serge; Higazi, Muhamed; Abdeen, Suhair; Basheer, Maamon; Maraga, Emad; Cines, Douglas B.

    2015-01-01

    Persistent intracerebral hemorrhage (ICH) is a major cause of death and disability after traumatic brain injury (TBI) for which no medical treatment is available. Delayed bleeding is often ascribed to consumptive coagulopathy initiated by exposed brain tissue factor. We examined an alternative hypothesis, namely, that marked release of tissue-type plasminogen activator (tPA) followed by delayed synthesis and release of urokinase plasminogen activator (uPA) from injured brain leads to posttraumatic bleeding by causing premature clot lysis. Using a murine model of severe TBI, we found that ICH is reduced in tPA−/− and uPA−/− mice but increased in PAI-1−/− mice compared with wild-type (WT) mice. tPA−/−, but not uPA−/−, mice developed a systemic coagulopathy post-TBI. Tranexamic acid inhibited ICH expansion in uPA−/−mice but not in tPA−/− mice. Catalytically inactive tPA-S481A inhibited plasminogen activation by tPA and uPA, attenuated ICH, lowered plasma d-dimers, lessened thrombocytopenia, and improved neurologic outcome in WT, tPA−/−, and uPA−/− mice. ICH expansion was also inhibited by tPA-S481A in WT mice anticoagulated with warfarin. These data demonstrate that protracted endogenous fibrinolysis induced by TBI is primarily responsible for persistent ICH and post-TBI coagulopathy in this model and offer a novel approach to interrupt bleeding. PMID:25673638

  18. Endogenous nitric oxide accumulation is involved in the antifungal activity of Shikonin against Candida albicans.

    PubMed

    Liao, Zebin; Yan, Yu; Dong, Huaihuai; Zhu, Zhenyu; Jiang, Yuanying; Cao, Yingying

    2016-01-01

    The aim of the present study was to investigate the role of nitric oxide (NO) in the antifungal activity of Shikonin (SK) against Candida albicans (C. albicans) and to clarify the underlying mechanism. The results showed that the NO donors S-nitrosoglutathione (GSNO) and L-arginine could enhance the antifungal activity of SK, whereas the NO production inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) attenuated antifungal action. Using the fluorescent dye 3-amino,4-aminomethyl-2', 7-difluorescein, diacetate (DAF-FM DA), we found that the accumulation of NO in C. albicans was increased markedly by SK in a time- and dose-dependent manner. In addition, the results of real-time reverse transcription-PCR (RT-PCR) demonstrated that the transcription level of YHB1 in C. albicans was greatly increased upon incubation of SK. Consistently, the YHB1-null mutant (yhb1Δ/Δ) exhibited a higher susceptibility to SK than wild-type cells. In addition, although the transcription level of CTA4 in C. albicans was not significantly changed when exposed to SK, the CTA4-null mutant (cta4Δ/Δ) was more susceptible to SK. Collectively, SK is the agent found to execute its antifungal activity directly via endogenous NO accumulation, and NO-mediated damage is related to the suppression of YHB1 and the function of CTA4. PMID:27530748

  19. Biological redundancy of endogenous GPCR ligands in the gut and the potential for endogenous functional selectivity

    PubMed Central

    Thompson, Georgina L.; Canals, Meritxell; Poole, Daniel P.

    2014-01-01

    This review focuses on the existence and function of multiple endogenous agonists of the somatostatin and opioid receptors with an emphasis on their expression in the gastrointestinal tract. These agonists generally arise from the proteolytic cleavage of prepropeptides during peptide maturation or from degradation of peptides by extracellular or intracellular endopeptidases. In other examples, endogenous peptide agonists for the same G protein-coupled receptors can be products of distinct genes but contain high sequence homology. This apparent biological redundancy has recently been challenged by the realization that different ligands may engender distinct receptor conformations linked to different intracellular signaling profiles and, as such the existence of distinct ligands may underlie mechanisms to finely tune physiological responses. We propose that further characterization of signaling pathways activated by these endogenous ligands will provide invaluable insight into the mechanisms governing biased agonism. Moreover, these ligands may prove useful in the design of novel therapeutic tools to target distinct signaling pathways, thereby favoring desirable effects and limiting detrimental on-target effects. Finally we will discuss the limitations of this area of research and we will highlight the difficulties that need to be addressed when examining endogenous bias in tissues and in animals. PMID:25506328

  20. Role of the non-opioid dynorphin peptide des-Tyr-dynorphin (DYN-A(2-17)) in food intake and physical activity, and its interaction with orexin-A.

    PubMed

    Gac, L; Butterick, T A; Duffy, C M; Teske, J A; Perez-Leighton, C E

    2016-02-01

    Food intake and physical activity are regulated by multiple neuropeptides, including orexin and dynorphin (DYN). Orexin-A (OXA) is one of two orexin peptides with robust roles in regulation of food intake and spontaneous physical activity (SPA). DYN collectively refers to several peptides, some of which act through opioid receptors (opioid DYN) and some whose biological effects are not mediated by opioid receptors (non-opioid DYN). While opioid DYN is known to increase food intake, the effects of non-opioid DYN peptides on food intake and SPA are unknown. Neurons that co-express and release OXA and DYN are located within the lateral hypothalamus. Limited evidence suggests that OXA and opioid DYN peptides can interact to modulate some aspects of behaviors classically related to orexin peptide function. The paraventricular hypothalamic nucleus (PVN) is a brain area where OXA and DYN peptides might interact to modulate food intake and SPA. We demonstrate that injection of des-Tyr-dynorphin (DYN-A(2-17), a non opioid DYN peptide) into the PVN increases food intake and SPA in adult mice. Co-injection of DYN-A(2-17) and OXA in the PVN further increases food intake compared to DYN-A(2-17) or OXA alone. This is the first report describing the effects of non-opioid DYN-A(2-17) on food intake and SPA, and suggests that DYN-A(2-17) interacts with OXA in the PVN to modulate food intake. Our data suggest a novel function for non-opioid DYN-A(2-17) on food intake, supporting the concept that some behavioral effects of the orexin neurons result from combined actions of the orexin and DYN peptides. PMID:26654796

  1. Differential activation of the μ-opioid receptor by oxycodone and morphine in pain-related brain regions in a bone cancer pain model

    PubMed Central

    Nakamura, Atsushi; Hasegawa, Minoru; Minami, Kazuhisa; Kanbara, Tomoe; Tomii, Takako; Nishiyori, Atsushi; Narita, Minoru; Suzuki, Tsutomu; Kato, Akira

    2013-01-01

    Background and Purpose Bone cancer pain is chronic and often difficult to control with opioids. However, recent studies have shown that several opioids have distinct analgesic profiles in chronic pain. Experimental Approach To clarify the mechanisms underlying these distinct analgesic profiles, functional changes in the μ-opioid receptor were examined using a mouse femur bone cancer (FBC) model. Key Results In the FBC model, the Bmax of [3H]-DAMGO binding was reduced by 15–45% in the periaqueductal grey matter (PAG), region ventral to the PAG (vPAG), mediodorsal thalamus (mTH), ventral thalamus and spinal cord. Oxycodone (10−8–10−5 M) and morphine (10−8–10−5 M) activated [35S]-GTPγS binding, but the activation was significantly attenuated in the PAG, vPAG, mTH and spinal cord in the FBC model. Interestingly, the attenuation of oxycodone-induced [35S]-GTPγS binding was quite limited (9–26%) in comparison with that of morphine (46–65%) in the PAG, vPAG and mTH, but not in the spinal cord. Furthermore, i.c.v. oxycodone at doses of 0.02–1.0 μg per mouse clearly inhibited pain-related behaviours, such as guarding, limb-use abnormalities and allodynia-like behaviour in the FBC model mice, while i.c.v. morphine (0.05–2.0 μg per mouse) had only partial or little analgesic effect on limb-use abnormalities and allodynia-like behaviour. Conclusion and Implications These results show that μ-opioid receptor functions are attenuated in several pain-related regions in bone cancer in an agonist-dependent manner, and suggest that modification of the μ-opioid receptor is responsible for the distinct analgesic effect of oxycodone and morphine. PMID:22889192

  2. Activation of adult rat CNS endothelial cells by opioid-induced toll-like receptor 4 (TLR4) signaling induces proinflammatory, biochemical, morphological, and behavioral sequelae

    PubMed Central

    Grace, Peter M.; Ramos, Khara M.; Rodgers, Krista M.; Wang, Xiaohui; Hutchinson, Mark R.; Lewis, Makenzie T.; Morgan, Kelly N.; Kroll, Juliet L.; Taylor, Frederick R.; Strand, Keith A.; Zhang, Yingning; Berkelhammer, Debra; Huey, Madeline G.; Greene, Lisa I.; Cochran, Thomas A.; Yin, Hang; Barth, Daniel S.; Johnson, Kirk W.; Rice, Kenner; Maier, Steven F.; Watkins, Linda R.

    2014-01-01

    CNS immune signaling contributes to deleterious opioid effects including hyperalgesia, tolerance, reward, and dependence/withdrawal. Such effects are mediated by opioid signaling at TLR4, presumptively of glial origin. Whether CNS endothelial cells express TLR4 is controversial. If so, they would be well positioned for activation by blood-borne opioids, contributing to opioid-induced pro-inflammatory responses. These studies examined adult primary rat CNS endothelial cell responses to (-)-morphine or its mu-opioid receptor (MOR) inactive metabolite morphine-3-glucuronide (M3G), both known TLR4 agonists. We demonstrate that adult rat CNS endothelial cells express functional TLR4. M3G activated NFκB, increased tumor necrosis factor-α (TNFα) and cyclooxygenase-2 (COX2) mRNAs, and released prostaglandin E2 from these cells. (-)-Morphine-induced upregulation of TNFα mRNA and prostaglandin E2 release were unmasked by pre-treatment with nalmefene, a MOR antagonist without TLR4 activity (unlike CTAP, shown to have both MOR- and TLR4-activity), suggestive of an interplay between MOR and TLR4 co-activation by (-)-morphine. In support, MOR-dependent Protein Kinase A (PKA) opposed TLR4 signaling, as PKA inhibition (H-89) also unmasked (-)-morphine-induced TNFα and COX2 mRNA upregulation. Intrathecal injection of CNS endothelial cells, stimulated in vitro with M3G, produced TLR4-dependent tactile allodynia. Further, cortical suffusion with M3G in vivo induced TLR4-dependent vasodilation. Finally, endothelial cell TLR4 activation by lipopolysaccharide and/or M3G was blocked by the glial inhibitors AV1013 and propentofylline, demonstrating endothelial cells as a new target of such drugs. These data indicate that (-)-morphine and M3G can activate CNS endothelial cells via TLR4, inducing proinflammatory, biochemical, morphological, and behavioral sequalae. CNS endothelial cells may have previously unanticipated roles in opioid-induced effects, in phenomena blocked by

  3. RAPID HETEROLOGOUS DESENSITIZATION OF ANTINOCICEPTIVE ACTIVITY BETWEEN MU OR DELTA OPIOID RECEPTORS AND CHEMOKINE RECEPTORS IN RATS

    PubMed Central

    Chen, Xiaohong; Geller, Ellen B.; Rogers, Thomas J.; Adler, Martin W.

    2007-01-01

    Previous studies have shown pretreatment with chemokines CCL5/RANTES (100 ng) or CXCL12/SDF-1alpha (100 ng) injected into the periaqueductal grey (PAG) region of the brain, 30 minutes (min) before the mu opioid agonist DAMGO (400 ng), blocked the antinociception induced by DAMGO in the in vivo cold water tail-flick (CWT) antinociceptive test in rats. In the present experiments, we tested whether the action of other agonists at mu and delta opioid receptors is blocked when CCL5/RANTES or CXCL12/SDF-1alpha is administered into the PAG 30 min before, or co-administered with, opioid agonists in the CWT assay. The results showed that (1) CXCL12/SDF-1alpha (100 ng, PAG) or CCL5/RANTES (100 ng, PAG), given 30 min before the opioid agonist morphine, or selective delta opioid receptor agonist DPDPE, blocked the antinociceptive effect of these drugs; (2) CXCL12/SDF-1alpha (100 ng, PAG) or CCL5/RANTES (100 ng, PAG), injected at the same time as DAMGO or DPDPE, significantly reduced the antinociceptive effect induced by these drugs. These results demonstrate that the heterologous desensitization is rapid between the mu or delta opioid receptors and either CCL5/RANTES receptor CCR5 or CXCL12/SDF-1alpha receptor CXCR4 in vivo, but the effect is greater if the chemokine is administered before the opioid. PMID:17049756

  4. Truncation of the peptide sequence in bifunctional ligands with mu and delta opioid receptor agonist and neurokinin 1 receptor antagonist activities

    PubMed Central

    Nair, Padma; Yamamoto, Takashi; Largent-Milnes, Tally M.; Cowell, Scott; Kulkarni, Vinod; Moye, Sharif; Navratilova, Edita; Davis, Peg; Ma, Shou-Wu; Vanderah, Todd W.; Lai, Josephine; Porreca, Frank; Hruby, Victor J.

    2013-01-01

    The optimization and truncation of our lead peptide-derived ligand TY005 possessing eight amino-acid residues was performed. Among the synthesized derivatives, NP30 (Tyr1-DAla2-Gly3-Phe4-Gly5-Trp6-O-[3′,5′-Bzl(CF3)2]) showed balanced and potent opioid agonist as well as substance P antagonist activities in isolated tissue-based assays, together with significant antinociceptive and antiallodynic activities in vivo. PMID:23899615

  5. Endogenous cannabinoid receptor CB1 activation promotes vascular smooth-muscle cell proliferation and neointima formation

    PubMed Central

    Molica, Filippo; Burger, Fabienne; Thomas, Aurélien; Staub, Christian; Tailleux, Anne; Staels, Bart; Pelli, Graziano; Zimmer, Andreas; Cravatt, Benjamin; Matter, Christian M.; Pacher, Pal; Steffens, Sabine

    2013-01-01

    Percutaneous transluminal angioplasty is frequently used in patients with severe arterial narrowing due to atherosclerosis. However, it induces severe arterial injury and an inflammatory response leading to restenosis. Here, we studied a potential activation of the endocannabinoid system and the effect of FA amide hydrolase (FAAH) deficiency, the major enzyme responsible for endocannabinoid anandamide degradation, in arterial injury. We performed carotid balloon injury in atherosclerosis-prone apoE knockout (apoE−/−) and apoE−/−FAAH−/− mice. Anandamide levels were systemically elevated in apoE−/− mice after balloon injury. ApoE−/−FAAH−/− mice had significantly higher baseline anandamide levels and enhanced neointima formation compared with apoE−/− controls. The latter effect was inhibited by treatment with CB1 antagonist AM281. Similarly, apoE−/− mice treated with AM281 had reduced neointimal areas, reduced lesional vascular smooth-muscle cell (SMC) content, and proliferating cell counts. The lesional macrophage content was unchanged. In vitro proliferation rates were significantly reduced in CB1−/− SMCs or when treating apoE−/− or apoE−/−FAAH−/− SMCs with AM281. Macrophage in vitro adhesion and migration were marginally affected by CB1 deficiency. Reendothelialization was not inhibited by treatment with AM281. In conclusion, endogenous CB1 activation contributes to vascular SMC proliferation and neointima formation in response to arterial injury. PMID:23479425

  6. Human endogenous retrovirus envelope proteins target dendritic cells to suppress T-cell activation.

    PubMed

    Hummel, Jonas; Kämmerer, Ulrike; Müller, Nora; Avota, Elita; Schneider-Schaulies, Sibylle

    2015-06-01

    Though mostly defective, human endogenous retroviruses (HERV) can retain open reading frames, which are especially expressed in the placenta. There, the envelope (env) proteins of HERV-W (Syncytin-1), HERV-FRD (Syncytin-2), and HERV-K (HML-2) were implicated in tolerance against the semi-allogenic fetus. Here, we show that the known HERV env-binding receptors ASCT-1 and -2 and MFSD2 are expressed by DCs and T-cells. When used as effectors in coculture systems, CHO cells transfected to express Syncytin-1, -2, or HML-2 did not affect T-cell expansion or overall LPS-driven phenotypic DC maturation, however, promoted release of IL-12 and TNF-α rather than IL-10. In contrast, HERV env expressing choriocarcinoma cell lines suppressed T-cell proliferation and LPS-induced TNF-α and IL-12 release, however, promoted IL-10 accumulation, indicating that these effects might not rely on HERV env interactions. However, DCs conditioned by choriocarcinoma, but also transgenic CHO cells failed to promote allogenic T-cell expansion. This was associated with a loss of DC/T-cell conjugate frequencies, impaired Ca(2+) mobilization, and aberrant patterning of f-actin and tyrosine phosphorylated proteins in T-cells. Altogether, these findings suggest that HERV env proteins target T-cell activation indirectly by modulating the stimulatory activity of DCs. PMID:25752285

  7. Duration of opioid receptor blockade determines biotherapeutic response.

    PubMed

    McLaughlin, Patricia J; Zagon, Ian S

    2015-10-01

    Historically, studies on endogenous and exogenous opioids and their receptors focused on the mediation of pain, with excess opiate consumption leading to addiction. Opioid antagonists such as naloxone and naltrexone blocked these interactions, and still are widely used to reverse drug and alcohol overdose. Although specific opioid antagonists have been designed for mu, delta, and kappa opioid receptors, the general antagonists remain the most effective. With the discovery of the opioid growth factor (OGF)-OGF receptor (OGFr) axis as a novel biological pathway involved in homeostasis of replicating cells and tissues, the role of opioid receptor antagonists was expanded. An intermittent OGFr blockade by low dosages of naltrexone resulted in depressed cell replication, whereas high (or sustained) dosages of naltrexone that conferred a continuous OGFr blockade resulted in enhanced growth. More than 3 decades of research have confirmed that the duration of opioid receptor blockade, not specifically the dosage, by general opioid antagonists determines the biotherapeutic outcome. Dysregulation of the OGF-OGFr pathway is apparent in a number of human disorders including diabetes, multiple sclerosis, and cancer, and thus opioid antagonist disruption of interaction prevails as a therapeutic intervention. We review evidence that the duration of opioid receptor blockade is correlated with the magnitude and direction of response, and discuss the potential therapeutic effectiveness of continuous receptor blockade for treatment of diabetic complications such as corneal defects and skin wounds, and of intermittent receptor blockade by low dosages of naltrexone for treatment of autoimmune diseases and cancer. PMID:26119823

  8. Micro-opioid receptor activation in the basolateral amygdala mediates the learning of increases but not decreases in the incentive value of a food reward.

    PubMed

    Wassum, Kate M; Cely, Ingrid C; Balleine, Bernard W; Maidment, Nigel T

    2011-02-01

    The decision to perform, or not perform, actions known to lead to a rewarding outcome is strongly influenced by the current incentive value of the reward. Incentive value is largely determined by the affective experience derived during previous consumption of the reward-the process of incentive learning. We trained rats on a two-lever, seeking-taking chain paradigm for sucrose reward, in which responding on the initial seeking lever of the chain was demonstrably controlled by the incentive value of the reward. We found that infusion of the μ-opioid receptor antagonist, CTOP (d-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH(2)), into the basolateral amygdala (BLA) during posttraining, noncontingent consumption of sucrose in a novel elevated-hunger state (a positive incentive learning opportunity) blocked the encoding of incentive value information normally used to increase subsequent sucrose-seeking responses. Similar treatment with δ [N, N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH (ICI 174,864)] or κ [5'-guanidinonaltrindole (GNTI)] antagonists was without effect. Interestingly, none of these drugs affected the ability of the rats to encode a decrease in incentive value resulting from experiencing the sucrose in a novel reduced-hunger state. However, the μ agonist, DAMGO ([d-Ala2, NMe-Phe4, Gly5-ol]-enkephalin), appeared to attenuate this negative incentive learning. These data suggest that upshifts and downshifts in endogenous opioid transmission in the BLA mediate the encoding of positive and negative shifts in incentive value, respectively, through actions at μ-opioid receptors, and provide insight into a mechanism through which opiates may elicit inappropriate desire resulting in their continued intake in the face of diminishing affective experience. PMID:21289167

  9. Activation of endogenous angiotensin converting enzyme 2 prevents early injuries induced by hyperglycemia in rat retina

    PubMed Central

    Foureaux, G.; Nogueira, B. S.; Coutinho, D. C. O.; Raizada, M. K.; Nogueira, J. C.; Ferreira, A. J.

    2015-01-01

    Diabetic retinopathy (DR) is a serious complication of diabetes mellitus that may result in blindness. We evaluated the effects of activation of endogenous angiotensin converting enzyme (ACE) 2 on the early stages of DR. Rats were administered an intravenous injection of streptozotocin to induce hyperglycemia. The ACE2 activator 1-[[2-(dimethylamino) ethyl] amino]-4-(hydroxymethyl)-7-[[(4-methylphenyl) sulfonyl] oxy]-9H-xanthone 9 (XNT) was administered by daily gavage. The death of retinal ganglion cells (RGC) was evaluated in histological sections, and retinal ACE2, caspase-3, and vascular endothelial growth factor (VEGF) expressions were analyzed by immunohistochemistry. XNT treatment increased ACE2 expression in retinas of hyperglycemic (HG) rats (control: 13.81±2.71 area%; HG: 14.29±4.30 area%; HG+XNT: 26.87±1.86 area%; P<0.05). Importantly, ACE2 activation significantly increased the RCG number in comparison with HG animals (control: 553.5±14.29; HG: 530.8±10.3 cells; HG+XNT: 575.3±16.5 cells; P<0.05). This effect was accompanied by a reduction in the expression of caspase-3 in RGC of the HG+XNT group when compared with untreated HG rats (control: 18.74±1.59; HG: 38.39±3.39 area%; HG+XNT: 27.83±2.80 area%; P<0.05). Treatment with XNT did not alter the VEGF expression in HG animals (P>0.05). Altogether, these findings indicate that activation of ACE2 reduced the death of retinal ganglion cells by apoptosis in HG rats. PMID:26421871

  10. Periaqueductal gray μ and κ opioid receptors determine behavioral selection from maternal to predatory behavior in lactating rats.

