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Castro-Macías JI, San-Juan D, Anschel D, Cuellar-Figueroa VA. Electrocorticographic Patterns in Frontal Epilepsy and Long-Term Outcomes. J Clin Neurophysiol 2024:00004691-990000000-00145. [PMID: 38916879 DOI: 10.1097/wnp.0000000000001085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024] Open
Abstract
INTRODUCTION The prognostic significance of tailored resection guided with intraoperative electrocorticography (iECoG) in frontal lobe epilepsy surgery has not been fully elucidated. OBJECTIVES To analyze influence of preresection and postresection iECoG patterns on long-term seizure control of adults with frontal lobe epilepsy undergoing epilepsy surgery. METHODS We retrospectively analyzed 27 patients undergoing epilepsy surgery from two centers with preresection and postresection iECoG and reported clinical variables, preresection and postresection iECoG patterns, and outcome using the Engel Outcome Scale. Descriptive statistics, Kaplan-Meier, the logistic regression model, and analysis of variance tests were used. RESULTS Fifteen males (55.6%), a mean and mode follow-up after surgery of 43 (range 2-117) and 19 months, respectively. At 