    PubMed

    Klein, Marianne Orlandini; Cruz, Aline de Mello; Machado, Franciele Corrêa; Picolo, Gisele; Canteras, Newton Sabino; Felicio, Luciano Freitas

    2014-11-01

    Every mother must optimize her time between caring for her young and her subsistence. The rostro lateral portion of the periaqueductal grey (rlPAG) is a critical site that modulates the switch between maternal and predatory behavior. Opioids play multiple roles in both maternal behavior and this switching process. The present study used a pharmacological approach to evaluate the functional role of rlPAG μ and κ opioid receptors in behavioral selection. Rat dams were implanted with a guide cannula in the rlPAG and divided into three experiments in which we tested the role of opioid agonists (Experiment 1), the influence of μ and κ opioid receptor blockade in the presence of morphine (Experiment 2), and the influence of μ and κ opioid receptor blockade (Experiment 3). After behavioral test, in Experiment 4, we evaluated rlPAG μ and κ receptor activation in all Experiments 1-3. The results showed that massive opioidergic activation induced by morphine in the rlPAG inhibited maternal behavior without interfering with predatory hunting. No behavioral changes and no receptor activation were promoted by the specific agonist alone. However, κ receptor blockade increased hunting behavior and increased the level of μ receptor activation in the rlPAG. Thus, endogenous opioidergic tone might be modulated by a functional interaction between opioid receptor subtypes. Such a compensatory receptor interaction appears to be relevant for behavioral selection among motivated behaviors. These findings indicate a role for multiple opioid receptor interactions in the modulation of behavioral selection between maternal and predatory behaviors in the PAG. PMID:25116253

  11. Neurokinin1 receptors regulate morphine-induced endocytosis and desensitization of mu opioid receptors in CNS neurons

    PubMed Central

    Yu, Y. Joy; Arttamangkul, Seksiri; Evans, Christopher J.; Williams, John T.; von Zastrow, Mark

    2009-01-01

    Mu opioid receptors (MORs) are G protein-coupled receptors (GPCRs) that mediate the physiological effects of endogenous opioid neuropeptides and opiate drugs such as morphine. MORs are co-expressed with neurokinin 1 receptors (NK1Rs) in several regions of the central nervous system (CNS) that control opioid dependence and reward. NK1R activation affects opioid reward specifically, however, and the cellular basis for this specificity is unknown. We found that ligand-induced activation of NK1Rs produces a cell autonomous and non-reciprocal inhibition of MOR endocytosis induced by diverse opioids. Studies using epitope-tagged receptors expressed in cultured striatal neurons and a neuroblastoma cell model indicated that this heterologous regulation is mediated by NK1R-dependent sequestration of arrestins on endosome membranes. First, endocytic inhibition mediated by wild type NK1Rs was overcome in cells over-expressing β-arrestin2, a major arrestin isoform expressed in striatum. Second, NK1R activation promoted sequestration of β-arrestin2 on endosomes, whereas MOR activation did not. Third, heterologous inhibition of MOR endocytosis was prevented by mutational disruption of β-arrestin2 sequestration by NK1Rs. NK1R-mediated regulation of MOR trafficking was associated with reduced opioid-induced desensitization of adenylyl cyclase signaling in striatal neurons. Further, heterologous regulation of MOR trafficking was observed in both amygdala and locus coeruleus neurons that naturally co-express these receptors. These results identify a cell autonomous mechanism that may underlie the highly specific effects of NK1R on opioid signaling and suggest, more generally, that receptor-specific trafficking of arrestins may represent a fundamental mechanism for coordinating distinct GPCR-mediated signals at the level of individual CNS neurons. PMID:19129399

  12. Dynorphin–Still an Extraordinarily Potent Opioid Peptide

    PubMed Central

    2013-01-01

    This issue of Molecular Pharmacology is dedicated to Dr. Avram Goldstein, the journal’s founding editor and one of the leaders in the development of modern pharmacology. This article focuses on his contributions to the discovery of the dynorphins and evidence that members of this family of opioid peptides are endogenous agonists for the kappa opioid receptor. In his original publication describing the purification and sequencing of dynorphin A, Avram described this peptide as ”extraordinarily potent” (“dyn” from the Greek, dynamis = power and “orphin” for endogenous morphine peptide). The name originally referred to its high affinity and great potency in the bioassay that was used to follow its activity during purification, but the name has come to have a second meaning: studies of its physiologic function in brain continue to provide powerful insights to the molecular mechanisms controlling mood disorders and drug addiction. During the 30 years since its discovery, we have learned that the dynorphin peptides are released in brain during stress exposure. After they are released, they activate kappa opioid receptors distributed throughout the brain and spinal cord, where they trigger cellular responses resulting in different stress responses: analgesia, dysphoria-like behaviors, anxiety-like responses, and increased addiction behaviors in experimental animals. Avram predicted that a detailed molecular analysis of opiate drug actions would someday lead to better treatments for drug addiction, and he would be gratified to know that subsequent studies enabled by his discovery of the dynorphins resulted in insights that hold great promise for new treatments for addiction and depressive disorders. PMID:23152558

  13. Variation of the net charge, lipophilicity and side chain flexibility in Dmt1-DALDA: effect on opioid activity and biodistribution

    PubMed Central

    Novoa, Alexandre; Van Dorpe, Sylvia; Wynendaele, Evelien; Spetea, Mariana; Bracke, Nathalie; Stalmans, Sofie; Betti, Cecilia; Chung, Nga N.; Lemieux, Carole; Zuegg, Johannes; Cooper, Matthew A.; Tourwé, Dirk; De Spiegeleer, Bart; Schiller, Peter W.; Ballet, Steven

    2012-01-01

    The influence of the side chain charges of the second and fourth amino acid residues in the peptidic μ opioid lead agonist Dmt-D-Arg-Phe-Lys-NH2 ([Dmt1]-DALDA) was examined. Additionally, to increase the overall lipophilicity of [Dmt1]-DALDA and to investigate the Phe3 side chain flexibility, the final amide bond was N-methylated and Phe3 was replaced by a constrained aminobenzazepine analogue. The in vitro receptor binding and activity of the peptides, as well as their in vivo transport (brain in- and efflux and tissue biodistribution) and antinociceptive properties after peripheral administration (i.p. and s.c.) in mice were determined. The structural modifications result in significant shifts of receptor binding, activity and transport properties. Strikingly, while [Dmt1]-DALDA and its N-methyl analogue, Dmt-D-Arg-Phe-NMeLys-NH2, showed a long-lasting antinociceptive effect (>7h), the peptides with D-Cit2 generate potent antinociception more rapidly (maximal effect at 1h post-injection) but also lose their analgesic activity faster, when compared to [Dmt1]-DALDA and [Dmt1,NMeLys4]-DALDA. PMID:23102273

  14. Deficiency in the Opioid Hypotheses of Self-Injurious Behavior.

    ERIC Educational Resources Information Center

    King, Bryan H.; And Others

    1991-01-01

    This commentary critiques two papers by Curt Sandman, pointing out interpretive problems in models explaining self-injurious behavior in terms of opioids. Withdrawal effects are emphasized as an alternative to hypotheses asserting congenital opioid excess as a cause of sensory depression or an addiction to a relative excess of opioid activity in…

  15. Endogenous cannabinoids induce fever through the activation of CB1 receptors

    PubMed Central

    Fraga, D; Zanoni, CIS; Rae, GA; Parada, CA; Souza, GEP

    2009-01-01

    Background and purpose: The effects of centrally administered cannabinoids on body core temperature (Tc) and the contribution of endogenous cannabinoids to thermoregulation and fever induced by lipopolysaccharide (LPS) (Sigma Chem. Co., St. Louis, MO, USA) were investigated. Experimental approach: Drug-induced changes in Tc of male Wistar rats were recorded over 6 h using a thermistor probe (Yellow Springs Instruments 402, Dayton, OH, USA) inserted into the rectum. Key results: Injection of anandamide [(arachidonoylethanolamide (AEA); Tocris, Ellisville, MO, USA], 0.01–1 µg i.c.v. or 0.1–100 ng intra-hypothalamic (i.h.), induced graded increases in Tc (peaks 1.5 and 1.6°C at 4 h after 1 µg i.c.v. or 10 ng i.h.). The effect of AEA (1 µg, i.c.v.) was preceded by decreases in tail skin temperature and heat loss index (values at 1.5 h: vehicle 0.62, AEA 0.48). Bell-shaped curves were obtained for the increase in Tc induced by the fatty acid amide hydrolase inhibitor [3-(3-carbamoylphenyl)phenyl] N-cyclohexylcarbamate (Cayman Chemical Co., Ann Arbor, MI, USA) (0.001–1 ng i.c.v.; peak 1.9°C at 5 h after 0.1 ng) and arachidonyl-2-chloroethylamide (ACEA; Tocris) (selective CB1 agonist; 0.001–1 µg i.c.v.; peak 1.4°C 5 h after 0.01 µg), but (R,S)-(+)-(2-Iodo-5-nitrobenzoyl)-[1-(1-methyl-piperidin-2-ylmethyl)-1H-indole-3-yl] methanone (Tocris) (selective CB2 agonist) had no effect on Tc. AEA-induced fever was unaffected by i.c.v. pretreatment with 6-Iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indole-3-yl](4-methoxyphenyl) methanone (Tocris) (selective CB2 antagonist), but reduced by i.c.v. pretreatment with N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251; Tocris) (selective CB1 antagonist). AM251 also reduced the fever induced by ACEA or LPS. Conclusions and implications: The endogenous cannabinoid AEA induces an integrated febrile response through activation of CB1 receptors. Endocannabinoids participate in

  16. Imaging of Endogenous Metabolites of Plant Leaves by Mass Spectrometry Based on Laser Activated Electron Tunneling

    PubMed Central

    Huang, Lulu; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Chen, Disong; Zhang, Juan; Zhong, Hongying

    2016-01-01

    A new mass spectrometric imaging approach based on laser activated electron tunneling (LAET) was described and applied to analysis of endogenous metabolites of plant leaves. LAET is an electron-directed soft ionization technique. Compressed thin films of semiconductor nanoparticles of bismuth cobalt zinc oxide were placed on the sample plate for proof-of-principle demonstration because they can not only absorb ultraviolet laser but also have high electron mobility. Upon laser irradiation, electrons are excited from valence bands to conduction bands. With appropriate kinetic energies, photoexcited electrons can tunnel away from the barrier and eventually be captured by charge deficient atoms present in neutral molecules. Resultant unpaired electron subsequently initiates specific chemical bond cleavage and generates ions that can be detected in negative ion mode of the mass spectrometer. LAET avoids the co-crystallization process of routinely used organic matrix materials with analyzes in MALDI (matrix assisted-laser desorption ionization) analysis. Thus uneven distribution of crystals with different sizes and shapes as well as background peaks in the low mass range resulting from matrix molecules is eliminated. Advantages of LAET imaging technique include not only improved spatial resolution but also photoelectron capture dissociation which produces predictable fragment ions. PMID:27053227

  17. Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase

    PubMed Central

    Fahey, Jed W.; Holtzclaw, W. David; Wehage, Scott L.; Wade, Kristina L.; Stephenson, Katherine K.; Talalay, Paul

    2015-01-01

    Glucoraphanin from broccoli and its sprouts and seeds is a water soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. Sulforaphane is difficult to deliver in an enriched and stable form for purposes of direct human consumption. We have focused upon evaluating the bioavailability of sulforaphane, either by direct administration of glucoraphanin (a glucosinolate, or β-thioglucoside-N-hydroxysulfate), or by co-administering glucoraphanin and the enzyme myrosinase to catalyze its conversion to sulforaphane at economic, reproducible and sustainable yields. We show that following administration of glucoraphanin in a commercially prepared dietary supplement to a small number of human volunteers, the volunteers had equivalent output of sulforaphane metabolites in their urine to that which they produced when given an equimolar dose of glucoraphanin in a simple boiled and lyophilized extract of broccoli sprouts. Furthermore, when either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable than sulforaphane from glucoraphanin delivered without active plant myrosinase. These data expand upon earlier reports of inter- and intra-individual variability, when glucoraphanin was delivered in either teas, juices, or gelatin capsules, and they confirm that a variety of delivery matrices may be equally suitable for glucoraphanin supplementation (e.g. fruit juices, water, or various types of capsules and tablets). PMID:26524341

  18. A Cell-Based Assay for Measuring Endogenous BcrAbl Kinase Activity and Inhibitor Resistance.

    PubMed

    Ouellette, Steven B; Noel, Brett M; Parker, Laurie L

    2016-01-01

    Kinase enzymes are an important class of drug targets, particularly in cancer. Cell-based kinase assays are needed to understand how potential kinase inhibitors act on their targets in a physiologically relevant context. Current cell-based kinase assays rely on antibody-based detection of endogenous substrates, inaccurate disease models, or indirect measurements of drug action. Here we expand on previous work from our lab to introduce a 96-well plate compatible approach for measuring cell-based kinase activity in disease-relevant human chronic myeloid leukemia cell lines using an exogenously added, multi-functional peptide substrate. Our cellular models natively express the BcrAbl oncogene and are either sensitive or have acquired resistance to well-characterized BcrAbl tyrosine kinase inhibitors. This approach measures IC50 values comparable to established methods of assessing drug potency, and its robustness indicates that it can be employed in drug discovery applications. This medium-throughput assay could bridge the gap between single target focused, high-throughput in vitro assays and lower-throughput cell-based follow-up experiments. PMID:27598410

  19. Imaging of Endogenous Metabolites of Plant Leaves by Mass Spectrometry Based on Laser Activated Electron Tunneling

    NASA Astrophysics Data System (ADS)

    Huang, Lulu; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Chen, Disong; Zhang, Juan; Zhong, Hongying

    2016-04-01

    A new mass spectrometric imaging approach based on laser activated electron tunneling (LAET) was described and applied to analysis of endogenous metabolites of plant leaves. LAET is an electron-directed soft ionization technique. Compressed thin films of semiconductor nanoparticles of bismuth cobalt zinc oxide were placed on the sample plate for proof-of-principle demonstration because they can not only absorb ultraviolet laser but also have high electron mobility. Upon laser irradiation, electrons are excited from valence bands to conduction bands. With appropriate kinetic energies, photoexcited electrons can tunnel away from the barrier and eventually be captured by charge deficient atoms present in neutral molecules. Resultant unpaired electron subsequently initiates specific chemical bond cleavage and generates ions that can be detected in negative ion mode of the mass spectrometer. LAET avoids the co-crystallization process of routinely used organic matrix materials with analyzes in MALDI (matrix assisted-laser desorption ionization) analysis. Thus uneven distribution of crystals with different sizes and shapes as well as background peaks in the low mass range resulting from matrix molecules is eliminated. Advantages of LAET imaging technique include not only improved spatial resolution but also photoelectron capture dissociation which produces predictable fragment ions.

  20. Imaging of Endogenous Metabolites of Plant Leaves by Mass Spectrometry Based on Laser Activated Electron Tunneling.

    PubMed

    Huang, Lulu; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Chen, Disong; Zhang, Juan; Zhong, Hongying

    2016-01-01

    A new mass spectrometric imaging approach based on laser activated electron tunneling (LAET) was described and applied to analysis of endogenous metabolites of plant leaves. LAET is an electron-directed soft ionization technique. Compressed thin films of semiconductor nanoparticles of bismuth cobalt zinc oxide were placed on the sample plate for proof-of-principle demonstration because they can not only absorb ultraviolet laser but also have high electron mobility. Upon laser irradiation, electrons are excited from valence bands to conduction bands. With appropriate kinetic energies, photoexcited electrons can tunnel away from the barrier and eventually be captured by charge deficient atoms present in neutral molecules. Resultant unpaired electron subsequently initiates specific chemical bond cleavage and generates ions that can be detected in negative ion mode of the mass spectrometer. LAET avoids the co-crystallization process of routinely used organic matrix materials with analyzes in MALDI (matrix assisted-laser desorption ionization) analysis. Thus uneven distribution of crystals with different sizes and shapes as well as background peaks in the low mass range resulting from matrix molecules is eliminated. Advantages of LAET imaging technique include not only improved spatial resolution but also photoelectron capture dissociation which produces predictable fragment ions. PMID:27053227

  1. Effect of pain chronification and chronic pain on an endogenous pain modulation circuit in rats.

    PubMed

    Miranda, J; Lamana, S M S; Dias, E V; Athie, M; Parada, C A; Tambeli, C H

    2015-02-12

    We tested the hypothesis that chronic pain development (pain chronification) and ongoing chronic pain (chronic pain) reduce the activity and induce plastic changes in an endogenous analgesia circuit, the ascending nociceptive control. An important mechanism mediating this form of endogenous analgesia, referred to as capsaicin-induced analgesia, is its dependence on nucleus accumbens μ-opioid receptor mechanisms. Therefore, we also investigated whether pain chronification and chronic pain alter the requirement for nucleus accumbens μ-opioid receptor mechanisms in capsaicin-induced analgesia. We used an animal model of pain chronification in which daily subcutaneous prostaglandin E2 (PGE2) injections into the rat's hind paw for 14 days, referred to as the induction period of persistent hyperalgesia, induce a long-lasting state of nociceptor sensitization referred to as the maintenance period of persistent hyperalgesia, that lasts for at least 30 days following the cessation of the PGE2 treatment. The nociceptor hypersensitivity was measured by the shortening of the time interval for the animal to respond to a mechanical stimulation of the hind paw. We found a significant reduction in the duration of capsaicin-induced analgesia during the induction and maintenance period of persistent mechanical hyperalgesia. Intra-accumbens injection of the μ-opioid receptor selective antagonist Cys(2),Tyr(3),Orn(5),Pen(7)amide (CTOP) 10 min before the subcutaneous injection of capsaicin into the rat's fore paw blocked capsaicin-induced analgesia. Taken together, these findings indicate that pain chronification and chronic pain reduce the duration of capsaicin-induced analgesia, without affecting its dependence on nucleus accumbens μ-opioid receptor mechanisms. The attenuation of endogenous analgesia during pain chronification and chronic pain suggests that endogenous pain circuits play an important role in the development and maintenance of chronic pain. PMID:25451282

  2. N-terminal guanidinylation of TIPP (Tyr-Tic-Phe-Phe) peptides results in major changes of the opioid activity profile.

    PubMed

    Weltrowska, Grazyna; Nguyen, Thi M-D; Chung, Nga N; Wilkes, Brian C; Schiller, Peter W

    2013-09-15

    Derivatives of peptides of the TIPP (Tyr-Tic-Phe-Phe; Tic=1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) family containing a guanidino (Guan) function in place of the N-terminal amino group were synthesized in an effort to improve their blood-brain barrier permeability. Unexpectedly, N-terminal amidination significantly altered the in vitro opioid activity profiles. Guan-analogues of TIPP-related δ opioid antagonists showed δ partial agonist or mixed δ partial agonist/μ partial agonist activity. Guanidinylation of the mixed μ agonist/δ antagonists H-Dmt-Tic-Phe-Phe-NH2 (DIPP-NH2) and H-Dmt-TicΨ[CH2NH]Phe-Phe-NH2 (DIPP-NH2[Ψ]) converted them to mixed μ agonist/δ agonists. A docking study revealed distinct positioning of DIPP-NH2 and Guan-DIPP-NH2 in the δ receptor binding site. Lys(3)-analogues of DIPP-NH2 and DIPP-NH2[Ψ] (guanidinylated or non-guanidinylated) turned out to be mixed μ/κ agonists with δ antagonist-, δ partial agonist- or δ full agonist activity. Compounds with some of the observed mixed opioid activity profiles have therapeutic potential as analgesics with reduced side effects or for treatment of cocaine addiction. PMID:23932788

  3. Detection, purification and identification of an endogenous inhibitor of L-Dopa decarboxylase activity from human placenta.

    PubMed

    Vassiliou, Alice-Georgia; Fragoulis, Emmanuel G; Vassilacopoulou, Dido

    2009-06-01

    An endogenous inhibitor of L-Dopa decarboxylase activity was identified and purified from human placenta. The endogenous inhibitor of L-Dopa decarboxylase (Ddc) was localized in the membrane fraction of placental tissue. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K did not affect membrane-associated Ddc inhibitory activity, suggesting that a population of the inhibitor is embedded within membranes. Purification was achieved by extraction from a nondenaturing polyacrylamide gel. The purification scheme resulted in the isolation of a single 35 kDa band, bearing L-Dopa decarboxylase inhibitory activity. The purified inhibitor was identified as Annexin V. The elucidation of the biological importance of the presence of an L-Dopa decarboxylase activity inhibitor in normal human tissues could provide us with new information leading to the better understanding of the biological pathways that Ddc is involved in. PMID:19005753

  4. Opioid and non-opioid mechanisms of footshock-induced analgesia: role of the spinal dorsolateral funiculus.

    PubMed

    Lewis, J W; Terman, G W; Watkins, L R; Mayer, D J; Liebeskind, J C

    1983-05-01

    Exposure to inescapable footshock causes either an opioid or non-opioid mediated analgesia in the rat depending on the temporal parameters of its administration. Lesions of the spinal dorsolateral funiculus significantly reduce both the opioid and non-opioid forms of this footshock-induced analgesia. Thus, these two neurochemically discrete pain-inhibitory systems appear to depend on the integrity of the same descending path, one known to be activated by morphine and by analgesic brain stimulation. PMID:6860939

  5. Selectively Promiscuous Opioid Ligands: Discovery of High Affinity/Low Efficacy Opioid Ligands with Substantial Nociceptin Opioid Peptide Receptor Affinity

    PubMed Central

    2015-01-01

    Emerging clinical and preclinical evidence suggests that a compound displaying high affinity for μ, κ, and δ opioid (MOP, KOP, and DOP) receptors and antagonist activity at each, coupled with moderate affinity and efficacy at nociceptin opioid peptide (NOP) receptors will have utility as a relapse prevention agent for multiple types of drug abuse. Members of the orvinol family of opioid ligands have the desired affinity profile but have typically displayed substantial efficacy at MOP and or KOP receptors. In this study it is shown that a phenyl ring analogue (1d) of buprenorphine displays the desired profile in vitro with high, nonselective affinity for the MOP, KOP, and DOP receptors coupled with moderate affinity for NOP receptors. In vivo, 1d lacked any opioid agonist activity and was an antagonist of both the MOP receptor agonist morphine and the KOP receptor agonist ethylketocyclazocine, confirming the desired opioid receptor profile in vivo. PMID:24761755

  6. 75 years of opioid research: the exciting but vain quest for the Holy Grail

    PubMed Central

    Corbett, Alistair D; Henderson, Graeme; McKnight, Alexander T; Paterson, Stewart J

    2006-01-01

    Over the 75-year lifetime of the British Pharmacological Society there has been an enormous expansion in our understanding of how opioid drugs act on the nervous system, with much of this effort aimed at developing powerful analgesic drugs devoid of the side effects associated with morphine – the Holy Grail of opioid research. At the molecular and cellular level multiple opioid receptors have been cloned and characterised, their potential for oligomerisation determined, a large family of endogenous opioid agonists has been discovered, multiple second messengers identified and our understanding of the adaptive changes to prolonged exposure to opioid drugs (tolerance and physical dependence) enhanced. In addition, we now have greater understanding of the processes by which opioids produce the euphoria that gives rise to the intense craving for these drugs in opioid addicts. In this article, we review the historical pathway of opioid research that has led to our current state of knowledge. PMID:16402099

  7. Cytoprotection against Hypoxic and/or MPP⁺ Injury: Effect of δ-Opioid Receptor Activation on Caspase 3.

    PubMed

    Xu, Yuan; Zhi, Feng; Shao, Naiyuan; Wang, Rong; Yang, Yilin; Xia, Ying

    2016-01-01

    The pathological changes of Parkinson's disease (PD) are, at least partially, associated with the dysregulation of PTEN-induced putative kinase 1 (PINK1) and caspase 3. Since hypoxic and neurotoxic insults are underlying causes of PD, and since δ-opioid receptor (DOR) is neuroprotective against hypoxic/ischemic insults, we sought to determine whether DOR activation could protect the cells from damage induced by hypoxia and/or MPP⁺ by regulating PINK1 and caspase 3 expressions. We exposed PC12 cells to either severe hypoxia (0.5%-1% O₂) for 24-48 h or to MPP⁺ at different concentrations (0.5, 1, 2 mM) and then detected the levels of PINK1 and cleaved caspase 3. Both hypoxia and MPP⁺ reduced cell viability, progressively suppressed the expression of PINK1 and increased the cleaved caspase 3. DOR activation using UFP-512, effectively protected the cells from hypoxia and/or MPP⁺ induced injury, reversed the reduction in PINK1 protein and significantly attenuated the increase in the cleaved caspase 3. On the other hand, the application of DOR antagonist, naltrindole, greatly decreased cell viability and increased cleaved caspase 3. These findings suggest that DOR is cytoprotective against both hypoxia and MPP⁺ through the regulation of PINK1 and caspase 3 pathways. PMID:27517901

  8. Cytoprotection against Hypoxic and/or MPP+ Injury: Effect of δ–Opioid Receptor Activation on Caspase 3

    PubMed Central

    Xu, Yuan; Zhi, Feng; Shao, Naiyuan; Wang, Rong; Yang, Yilin; Xia, Ying

    2016-01-01

    The pathological changes of Parkinson’s disease (PD) are, at least partially, associated with the dysregulation of PTEN-induced putative kinase 1 (PINK1) and caspase 3. Since hypoxic and neurotoxic insults are underlying causes of PD, and since δ-opioid receptor (DOR) is neuroprotective against hypoxic/ischemic insults, we sought to determine whether DOR activation could protect the cells from damage induced by hypoxia and/or MPP+ by regulating PINK1 and caspase 3 expressions. We exposed PC12 cells to either severe hypoxia (0.5%–1% O2) for 24–48 h or to MPP+ at different concentrations (0.5, 1, 2 mM) and then detected the levels of PINK1 and cleaved caspase 3. Both hypoxia and MPP+ reduced cell viability, progressively suppressed the expression of PINK1 and increased the cleaved caspase 3. DOR activation using UFP-512, effectively protected the cells from hypoxia and/or MPP+ induced injury, reversed the reduction in PINK1 protein and significantly attenuated the increase in the cleaved caspase 3. On the other hand, the application of DOR antagonist, naltrindole, greatly decreased cell viability and increased cleaved caspase 3. These findings suggest that DOR is cytoprotective against both hypoxia and MPP+ through the regulation of PINK1 and caspase 3 pathways. PMID:27517901

  9. Molecular Mechanisms of Opioid Receptor-Dependent Signaling and Behavior

    PubMed Central

    Al-Hasani, Ream; Bruchas, Michael R.

    2013-01-01

    Opioid receptors have been targeted for the treatment of pain and related disorders for thousands of years, and remain the most widely used analgesics in the clinic. Mu (μ), kappa (κ), and delta (δ) opioid receptors represent the originally classified receptor subtypes, with opioid receptor like-1 (ORL1) being the least characterized. All four receptors are G-protein coupled, and activate inhibitory G-proteins. These receptors form homo- and hetereodimeric complexes, signal to kinase cascades, and scaffold a variety of proteins. In this review, we discuss classical mechanisms and developments in understanding opioid tolerance, opioid receptor signaling, and highlight advances in opioid molecular pharmacology, behavioral pharmacology, and human genetics. We put into context how opioid receptor signaling leads to the modulation of behavior with the potential for therapeutic intervention. Finally, we conclude that there is a continued need for more translational work on opioid receptors in vivo. PMID:22020140

  10. Central non-opioid physiological and pathophysiological effects of dynorphin A and related peptides.

    PubMed Central

    Shukla, V K; Lemaire, S

    1992-01-01

    Dynorphin A (Dyn A) and related opioid peptides derived from prodynorphin possess a high affinity for kappa opioid receptors, but they also bind to other opioid receptors (mu and delta) as well as to some non-opioid receptor sites. Although the physiological role of these peptides is not well established, recent experimental data pinpoint their particular involvement in physiological and pathophysiological conditions that relate to algesia, spinal cord injury and epilepsy. In this paper, we review data which support the concept that the non-opioid behavioral effects of Dyn A and related endogenous peptides which are observed under these conditions are physiologically and pathophysiologically relevant. PMID:1356430

  11. Bioluminescence Imaging Captures the Expression and Dynamics of Endogenous p21 Promoter Activity in Living Mice and Intact Cells▿

    PubMed Central

    Tinkum, Kelsey L.; Marpegan, Luciano; White, Lynn S.; Sun, Jinwu; Herzog, Erik D.; Piwnica-Worms, David; Piwnica-Worms, Helen

    2011-01-01

    To interrogate endogenous p21WAF1/CIP1 (p21) promoter activity under basal conditions and in response to various forms of stress, knock-in imaging reporter mice in which expression of firefly luciferase (FLuc) was placed under the control of the endogenous p21 promoter within the Cdkn1a gene locus were generated. Bioluminescence imaging (BLI) of p21 promoter activity was performed noninvasively and repetitively in mice and in cells derived from these mice. We demonstrated that expression of FLuc accurately reported endogenous p21 expression at baseline and under conditions of genotoxic stress and that photon flux correlated with mRNA abundance and, therefore, bioluminescence provided a direct readout of p21 promoter activity in vivo. BLI confirmed that p53 was required for activation of the p21 promoter in vivo in response to ionizing radiation. Interestingly, imaging of reporter cells demonstrated that p53 prevents the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway from activating p21 expression when quiescent cells are stimulated with serum to reenter the cell cycle. In addition, low-light BLI identified p21 expression in specific regions of individual organs that had not been observed previously. This inducible p21FLuc knock-in reporter strain will facilitate imaging studies of p53-dependent and -independent stress responses within the physiological context of the whole animal. PMID:21791610

  12. Bioluminescence imaging captures the expression and dynamics of endogenous p21 promoter activity in living mice and intact cells.

    PubMed

    Tinkum, Kelsey L; Marpegan, Luciano; White, Lynn S; Sun, Jinwu; Herzog, Erik D; Piwnica-Worms, David; Piwnica-Worms, Helen

    2011-09-01

    To interrogate endogenous p21(WAF1/CIP1) (p21) promoter activity under basal conditions and in response to various forms of stress, knock-in imaging reporter mice in which expression of firefly luciferase (FLuc) was placed under the control of the endogenous p21 promoter within the Cdkn1a gene locus were generated. Bioluminescence imaging (BLI) of p21 promoter activity was performed noninvasively and repetitively in mice and in cells derived from these mice. We demonstrated that expression of FLuc accurately reported endogenous p21 expression at baseline and under conditions of genotoxic stress and that photon flux correlated with mRNA abundance and, therefore, bioluminescence provided a direct readout of p21 promoter activity in vivo. BLI confirmed that p53 was required for activation of the p21 promoter in vivo in response to ionizing radiation. Interestingly, imaging of reporter cells demonstrated that p53 prevents the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway from activating p21 expression when quiescent cells are stimulated with serum to reenter the cell cycle. In addition, low-light BLI identified p21 expression in specific regions of individual organs that had not been observed previously. This inducible p21(FLuc) knock-in reporter strain will facilitate imaging studies of p53-dependent and -independent stress responses within the physiological context of the whole animal. PMID:21791610

  13. mu Opioid receptor-mediated G-protein activation by heroin metabolites: evidence for greater efficacy of 6-monoacetylmorphine compared with morphine.

    PubMed

    Selley, D E; Cao, C C; Sexton, T; Schwegel, J A; Martin, T J; Childers, S R

    2001-08-15

    The efficacy of heroin metabolites for the stimulation of mu opioid receptor-mediated G-protein activation was investigated using agonist-stimulated [(35)S]guanosine-5'-O-(gamma-thio)-triphosphate binding. In rat thalamic membranes, heroin and its primary metabolite, 6-monoacetylmorphine (6-MAM), were more efficacious than morphine or morphine-6-beta D-glucuronide. This increased efficacy was not due to increased action of heroin and 6-MAM at delta receptors, as determined by competitive antagonism by naloxone, lack of antagonism by naltrindole, and competitive partial antagonism with morphine. In agreement with this interpretation, the same relative efficacy profile of heroin and its metabolites was observed at the cloned human mu opioid receptor expressed in C6 glioma cells. Moreover, these efficacy differences were GDP-dependent in a manner consistent with accepted mechanisms of receptor-mediated G-protein activation. The activity of heroin was attributed to in vitro deacetylation to 6-MAM, as confirmed by HPLC analysis. These results indicate that the heroin metabolite 6-MAM possesses higher efficacy than other heroin metabolites at mu opioid receptors, which may contribute to the higher efficacy of heroin compared with morphine in certain behavioral paradigms in vivo. PMID:11448454

  14. Kappa-opioid receptor signaling and brain reward function

    PubMed Central

    Bruijnzeel, Adrie W.

    2009-01-01

    The dynorphin-like peptides have profound effects on the state of the brain reward system and human and animal behavior. The dynorphin-like peptides affect locomotor activity, food intake, sexual behavior, anxiety-like behavior, and drug intake. Stimulation of kappa-opioid receptors, the endogenous receptor for the dynorphin-like peptides, inhibits dopamine release in the striatum (nucleus accumbens and caudate putamen) and induces a negative mood state in humans and animals. The administration of drugs of abuse increases the release of dopamine in the striatum and mediates the concomitant release of dynorphin-like peptides in this brain region. The reviewed studies suggest that chronic drug intake leads to an upregulation of the brain dynorphin system in the striatum and in particular in the dorsal part of the striatum/caudate putamen. This might inhibit drug-induced dopamine release and provide protection against the neurotoxic effects of high dopamine levels. After the discontinuation of chronic drug intake these neuroadaptations remain unopposed which has been suggested to contribute to the negative emotional state associated with drug withdrawal and increased drug intake. Kappa-opioid receptor agonists have also been shown to inhibit calcium channels. Calcium channel inhibitors have antidepressant-like effects and inhibit the release of norepinephrine. This might explain that in some studies kappa-opioid receptor agonists attenuate nicotine and opioid withdrawal symptomatology. A better understanding of the role of dynorphins in the regulation of brain reward function might contribute to the development of novel treatments for mood disorders and other disorders that stem from a dysregulation of the brain reward system. PMID:19804796

  15. Differential regulation of hippocampal progenitor proliferation by opioid receptor antagonists in running and non-running spontaneously hypertensive rats.

    PubMed

    Persson, Anders I; Naylor, Andrew S; Jonsdottir, Ingibjörg H; Nyberg, Fred; Eriksson, Peter S; Thorlin, Thorleif

    2004-04-01

    Voluntary running in mice and forced treadmill running in rats have been shown to increase the amount of proliferating cells in the hippocampus. Little is known as yet about the mechanisms involved in these processes. It is well known that the endogenous opioid system is affected during running and other forms of physical exercise. In this study, we evaluated the involvement of the endogenous opioids in the regulation of hippocampal proliferation in non-running and voluntary running rats. Nine days of wheel running was compared with non-running in spontaneously hypertensive rats (SHR), a rat strain known to run voluntarily. On the last 2 days of the experimental period all rats received two daily injections of the opioid receptor antagonists naltrexone or naltrindole together with injections of bromodeoxyuridine to label dividing cells. Brain sections from the running rats showed approximately a five-fold increase in newly generated cells in the hippocampus, and this increase was partly reduced by naltrexone but not by naltrindole. By contrast, both naltrexone and naltrindole increased hippocampal proliferation in non-running rats. In non-running rats the administration of naltrexone decreased corticosterone levels and adrenal gland weights, whereas no significant effects on these parameters could be detected for naltrindole. However, adrenal gland weights were increased in naltrexone- but not in naltrindole-administered running rats. In addition, in voluntary running rats there was a three-fold increase in the hippocampal levels of Met-enkephalin-Arg-Phe compared with non-runners, indicating an increase in opioid activity in the hippocampus during running. These data suggest an involvement of endogenous opioids in the regulation of hippocampal proliferation in non-running rats, probably through hypothalamic-pituitary-adrenal axis modulation. During voluntary running in SHR naltrexone altered hippocampal proliferation via as yet unknown mechanisms. PMID:15078558

  16. Kappa Opioid Receptor Activation of p38 MAPK Is GRK3- and Arrestin-dependent in Neurons and Astrocytes*

    PubMed Central

    Bruchas, Michael R.; Macey, Tara A.; Lowe, Janet D.; Chavkin, Charles

    2007-01-01

    AtT-20 cells expressing the wild-type kappa opioid receptor (KOR) increased phospho-p38 MAPK following treatment with the kappa agonist U50,488. The increase was blocked by the kappa antagonist norbinaltorphimine and not evident in untransfected cells. In contrast, U50,488 treatment of AtT-20 cells expressing KOR having alanine substituted for serine-369 (KSA) did not increase phospho-p38. Phosphorylation of serine 369 in the KOR carboxyl terminus by G-protein receptor kinase 3 (GRK3) was previously shown to be required for receptor desensitization, and the results suggest that p38 MAPK activation by KOR may require arrestin recruitment. This hypothesis was tested by transfecting arrestin3-(R170E), a dominant positive form of arrestin that does not require receptor phosphorylation for activation. AtT-20 cells expressing both KSA and arrestin3-(R170E) responded to U50,488 treatment with an increase in phospho-p38 consistent with the hypothesis. Primary cultured astrocytes (glial fibrillary acidic protein-positive) and neurons (γ-aminobutyric acid-positive) isolated from mouse striata also responded to U50,488 by increasing phospho-p38 immunolabeling. p38 activation was not evident in either striatal astrocytes or neurons isolated from KOR knock-out mice or GRK3 knock-out mice. Astrocytes pretreated with small interfering RNA for arrestin3 were also unable to activate p38 in response to U50,488 treatment. Furthermore, in striatal neurons, the kappa-mediated phospho-p38 labeling was colocalized with arrestin3. These findings suggest that KOR may activate p38 MAPK in brain by a GRK3 and arrestin-dependent mechanism. PMID:16648139

  17. Mediation of opioid analgesia by a truncated 6-transmembrane GPCR

    PubMed Central

    Lu, Zhigang; Xu, Jin; Rossi, Grace C.; Majumdar, Susruta; Pasternak, Gavril W.; Pan, Ying-Xian

    2015-01-01

    The generation of potent opioid analgesics that lack the side effects of traditional opioids may be possible by targeting truncated splice variants of the μ-opioid receptor. μ-Opioids act through GPCRs that are generated from the Oprm1 gene, which undergoes extensive alternative splicing. The most abundant set of Oprm1 variants encode classical full-length 7 transmembrane domain (7TM) μ-opioid receptors that mediate the actions of the traditional μ-opioid drugs morphine and methadone. In contrast, 3-iodobenzoyl-6β-naltrexamide (IBNtxA) is a potent analgesic against thermal, inflammatory, and neuropathic pain that acts independently of 7TM μ-opioid receptors but has no activity in mice lacking a set of 6TM truncated μ-opioid receptor splice variants. Unlike traditional opioids, IBNtxA does not depress respiration or result in physical dependence or reward behavior, suggesting it acts through an alternative μ-opioid receptor target. Here we demonstrated that a truncated 6TM splice variant, mMOR-1G, can rescue IBNtxA analgesia in a μ-opioid receptor–deficient mouse that lacks all Oprm1 splice variants, ablating μ-opioid activity in these animals. Intrathecal administration of lentivirus containing the 6TM variant mMOR-1G restored IBNtxA, but not morphine, analgesia in Oprm1-deficient animals. Together, these results confirm that a truncated 6TM GPCR is both necessary and sufficient for IBNtxA analgesia. PMID:26011641

  18. Hollows on Mercury: Bright-haloed depressions imply recent endogenic activity

    NASA Astrophysics Data System (ADS)

    Blewett, D. T.; Fontanella, N. R.; Peel, S. E.; Zhong, E. D.; Pashai, P.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.; Izenberg, N. R.; Murchie, S. L.; Xiao, Z.; Braden, S.; Baker, D. M.; Hurwitz, D. M.; Head, J. W.; McCoy, T. J.; Nittler, L. R.; Solomon, S. C.

    2011-12-01

    activity was generally thought to have ended long ago. The presence of potentially recent surface modification by non-impact processes implies that Mercury's endogenic geological evolution may still be ongoing.

  19. Endogenous Thrombospondin-1 Regulates Leukocyte Recruitment and Activation and Accelerates Death from Systemic Candidiasis

    PubMed Central

    Martin-Manso, Gema; Navarathna, Dhammika H. M. L. P.; Galli, Susana; Soto-Pantoja, David R.; Kuznetsova, Svetlana A.; Tsokos, Maria; Roberts, David D.

    2012-01-01

    Disseminated Candida albicans infection results in high morbidity and mortality despite treatment with existing antifungal drugs. Recent studies suggest that modulating the host immune response can improve survival, but specific host targets for accomplishing this goal remain to be identified. The extracellular matrix protein thrombospondin-1 is released at sites of tissue injury and modulates several immune functions, but its role in C. albicans pathogenesis has not been investigated. Here, we show that mice lacking thrombospondin-1 have an advantage in surviving disseminated candidiasis and more efficiently clear the initial colonization from kidneys despite exhibiting fewer infiltrating leukocytes. By examining local and systemic cytokine responses to C. albicans and other standard inflammatory stimuli, we identify a crucial function of phagocytes in this enhanced resistance. Subcutaneous air pouch and systemic candidiasis models demonstrated that endogenous thrombospondin-1 enhances the early innate immune response against C. albicans and promotes activation of inflammatory macrophages (inducible nitric oxide synthase+, IL-6high, TNF-αhigh, IL-10low), release of the chemokines MIP-2, JE, MIP-1α, and RANTES, and CXCR2-driven polymorphonuclear leukocytes recruitment. However, thrombospondin-1 inhibited the phagocytic capacity of inflammatory leukocytes in vivo and in vitro, resulting in increased fungal burden in the kidney and increased mortality in wild type mice. Thus, thrombospondin-1 enhances the pathogenesis of disseminated candidiasis by creating an imbalance in the host immune response that ultimately leads to reduced phagocytic function, impaired fungal clearance, and increased mortality. Conversely, inhibitors of thrombospondin-1 may be useful drugs to improve patient recovery from disseminated candidiasis. PMID:23144964

  20. In vivo opioid receptor heteromerization: where do we stand?

    PubMed Central

    Massotte, D

    2015-01-01

    Opioid receptors are highly homologous GPCRs that modulate brain function at all levels of neural integration, including autonomous, sensory, emotional and cognitive processing. Opioid receptors functionally interact in vivo, but the underlying mechanisms involving direct receptor–receptor interactions, affecting signalling pathways or engaging different neuronal circuits, remain unsolved. Heteromer formation through direct physical interaction between two opioid receptors or between an opioid receptor and a non-opioid one has been postulated and can be characterized by specific ligand binding, receptor signalling and trafficking properties. However, despite numerous studies in heterologous systems, evidence for physical proximity in vivo is only available for a limited number of opioid heteromers, and their physiopathological implication remains largely unknown mostly due to the lack of appropriate tools. Nonetheless, data collected so far using endogenous receptors point to a crucial role for opioid heteromers as a molecular entity that could underlie human pathologies such as alcoholism, acute or chronic pain as well as psychiatric disorders. Opioid heteromers therefore stand as new therapeutic targets for the drug discovery field. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24666391

  1. Pyrrolo- and Pyridomorphinans: Non-selective opioid antagonists and delta opioid agonists/mu opioid partial agonists

    PubMed Central

    Kumar, V.; Clark, M.J.; Traynor, J.R.; Lewis, J.W.; Husbands, S.M.

    2014-01-01

    Opioid ligands have found use in a number of therapeutic areas, including for the treatment of pain and opiate addiction (using agonists) and alcohol addiction (using antagonists such as naltrexone and nalmefene). The reaction of imines, derived from the opioid ligands oxymorphone and naltrexone, with Michael acceptors leads to pyridomorphinans with structures similar to known pyrrolo- and indolomorphinans. One of the synthesized compounds, 5e, derived from oxymorphone had substantial agonist activity at delta opioid receptors but not at mu and/or kappa opioid receptors and in that sense profiled as a selective delta opioid receptor agonist. The pyridomorphinans derived from naltrexone and naloxone were all found to be non-selective potent antagonists and as such could have utility as treatments for alcohol abuse. PMID:24973818

  2. Pyrrolo- and pyridomorphinans: non-selective opioid antagonists and delta opioid agonists/mu opioid partial agonists.

    PubMed

    Kumar, V; Clark, M J; Traynor, J R; Lewis, J W; Husbands, S M

    2014-08-01

    Opioid ligands have found use in a number of therapeutic areas, including for the treatment of pain and opiate addiction (using agonists) and alcohol addiction (using antagonists such as naltrexone and nalmefene). The reaction of imines, derived from the opioid ligands oxymorphone and naltrexone, with Michael acceptors leads to pyridomorphinans with structures similar to known pyrrolo- and indolomorphinans. One of the synthesized compounds, 5e, derived from oxymorphone had substantial agonist activity at delta opioid receptors but not at mu and/or kappa opioid receptors and in that sense profiled as a selective delta opioid receptor agonist. The pyridomorphinans derived from naltrexone and naloxone were all found to be non-selective potent antagonists and as such could have utility as treatments for alcohol abuse. PMID:24973818

  3. Activation of κ Opioid Receptors in Cutaneous Nerve Endings by Conorphin-1, a Novel Subtype-Selective Conopeptide, Does Not Mediate Peripheral Analgesia.

    PubMed

    Deuis, Jennifer R; Whately, Ella; Brust, Andreas; Inserra, Marco C; Asvadi, Naghmeh H; Lewis, Richard J; Alewood, Paul F; Cabot, Peter J; Vetter, Irina

    2015-10-21

    Selective activation of peripheral κ opioid receptors (KORs) may overcome the dose-limiting adverse effects of conventional opioid analgesics. We recently developed a vicinal disulfide-stabilized class of peptides with subnanomolar potency at the KOR. The aim of this study was to assess the analgesic effects of one of these peptides, named conorphin-1, in comparison with the prototypical KOR-selective small molecule agonist U-50488, in several rodent pain models. Surprisingly, neither conorphin-1 nor U-50488 were analgesic when delivered peripherally by intraplantar injection at local concentrations expected to fully activate the KOR at cutaneous nerve endings. While U-50488 was analgesic when delivered at high local concentrations, this effect could not be reversed by coadministration with the selective KOR antagonist ML190 or the nonselective opioid antagonist naloxone. Instead, U-50488 likely mediated its peripheral analgesic effect through nonselective inhibition of voltage-gated sodium channels, including peripheral sensory neuron isoforms NaV1.8 and NaV1.7. Our study suggests that targeting the KOR in peripheral sensory nerve endings innervating the skin is not an alternative analgesic approach. PMID:26225903

  4. Buprenorphine-elicited alteration of adenylate cyclase activity in human embryonic kidney 293 cells coexpressing κ-, μ-opioid and nociceptin receptors

    PubMed Central

    Wang, Pei-Chen; Ho, Ing-Kang; Lee, Cynthia Wei-Sheng

    2015-01-01

    Buprenorphine, a maintenance drug for heroin addicts, exerts its pharmacological function via κ- (KOP), μ-opioid (MOP) and nociceptin/opioid receptor-like 1 (NOP) receptors. Previously, we investigated its effects in an in vitro model expressing human MOP and NOP receptors individually or simultaneously (MOP, NOP, and MOP+NOP) in human embryonic kidney 293 cells. Here, we expanded this cell model by expressing human KOP, MOP and NOP receptors individually or simultaneously (KOP, KOP+MOP, KOP+NOP and KOP+MOP+NOP). Radioligand binding with tritium-labelled diprenorphine confirmed the expression of KOP receptors. Immunoblotting and immunocytochemistry indicated that the expressed KOP, MOP and NOP receptors are N-linked glycoproteins and colocalized in cytoplasmic compartments. Acute application of the opioid receptor agonists— U-69593, DAMGO and nociceptin— inhibited adenylate cyclase (AC) activity in cells expressing KOP, MOP and NOP receptors respectively. Buprenorphine, when applied acutely, inhibited AC activity to ~90% in cells expressing KOP+MOP+NOP receptors. Chronic exposure to buprenorphine induced concentration-dependent AC superactivation in cells expressing KOP+NOP receptors, and the level of this superactivation was even higher in KOP+MOP+NOP-expressing cells. Our study demonstrated that MOP receptor could enhance AC regulation in the presence of coexpressed KOP and NOP receptors, and NOP receptor is essential for concentration-dependent AC superactivation elicited by chronic buprenorphine exposure. PMID:26153065

  5. Buprenorphine-elicited alteration of adenylate cyclase activity in human embryonic kidney 293 cells coexpressing κ-, μ-opioid and nociceptin receptors.

    PubMed

    Wang, Pei-Chen; Ho, Ing-Kang; Lee, Cynthia Wei-Sheng

    2015-11-01

    Buprenorphine, a maintenance drug for heroin addicts, exerts its pharmacological function via κ- (KOP), μ-opioid (MOP) and nociceptin/opioid receptor-like 1 (NOP) receptors. Previously, we investigated its effects in an in vitro model expressing human MOP and NOP receptors individually or simultaneously (MOP, NOP, and MOP+NOP) in human embryonic kidney 293 cells. Here, we expanded this cell model by expressing human KOP, MOP and NOP receptors individually or simultaneously (KOP, KOP+MOP, KOP+NOP and KOP+MOP+NOP). Radioligand binding with tritium-labelled diprenorphine confirmed the expression of KOP receptors. Immunoblotting and immunocytochemistry indicated that the expressed KOP, MOP and NOP receptors are N-linked glycoproteins and colocalized in cytoplasmic compartments. Acute application of the opioid receptor agonists- U-69593, DAMGO and nociceptin- inhibited adenylate cyclase (AC) activity in cells expressing KOP, MOP and NOP receptors respectively. Buprenorphine, when applied acutely, inhibited AC activity to ~90% in cells expressing KOP+MOP+NOP receptors. Chronic exposure to buprenorphine induced concentration-dependent AC superactivation in cells expressing KOP+NOP receptors, and the level of this superactivation was even higher in KOP+MOP+NOP-expressing cells. Our study demonstrated that MOP receptor could enhance AC regulation in the presence of coexpressed KOP and NOP receptors, and NOP receptor is essential for concentration-dependent AC superactivation elicited by chronic buprenorphine exposure. PMID:26153065

  6. Conformational Dynamics of Kir3.1/Kir3.2 Channel Activation Via δ-Opioid Receptors

    PubMed Central

    Richard-Lalonde, Melissa; Nagi, Karim; Audet, Nicolas; Sleno, Rory; Amraei, Mohammad; Hogue, Mireille; Balboni, Gianfranco; Schiller, Peter W.; Bouvier, Michel; Hébert, Terence E.; Pineyro, Graciela

    2013-01-01

    This study assessed how conformational information encoded by ligand binding to δ-opioid receptors (DORs) is transmitted to Kir3.1/Kir3.2 channels. Human embryonic kidney 293 cells were transfected with bioluminescence resonance energy transfer (BRET) donor/acceptor pairs that allowed us to evaluate independently reciprocal interactions among signaling partners. These and coimmunoprecipitation studies indicated that DORs, Gβγ, and Kir3 subunits constitutively interacted with one another. GαoA associated with DORs and Gβγ, but despite being part of the complex, no evidence of its direct association with the channel was obtained. DOR activation by different ligands left DOR-Kir3 interactions unmodified but modulated BRET between DOR-GαoA, DOR-Gβγ, GαoA-Gβγ, and Gβγ-Kir3 interfaces. Ligand-induced BRET changes assessing Gβγ-Kir3.1 subunit interaction 1) followed similar kinetics to those monitoring the GαoA-Gβγ interface, 2) displayed the same order of efficacy as those observed at the DOR-Gβγ interface, 3) were sensitive to pertussis toxin, and 4) were predictive of whether a ligand could evoke channel currents. Conformational changes at the Gβγ/Kir3 interface were lost when Kir3.1 subunits were replaced by a mutant lacking essential sites for Gβγ-mediated activation. Thus, conformational information encoded by agonist binding to the receptor is relayed to the channel via structural rearrangements that involve repositioning of Gβγ with respect to DORs, GαoA, and channel subunits. Further, the fact that BRET changes at the Gβγ-Kir3 interface are predictive of a ligand’s ability to induce channel currents points to these conformational biosensors as screening tools for identifying GPCR ligands that induce Kir3 channel activation. PMID:23175530

  7. Activation of μ-opioid receptors inhibits calcium-currents in the vestibular afferent neurons of the rat through a cAMP dependent mechanism

    PubMed Central

    Seseña, Emmanuel; Vega, Rosario; Soto, Enrique

    2014-01-01

    Opioid receptors are expressed in the vestibular endorgans (afferent neurons and hair cells) and are activated by the efferent system, which modulates the discharge of action potentials in vestibular afferent neurons (VANs). In mammals, VANs mainly express the μ opioid-receptor, but the function of this receptors activation and the cellular mechanisms by which they exert their actions in these neurons are poorly studied. To determine the actions of μ opioid receptor (MOR) and cell signaling mechanisms in VANs, we made perforated patch-clamp recordings of VANs that were obtained from postnatal days 7 to 10 (P7–10) rats and then maintained in primary culture. The MOR agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO) inhibited the total voltage-gated outward current; this effect was prevented by the perfusion of a Ca2+-free extracellular solution. We then studied the voltage-gated calcium current (Ica) and found that DAMGO Met-enkephalin or endomorphin-1 inhibited the ICa in a dose-response fashion. The effects of DAMGO were prevented by the MOR antagonist (CTAP) or by pertussis toxin (PTX). The use of specific calcium channel blockers showed that MOR activation inhibited T-, L- and N-type ICa. The use of various enzyme activators and inhibitors and of cAMP analogs allowed us to demonstrate that the MOR acts through a cAMP dependent signaling mechanism. In current clamp experiments, MOR activation increased the duration and decreased the amplitude of the action potentials and modulated the discharge produced by current injection. Pre-incubation with PTX occluded MOR activation effect. We conclude that MOR activation inhibits the T-, L- and N-type ICa through activation of a Gαi/o protein that involves a decrease in AC-cAMP-PKA activity. The modulation of ICa may have an impact on the synaptic integration, excitability, and neurotransmitter release from VANs. PMID:24734002

  8. Synthesis and biological activity of small peptides as NOP and opioid receptors' ligands: view on current developments.

    PubMed

    Naydenova, Emilia; Todorov, Petar; Zamfirova, Rositza

    2015-01-01

    The heptadecapeptide nociceptin, also called orphanin FQ (N/OFQ), is the endogenous agonist of the N/OFQ peptide receptor (NOP receptor) and is involved in several central nervous system pathways, such as nociception, reward, tolerance, and feeding. The discovery of small molecule ligands for NOP is being actively pursued for several therapeutic applications. This review presents overview of the several recently reported NOP ligands (agonists and antagonists), with an emphasis of the structural features that may be important for modulating the intrinsic activity of these ligands. In addition, a brief account on the characterization of newly synthesized ligands of NOP receptor with aminophosphonate moiety and β-tryptophan analogues will be presented. PMID:25677770

  9. MicroRNA 339 down-regulates μ-opioid receptor at the post-transcriptional level in response to opioid treatment.

    PubMed

    Wu, Qifang; Hwang, Cheol Kyu; Zheng, Hui; Wagley, Yadav; Lin, Hong-Yiou; Kim, Do Kyung; Law, Ping-Yee; Loh, Horace H; Wei, Li-Na

    2013-02-01

    μ-Opioid receptor (MOR) level is directly related to the function of opioid drugs, such as morphine and fentanyl. Although agonist treatment generally does not affect transcription of mor, previous studies suggest that morphine can affect the translation efficiency of MOR transcript via microRNAs (miRNAs). On the basis of miRNA microarray analyses of the hippocampal total RNA isolated from mice chronically treated with μ-opioid agonists, we found a miRNA (miR-339-3p) that was consistently and specifically increased by morphine (2-fold) and by fentanyl (3.8-fold). miR-339-3p bound to the MOR 3'-UTR and specifically suppressed reporter activity. Suppression was blunted by adding miR-339-3p inhibitor or mutating the miR-339-3p target site. In cells endogenously expressing MOR, miR-339-3p inhibited the production of MOR protein by destabilizing MOR mRNA. Up-regulation of miR-339-3p by fentanyl (EC(50)=0.75 nM) resulted from an increase in primary miRNA transcript. Mapping of the miR-339-3p primary RNA and its promoter revealed that the primary miR-339-3p was embedded in a noncoding 3'-UTR region of an unknown host gene and was coregulated by the host promoter. The identified promoter was activated by opioid agonist treatment (10 nM fentanyl or 10 μM morphine), a specific effect blocked by the opioid antagonist naloxone (10 μM). Taken together, these results suggest that miR-339-3p may serve as a negative feedback modulator of MOR signals by regulating intracellular MOR biosynthesis. PMID:23085997

  10. New perspective on the pathophysiology of panic: merging serotonin and opioids in the periaqueductal gray

    PubMed Central

    Graeff, F.G.

    2012-01-01

    Panic disorder patients are vulnerable to recurrent panic attacks. Two neurochemical hypotheses have been proposed to explain this susceptibility. The first assumes that panic patients have deficient serotonergic inhibition of neurons localized in the dorsal periaqueductal gray matter of the midbrain that organize defensive reactions to cope with proximal threats and of sympathomotor control areas of the rostral ventrolateral medulla that generate most of the neurovegetative symptoms of the panic attack. The second suggests that endogenous opioids buffer normal subjects from the behavioral and physiological manifestations of the panic attack, and their deficit brings about heightened suffocation sensitivity and separation anxiety in panic patients, making them more vulnerable to panic attacks. Experimental results obtained in rats performing one-way escape in the elevated T-maze, an animal model of panic, indicate that the inhibitory action of serotonin on defense is connected with activation of endogenous opioids in the periaqueductal gray. This allows reconciliation of the serotonergic and opioidergic hypotheses of panic pathophysiology, the periaqueductal gray being the fulcrum of serotonin-opioid interaction. PMID:22437485

  11. Molecular characterization of opioid receptors

    SciTech Connect

    Howard, A.D.

    1986-01-01

    The aim of this research was to purify and characterize active opioid receptors and elucidate molecular aspects of opioid receptor heterogeneity. Purification to apparent homogeneity of an opioid binding protein from bovine caudate was achieved by solubilization in the non-ionic detergent, digitonin, followed by sequential chromatography on the opiate affinity matrix, ..beta..-naltrexylethylenediamine-CH-Sepharose 4B, and on the lectine affinity matrix, wheat germ agglutinin-agarose. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) followed by autoradiography revealed that radioiodinated purified receptor gave a single band. Purified receptor preparations showed a specific activity of 12,000-15,000 fmol of opiate bound per mg of protein. Radioiodinated human beta-endorphin (/sup 125/I-beta-end/sub H/) was used as a probe to investigate the ligand binding subunits of mu and delta opioid receptors. /sup 125/I-beta-end/sub H/ was shown to bind to a variety of opioid receptor-containing tissues with high affinity and specificity with preference for mu and delta sites, and with little, if any, binding to kappa sites. Affinity crosslinking techniques were employed to covalently link /sup 125/I-beta-end/sub H/ to opioid receptors, utilizing derivatives of bis-succinimidyl esters that are bifunctional crosslinkers with specificities for amino and sulfhydryl groups. This, and competition experiments with high type-selective ligands, permitted the assignment of two labeled peptides to their receptor types, namely a peptide of M/sub r/ = 65,000 for mu receptors and one of M/sub r/ = 53,000 for delta receptors.

  12. Effects of the Mu Opioid Receptor Polymorphism (OPRM1 A118G) on Pain Regulation, Placebo Effects and Associated Personality Trait Measures

    PubMed Central

    Peciña, Marta; Love, Tiffany; Stohler, Christian S; Goldman, David; Zubieta, Jon-Kar

    2015-01-01

    Mu-opioid receptors (MOPRs) are critically involved in the modulation of pain and analgesia, and represent a candidate mechanism for the development of biomarkers of pain conditions and their responses to treatment. To further understand the human implications of genetic variation within the opioid system in pain and opioid-mediated placebo responses, we investigated the association between the functional single-nucleotide polymorphism (SNP) in the μ-opioid receptor gene (OPRM1), A118G, and psychophysical responses, personality traits, and neurotransmitter systems (dopamine (DA), opioid) related to pain and placebo analgesia. OPRM1 G carriers, compared with AA homozygotes, showed an overall reduction of baseline μ-opioid receptor availability in regions implicated in pain and affective regulation. In response to a sustained painful stimulus, we found no effect of A118G on pain-induced endogenous opioid release. Instead, AA homozygotes showed a blunted DA response in the nucleus accumbens (NAc) in response to the pain challenge. After placebo administration, G carriers showed more pronounced mood disturbances and lower placebo-induced μ-opioid system activation in the anterior insula (aINS), the amygdala (AMY), the NAc, the thalamus (THA), and the brainstem, as well as lower levels of DA D2/3 activation in the NAc. At a trait level, G carriers reported higher NEO-Neuroticism scores; a personality trait previously associated with increased pain and lower placebo responses, which were negatively correlated with baseline μ-opioid receptor availability in the aINS and subgenual anterior cingulate cortex (sgACC). Our results demonstrate that the A118G OPRM1 polymorphism contributes to interindividual variations in the function of neurotransmitters responsive to pain (endogenous opioid and dopamine), as well as their regulation through cognitive-emotional influences in the context of therapeutic expectations, the so-called placebo effect. These effects are relevant to

  13. The effect of opioid receptor blockade on the neural processing of thermal stimuli.

    PubMed

    Schoell, Eszter D; Bingel, Ulrike; Eippert, Falk; Yacubian, Juliana; Christiansen, Kerrin; Andresen, Hilke; May, Arne; Buechel, Christian

    2010-01-01

    The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent) signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone. PMID:20811582

  14. The Effect of Opioid Receptor Blockade on the Neural Processing of Thermal Stimuli

    PubMed Central

    Schoell, Eszter D.; Bingel, Ulrike; Eippert, Falk; Yacubian, Juliana; Christiansen, Kerrin; Andresen, Hilke; May, Arne; Buechel, Christian

    2010-01-01

    The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent) signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone. PMID:20811582

  15. Nascent structure-activity relationship study of a diastereomeric series of kappa opioid receptor antagonists derived from CJ-15,208.

    PubMed

    Dolle, Roland E; Michaut, Mathieu; Martinez-Teipel, Blanca; Seida, Pamela R; Ajello, Christopher W; Muller, Alison L; DeHaven, Robert N; Carroll, Patrick J

    2009-07-01

    Cyclic tetrapeptide c[Phe-pro-Phe-trp] 2, a diastereomer of CJ-15,208 (1), was identified as a potent dual kappa/mu opioid receptor antagonist devoid of delta opioid receptor affinity against cloned human receptors: K(i) (2)=3.8nM (kappa), 30nM (mu); IC(50) ([(35)S]GTPgammaS binding)=140nM (kappa), 21nM (mu). The d-tryptophan residue rendered 2 ca. eightfold and fourfold more potent at kappa and mu, respectively, than the corresponding l-configured tryptophan in the natural product 1. Phe analogs 3-10, designed to probe the effect of substituents on receptor affinity and selectivity, possessed K(i) values ranging from 14 to 220nM against the kappa opioid receptor with mu/kappa ratios of 0.45-3.0. An alanine scan of 2 yielded c[Ala-pro-Phe-trp] 12, an analog equipotent to 2. Agents 2 and 12 were pure antagonists in vitro devoid of agonist activity. Ac-pro-Phe-trp-Phe-NH(2)16 and Ac-Phe-trp-Phe-pro-NH(2)17 two of the eight possible acyclic peptides derived from 1 and 2, were selective, modestly potent mu ligands: K(i) (16)=340nM (mu); K(i) (17)=360nM (mu). PMID:19464172

  16. Kappa Opioids, Salvinorin A and Major Depressive Disorder

    PubMed Central

    Taylor, George T.; Manzella, Francesca

    2016-01-01

    Opioids are traditionally associated with pain, analgesia and drug abuse. It is now clear, however, that the opioids are central players in mood. The implications for mood disorders, particularly clinical depression, suggest a paradigm shift from the monoamine neurotransmitters to the opioids either alone or in interaction with monoamine neurons. We have a special interest in dynorphin, the last of the major endogenous opioids to be isolated and identified. Dynorphin is derived from the Greek word for power, dynamis, which hints at the expectation that the neuropeptide held for its discoverers. Yet, dynorphin and its opioid receptor subtype, kappa, has always taken a backseat to the endogenous b-endorphin and the exogenous morphine that both bind the mu opioid receptor subtype. That may be changing as the dynorphin/ kappa system has been shown to have different, often opposite, neurophysiological and behavioral influences. This includes major depressive disorder (MDD). Here, we have undertaken a review of dynorphin/ kappa neurobiology as related to behaviors, especially MDD. Highlights include the unique features of dynorphin and kappa receptors and the special relation of a plant-based agonist of the kappa receptor salvinorin A. In addition to acting as a kappa opioid agonist, we conclude that salvinorin A has a complex pharmacologic profile, with potential additional mechanisms of action. Its unique neurophysiological effects make Salvinorina A an ideal candidate for MDD treatment research. PMID:26903446

  17. µ- and κ-Opioid receptor activation in the dorsal periaqueductal grey matter differentially modulates panic-like behaviours induced by electrical and chemical stimulation of the inferior colliculus.

    PubMed

    Twardowschy, André; Coimbra, Norberto Cysne

    2015-02-01

    It has been shown that electrical stimulation of the mesencephalic tectum (MT) provokes defensive responses in both humans and rodents. During an emotional aversive state, some convergent studies have also demonstrated the existence of a complex interaction between endogenous opioid peptide- and γ-aminobutyric acid (GABA)-containing connections during fear-induced responses. It has been proposed that opioid neurons exert an influence on GABAergic interneurons, which, in turn, exert inhibitory tonic control on the mesencephalic excitatory pathways. Thus, opioid peptides can disinhibit neurons that are tonically inhibited by GABA, therefore, modulating the expression of defensive behavioural reactions. In the present work, we used both electric stimulation and microinjections of the GABAA receptor antagonist bicuculline in the inferior colliculus (IC) of Wistar rats in combination with microinjections of µ- and κ-opioid receptor selective agonists into the dorsal columns of periaqueductal grey matter (dPAG) to evaluate the effects on panic-like behaviours elicited by IC electrical and chemical stimulation. The present results showed that neurochemical lesions of the dPAG caused a significant impairment in the organisation of defensive responses by IC neurons, reducing the duration [t(14)=3.0; p<0.01] of defensive immobility and the duration [t(14)=2.8; p<0.05] and frequency [t(14)=2.5; p<0.05] of escape. Paradoxically, treating the dPAG with the µ-opioid receptor agonist met-enkephalin caused a significant reduction of panic-like behaviours induced by both electrical and chemical stimulation of the IC, increasing the escape behaviour threshold [F(2,23)=13.5; p<0.001] and decreasing the frequency [F(3,36)=11.7; p<0.001] and duration [F(3,36)=11.6; p<0.001] of escape and the duration of defensive immobility [F(3,36)=16.1; p<0.05]. In contrast, treating the dPAG with the κ-opioid receptor agonist salvinorin-A increased the frequency [F(3,36)=12.4; p<0.01] and

  18. Mu Opioid Splice Variant MOR-1K Contributes to the Development of Opioid-Induced Hyperalgesia

    PubMed Central

    Oladosu, Folabomi A.; Conrad, Matthew S.; O’Buckley, Sandra C.; Rashid, Naim U.; Slade, Gary D.; Nackley, Andrea G.

    2015-01-01

    Background A subset of the population receiving opioids for the treatment of acute and chronic clinical pain develops a paradoxical increase in pain sensitivity known as opioid-induced hyperalgesia. Given that opioid analgesics are one of few treatments available against clinical pain, it is critical to determine the key molecular mechanisms that drive opioid-induced hyperalgesia in order to reduce its prevalence. Recent evidence implicates a splice variant of the mu opioid receptor known as MOR-1K in the emergence of opioid-induced hyperalgesia. Results from human genetic association and cell signaling studies demonstrate that MOR-1K contributes to decreased opioid analgesic responses and produces increased cellular activity via Gs signaling. Here, we conducted the first study to directly test the role of MOR-1K in opioid-induced hyperalgesia. Methods and Results In order to examine the role of MOR-1K in opioid-induced hyperalgesia, we first assessed pain responses to mechanical and thermal stimuli prior to, during, and following chronic morphine administration. Results show that genetically diverse mouse strains (C57BL/6J, 129S6, and CXB7/ByJ) exhibited different morphine response profiles with corresponding changes in MOR-1K gene expression patterns. The 129S6 mice exhibited an analgesic response correlating to a measured decrease in MOR-1K gene expression levels, while CXB7/ByJ mice exhibited a hyperalgesic response correlating to a measured increase in MOR-1K gene expression levels. Furthermore, knockdown of MOR-1K in CXB7/ByJ mice via chronic intrathecal siRNA administration not only prevented the development of opioid-induced hyperalgesia, but also unmasked morphine analgesia. Conclusions These findings suggest that MOR-1K is likely a necessary contributor to the development of opioid-induced hyperalgesia. With further research, MOR-1K could be exploited as a target for antagonists that reduce or prevent opioid-induced hyperalgesia. PMID:26270813

  19. Activation of delta-type opioid receptors modulates the responses of cat terminal ileum to field electrical stimulation.

    PubMed

    Venkova, K; Pencheva, N; Radomirov, R

    1990-01-01

    1. The effects of (D-Ala2, D-Leu5) enkephalin amide (DADLE) on the responses of the cat terminal ileum to field electrical stimulation (pulse duration of 0.5 msec, train duration of 10 sec, 30 V) were evaluated by the changes in the contractile or the relaxatory responses of longitudinal and circular strips to electrical stimuli with a frequency of 2, 10 or 30 Hz. 2. Stimulation with a frequency of 2, 10 or 30 Hz elicited contractile responses from the longitudinal strips while in the circular strips 2 Hz stimulation induced contractions and 10 or 30 Hz stimulation caused relaxation. Tetrodotoxin (TTX) (0.1 mumol/l) abolished the electrically-induced responses in both longitudinal and circular strips. 3. DADLE (1 nmol/l) significantly inhibited the cholinergic contractile responses of the longitudinal strips to 2, 10 or 30 Hz stimulation and the contractile responses of the circular strips to 2 Hz stimulation. The relaxatory responses of the circular strips to 10 or 30 Hz stimulation were insignificantly increased by DADLE. 4. On the background of guanetidine (10 mumol/l) and atropine (3 mumol/l) DADLE significantly decreased the nonadrenergic, noncholinergic relaxatory responses of the circular strips to 2, 10 or 30 Hz stimulation. 5. DADLE did not change the maximum effects and the EC50 values of acetylcholine and noradrenaline in both longitudinal and circular strips. 6. It is suggested that in the cat terminal ileum activation of delta-type opioid receptors modulates the mechanical activity suppressing the cholinergic responses in the longitudinal and circular layers as well as the adrenergic and nonadrenergic, noncholinergic responses in the circular layer. PMID:2153605

  20. Neural activation patterns underlying basolateral amygdala influence on intra-accumbens opioid-driven consummatory versus appetitive high-fat feeding behaviors in the rat.

    PubMed

    Parker, Kyle E; McCabe, Matt P; Johns, Howard W; Lund, Dane K; Odu, Fiona; Sharma, Rishi; Thakkar, Mahesh M; Cornelison, D D W; Will, Matthew J

    2015-12-01

    The present study explored the role of the amygdala in mediating a unique pattern of feeding behavior driven by intra-accumbens (intra-Acb) opioid activation in the rat. Temporary inactivation of the basolateral amygdala (BLA), via GABAA agonist muscimol administration prevents increased consumption following intra-Acb opioid administration of the selective μ-opioid agonist D-Ala2, NMe-Phe4, Glyol5-enkephalin (DAMGO), yet leaves food approach behaviors intact, particularly after consumption has ended. One interpretation is that inactivation of the BLA selectively blocks neural activity underlying DAMGO-driven consummatory (consumption) but not appetitive (approach) behaviors. The present experiments take advantage of this temporal dissociation of consumption and approach behaviors to investigate their associated neural activity. Following either intra-Acb saline or DAMGO administration, with or without BLA muscimol administration, rats were given 2-hr access to a limited amount of high-fat diet. Immediately following the feeding session, rats were sacrificed and brains assayed for neural activity patterns across critical brain regions known to regulate both appetitive and consummatory feeding behaviors. The results show that intra-Acb DAMGO administration increased c-Fos activation in orexin neurons within the perifornical area of the hypothalamus and that this increase in activation is blocked by BLA muscimol inactivation. Intra-Acb DAMGO administration significantly increased c-Fos activation within dopaminergic neurons of the ventral tegmental area, compared to saline controls, and BLA inactivation had no effect on this increase. Overall, these data provide underlying circuitry that may mediate the selective influence of the BLA on driving consummatory, but not appetitive, feeding behaviors in a model of hedonically driven feeding behavior. PMID:26501175

  1. Neural activation patterns underlying basolateral amygdala influence on intra-accumbens opioid-driven consummatory vs. appetitive high-fat feeding behaviors in the rat

    PubMed Central

    Parker, Kyle E.; McCabe, Matt P.; Johns, Howard W.; Lund, Dane K.; Odu, Fiona; Sharma, Rishi; Thakkar, Mahesh M.; Cornelison, DDW; Will, Matthew J.

    2015-01-01

    The present study explored the role of the amygdala in mediating a unique pattern of feeding behavior driven by intra-accumbens (Acb) opioid activation in the rat. Temporary inactivation of the basolateral amygdala (BLA), via GABAA agonist muscimol administration prevents increased consumption following intra-Acb opioid administration of the selective µ-opioid agonist D-Ala2, NMe-Phe4, Glyol5-enkephalin (DAMGO), yet leaves food approach behaviors intact, particularly after consumption has ended. One interpretation is that inactivation of the BLA selectively blocks neural activity underlying DAMGO-driven consummatory (consumption), but not appetitive (approach) behaviors. The present experiments take advantage of this temporal dissociation of consumption and approach behaviors to investigate their associated neural activity. Following either intra-Acb saline or DAMGO administration, with or without BLA muscimol administration, rats were given 2hr access to a limited amount of high-fat diet. Immediately following the feeding session, rats were sacrificed and brains assayed for neural activity patterns across critical brain regions known to regulate both appetitive and consummatory feeding behaviors. The results show that intra-Acb DAMGO administration increased c-Fos activation in orexin neurons within the perifornical area of the hypothalamus and that this increase in activation is blocked by BLA muscimol inactivation. Intra-Acb DAMGO administration significantly increased c-Fos activation within dopaminergic neurons of the ventral tegmental area, compared to saline controls, and BLA inactivation had no effect on this increase. Overall, these data provide underlying circuitry that may mediate the selective influence of the BLA on driving consummatory, but not appetitive, feeding behaviors in a model of hedonically-driven feeding behavior. PMID:26501175

  2. Modulation of the behavioral and neurochemical effects of psychostimulants by kappa-opioid receptor systems.

    PubMed

    Shippenberg, T S; Chefer, V I; Zapata, A; Heidbreder, C A

    2001-06-01

    The repeated, intermittent use of cocaine and other drugs of abuse produces profound and often long-lasting alterations in behavior and brain chemistry. It has been suggested that these consequences of drug use play a critical role in drug craving and relapse to addiction. This article reviews the effects of psychostimulant administration on dopaminergic and excitatory amino acid neurotransmission in brain regions comprising the brain's motive circuit and provides evidence that the activation of endogenous kappa-opioid receptor systems in these regions opposes the behavioral and neurochemical consequences of repeated drug use. The role of this opioid system in mediating alterations in mood and affect that occur during abstinence from repeated psychostimulant use are also discussed. PMID:11458540

  3. Stimulation of peripheral Kappa opioid receptors inhibits inflammatory hyperalgesia via activation of the PI3Kγ/AKT/nNOS/NO signaling pathway

    PubMed Central

    2012-01-01

    Background In addition to their central effects, opioids cause peripheral analgesia. There is evidence showing that peripheral activation of kappa opioid receptors (KORs) inhibits inflammatory pain. Moreover, peripheral μ-opioid receptor (MOR) activation are able to direct block PGE2-induced ongoing hyperalgesia However, this effect was not tested for KOR selective activation. In the present study, the effect of the peripheral activation of KORs on PGE2-induced ongoing hyperalgesia was investigated. The mechanisms involved were also evaluated. Results Local (paw) administration of U50488 (a selective KOR agonist) directly blocked, PGE2-induced mechanical hyperalgesia in both rats and mice. This effect was reversed by treating animals with L-NMMA or N-propyl-L-arginine (a selective inhibitor of neuronal nitric oxide synthase, nNOS), suggesting involvement of the nNOS/NO pathway. U50488 peripheral effect was also dependent on stimulation of PI3Kγ/AKT because inhibitors of these kinases also reduced peripheral antinociception induced by U50488. Furthermore, U50488 lost its peripheral analgesic effect in PI3Kγ null mice. Observations made in vivo were confirmed after incubation of dorsal root ganglion cultured neurons with U50488 produced an increase in the activation of AKT as evaluated by western blot analyses of its phosphorylated form. Finally, immunofluorescence of DRG neurons revealed that KOR-expressing neurons also express PI3Kγ (≅ 43%). Conclusions The present study indicates that activation of peripheral KORs directly blocks inflammatory hyperalgesia through stimulation of the nNOS/NO signaling pathway which is probably stimulated by PI3Kγ/AKT signaling. This study extends a previously study of our group suggesting that PI3Kγ/AKT/nNOS/NO is an important analgesic pathway in primary nociceptive neurons. PMID:22316281

  4. Treating pain with pain: supraspinal mechanisms of endogenous analgesia elicited by heterotopic noxious conditioning stimulation.

    PubMed

    Sprenger, Christian; Bingel, Ulrike; Büchel, Christian

    2011-02-01

    While being exposed to an intensive tonic pain stimulus at one area of the body, another phasic pain stimulus applied to a remote site is perceived as less painful. The neurophysiological basis for this "pain inhibits pain" phenomenon has been presumed to be an activation of the spino-bulbo-spinal mechanism termed "diffuse noxious inhibitory controls." However, several additional mechanisms such as an activation of the descending pain control system may contribute to this observation. Here we investigated the underlying supraspinal mechanisms of "heterotopic noxious conditioning stimulations" (HNCS), representing this specific experimental constellation. We used functional magnetic resonance imaging and behavioral recordings in combination with a modified cold-pressor task and phasic painful stimuli, and investigated the contribution of endogenous opioids to this mechanism using the opioid antagonist naloxone in a double-blind crossover design. HNCS led to marked endogenous analgesia and this effect correlated positively with the perceived intensity of the tonic painful stimulus. Furthermore, HNCS was paralleled by reduced blood oxygen level dependent (BOLD) responses in classical pain-responsive regions. Conversely, HNCS led to tonic BOLD increases in subregions of the anterior cingulate cortex. The strength of functional coupling between the subgenual anterior cingulate cortex and key structures of the descending pain control system was enhanced during HNCS, which correlated positively with the individual endogenous analgesia during HNCS. These effects were in part reversed by naloxone, speaking for the contribution of endogenous opioid neurotransmission to this mechanism. Taken together, these results demonstrate a substantial contribution of higher-order brain regions to the phenomenon of hypoalgesia during HNCS. Functional magnetic resonance imaging shows how the human brain is involved in heterotopic noxious conditioning and reveals active supraspinal pain

  5. Chondroitinase and growth factors enhance activation and oligodendrocyte differentiation of endogenous neural precursor cells after spinal cord injury.

    PubMed

    Karimi-Abdolrezaee, Soheila; Schut, Desiree; Wang, Jian; Fehlings, Michael G

    2012-01-01

    The adult spinal cord harbours a population of multipotent neural precursor cells (NPCs) with the ability to replace oligodendrocytes. However, despite this capacity, proliferation and endogenous remyelination is severely limited after spinal cord injury (SCI). In the post-traumatic microenvironment following SCI, endogenous spinal NPCs mainly differentiate into astrocytes which could contribute to astrogliosis that exacerbate the outcomes of SCI. These findings emphasize a key role for the post-SCI niche in modulating the behaviour of spinal NPCs after SCI. We recently reported that chondroitin sulphate proteoglycans (CSPGs) in the glial scar restrict the outcomes of NPC transplantation in SCI by reducing the survival, migration and integration of engrafted NPCs within the injured spinal cord. These inhibitory effects were attenuated by administration of chondroitinase (ChABC) prior to NPC transplantation. Here, in a rat model of compressive SCI, we show that perturbing CSPGs by ChABC in combination with sustained infusion of growth factors (EGF, bFGF and PDGF-AA) optimize the activation and oligodendroglial differentiation of spinal NPCs after injury. Four days following SCI, we intrathecally delivered ChABC and/or GFs for seven days. We performed BrdU incorporation to label proliferating cells during the treatment period after SCI. This strategy increased the proliferation of spinal NPCs, reduced the generation of new astrocytes and promoted their differentiation along an oligodendroglial lineage, a prerequisite for remyelination. Furthermore, ChABC and GF treatments enhanced the response of non-neural cells by increasing the generation of new vascular endothelial cells and decreasing the number of proliferating macrophages/microglia after SCI. In conclusions, our data strongly suggest that optimization of the behaviour of endogenous spinal NPCs after SCI is critical not only to promote endogenous oligodendrocyte replacement, but also to reverse the otherwise

  6. Activation autoradiography: imaging and quantitative determination of endogenous and exogenous oxygen in the rat brain

    SciTech Connect

    Kawashima, K.; Iwata, R.; Kogure, K.; Ohtomo, H.; Orihara, H.; Ido, T.

    1987-06-01

    Endogenous and exogenous oxygen in the rat brain were quantitatively determined using an autoradiographic technique. The oxygen images of frozen and dried rat brain sections were obtained as /sup 18/F images by using the /sup 16/O (/sup 3/He,p)/sup 18/F reaction for endogenous /sup 16/O images and the /sup 18/O(p,n)/sup 18/F reaction for endogenous and exogenous /sup 18/O images. These autoradiograms demonstrated the different distribution of oxygen between gray and white matter. These images also allowed differentiation of the individual structures of hippocampal formation, owing to the differing water content of the various structures. Local oxygen contents were quantitatively determined from autoradiograms of brain sections and standard sections with known oxygen contents. The estimated values were 75.6 +/- 4.6 wt% in gray matter and 72.2 +/- 4.0 wt% in white matter. The systematic error in the present method was estimated to be 4.9%.

  7. Salvinorin A inhibits colonic transit and neurogenic ion transport in mice by activating kappa-opioid and cannabinoid receptors.

    PubMed

    Fichna, J; Schicho, R; Andrews, C N; Bashashati, M; Klompus, M; McKay, D M; Sharkey, K A; Zjawiony, J K; Janecka, A; Storr, M A

    2009-12-01

    The major active ingredient of the plant Salvia divinorum, salvinorin A (SA) has been used to treat gastrointestinal (GI) symptoms. As the action of SA on the regulation of colonic function is unknown, our aim was to examine the effects of SA on mouse colonic motility and secretion in vitro and in vivo. The effects of SA on GI motility were studied using isolated preparations of colon, which were compared with preparations from stomach and ileum. Colonic epithelial ion transport was evaluated using Ussing chambers. Additionally, we studied GI motility in vivo by measuring colonic propulsion, gastric emptying, and upper GI transit. Salvinorin A inhibited contractions of the mouse colon, stomach, and ileum in vitro, prolonged colonic propulsion and slowed upper GI transit in vivo. Salvinorin A had no effect on gastric emptying in vivo. Salvinorin A reduced veratridine-, but not forskolin-induced epithelial ion transport. The effects of SA on colonic motility in vitro were mediated by kappa-opioid receptors (KORs) and cannabinoid (CB) receptors, as they were inhibited by the antagonists nor-binaltorphimine (KOR), AM 251 (CB(1) receptor) and AM 630 (CB(2) receptor). However, in the colon in vivo, the effects were largely mediated by KORs. The effects of SA on veratridine-mediated epithelial ion transport were inhibited by nor-binaltorphimine and AM 630. Salvinorin A slows colonic motility in vitro and in vivo and influences neurogenic ion transport. Due to its specific regional action, SA or its derivatives may be useful drugs in the treatment of lower GI disorders associated with increased GI transit and diarrhoea. PMID:19650775

  8. Announcing the CDC guideline for prescribing opioids for chronic pain.

    PubMed

    Houry, Debra; Baldwin, Grant

    2016-06-01

    This guideline provides recommendations for primary care providers who are prescribing opioids for chronic pain outside of active cancer treatment, palliative care, and end-of-life care. The guideline addresses: (a) when to initiate or continue opioids for chronic pain; (b) opioid selection, dosage, duration, follow-up, and discontinuation; and (c) assessing risk and addressing harms of opioid use. This guideline is intended to improve communication between providers and patients about the risks and benefits of opioid therapy for chronic pain, improve the safety and effectiveness of pain treatment, and reduce the risks associated with long-term opioid therapy, including abuse, dependence, overdose, and death (Dowell D, Haegerich TM, Chou R. CDC Guideline for Prescribing Opioids for Chronic Pain - United States, 2016. MMWR Recomm Rep 2016;65:1-49. DOI: http://dx.doi.org/10.15585/mmwr.rr6501e1.). PMID:27178083

  9. Chronic stress increases the opioid-mediated inhibition of the pituitary-adrenocortical response to acute stress in pigs.

    PubMed

    Janssens, C J; Helmond, F A; Loyens, L W; Schouten, W G; Wiegant, V M

    1995-04-01

    The role of endogenous opioid mechanisms in the pituitary-adrenocortical response to acute stress was investigated in a longitudinal study in cyclic female pigs before and after exposure to chronic stress (long term tethered housing). Challenge of loose-housed pigs with acute nose-sling stress for 15 min induced an activation of the hypothalamic-pituitary-adrenocortical axis, evidenced by a transient increase in plasma ACTH (peak height above basal, 98 +/- 12 pg/ml; mean +/- SEM) and cortisol (54 +/- 3 ng/ml) concentrations. Pretreatment with the opioid receptor antagonist naloxone (0.5 mg/kg BW, iv bolus) increased the challenge-induced ACTH and cortisol responses to 244 +/- 36 pg/ml and 65 +/- 5 ng/ml, respectively. This indicates that during acute nose-sling stress, endogenous opioid systems are activated that inhibit the pituitary-adrenocortical response. After exposure of the pigs to chronic stress (10-11 weeks of tethered housing), the challenge-induced ACTH response was attenuated, whereas the cortisol response remained unchanged, suggesting an increased adrenocortical sensitivity to circulating ACTH. In addition, pretreatment with naloxone induced a greater increment in the ACTH and cortisol responses in tethered pigs than in loose-housed pigs. As no such changes were found in control animals housed loose during the entire experimental period, this indicates that the impact of opioid systems had increased due to chronic stress. The increased impact of opioid systems during chronic stress may prevent excessive hypothalamic-pituitary-adrenocortical responses to acute stressors and, thus, may be of adaptive value. PMID:7895656

  10. Structure of the [delta]-opioid receptor bound to naltrindole

    SciTech Connect

    Granier, Sébastien; Manglik, Aashish; Kruse, Andrew C.; Kobilka, Tong Sun; Thian, Foon Sun; Weis, William I.; Kobilka, Brian K.

    2012-07-11

    The opioid receptor family comprises three members, the {mu}-, {delta}- and {kappa}-opioid receptors, which respond to classical opioid alkaloids such as morphine and heroin as well as to endogenous peptide ligands like endorphins. They belong to the G-protein-coupled receptor (GPCR) superfamily, and are excellent therapeutic targets for pain control. The {delta}-opioid receptor ({delta}-OR) has a role in analgesia, as well as in other neurological functions that remain poorly understood. The structures of the {mu}-OR and {kappa}-OR have recently been solved. Here we report the crystal structure of the mouse {delta}-OR, bound to the subtype-selective antagonist naltrindole. Together with the structures of the {mu}-OR and {kappa}-OR, the {delta}-OR structure provides insights into conserved elements of opioid ligand recognition while also revealing structural features associated with ligand-subtype selectivity. The binding pocket of opioid receptors can be divided into two distinct regions. Whereas the lower part of this pocket is highly conserved among opioid receptors, the upper part contains divergent residues that confer subtype selectivity. This provides a structural explanation and validation for the 'message-address' model of opioid receptor pharmacology, in which distinct 'message' (efficacy) and 'address' (selectivity) determinants are contained within a single ligand. Comparison of the address region of the {delta}-OR with other GPCRs reveals that this structural organization may be a more general phenomenon, extending to other GPCR families as well.

  11. sup. alpha. N-acetyl derivatives of. beta. -endorphin-(1-31) and -(1-27) regulate the supraspinal antinociceptive activity of different opioids in mice

    SciTech Connect

    Garzon, J.; Sanchez-Blazquez, P. )

    1991-01-01

    {sup {alpha}}N-acetyl human {beta}-endorphin(1-31) injected icv to mice antagonized the analgesic activity of {beta}-endorphin-(1-31) and morphine whereas the analgesia evoked by DADLE and DAGO was enhanced by this treatment. The modulatory activity of {sup {alpha}}N-acetyl {beta}-endorphin-(1-31) was exhibited at remarkable low doses (fmols) reaching a maximum that persisted even though the dose was increased 100,000 times. The regulatory effect of a single dose of the acetylated neuropeptide lasted for 24h. The activity of {sup {alpha}}N-acetyl human {beta}-endorphin(1-31) was partially retained by the shorter peptide {sup {alpha}}N-acetyl human {beta}-endorphin-(1-27) and to a lesser extent by {beta}-endorphin-(1-27), {beta}-endorphin-(1-31) lacked this regulatory activity on opioid analgesia. Acetylated {beta}-endorphin-(1-31) displayed a biphasic curve when competing with 5 pM ({sup 125}I)-Tyr{sup 27} human {beta}-endorphin-(1-31) specific binding, the first step was abolished with an apparent IC{sub 50} of 0.35 nM, and the rest with an IC{sub 50} of 200 nM. It is suggested that {sup {alpha}}N-acetyl {beta}-endorphin-(1-31) changed the efficiency of the opioid analgesics by acting upon a specific substrate that is functionally coupled to the opioid receptor, presumably the guanine nucleotide binding regulatory proteins G{sub i}/G{sub 0}.

  12. Endogenous cholinergic tone modulates spontaneous network level neuronal activity in primary cortical cultures grown on multi-electrode arrays

    PubMed Central

    2013-01-01

    Background Cortical cultures grown long-term on multi-electrode arrays (MEAs) are frequently and extensively used as models of cortical networks in studies of neuronal firing activity, neuropharmacology, toxicology and mechanisms underlying synaptic plasticity. However, in contrast to the predominantly asynchronous neuronal firing activity exhibited by intact cortex, electrophysiological activity of mature cortical cultures is dominated by spontaneous epileptiform-like global burst events which hinders their effective use in network-level studies, particularly for neurally-controlled animat (‘artificial animal’) applications. Thus, the identification of culture features that can be exploited to produce neuronal activity more representative of that seen in vivo could increase the utility and relevance of studies that employ these preparations. Acetylcholine has a recognised neuromodulatory role affecting excitability, rhythmicity, plasticity and information flow in vivo although its endogenous production by cortical cultures and subsequent functional influence upon neuronal excitability remains unknown. Results Consequently, using MEA electrophysiological recording supported by immunohistochemical and RT-qPCR methods, we demonstrate for the first time, the presence of intrinsic cholinergic neurons and significant, endogenous cholinergic tone in cortical cultures with a characterisation of the muscarinic and nicotinic components that underlie modulation of spontaneous neuronal activity. We found that tonic muscarinic ACh receptor (mAChR) activation affects global excitability and burst event regularity in a culture age-dependent manner whilst, in contrast, tonic nicotinic ACh receptor (nAChR) activation can modulate burst duration and the proportion of spikes occurring within bursts in a spatio-temporal fashion. Conclusions We suggest that the presence of significant endogenous cholinergic tone in cortical cultures and the comparability of its modulatory effects

  13. Modelling the vicious circle between obesity and physical activity in children and adolescents using a bivariate probit model with endogenous regressors.

    PubMed

    Yeh, C-Y; Chen, L-J; Ku, P-W; Chen, C-M

    2015-01-01

    The increasing prevalence of obesity in children and adolescents has become one of the most important public health issues around the world. Lack of physical activity is a risk factor for obesity, while being obese could reduce the likelihood of participating in physical activity. Failing to account for the endogeneity between obesity and physical activity would result in biased estimation. This study investigates the relationship between overweight and physical activity by taking endogeneity into consideration. It develops an endogenous bivariate probit model estimated by the maximum likelihood method. The data included 4008 boys and 4197 girls in the 5th-9th grades in Taiwan in 2007-2008. The relationship between overweight and physical activity is significantly negative in the endogenous model, but insignificant in the comparative exogenous model. This endogenous relationship presents a vicious circle in which lower levels of physical activity lead to overweight, while those who are already overweight engage in less physical activity. The results not only reveal the importance of endogenous treatment, but also demonstrate the robust negative relationship between these two factors. An emphasis should be put on overweight and obese children and adolescents in order to break the vicious circle. Promotion of physical activity by appropriate counselling programmes and peer support could be effective in reducing the prevalence of obesity in children and adolescents. PMID:24423649

  14. Label-free integrative pharmacology on-target of opioid ligands at the opioid receptor family

    PubMed Central

    2013-01-01

    Background In vitro pharmacology of ligands is typically assessed using a variety of molecular assays based on predetermined molecular events in living cells. Many ligands including opioid ligands pose the ability to bind more than one receptor, and can also provide distinct operational bias to activate a specific receptor. Generating an integrative overview of the binding and functional selectivity of ligands for a receptor family is a critical but difficult step in drug discovery and development. Here we applied a newly developed label-free integrative pharmacology on-target (iPOT) approach to systematically survey the selectivity of a library of fifty-five opioid ligands against the opioid receptor family. All ligands were interrogated using dynamic mass redistribution (DMR) assays in both recombinant and native cell lines that express specific opioid receptor(s). The cells were modified with a set of probe molecules to manifest the binding and functional selectivity of ligands. DMR profiles were collected and translated to numerical coordinates that was subject to similarity analysis. A specific set of opioid ligands were then selected for quantitative pharmacology determination. Results Results showed that among fifty-five opioid ligands examined most ligands displayed agonist activity in at least one opioid receptor expressing cell line under different conditions. Further, many ligands exhibited pathway biased agonism. Conclusion We demonstrate that the iPOT effectively sorts the ligands into distinct clusters based on their binding and functional selectivity at the opioid receptor family. PMID:23497702

  15. Crosstalk between cdk5 and MEK-ERK signalling upon opioid receptor stimulation leads to upregulation of activator p25 and MEK1 inhibition in rat brain.

    PubMed

    Ramos-Miguel, A; García-Sevilla, J A

    2012-07-26

    Cyclin-dependent kinase 5 (cdk5) participates in opioid receptor signalling through complex molecular mechanisms. The acute effects of selective μ-(fentanyl) and δ-(SNC-80) opioid receptor agonists, as well as the chronic effects of morphine (the prototypic opiate agonist mainly acting at μ-receptors), modulating cdk5 and activators p35/p25 and their interactions with neurotoxic/apoptotic factors, dopamine- and cAMP-regulated phosphoprotein of 32kDa (DARPP-32) and extracellular signal-regulated kinase (ERK) were quantified (Western Blot analyses) in the rat corpus striatum and/or cerebral cortex. To assess the involved mechanisms, MDL28170 was used to inhibit calpain activity and SL327 to disrupt MEK (ERK kinase)-ERK activation. Acute fentanyl (0.1mg/kg) and SNC-80 (10mg/kg) induced rapid (7-60 min) 2- to 4-fold increases of p25 content, without induction of cdk5/p25 pro-apoptotic c-Jun NH(2)-terminal protein kinase or aberrant cleavage of poly(ADP-ribose)-polymerase-1, a hallmark of apoptosis. In contrast, fentanyl and SNC-80 stimulated cdk5-mediated p-Thr75 DARPP-32 (+116-166%; PKA inhibition) and p-Thr286 MEK1 (+21-82%; MEK inactivation), and this latter effect resulted in uncoupling of MEK to ERK signals. Calpain inhibition with MDL28170 (cleavage of p35 to p25) attenuated fentanyl-induced p25 accumulation (-57%), but not the stimulation of p-Thr286 MEK1 or p-Thr75 DARPP-32. MEK-ERK inhibition with SL327 fully prevented fentanyl-induced p25 upregulation. Notably, chronic morphine treatment (10-100mg/kg for 6 days) also increased p25 content and p25/p35 ratio (and activated/inactivated MEK1) in rat brain cortex, which indicated that p25 upregulation persisted under the sustained stimulation of μ-opioid receptors. The results demonstrate that the acute stimulation of opioid receptors leads to upregulation of p25 activator through a MEK-ERK and calpain-dependent pathway, and to disruption of MEK-ERK signalling by a cdk5/p35-induced MEK1 inhibition. Moreover

  16. Endogenous Human MDM2-C Is Highly Expressed in Human Cancers and Functions as a p53-Independent Growth Activator

    PubMed Central

    Okoro, Danielle R.; Arva, Nicoleta; Gao, Chong; Polotskaia, Alla; Puente, Cindy; Rosso, Melissa; Bargonetti, Jill

    2013-01-01

    Human cancers over-expressing mdm2, through a T to G variation at a single nucleotide polymorphism at position 309 (mdm2 SNP309), have functionally inactivated p53 that is not effectively degraded. They also have high expression of the alternatively spliced transcript, mdm2-C. Alternatively spliced mdm2 transcripts are expressed in many forms of human cancer and when they are exogenously expressed they transform human cells. However no study to date has detected endogenous MDM2 protein isoforms. Studies with exogenous expression of splice variants have been carried out with mdm2-A and mdm2-B, but the mdm2-C isoform has remained virtually unexplored. We addressed the cellular influence of exogenously expressed MDM2-C, and asked if endogenous MDM2-C protein was present in human cancers. To detect endogenous MDM2-C protein, we created a human MDM2-C antibody to the splice junction epitope of exons four and ten (MDM2 C410) and validated the antibody with in vitro translated full length MDM2 compared to MDM2-C. Interestingly, we discovered that MDM2-C co-migrates with MDM2-FL at approximately 98 kDa. Using the validated C410 antibody, we detected high expression of endogenous MDM2-C in human cancer cell lines and human cancer tissues. In the estrogen receptor positive (ER+) mdm2 G/G SNP309 breast cancer cell line, T47D, we observed an increase in endogenous MDM2-C protein with estrogen treatment. MDM2-C localized to the nucleus and the cytoplasm. We examined the biological activity of MDM2-C by exogenously expressing the protein and observed that MDM2-C did not efficiently target p53 for degradation or reduce p53 transcriptional activity. Exogenous expression of MDM2-C in p53-null human cancer cells increased colony formation, indicating p53-independent tumorigenic properties. Our data indicate a role for MDM2-C that does not require the inhibition of p53 for increasing cancer cell proliferation and survival. PMID:24147044

  17. Methanolic Extract of Clinacanthus nutans Exerts Antinociceptive Activity via the Opioid/Nitric Oxide-Mediated, but cGMP-Independent, Pathways.

    PubMed

    Abdul Rahim, Mohammad Hafiz; Zakaria, Zainul Amiruddin; Mohd Sani, Mohd Hijaz; Omar, Maizatul Hasyima; Yakob, Yusnita; Cheema, Manraj Singh; Ching, Siew Mooi; Ahmad, Zuraini; Abdul Kadir, Arifah

    2016-01-01

    The objectives of the present study were to determine the mechanisms of antinociceptive effect of methanol extract of Clinacanthus nutans (Acanthaceae) leaves (MECN) using various animal nociceptive models. The antinociceptive activity of orally administered 10% DMSO, 100 mg/kg acetylsalicylic acid (ASA), 5 mg/kg morphine, or MECN (100, 250, and 500 mg/kg) was determined using the acetic acid-induced abdominal constriction (ACT), formalin-induced paw licking (FT), and hot plate tests (HPT). The role of opioid and nitric oxide/cyclic guanosine monophosphate (NO/cGMP) systems was also investigated. The results showed that MECN produced a significant (p < 0.05) antinociceptive response in all nociceptive models with the recorded ED50 value of 279.3 mg/kg for the ACT, while, for the early and late phases of the FT, the value was >500 mg/kg or 227.7 mg/kg, respectively. This antinociceptive activity was fully antagonized by naloxone (a nonselective opioid antagonist) but was partially reversed by l-arginine (l-arg; a nitric oxide [NO] precursor), Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; an NO synthase inhibitor), or their combinations thereof. In contrast, 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ; a soluble guanylyl cyclase inhibitor) enhanced the extract's antinociception. UHPLC analysis revealed the presence of several flavonoid-based compounds with antinociceptive action. In conclusion, MECN exerted the peripherally and centrally mediated antinociceptive activity via the modulation of the opioid/NO-mediated, but cGMP-independent, systems. PMID:27190528

  18. Methanolic Extract of Clinacanthus nutans Exerts Antinociceptive Activity via the Opioid/Nitric Oxide-Mediated, but cGMP-Independent, Pathways

    PubMed Central

    Abdul Rahim, Mohammad Hafiz; Zakaria, Zainul Amiruddin; Mohd Sani, Mohd Hijaz; Omar, Maizatul Hasyima; Yakob, Yusnita; Cheema, Manraj Singh; Ching, Siew Mooi; Ahmad, Zuraini; Abdul Kadir, Arifah

    2016-01-01

    The objectives of the present study were to determine the mechanisms of antinociceptive effect of methanol extract of Clinacanthus nutans (Acanthaceae) leaves (MECN) using various animal nociceptive models. The antinociceptive activity of orally administered 10% DMSO, 100 mg/kg acetylsalicylic acid (ASA), 5 mg/kg morphine, or MECN (100, 250, and 500 mg/kg) was determined using the acetic acid-induced abdominal constriction (ACT), formalin-induced paw licking (FT), and hot plate tests (HPT). The role of opioid and nitric oxide/cyclic guanosine monophosphate (NO/cGMP) systems was also investigated. The results showed that MECN produced a significant (p < 0.05) antinociceptive response in all nociceptive models with the recorded ED50 value of 279.3 mg/kg for the ACT, while, for the early and late phases of the FT, the value was >500 mg/kg or 227.7 mg/kg, respectively. This antinociceptive activity was fully antagonized by naloxone (a nonselective opioid antagonist) but was partially reversed by l-arginine (l-arg; a nitric oxide [NO] precursor), Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; an NO synthase inhibitor), or their combinations thereof. In contrast, 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ; a soluble guanylyl cyclase inhibitor) enhanced the extract's antinociception. UHPLC analysis revealed the presence of several flavonoid-based compounds with antinociceptive action. In conclusion, MECN exerted the peripherally and centrally mediated antinociceptive activity via the modulation of the opioid/NO-mediated, but cGMP-independent, systems. PMID:27190528

  19. Isoquercitrin inhibits the progression of pancreatic cancer in vivo and in vitro by regulating opioid receptors and the mitogen-activated protein kinase signalling pathway.

    PubMed

    Chen, Quan; Li, Ping; Li, Ping; Xu, Yong; Li, Yang; Tang, Bo

    2015-02-01

    Pancreatic cancer is a common malignant tumour that affects individuals worldwide. In recent years, the incidence and mortality rates of pancreatic cancer have continuously increased. Currently, the primary clinical treatment methods for pancreatic cancer include surgical resection, chemotherapy and radiotherapy. However, these treatment methods rarely produce satisfactory therapeutic outcomes. Extensive research has also proven that the effective components of several traditional Chinese medicines, particularly flavonoids extracted from plants, have significant antitumour effects. Isoquercitrin, which is one of the flavonoids found in Bidens pilosa extracts, has a significant antitumour effect. However, the antitumour effect of isoquercitrin and its mechanism of action remain unclear. The objective of the present study was to investigate the effect of isoquercitrin on the progression of pancreatic cancer and to further understand the biological characteristics of the participation of isoquercitrin in the progression of pancreatic cancer. In vitro, we found that a therapeutic dose of isoquercitrin significantly inhibited proliferation, promoted apoptosis and induced cell cycle arrest within the G1 phase in pancreatic cancer cells. Isoquercitrin activated caspase-3, -8 and -9 and reduced the mitochondrial membrane potential. In addition, isoquercitrin inhibited the expression level of the δ opioid receptor; however, isoquercitrin had no effect on the κ and µ opioid receptors. Furthermore, isoquercitrin inhibited extracellular signal-regulated kinase (ERK) phosphorylation and promoted c-Jun N-terminal kinase (JNK) phosphorylation. In vivo, we found that a therapeutic dose of isoquercitrin significantly inhibited xenograft growth in nude mice. In summary, the present study demonstrated that isoquercitrin inhibits human pancreatic cancer progression in vivo and in vitro and that its molecular mechanism may be closely related to opioid receptors and to the activation

  20. Thrombospondin-1 is a CD47-dependent endogenous inhibitor of hydrogen sulfide signaling in T cell activation

    PubMed Central

    Miller, Thomas W.; Kaur, Sukhbir; Ivins-O’Keefe, Kelly; Roberts, David D.

    2013-01-01

    Thrombospondin-1 is a potent suppressor of T cell activation via its receptor CD47. However, the precise mechanism for this inhibition remains unclear. Because H2S is an endogenous potentiator of T cell activation and is necessary for full T cell activation, we hypothesized that thrombospondin-1 signaling through CD47 inhibits T cell activation by antagonizing H2S signaling. Primary T cells from thrombospondin-1 null mice were more sensitive to H2S-dependent activation assessed by proliferation and induction of interleukin-2 and CD69 mRNAs. Exogenous thrombospondin-1 inhibited H2S responses in wild type and thrombospondin-1 null T cells but enhanced the same responses in CD47 null T cells. Fibronectin, which shares integrin and glycosaminoglycan binding properties with thrombospondin-1 but not CD47 binding, did not inhibit H2S signaling. A CD47-binding peptide derived from thrombospondin-1 inhibited H2S-induced activation, whereas two other functional sequences from thrombospondin-1 enhanced H2S signaling. Therefore, engaging CD47 is necessary and sufficient for thrombospondin-1 to inhibit H2S-dependent T cell activation. H2S stimulated T cell activation by potentiating MEK-dependent ERK phosphorylation, and thrombospondin-1 inhibited this signaling in a CD47-dependent manner. Thrombospondin-1 also limited activation-dependent T cell expression of the H2S biosynthetic enzymes cystathionine β-synthase and cystathionine γ-lyase, thereby limiting the autocrine role of H2S in T cell activation. Thus, thrombospondin-1 signaling through CD47 is the first identified endogenous inhibitor of H2S signaling and constitutes a novel mechanism that negatively regulates T cell activation. PMID:23499828

  1. Exploring the Neuroimmunopharmacology of Opioids: An Integrative Review of Mechanisms of Central Immune Signaling and Their Implications for Opioid Analgesia

    PubMed Central

    Shavit, Yehuda; Grace, Peter M.; Rice, Kenner C.; Maier, Steven F.; Watkins, Linda R.

    2011-01-01

    Vastly stimulated by the discovery of opioid receptors in the early 1970s, preclinical and clinical research was directed at the study of stereoselective neuronal actions of opioids, especially those played in their crucial analgesic role. However, during the past decade, a new appreciation of the non-neuronal actions of opioids has emerged from preclinical research, with specific appreciation for the nonclassic and nonstereoselective sites of action. Opioid activity at Toll-like receptors, newly recognized innate immune pattern recognition receptors, adds substantially to this unfolding story. It is now apparent from molecular and rodent data that these newly identified signaling events significantly modify the pharmacodynamics of opioids by eliciting proinflammatory reactivity from glia, the immunocompetent cells of the central nervous system. These central immune signaling events, including the release of cytokines and chemokines and the associated disruption of glutamate homeostasis, cause elevated neuronal excitability, which subsequently decreases opioid analgesic efficacy and leads to heightened pain states. This review will examine the current preclinical literature of opioid-induced central immune signaling mediated by classic and nonclassic opioid receptors. A unification of the preclinical pharmacology, neuroscience, and immunology of opioids now provides new insights into common mechanisms of chronic pain, naive tolerance, analgesic tolerance, opioid-induced hyperalgesia, and allodynia. Novel pharmacological targets for future drug development are discussed in the hope that disease-modifying chronic pain treatments arising from the appreciation of opioid-induced central immune signaling may become practical. PMID:21752874

  2. Hypoxemia and hypercapnia in conscious dogs: opioid modulation of catecholamines.

    PubMed

    Rose, C E; Latham, L B; Brashers, V L; Rose, K Y; Sandridge, M P; Carey, R M; Althaus, J S; Miller, E D

    1988-01-01

    The role of endogenous opioids in systemic and renal circulatory changes during combined acute hypoxemia and hypercapnic acidosis was evaluated in seven conscious female mongrel dogs in rigid sodium balance. Animals were studied 2 wk apart in separate protocols of combined acute hypoxemia (arterial O2 tension = 33 +/- 1 mmHg) and hypercapnic acidosis (arterial CO2 tension = 56 +/- 1 mmHg, pH = 7.19 +/- 0.01) of 40 min duration during 1) naloxone, 5 mg/kg iv bolus followed by an intravenous infusion of 5 mg.kg-1.h-1, and 2) vehicle (5% dextrose in water) alone. Systemic circulatory changes during the combined acute blood-gas derangement including increased mean arterial pressure, heart rate, and cardiac output and decreased total peripheral resistance were comparable between naloxone and vehicle treatments. However, in striking contrast to the brief fall in renal hemodynamic function during combined acute hypoxemia and hypercapnic acidosis with vehicle, naloxone administration during the combined acute blood-gas derangement resulted in a sustained decrease in effective renal plasma flow, glomerular filtration rate, and filtered sodium load and enhanced rise in circulating norepinephrine and epinephrine. Changes in plasma renin activity were comparable between vehicle and naloxone protocols except that plasma renin activity increased from the first to the second 20-min periods of combined hypoxemia and hypercapnic acidosis with naloxone. These observations suggest that endogenous opioids may contribute to preservation of renal hemodynamic function during acute blood-gas derangements, possibly through attenuation of sympathetic nervous system and renin-angiotension activation. PMID:3276221

  3. Buprenorphine for opioid dependence.

    PubMed

    Ling, Walter

    2009-05-01

    As a treatment agent for opioid dependence, buprenorphine is a nearly ideal medication at our current stage of medication development. Unlike methadone, buprenorphine dosage can be rapidly adjusted with minimal potential for inducing severe consequences. In addition to its intrinsic safety, buprenorphine's relatively low abuse liability in the combination product (i.e., with naloxone as Suboxone) makes it even more acceptable in regulatory quarters as well as to prescribing physicians. The approval of buprenorphine as a pharmacotherapy for opioid dependence returns to physicians the ability to treat their opioid-dependent patients with an effective opioid-based treatment for the first time in nearly 100 years. Buprenorphine is an opioid, however, and potential for misuse remains, even in combination with naloxone. Whether buprenorphine will be increasingly accepted as a treatment for opioid-dependent patients depends on clinicians recognizing the advantages of its uniquely useful properties while still heeding the need to manage their patients' therapy with reasonable vigilance. PMID:19402772

  4. Opioids and endocrine dysfunction

    PubMed Central

    Hester, Joan

    2012-01-01

    The endocrine effects of opioids used for the management of persistent pain are poorly understood by clinicians and patients, and hormone levels are rarely measured. It is recognized that opioids exert this effect via the hypothalamic-pituitary-gonadal axis. Additional effects on adrenal hormones, weight, blood pressure and bone density may also occur. Symptoms and signs of sex hormone deficiency occur in both men and women but are under-reported and are often clinically unrecognized. The potential effects of long term opioid therapy on the endocrine system should be explained to patients before opioid therapy is commenced. Monitoring of sex hormones is recommended; if there are deficiencies opioids should be tapered and withdrawn, if this is clinically acceptable. If opioid therapy has to continue, hormone replacement therapy should be initiated and monitored by an endocrinologist. PMID:26516462

  5. Attenuated vasodilatation in lambs with endogenous and exogenous activation of cGMP signaling: Role of protein kinase G nitration

    PubMed Central

    Aggarwal, Saurabh; Gross, Christine M.; Kumar, Sanjiv; Datar, Sanjeev; Oishi, Peter; Kalka, Gokhan; Schreiber, Christian; Fratz, Sohrab; Fineman, Jeffrey R.; Black, Stephen M.

    2012-01-01

    Pulmonary vasodilation is mediated through the activation of protein kinase G (PKG) via a signaling pathway involving nitric oxide (NO), natriuretic peptides (NP), and cyclic guanosine monophosphate (cGMP). In pulmonary hypertension secondary to congenital heart disease, this pathway is endogenously activated by an early vascular upregulation of NO and increased myocardial B-type NP expression and release. In the treatment of pulmonary hypertension, this pathway is exogenously activated using inhaled NO or other pharmacological agents. Despite this activation of cGMP, vascular dysfunction is present, suggesting that NO-cGMP independent mechanisms are involved and were the focus of this study. Exposure of pulmonary artery endothelial or smooth muscle cells to the NO donor, Spermine NONOate (SpNONOate), increased peroxynitrite (ONOO−) generation and PKG-1α nitration, while PKG-1α activity was decreased. These changes were prevented by superoxide dismutase (SOD) or manganese(III)tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP) and mimicked by the ONOO− donor, 3-morpholinosydnonimine N-ethylcarbamide (SIN-1). Peripheral lung extracts from 4-week old lambs with increased pulmonary blood flow and pulmonary hypertension (Shunt lambs with endogenous activation of cGMP) or juvenile lambs treated with inhaled NO for 24h (with exogenous activation of cGMP) revealed increased ONOO− levels, elevated PKG-1α nitration, and decreased kinase activity without changes in PKG-1α protein levels. However, in Shunt lambs treated with L-arginine or lambs administered polyethylene glycol conjugated-SOD (PEG-SOD) during inhaled NO exposure, ONOO− and PKG-1α nitration were diminished and kinase activity was preserved. Together our data reveal that vascular dysfunction can occur, despite elevated levels of cGMP, due to PKG-1α nitration and subsequent attenuation of activity. PMID:21351102

  6. Stress and opioids: role of opioids in modulating stress-related behavior and effect of stress on morphine conditioned place preference.

    PubMed

    Bali, Anjana; Randhawa, Puneet Kaur; Jaggi, Amteshwar Singh

    2015-04-01

    Research studies have defined the important role of endogenous opioids in modulating stress-associated behavior. The release of β-endorphins in the amygdala in response to stress helps to cope with a stressor by inhibiting the over-activation of HPA axis. Administration of mu opioid agonists reduces the risk of developing post-traumatic stress disorder (PTSD) following a traumatic event by inhibiting fear-related memory consolidation. Similarly, the release of endogenous enkephalin and nociceptin in the basolateral amygdala and the nucleus accumbens tends to produce the anti-stress effects. An increase in dynorphin levels during prolonged exposure to stress may produce learned helplessness, dysphoria and depression. Stress also influences morphine-induced conditioned place preference (CPP) depending upon the intensity and duration of the stressor. Acute stress inhibits morphine CPP, while chronic stress potentiates CPP. The development of dysphoria due to increased dynorphin levels may contribute to chronic stress-induced potentiation of morphine CPP. The activation of ERK/cyclic AMP responsive element-binding (CREB) signaling in the mesocorticolimbic area, glucocorticoid receptors in the basolateral amygdala, and norepinephrine and galanin system in the nucleus accumbens may decrease the acute stress-induced inhibition of morphine CPP. The increase in dopamine levels in the nucleus accumbens and augmentation of GABAergic transmission in the median prefrontal cortex may contribute in potentiating morphine CPP. Stress exposure reinstates the extinct morphine CPP by activating the orexin receptors in the nucleus accumbens, decreasing the oxytocin levels in the lateral septum and amygdala, and altering the GABAergic transmission (activation of GABAA and inactivation of GABAB receptors). The present review describes these varied interactions between opioids and stress along with the possible mechanism. PMID:25636946

  7. The mechanism of μ-opioid receptor (MOR)-TRPV1 crosstalk in TRPV1 activation involves morphine anti-nociception, tolerance and dependence.

    PubMed

    Bao, Yanju; Gao, Yebo; Yang, Liping; Kong, Xiangying; Yu, Jing; Hou, Wei; Hua, Baojin

    2015-01-01

    Initiated by the activation of various nociceptors, pain is a reaction to specific stimulus modalities. The μ-opioid receptor (MOR) agonists, including morphine, remain the most potent analgesics to treat patients with moderate to severe pain. However, the utility of MOR agonists is limited by the adverse effects associated with the use of these drugs, including analgesic tolerance and physical dependence. A strong connection has been suggested between the expression of the transient receptor potential vanilloid type 1 (TRPV1) ion channel and the development of inflammatory hyperalgesia. TRPV1 is important for thermal nociception induction, and is mainly expressed on sensory neurons. Recent reports suggest that opioid or TRPV1 receptor agonist exposure has contrasting consequences for anti-nociception, tolerance and dependence. Chronic morphine exposure modulates TRPV1 activation and induces the anti-nociception effects of morphine. The regulation of many downstream targets of TRPV1 plays a critical role in this process, including calcitonin gene-related peptide (CGRP) and substance P (SP). Additional factors also include capsaicin treatment blocking the anti-nociception effects of morphine in rats, as well as opioid modulation of TRPV1 responses through the cAMP-dependent PKA pathway and MAPK signaling pathways. Here, we review new insights concerning the mechanism underlying MOR-TRPV1 crosstalk and signaling pathways and discuss the potential mechanisms of morphine-induced anti-nociception, tolerance and dependence associated with the TRPV1 signaling pathway and highlight how understanding these mechanisms might help find therapeutic targets for the treatment of morphine induced antinociception, tolerance and dependence. PMID:26176938

  8. Mu-opioid receptor activation prevents apoptosis following serum withdrawal in differentiated SH-SY5Y cells and cortical neurons via phosphatidylinositol 3-kinase.

    PubMed

    Iglesias, M; Segura, M F; Comella, J X; Olmos, G

    2003-03-01

    Opioid peptides and alkaloids exert their effects via G protein-coupled receptors (GPCRs). It has been shown that, in addition to trophic factors, some GPCRs are able to activate the phosphatidylinositol 3-kinase/Akt (PI 3-K/Akt) signal transduction pathway, thus leading to cell survival. The aim of this study was to test whether activation of mu-opioid receptors has protective effects on serum withdrawal-induced cell death and to study the possible implication of PI 3-K in this process. In SH-SY5Y neuroblastoma cells fully differentiated by exposure to retinoic acid for five days, the enkephalin derivative selective mu-agonist DAMGO (0.1-2 microM) and the alkaloid morphine (0.1-10 microM) promoted cell survival after serum deprivation (MTT and trypan blue exclusion assays), without inducing cell proliferation. These effects were fully reversed by naloxone, by the selective mu-antagonist beta-funaltrexamine (beta-FNA) and also by the specific PI 3-K inhibitor LY294002. The two agonists stimulated Akt phosphorylation and the effect was also abolished by beta-FNA and by LY294002. In mouse primary cortical neurons, DAMGO reduced the percentage of apoptosis after 6, 12, 24 and 48 h of serum withdrawal; as determined by Hoechst staining. This effect was blocked by beta-FNA, by pre-treatment with pertussis toxin and by LY294002. DAMGO also stimulated Akt phosphorylation via PI 3-K in this primary neuronal culture. Together, these results indicate that stimulation of the mu-opioid receptor promotes neuronal survival in a G(i/o)-linked, PI 3-K-dependent signaling cascade and suggest that Akt may be a key downstream kinase involved in this anti-apoptotic effect. PMID:12646285

  9. Naloxegol: First oral peripherally acting mu opioid receptor antagonists for opioid-induced constipation

    PubMed Central

    Anantharamu, Tejus; Sharma, Sushil; Gupta, Ajay Kumar; Dahiya, Navdeep; Singh Brashier, Dick B.; Sharma, Ashok Kumar

    2015-01-01

    Opioid-induced constipation (OIC) is one of the most troublesome and the most common effects of opioid use leading to deterioration in quality of life of the patients and also has potentially deleterious repercussions on adherence and compliance to opioid therapy. With the current guidelines advocating liberal use of opioids by physicians even for non-cancer chronic pain, the situation is further complicated as these individuals are not undergoing palliative care and hence there cannot be any justification to subject these patients to the severe constipation brought on by opioid therapy which is no less debilitating than the chronic pain. The aim in these patients is to prevent the opioid-induced constipation but at the same time allow the analgesic activity of opioids. Many drugs have been used with limited success but the most specific among them were the peripherally acting mu opioid receptor antagonists (PAMORA). Methylnaltrexone and alvimopan were the early drugs in this group but were not approved for oral use in OIC. However naloxegol, the latest PAMORA has been very recently approved as the first oral drug for OIC. This article gives an overview of OIC, its current management and more specifically the development and approval of naloxegol, including pharmacokinetics, details of various clinical trials, adverse effects and its current status for the management of OIC. PMID:26312011

  10. [Pain and opioids].

    PubMed

    Murányi, Marianna; Radák, Zsolt

    2008-12-14

    Noxious stimuli cause pain to protect the body from harmful situations and attract attention to pathophysiologic changes of the body. Specific receptors of pain (nociceptors) can be found all over our body. Pain initiates protecting mechanisms such as vegetative and motor reflexes, and emotional, behavioral changes. However, chronic pain is practically useless and leads to psychopathological changes. There are several ways to relieve pain including non-steroid anti-inflammatory agents, opioids, neurosurgical and non-invasive methods. Central and peripheral effects of opioids can be realized through opioid receptors of the central and the enteric nervous system. In the central nervous system, they can inhibit the perception of pain or change the emotional reactions. Opioids are indicated in postoperative pain, neuropathic pain and cancer. However, the use of opioids has severe side-effects such as breathing depression and the development of tolerance and dependence which do not make opioids optimal painkillers. There are several laboratories in Hungary and abroad working on the design of optimal pain relievers. Furthermore, the euphoric effects of opioids lead to abuse which makes the research important on the mechanisms of opioid addiction. Taken together, opioid research, the design of new compounds and the exploration of the mechanisms of opiate addiction are very important. PMID:19073443

  11. Response of the μ-opioid system to social rejection and acceptance.

    PubMed

    Hsu, D T; Sanford, B J; Meyers, K K; Love, T M; Hazlett, K E; Wang, H; Ni, L; Walker, S J; Mickey, B J; Korycinski, S T; Koeppe, R A; Crocker, J K; Langenecker, S A; Zubieta, J-K

    2013-11-01

    The endogenous opioid system, which alleviates physical pain, is also known to regulate social distress and reward in animal models. To test this hypothesis in humans (n=18), we used an μ-opioid receptor (MOR) radiotracer to measure changes in MOR availability in vivo with positron emission tomography during social rejection (not being liked by others) and acceptance (being liked by others). Social rejection significantly activated the MOR system (i.e., reduced receptor availability relative to baseline) in the ventral striatum, amygdala, midline thalamus and periaqueductal gray (PAG). This pattern of activation is consistent with the hypothesis that the endogenous opioids have a role in reducing the experience of social pain. Greater trait resiliency was positively correlated with MOR activation during rejection in the amygdala, PAG and subgenual anterior cingulate cortex (sgACC), suggesting that MOR activation in these areas is protective or adaptive. In addition, MOR activation in the pregenual ACC was correlated with reduced negative affect during rejection. In contrast, social acceptance resulted in MOR activation in the amygdala and anterior insula, and MOR deactivation in the midline thalamus and sgACC. In the left ventral striatum, MOR activation during acceptance predicted a greater desire for social interaction, suggesting a role for the MOR system in social reward. The ventral striatum, amygdala, midline thalamus, PAG, anterior insula and ACC are rich in MORs and comprise a pathway by which social cues may influence mood and motivation. MOR regulation of this pathway may preserve and promote emotional well being in the social environment. PMID:23958960

  12. Activation of Endogenous Anti-Inflammatory Mediator Cyclic AMP Attenuates Acute Pyelonephritis in Mice Induced by Uropathogenic Escherichia coli

    PubMed Central

    Wei, Yang; Li, Ke; Wang, Na; Cai, Gui-Dong; Zhang, Ting; Lin, Yan; Gui, Bao-Song; Liu, En-Qi; Li, Zong-Fang; Zhou, Wuding

    2015-01-01

    The pathogenesis of pyelonephritis caused by uropathogenic Escherichia coli (UPEC) is not well understood. Here, we show that besides UPEC virulence, the severity of the host innate immune response and invasion of renal epithelial cells are important pathogenic factors. Activation of endogenous anti-inflammatory mediator cAMP significantly attenuated acute pyelonephritis in mice induced by UPEC. Administration of forskolin (a potent elevator of intracellular cAMP) reduced kidney infection (ie, bacterial load, tissue destruction); this was associated with attenuated local inflammation, as evidenced by the reduction of renal production of proinflammatory mediators, renal infiltration of inflammatory cells, and renal myeloperoxidase activity. In primary cell culture systems, forskolin not only down-regulated UPEC-stimulated production of proinflammatory mediators by renal tubular epithelial cells and inflammatory cells (eg, monocyte/macrophages) but also reduced bacterial internalization by renal tubular epithelial cells. Our findings clearly indicate that activation of endogenous anti-inflammatory mediator cAMP is beneficial for controlling UPEC-mediated acute pyelonephritis in mice. The beneficial effect can be explained at least in part by limiting excessive inflammatory responses through acting on both renal tubular epithelial cells and inflammatory cells and by inhibiting bacteria invasion of renal tubular epithelial cells. PMID:25478807

  13. Activation of endogenous anti-inflammatory mediator cyclic AMP attenuates acute pyelonephritis in mice induced by uropathogenic Escherichia coli.

    PubMed

    Wei, Yang; Li, Ke; Wang, Na; Cai, Gui-Dong; Zhang, Ting; Lin, Yan; Gui, Bao-Song; Liu, En-Qi; Li, Zong-Fang; Zhou, Wuding

    2015-02-01

    The pathogenesis of pyelonephritis caused by uropathogenic Escherichia coli (UPEC) is not well understood. Here, we show that besides UPEC virulence, the severity of the host innate immune response and invasion of renal epithelial cells are important pathogenic factors. Activation of endogenous anti-inflammatory mediator cAMP significantly attenuated acute pyelonephritis in mice induced by UPEC. Administration of forskolin (a potent elevator of intracellular cAMP) reduced kidney infection (ie, bacterial load, tissue destruction); this was associated with attenuated local inflammation, as evidenced by the reduction of renal production of proinflammatory mediators, renal infiltration of inflammatory cells, and renal myeloperoxidase activity. In primary cell culture systems, forskolin not only down-regulated UPEC-stimulated production of proinflammatory mediators by renal tubular epithelial cells and inflammatory cells (eg, monocyte/macrophages) but also reduced bacterial internalization by renal tubular epithelial cells. Our findings clearly indicate that activation of endogenous anti-inflammatory mediator cAMP is beneficial for controlling UPEC-mediated acute pyelonephritis in mice. The beneficial effect can be explained at least in part by limiting excessive inflammatory responses through acting on both renal tubular epithelial cells and inflammatory cells and by inhibiting bacteria invasion of renal tubular epithelial cells. PMID:25478807

  14. Contribution of Endogenously Produced Reactive Oxygen Species to the Activation of Podocyte NLRP3 Inflammasomes in Hyperhomocysteinemia

    PubMed Central

    Abais, Justine M.; Xia, Min; Li, Guangbi; Gehr, Todd W. B.; Boini, Krishna M.; Li, Pin-Lan

    2013-01-01

    Hyperhomocysteinemia (hHcys) is an important pathogenic factor contributing to the progression of end-stage renal disease. Recent studies have demonstrated the implication of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-mediated NLRP3 inflammasome activation in the development of podocyte injury and glomerular sclerosis during hHcys. However, it remains unknown which reactive oxygen species (ROS) are responsible for this activation of NLRP3 inflammasomes and how such action of ROS is controlled. The present study tested the contribution of common endogenous ROS including superoxide (O2•−), hydrogen peroxide (H2O2), and hydroxyl radical (•OH) to the activation of NLRP3 inflammasomes in mouse podocytes and glomeruli. In vitro, confocal microscopy and size exclusion chromatography demonstrated that dismutation of O2•− by 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL) and decomposition of H2O2 by catalase prevented Hcys-induced aggregation of NLRP3 inflammasome proteins and inhibited Hcys-induced caspase-1 activation and IL-1β production in mouse podocytes. However, •OH scavenger tetramethylthiourea (TMTU) had no significant effect on either Hcys-induced NLRP3 inflammasome formation or activation. In vivo, scavenging of O2•− by TEMPOL and removal of H2O2 by catalase substantially inhibited NLRP3 inflammasome formation and activation in glomeruli of hHcys mice as shown by reduced colocalization of NLRP3 with ASC or caspase-1 and inhibition of caspase-1 activation and IL-1β production. Furthermore, TEMPOL and catalase significantly attenuated hHcys-induced glomerular injury. In conclusion, endogenously produced O2•− and H2O2 primarily contribute to NLRP3 inflammasome formation and activation in mouse glomeruli resulting in glomerular injury or consequent sclerosis during hHcys. PMID:24140862

  15. Comparison of [Dmt1]DALDA and DAMGO in binding and G protein activation at mu, delta, and kappa opioid receptors.

    PubMed

    Zhao, Guo-Min; Qian, Xuanxuan; Schiller, Peter W; Szeto, Hazel H

    2003-12-01

    [Dmt1]DALDA (H-Dmt-d-Arg-Phe-Lys-NH2; Dmt = 2',6'-dimethyltyrosine) binds with high affinity and selectivity to the mu opioid receptor and is a surprisingly potent and long-acting analgesic, especially after intrathecal administration. In an attempt to better understand the unique pharmacological profile of [Dmt1]DALDA, we have prepared [3H][Dmt1]DALDA and compared its binding properties with that of [3H]DAMGO ([d-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin). Kinetic studies revealed rapid association of [3H][Dmt1]DALDA when incubated with mouse brain membranes (K+1 = 0.155 nM(-1) min(-1)). Dissociation of [3H][Dmt1]DALDA was also rapid (K(-1) = 0.032 min(-1)) and indicated binding to a single site. [3H][Dmt1]DALDA binds with very high affinity to human mu opioid receptor (hMOR) (Kd = 0.199 nM), and Kd and Bmax were reduced by sodium but not Gpp(NH)p [guanosine 5'-(beta,gamma-imido)triphosphate]. Similar Kd values were obtained in brain and spinal cord tissues and SH-SY5Y cells. The hMOR:hDOR (human delta opioid receptor) selectivity of [Dmt1]DALDA ( approximately 10,000) is 8-fold higher than DAMGO. However, [Dmt1]DALDA is less selective than DAMGO against hKOR (human kappa opioid receptor) (26-versus 180-fold). The Ki values for a number of opioid ligands were generally higher when determined by competitive displacement binding against [3H][Dmt1]DALDA compared with [3H]DAMGO, with the exception of Dmt1-substituted peptide analogs. All Dmt1 analogs showed much higher affinity for the mu receptor than corresponding Tyr1 analogs. [35S]GTPgammaS (guanosine 5'-O -(3-[35S]thio)triphosphate) binding showed that [Dmt1]DALDA and DAMGO are full agonists at hMOR and hDOR but are only partial agonists at hKOR. The very high affinity and selectivity of [3H][Dmt1]DALDA for the mu receptor, together with its very low nonspecific binding (10-15%) and metabolic stability, make [3H][Dmt1]DALDA an ideal radioligand for labeling mu receptors. PMID:14534366

  16. Irradiation exposure modulates central opioid functions

    SciTech Connect

    Dougherty, P.M.; Dafny, N.

    1987-11-01

    Exposure to low doses of gamma irradiation results in the modification of both the antinociceptive properties of morphine and the severity of naloxone-precipitated withdrawal in morphine-dependent rats. To better define the interactions between gamma irradiation and these opiate-mediated phenomena, dose-response studies were undertaken of the effect of irradiation on morphine-induced antinociception, and on the naloxone-precipitated withdrawal syndrome of morphine-dependent rats. In addition, electrophysiologic studies were conducted in rats after irradiation exposure and morphine treatment correlating with the behavioral studies. The observations obtained demonstrated that the antinociceptive effects of morphine as well as naloxone-precipitated withdrawal were modified in a dose-dependent manner by irradiation exposure. In addition, irradiation-induced changes in the evoked responses obtained from four different brain regions demonstrated transient alterations in both baseline and morphine-treated responses that may reflect the alterations observed in the behavioral paradigms. These results suggest that the effects of irradiation on opiate activities resulted from physiologic alterations of central endogenous opioid systems due to alterations manifested within peripheral targets.

  17. Changing Paradigms in Cranio-Facial Regeneration: Current and New Strategies for the Activation of Endogenous Stem Cells.

    PubMed

    Mele, Luigi; Vitiello, Pietro Paolo; Tirino, Virginia; Paino, Francesca; De Rosa, Alfredo; Liccardo, Davide; Papaccio, Gianpaolo; Desiderio, Vincenzo

    2016-01-01

    Craniofacial area represent a unique district of human body characterized by a very high complexity of tissues, innervation and vascularization, and being deputed to many fundamental function such as eating, speech, expression of emotions, delivery of sensations such as taste, sight, and earing. For this reasons, tissue loss in this area following trauma or for example oncologic resection, have a tremendous impact on patients' quality of life. In the last 20 years regenerative medicine has emerged as one of the most promising approach to solve problem related to trauma, tissue loss, organ failure etc. One of the most powerful tools to be used for tissue regeneration is represented by stem cells, which have been successfully implanted in different tissue/organs with exciting results. Nevertheless, both autologous and allogeneic stem cell transplantation raise many practical and ethical concerns that make this approach very difficult to apply in clinical practice. For this reason different cell free approaches have been developed aiming to the mobilization, recruitment, and activation of endogenous stem cells into the injury site avoiding exogenous cells implant but instead stimulating patients' own stem cells to repair the lesion. To this aim many strategies have been used including functionalized bioscaffold, controlled release of stem cell chemoattractants, growth factors, BMPs, Platelet-Rich-Plasma, and other new strategies such as ultrasound wave and laser are just being proposed. Here we review all the current and new strategies used for activation and mobilization of endogenous stem cells in the regeneration of craniofacial tissue. PMID:26941656

  18. Fibrinogen, an endogenous ligand of Toll-like receptor 4, activates monocytes in pre-eclamptic patients.

    PubMed

    Al-ofi, Ebtisam; Coffelt, Seth B; Anumba, Dilly O

    2014-06-01

    Pre-eclampsia (PE) remains the leading cause of pregnancy-associated mortality and morbidity, urging the need for a better understanding of its aetiology and pathophysiological progression. A key characteristic of PE is a systemic, exaggerated, inflammatory condition involving abnormal cytokine levels in serum, altered immune cell phenotype and Th1/Th2-type immunological imbalance. However, it is unknown how this heightened inflammatory condition manifests. We previously reported increased expression of the lipopolysaccharide receptor, Toll-like receptor 4 (TLR4), on monocytes from PE patients compared with normotensive, pregnant patients (NP). This upregulation of TLR4 on PE monocytes was accompanied by a hyper-responsiveness to bacterial TLR4 ligands. To determine whether non-microbial, endogenous TLR4 ligands also activate monocytes from PE patients, we investigated the expression of host-derived TLR4 ligands and the response of monocytes to these endogenous ligands. Plasma levels of fibrinogen - but not fibronectin or heparan sulphate - were higher in PE patients than in NP. Exposure to fibrinogen was associated with significantly increased production of inflammatory cytokines by monocytes from PE patients. Interestingly, this effect was not observed with NP monocytes. Our findings suggest that the fibrinogen-TLR4 axis might play an important role in the atypical activation of monocytes observed in PE patients that may contribute to the exaggerated inflammatory condition. PMID:24661950

  19. The activation of human endogenous retrovirus K (HERV-K) is implicated in melanoma cell malignant transformation

    SciTech Connect

    Serafino, A. Balestrieri, E.; Pierimarchi, P.; Matteucci, C.; Moroni, G.; Oricchio, E.; Rasi, G.; Mastino, A.; Spadafora, C.; Garaci, E.; Vallebona, P. Sinibaldi

    2009-03-10

    Melanoma development is a multi-step process arising from a series of genetic and epigenetic events. Although the sequential stages involved in progression from melanocytes to malignant melanoma are clearly defined, our current understanding of the mechanisms leading to melanoma onset is still incomplete. Growing evidence show that the activation of endogenous retroviral sequences might be involved in transformation of melanocytes as well as in the increased ability of melanoma cells to escape immune surveillance. Here we show that human melanoma cells in vitro undergo a transition from adherent to a more malignant, non-adherent phenotype when exposed to stress conditions. Melanoma-derived non-adherent cells are characterized by an increased proliferative potential and a decreased expression of both HLA class I molecules and Melan-A/MART-1 antigen, similarly to highly malignant cells. These phenotypic and functional modifications are accompanied by the activation of human endogenous retrovirus K expression (HERV-K) and massive production of viral-like particles. Down-regulation of HERV-K expression by RNA interference prevents the transition from the adherent to the non-adherent growth phenotype in low serum. These results implicate HERV-K in at least some critical steps of melanoma progression.

  20. Changing Paradigms in Cranio-Facial Regeneration: Current and New Strategies for the Activation of Endogenous Stem Cells

    PubMed Central

    Mele, Luigi; Vitiello, Pietro Paolo; Tirino, Virginia; Paino, Francesca; De Rosa, Alfredo; Liccardo, Davide; Papaccio, Gianpaolo; Desiderio, Vincenzo

    2016-01-01

    Craniofacial area represent a unique district of human body characterized by a very high complexity of tissues, innervation and vascularization, and being deputed to many fundamental function such as eating, speech, expression of emotions, delivery of sensations such as taste, sight, and earing. For this reasons, tissue loss in this area following trauma or for example oncologic resection, have a tremendous impact on patients' quality of life. In the last 20 years regenerative medicine has emerged as one of the most promising approach to solve problem related to trauma, tissue loss, organ failure etc. One of the most powerful tools to be used for tissue regeneration is represented by stem cells, which have been successfully implanted in different tissue/organs with exciting results. Nevertheless, both autologous and allogeneic stem cell transplantation raise many practical and ethical concerns that make this approach very difficult to apply in clinical practice. For this reason different cell free approaches have been developed aiming to the mobilization, recruitment, and activation of endogenous stem cells into the injury site avoiding exogenous cells implant but instead stimulating patients' own stem cells to repair the lesion. To this aim many strategies have been used including functionalized bioscaffold, controlled release of stem cell chemoattractants, growth factors, BMPs, Platelet–Rich-Plasma, and other new strategies such as ultrasound wave and laser are just being proposed. Here we review all the current and new strategies used for activation and mobilization of endogenous stem cells in the regeneration of craniofacial tissue. PMID:26941656

  1. An early granulocyte colony-stimulating factor treatment attenuates neuropathic pain through activation of mu opioid receptors on the injured nerve

    PubMed Central

    Liao, Ming-Feng; Yeh, Shin-Rung; Lo, Ai-Lun; Chao, Po-Kuan; Lee, Yun-Lin; Hung, Yu-Hui; Lu, Kwok-Tung; Ro, Long-Sun

    2016-01-01

    Several studies have shown that the mu opioid receptor (MOR) located in the peripheral nerves can be activated after nerve injury and that it attenuates peripheral nociceptive signals to the spinal dorsal horn. Various cytokines and phosphorylated-p38 (p-p38) activation in the dorsal horn also play an important role in neuropathic pain development. Granulocyte-colony stimulating factor (GCSF) is a growth factor that can stimulate granulocyte formation and has been shown to exert an analgesic effect on neuropathic pain through recruiting opioid-containing leukocytes to the injured nerve. However, the underlying mechanisms are not well understood. Herein, the results of behavior tests in addition to MOR levels in the injured sciatic nerve and the levels of p-p38 and various cytokines in the spinal dorsal horn were studied in vehicle-treated or GCSF-treated chronic constriction injured (CCI) rats at different time points (i.e., 1, 3, and 7 days, respectively) after nerve injury. The results showed that a single early systemic GCSF treatment after nerve injury can up-regulate MORs in the injured nerve, which can decrease peripheral nociceptive signals. Thereafter, those changes suppress the pro-inflammatory cytokine IL-6 but enhance the anti-inflammatory cytokine IL-4, followed by decreases in p-p38 in the dorsal horn, and thus further attenuate neuropathic pain. PMID:27180600

  2. An early granulocyte colony-stimulating factor treatment attenuates neuropathic pain through activation of mu opioid receptors on the injured nerve.

    PubMed

    Liao, Ming-Feng; Yeh, Shin-Rung; Lo, Ai-Lun; Chao, Po-Kuan; Lee, Yun-Lin; Hung, Yu-Hui; Lu, Kwok-Tung; Ro, Long-Sun

    2016-01-01

    Several studies have shown that the mu opioid receptor (MOR) located in the peripheral nerves can be activated after nerve injury and that it attenuates peripheral nociceptive signals to the spinal dorsal horn. Various cytokines and phosphorylated-p38 (p-p38) activation in the dorsal horn also play an important role in neuropathic pain development. Granulocyte-colony stimulating factor (GCSF) is a growth factor that can stimulate granulocyte formation and has been shown to exert an analgesic effect on neuropathic pain through recruiting opioid-containing leukocytes to the injured nerve. However, the underlying mechanisms are not well understood. Herein, the results of behavior tests in addition to MOR levels in the injured sciatic nerve and the levels of p-p38 and various cytokines in the spinal dorsal horn were studied in vehicle-treated or GCSF-treated chronic constriction injured (CCI) rats at different time points (i.e., 1, 3, and 7 days, respectively) after nerve injury. The results showed that a single early systemic GCSF treatment after nerve injury can up-regulate MORs in the injured nerve, which can decrease peripheral nociceptive signals. Thereafter, those changes suppress the pro-inflammatory cytokine IL-6 but enhance the anti-inflammatory cytokine IL-4, followed by decreases in p-p38 in the dorsal horn, and thus further attenuate neuropathic pain. PMID:27180600

  3. Endogenous Cytosolic Ca2+ Buffering is Necessary for TRPM4 Activity in Cerebral Artery Smooth Muscle Cells

    PubMed Central

    Gonzales, Albert L.; Earley, Scott

    2011-01-01

    The melastatin transient receptor potential (TRP) channel, TRPM4, is a critical regulator of smooth muscle membrane potential and arterial tone. Activation of the channel is Ca2+-dependent, but prolonged exposures to high global Ca2+ causes rapid inactivation under conventional whole-cell patch clamp conditions. Using amphotericin B perforated whole cell patch clamp electrophysiology, which minimally disrupts cytosolic Ca2+ dynamics, we recently showed that Ca2+ released from inositol trisphosphate receptors (IP3R) on the sarcoplasmic reticulum (SR) activates TRPM4 channels, producing sustained Transient Inward Cation Currents (TICCs). Thus, Ca2+-dependent inactivation of TRPM4 may not be inherent to the channel itself but rather is a result of the recording conditions. We hypothesized that under conventional whole-cell configurations, loss of intrinsic cytosolic Ca2+ buffering following cell dialysis contributes to inactivation of TRPM4 channels. With the inclusion of the Ca2+ buffers ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA, 10 mM) or bis-ethane-N,N,N′,N′-tetraacetic acid (BAPTA, 0.1 mM) in the pipette solution, we mimic endogenous Ca2+ buffering and record novel, sustained whole-cell TICC activity from freshly-isolated cerebral artery myocytes. Biophysical properties of TICCs recorded under perforated and whole-cell patch clamp were nearly identical. Furthermore, whole-cell TICC activity was reduced by the selective TRPM4 inhibitor, 9-phenanthrol, and by siRNA-mediated knockdown of TRPM4. When a higher concentration (10 mM) of BAPTA was included in the pipette solution, TICC activity was disrupted, suggesting that TRPM4 channels on the plasma membrane and IP3R on the SR are closely opposed but not physically coupled, and that endogenous Ca2+ buffer proteins play a critical role in maintaining TRPM4 channel activity in native cerebral artery smooth muscle cells. PMID:22153976

  4. Guideline for Prescribing Opioids for Chronic Pain.

    PubMed

    Centers For Disease Control And Prevention Public Health Service U S Department Of Health And Human Services

    2016-06-01

    Improving the way opioids are prescribed through clinical practice guidelines can ensure patients have access to safer, more effective chronic pain treatment while reducing the number of people who misuse, abuse, or overdose from these drugs. The Centers for Disease Control and Prevention (CDC) developed and published the Guideline for Prescribing Opioids for Chronic Pain to provide recommendations for the prescribing of opioid pain medication for patients 18 and older in primary care settings. Recommendations focus on the use of opioids in treating chronic pain (pain lasting longer than 3 months or past the time of normal tissue healing) outside of active cancer treatment, palliative care, and end-of-life care. PMID:27301691

  5. Orally active opioid μ/δ dual agonist MGM-16, a derivative of the indole alkaloid mitragynine, exhibits potent antiallodynic effect on neuropathic pain in mice.

    PubMed

    Matsumoto, Kenjiro; Narita, Minoru; Muramatsu, Naotaka; Nakayama, Terumi; Misawa, Kaori; Kitajima, Mariko; Tashima, Kimihito; Devi, Lakshmi A; Suzuki, Tsutomu; Takayama, Hiromitsu; Horie, Syunji

    2014-03-01

    (E)-Methyl 2-((2S,3S,7aS,12bS)-3-ethyl-7a-hydroxy-8-methoxy-1,2,3,4,6,7,7a,12b-octahydroindolo[2,3-a]quinolizin-2-yl)-3-methoxyacrylate (7-hydroxymitragynine), a main active constituent of the traditional herbal medicine Mitragyna speciosa, is an indole alkaloid that is structurally different from morphine. 7-Hydroxymitragynine induces a potent antinociceptive effect on mouse acute pain through μ-opioid receptors. In this study, we developed dual-acting μ- and δ-opioid agonists MGM-15 and MGM-16 from 7-hydroxymitragynine for the treatment of acute and chronic pain. MGM-16 showed a higher potency than that of 7-hydroxymitragynine and MGM-15 in in vitro and in vivo assays. MGM-16 exhibited a high affinity for μ- and δ-opioid receptors, with K(i) values of 2.1 and 7.0 nM, respectively. MGM-16 showed μ- and δ-opioid full agonistic effects in a guanosine 5'-O-(3-[(35)S]thiotriphosphate) binding assay and in a functional test using electrically elicited guinea pig ileum and mouse vas deferens contractions. Systemic administration of MGM-16 produced antinociceptive effects in a mouse acute pain model and antiallodynic effects in a chronic pain model. The antinociceptive effect of MGM-16 was approximately 240 times more potent than that of morphine in a mouse tail-flick test, and its antiallodynic effect was approximately 100 times more potent than that of gabapentin in partial sciatic nerve-ligated mice, especially with oral administration. The antinociceptive effect of MGM-16 was completely and partially blocked by the μ-selective antagonist β-funaltrexamine hydrochloride (β-FNA) and by the δ-selective antagonist naltrindole, respectively, in a tail-flick test. The antiallodynic effect of MGM-16 was completely blocked by β-FNA and naltrindole in a neuropathic pain model. These findings suggest that MGM-16 could become a class of a compound with potential therapeutic utility for treating neuropathic pain. PMID:24345467

  6. Obstructive sleep apnea, pain, and opioids: is the riddle solved?

    PubMed Central

    Lam, Karen K.; Kunder, Samuel; Wong, Jean; Doufas, Anthony G.; Chung, Frances

    2016-01-01

    Purpose of review Perioperative opioid-based pain management of patients suffering from obstructive sleep apnea (OSA) may present challenges because of concerns over severe ventilatory compromise. The interaction between intermittent hypoxia, sleep fragmentation, pain, and opioid responses in OSA, is complex and warrants a special focus of perioperative outcomes research. Recent findings Life-threatening opioid-related respiratory events are rare. Epidemiologic evidence suggests that OSA together with other serious renal and heart disease, is among those conditions predisposing patients for opioid-induced ventilatory impairment (OIVI) in the postoperative period. Both intermittent hypoxia and sleep fragmentation, two distinct components of OSA, enhance pain. Intermittent hypoxia may also potentiate opioid analgesic effects. Activation of major inflammatory pathways may be responsible for the effects of sleep disruption and intermittent hypoxia on pain and opioid analgesia. Recent experimental evidence supports that these, seemingly contrasting, phenotypes of pain-increasing and opioid-enhancing effects of intermittent hypoxia, are not mutually exclusive. Although the effect of intermittent hypoxia on OIVI has not been elucidated, opioids worsen postoperative sleep-disordered breathing in OSA patients. A subset of these patients, characterized by decreased chemoreflex responsiveness and high arousal thresholds, might be at higher risk for OIVI. Summary OSA may complicate opioid-based perioperative management of pain by altering both pain processing and sensitivity to opioid effect. PMID:26545144

  7. Imaging of opioid receptors in the central nervous system

    PubMed Central

    Henriksen, Gjermund

    2008-01-01

    In vivo functional imaging by means of positron emission tomography (PET) is the sole method for providing a quantitative measurement of μ-, κ and δ-opioid receptor-mediated signalling in the central nervous system. During the last two decades, measurements of changes to the regional brain opioidergic neuronal activation—mediated by endogenously produced opioid peptides, or exogenously administered opioid drugs—have been conducted in numerous chronic pain conditions, in epilepsy, as well as by stimulant- and opioidergic drugs. Although several PET-tracers have been used clinically for depiction and quantification of the opioid receptors changes, the underlying mechanisms for regulation of changes to the availability of opioid receptors are still unclear. After a presentation of the general signalling mechanisms of the opioid receptor system relevant for PET, a critical survey of the pharmacological properties of some currently available PET-tracers is presented. Clinical studies performed with different PET ligands are also reviewed and the compound-dependent findings are summarized. An outlook is given concluding with the tailoring of tracer properties, in order to facilitate for a selective addressment of dynamic changes to the availability of a single subclass, in combination with an optimization of the quantification framework are essentials for further progress in the field of in vivo opioid receptor imaging. PMID:18048446

  8. Blockade of Endocannabinoid Hydrolytic Enzymes Attenuates Precipitated Opioid Withdrawal Symptoms in MiceS⃞

    PubMed Central

    Ramesh, Divya; Ross, Gracious R.; Schlosburg, Joel E.; Owens, Robert A.; Abdullah, Rehab A.; Kinsey, Steven G.; Long, Jonathan Z.; Nomura, Daniel K.; Sim-Selley, Laura J.; Cravatt, Benjamin F.; Akbarali, Hamid I.

    2011-01-01

    Δ9-Tetrahydrocannbinol (THC), the primary active constituent of Cannabis sativa, has long been known to reduce opioid withdrawal symptoms. Although THC produces most of its pharmacological actions through the activation of CB1 and CB2 cannabinoid receptors, the role these receptors play in reducing the variety of opioid withdrawal symptoms remains unknown. The endogenous cannabinoids, N-arachidonoylethanolamine (anandamide; AEA) and 2-arachidonylglycerol (2-AG), activate both cannabinoid receptors but are rapidly metabolized by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively. The objective of this study was to test whether increasing AEA or 2-AG, via inhibition of their respective hydrolytic enzymes, reduces naloxone-precipitated morphine withdrawal symptoms in in vivo and in vitro models of opioid dependence. Morphine-dependent mice challenged with naloxone reliably displayed a profound withdrawal syndrome, consisting of jumping, paw tremors, diarrhea, and weight loss. THC and the MAGL inhibitor 4-nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate (JZL184) dose dependently reduced the intensity of most measures through the activation of CB1 receptors. JZL184 also attenuated spontaneous withdrawal signs in morphine-dependent mice. The FAAH inhibitor N-(pyridin-3-yl)-4-(3-(5-(trifluoromethyl)pyridin-2-yloxy)benzyl)-piperdine-1-carboxamide (PF-3845) reduced the intensity of naloxone-precipitated jumps and paw flutters through the activation of CB1 receptors but did not ameliorate incidence of diarrhea or weight loss. In the final series of experiments, we investigated whether JZL184 or PF-3845 would attenuate naloxone-precipitated contractions in morphine-dependent ilea. Both enzyme inhibitors attenuated the intensity of naloxone-induced contractions, although this model does not account mechanistically for the autonomic withdrawal responses (i.e., diarrhea) observed in vivo. These results indicate

  9. Molecular Pharmacology of δ-Opioid Receptors.

    PubMed

    Gendron, Louis; Cahill, Catherine M; von Zastrow, Mark; Schiller, Peter W; Pineyro, Graciela

    2016-07-01

    Opioids are among the most effective analgesics available and are the first choice in the treatment of acute severe pain. However, partial efficacy, a tendency to produce tolerance, and a host of ill-tolerated side effects make clinically available opioids less effective in the management of chronic pain syndromes. Given that most therapeutic opioids produce their actions via µ-opioid receptors (MOPrs), other targets are constantly being explored, among which δ-opioid receptors (DOPrs) are being increasingly considered as promising alternatives. This review addresses DOPrs from the perspective of cellular and molecular determinants of their pharmacological diversity. Thus, DOPr ligands are examined in terms of structural and functional variety, DOPrs' capacity to engage a multiplicity of canonical and noncanonical G protein-dependent responses is surveyed, and evidence supporting ligand-specific signaling and regulation is analyzed. Pharmacological DOPr subtypes are examined in light of the ability of DOPr to organize into multimeric arrays and to adopt multiple active conformations as well as differences in ligand kinetics. Current knowledge on DOPr targeting to the membrane is examined as a means of understanding how these receptors are especially active in chronic pain management. Insight into cellular and molecular mechanisms of pharmacological diversity should guide the rational design of more effective, longer-lasting, and better-tolerated opioid analgesics for chronic pain management. PMID:27343248

  10. Intraventricular injections of mesenchymal stem cells activate endogenous functional remyelination in a chronic demyelinating murine model

    PubMed Central

    Cruz-Martinez, P; González-Granero, S; Molina-Navarro, M M; Pacheco-Torres, J; García-Verdugo, J M; Geijo-Barrientos, E; Jones, J; Martinez, S

    2016-01-01

    Current treatments for demyelinating diseases are generally only capable of ameliorating the symptoms, with little to no effect in decreasing myelin loss nor promoting functional recovery. Mesenchymal stem cells (MSCs) have been shown by many researchers to be a potential therapeutic tool in treating various neurodegenerative diseases, including demyelinating disorders. However, in the majority of the cases, the effect was only observed locally, in the area surrounding the graft. Thus, in order to achieve general remyelination in various brain structures simultaneously, bone marrow-derived MSCs were transplanted into the lateral ventricles (LVs) of the cuprizone murine model. In this manner, the cells may secrete soluble factors into the cerebrospinal fluid (CSF) and boost the endogenous oligodendrogenic potential of the subventricular zone (SVZ). As a result, oligodendrocyte progenitor cells (OPCs) were recruited within the corpus callosum (CC) over time, correlating with an increased myelin content. Electrophysiological studies, together with electron microscopy (EM) analysis, indicated that the newly formed myelin correctly enveloped the demyelinated axons and increased signal transduction through the CC. Moreover, increased neural stem progenitor cell (NSPC) proliferation was observed in the SVZ, possibly due to the tropic factors released by the MSCs. In conclusion, the findings of this study revealed that intraventricular injections of MSCs is a feasible method to elicit a paracrine effect in the oligodendrogenic niche of the SVZ, which is prone to respond to the factors secreted into the CSF and therefore promoting oligodendrogenesis and functional remyelination. PMID:27171265

  11. Temperament trait Harm Avoidance associates with μ-opioid receptor availability in frontal cortex: a PET study using [(11)C]carfentanil.

    PubMed

    Tuominen, Lauri; Salo, Johanna; Hirvonen, Jussi; Någren, Kjell; Laine, Pauliina; Melartin, Tarja; Isometsä, Erkki; Viikari, Jorma; Raitakari, Olli; Keltikangas-Järvinen, Liisa; Hietala, Jarmo

    2012-07-01

    Harm Avoidance is a temperament trait that associates with sensitivity to aversive and non-rewarding stimuli, higher anticipated threat and negative emotions during stress as well as a higher risk for affective disorders. The neurobiological correlates of interindividual differences in Harm Avoidance are largely unknown. We hypothesized that variability in Harm Avoidance trait would be explained by differences in the activity of μ-opioid system as the opioid system is known to regulate affective states and stress sensitivity. Brain μ-opioid receptor availability was measured in 22 healthy subjects using positron emission tomography and [(11)C]carfentanil, a selective μ-opioid receptor agonist. The subjects were selected from a large Finish population-based cohort (N=2075) on the basis of their pre-existing Temperament and Character Scores. Subjects scoring consistently in the upper (10) and lower (12) quartiles for the Harm Avoidance trait were studied. High Harm Avoidance score associated with high μ-opioid receptor availability (i.e. lower endogenous μ-opioid drive) in anterior cingulate cortex, ventromedial and dorsolateral prefrontal cortices and anterior insular cortex. These associations were driven by two subscales of Harm Avoidance; Shyness with Strangers and Fatigability and Asthenia. In conclusion, higher Harm Avoidance score in healthy subjects is associated with higher μ-opioid availability in regions involved in the regulation of anxiety as well as in the control of emotions, affective component of pain and interoceptive awareness. The results have relevance in the research of vulnerability factors for affective disorders. PMID:22484309

  12. Opioid-induced redistribution of 6TM and 7TM μ opioid receptors: A hypothesized mechanistic facilitator model of opioid-induced hyperalgesia.

    PubMed

    Wang, Wei; Wang, Yan; Zhang, Wei; Jin, Xiaoju; Liu, Yusheng; Xu, Shiqin; Lei, Liming; Shen, Xiaofeng; Guo, Xirong; Xia, Xiaoqiong; Wang, Fuzhou

    2016-08-01

    Opioids are still the most popular form of pain treatment, but many unavoidable side effects make opioids a big challenge in effective pain management. Opioid-induced hyperalgesia (OIH), a paradoxical phenomenon, portrays an increased sensitivity to harmful stimuli caused by opioid exposure. Changes in the neural modulation are considered a major contributor to the development of OIH. Activation of opioid receptors (ORs) and corresponding downstream molecules are the vital composition of functional performance of opioids. Increasing interests were proposed of the interaction between ORs and other neural transmitter systems such as glutamatergic, GABAergic and adrenergic ones to the genesis of OIH. G protein coupled μ-opioid receptor (MOR) was studied comprehensively on its role in the development of OIH. In addition to the relationship between MOR and other neurotransmitter receptors, a new intracellular MOR that has six transmembrane (6TM) domains was identified, and found to perform a pro-nociceptive task in contrast to the counterpart 7TM isoform. A mechanistic model of OIH in which both 6TM and 7TM MORs undergoing membrane redistribution upon opioid exposure is proposed which eventually facilitates the neurons more sensitive to nociceptive stimulation than that of the preceding opioid exposure. PMID:27116700

  13. Truncated mu opioid GPCR variant involvement in opioid-dependent and opioid-independent pain modulatory systems within the CNS.

    PubMed

    Marrone, Gina F; Grinnell, Steven G; Lu, Zhigang; Rossi, Grace C; Le Rouzic, Valerie; Xu, Jin; Majumdar, Susruta; Pan, Ying-Xian; Pasternak, Gavril W

    2016-03-29

    The clinical management of severe pain depends heavily on opioids acting through mu opioid receptors encoded by the Oprm1 gene, which undergoes extensive alternative splicing. In addition to generating a series of prototypic seven transmembrane domain (7TM) G protein-coupled receptors (GPCRs), Oprm1 also produces a set of truncated splice variants containing only six transmembrane domains (6TM) through which selected opioids such as IBNtxA (3'-iodobenzoyl-6β-naltrexamide) mediate a potent analgesia without many undesirable effects. Although morphine analgesia is independent of these 6TM mu receptor isoforms, we now show that the selective loss of the 6TM variants in a knockout model eliminates the analgesic actions of delta and kappa opioids and of α2-adrenergic compounds, but not cannabinoid, neurotensin, or muscarinic drugs. These observations were confirmed by using antisense paradigms. Despite their role in analgesia, loss of the 6TM variants were not involved with delta opioid-induced seizure activity, aversion to the kappa drug U50, 488H, or α2-mediated hypolocomotion. These observations support the existence of parallel opioid and nonopioid pain modulatory systems and highlight the ability to dissociate unwanted delta, kappa1, and α2 actions from analgesia. PMID:26976581

  14. ASIC-like Currents in Freshly Isolated Cerebral Artery Smooth Muscle Cells are Inhibited by Endogenous Oxidase Activity

    PubMed Central

    Chung, Wen-Shuo; Farley, Jerry M.; Drummond, Heather A.

    2011-01-01

    Background/Aims: The aim of this study was to determine if VSMC ASIC-like currents are regulated by oxidative state. Methods: We used whole-cell patch clamp of isolated mouse cerebral VSMCs to determine if 1) reducing agents, such as DTT and GSH, and 2) inhibition of endogenous oxidase activity from NADPH and Xanthine oxidases potentiate active currents and activate electrically silent currents. Results: Pretreatment with 2 mM DTT or GSH, increased the mean peak amplitude of ASIC-like currents evoked by pH 6.0 from 0.4 ± 0.1 to 14.9 ± 3.6 pA/pF, and from 0.9 ± 0.3 to 11.3 ± 2.4 pA/pF, respectively. Pretreatment with apocynin, a NADPH oxidase inhibitor, mimics the effect of the reducing agents, with the mean peak current amplitude increased from 0.9 ± 0.5 to 7.0 ± 2.6 pA/pF and from 0.5 ± 0.2 to 26.4 ± 6.8 pA/pF by 50 and 200 μM apocynin, respectively. Pretreatment with allopurinol, a xanthine oxidase inhibitor, also potentiates the VSMC ASIC-like activity. Conclusion: These findings suggest that VSMC ASIC-like channels are regulated by oxidative state and may be inhibited by basal endogenous oxidative sources such as NADPH and xanthine oxidase. PMID:21325830

  15. Comparison of endogenous cytokinins and cytokinin oxidase/dehydrogenase activity in germinating and thermoinhibited Tagetes minuta achenes.

    PubMed

    Stirk, Wendy A; Novák, Ondřej; Zižková, Eva; Motyka, Vaclav; Strnad, Miroslav; van Staden, Johannes

    2012-05-01

    Tagetes minuta L. achenes are thermoinhibited at temperatures above 35°C and have accelerated radicle emergence (germination) when subsequently transferred to an optimal temperature (25°C). Endogenous cytokinins and cytokinin oxidase/dehydrogenase (CKX) activity were compared in normally germinating (25°C) and thermoinhibited (72h at 36°C then transferred to 25°C) T. minuta achenes. Following imbibition, endogenous cytokinin concentrations changed in normally germinating T. minuta achenes, with a gradual decrease in dihydrozeatin-type (DHZ) cytokinins, a large increase in cis-zeatin-type (cZ) cytokinins, a smaller increase in N⁶-(2-isopentenyl)adenine-type (iP) cytokinins and a peak of trans-zeatin-type (tZ) cytokinins at 13 h. These changes in the isoprenoid cytokinin profile were similar in the thermoinhibited achenes imbibed at 36°C, despite the thermal block preventing radicle emergence. The exception was the iP-type cytokinins that only increased when transferred to 25°C. Profiles of the physiologically active free bases showed an increase in tZ prior to radical emergence in both normally germinating (13 h) and thermoinhibited achenes. A large transient peak in aromatic cytokinins [N⁶-benzyladenine-type (BA)] occurred during early seedling establishment in normally germinating achenes (40 h) while a transient maximum in BA-type cytokinins was found prior to radicle emergence in the thermoinhibited achenes (24 h). The CKX activity was enhanced in normally germinating achenes as the cytokinin concentration increased following imbibition. In thermoinhibited achenes, an elevated temperature negatively affected the CKX activity that only increased when the achenes were transferred to 25°C, corresponding to an increase in iP-type cytokinins. However, the favored cytokinin deactivation pathway in T. minuta appears to be 9-glycosylation, as 9-glucosides accounted for over 50% of the total cytokinin pool in both normal and thermoinhibited achenes. PMID

  16. Endogenous plasma activated protein C levels and the effect of enoxaparin and drotrecogin alfa (activated) on markers of coagulation activation and fibrinolysis in pulmonary embolism

    PubMed Central

    2011-01-01

    Introduction There are no published data on the status of endogenous activated protein C (APC) in pulmonary embolism (PE), and no data on the effect of drotrecogin alfa (activated) (DAA) given in addition to therapeutic dose enoxaparin. Methods In this double-blind clinical trial, 47 patients with computed tomography (CT)-confirmed acute submassive PE treated with 1 mg/kg body weight of enoxaparin twice daily were randomized to groups receiving a 12-hour intravenous infusion of 6, 12, 18, or 24 μg/kg/hour of DAA or a placebo. Blood samples were drawn before starting DAA infusion, after 4, 8 and 12 hours (at the end of the infusion period), and on treatment days 2, 3, 4, 5 and 6. Results Initial endogenous plasma activated protein C (APC) levels were 0.36 ± 0.48 ng/ml (<0.10 to 1.72 ng/ml) and remained in the same range in the placebo group. APC levels in patients treated with DAA were 13.67 ± 3.57 ng/ml, 32.71 ± 8.76 ng/ml, 36.13 ± 7.60 ng/ml, and 51.79 ± 15.84 ng/ml in patients treated with 6, 12, 18, and 24 μg/kg/hour DAA, respectively. In patients with a D-dimer level >4 mg/L indicating a high level of acute fibrin formation and dissolution, DAA infusion resulted in a more rapid drop in soluble fibrin, D-dimer, and fibrinogen/fibrin degradation products (FDP) levels, compared to enoxaparin alone. There was a parallel decline of soluble fibrin, D-dimer, FDP, and plasmin-plasmin inhibitor complex (PPIC) in response to treatment with enoxaparin ± DAA, with no evidence of a systemic profibrinolytic effect of the treatment. Conclusions In patients with acute submassive PE endogenous APC levels are low. DAA infusion enhances the inhibition of fibrin formation. Trial registration ClinicalTrials.gov: NCT00191724 PMID:21241489

  17. Bisphenol AF-induced endogenous transcription is mediated by ERα and ERK1/2 activation in human breast cancer cells.

    PubMed

    Li, Ming; Guo, Jing; Gao, Wenhui; Yu, Jianlong; Han, Xiaoyu; Zhang, Jing; Shao, Bing

    2014-01-01

    Bisphenol AF (BPAF)-induced transcriptional activity has been evaluated by luciferase reporter assay. However, the molecular mechanism of BPAF-induced endogenous transcription in human breast cancer cells has not been fully elucidated. In the present study, we investigated the effect and mechanism of BPAF-induced endogenous transcription detected by real-time PCR in human breast cancer cells. We found that BPAF stimulated transcription of estrogen responsive genes, such as trefoil factor 1 (TFF1), growth regulation by estrogen in breast cancer 1 (GREB1) and cathepsin D (CTSD), through dose-dependent and time-dependent manners in T47D and MCF7 cells. Gene-silencing of ERα, ERβ and G protein-coupled estrogen receptor 1 (GPER) by small interfering RNA revealed that BPAF-induced endogenous transcription was dependent on ERα and GPER, implying both genomic and nongenomic pathways might be involved in the endogenous transcription induced by BPAF. ERα-mediated gene transcription was further confirmed by inhibition of ER activity using ICI 182780 in ERα-positive T47D and MCF7 cells as well as overexpression of ERα in ERα-negative MDA-MB-231 breast cancer cells. Moreover, we utilized Src tyrosine kinase inhibitor PP2 and two MEK inhibitors PD98059 and U0126 to elucidate the rapid nongenomic activation of Src/MEK/ERK1/2 cascade on endogenous transcription. Our data showed that BPAF-induced transcription could be significantly blocked by PP2, PD98059 and U0126, suggesting activation of ERK1/2 was also required to regulate endogenous transcription. Taken together, these results indicate that BPAF-induced endogenous transcription of estrogen responsive genes is mediated through both genomic and nongenomic pathways involving the ERα and ERK1/2 activation in human breast cancer cells. PMID:24727858

  18. Bisphenol AF-Induced Endogenous Transcription Is Mediated by ERα and ERK1/2 Activation in Human Breast Cancer Cells

    PubMed Central

    Li, Ming; Guo, Jing; Gao, Wenhui; Yu, Jianlong; Han, Xiaoyu; Zhang, Jing; Shao, Bing

    2014-01-01

    Bisphenol AF (BPAF)-induced transcriptional activity has been evaluated by luciferase reporter assay. However, the molecular mechanism of BPAF-induced endogenous transcription in human breast cancer cells has not been fully elucidated. In the present study, we investigated the effect and mechanism of BPAF-induced endogenous transcription detected by real-time PCR in human breast cancer cells. We found that BPAF stimulated transcription of estrogen responsive genes, such as trefoil factor 1 (TFF1), growth regulation by estrogen in breast cancer 1 (GREB1) and cathepsin D (CTSD), through dose-dependent and time-dependent manners in T47D and MCF7 cells. Gene-silencing of ERα, ERβ and G protein-coupled estrogen receptor 1 (GPER) by small interfering RNA revealed that BPAF-induced endogenous transcription was dependent on ERα and GPER, implying both genomic and nongenomic pathways might be involved in the endogenous transcription induced by BPAF. ERα-mediated gene transcription was further confirmed by inhibition of ER activity using ICI 182780 in ERα-positive T47D and MCF7 cells as well as overexpression of ERα in ERα-negative MDA-MB-231 breast cancer cells. Moreover, we utilized Src tyrosine kinase inhibitor PP2 and two MEK inhibitors PD98059 and U0126 to elucidate the rapid nongenomic activation of Src/MEK/ERK1/2 cascade on endogenous transcription. Our data showed that BPAF-induced transcription could be significantly blocked by PP2, PD98059 and U0126, suggesting activation of ERK1/2 was also required to regulate endogenous transcription. Taken together, these results indicate that BPAF-induced endogenous transcription of estrogen responsive genes is mediated through both genomic and nongenomic pathways involving the ERα and ERK1/2 activation in human breast cancer cells. PMID:24727858

  19. Aromatase activity in the mare ovary during estrous cycle. Measurement of endogenous steroids and of their in vitro inhibitory effect.

    PubMed

    Amri, H; Silberzahn, P; al-Timimi, I; Gaillard, J L

    1993-12-01

    This present study was undertaken to clarify estrogen synthesis in the mare ovary. First of all, an evaluation of endogenous steroid contents was carried out in the follicular fluid and in the luteal tissue at different stages of the luteal phase. Radioimmunoassays were performed after separation and purification of each hormone by chromatography. High amounts of conjugated (0.9 mg/l) and unconjugated (4 mg/l) estradiol-17 beta were found in the follicular fluid of the large follicules (50 mm). These concentrations of estrogens decreased drastically in the luteal tissue, and only low levels of circulating estrogens are found during the luteal phase. On the other hand, a high aromatization ability has been evidenced in the cyclic corpus luteum in vitro. In an attempt to clarify the regulation of estrogen synthesis, we have tested the i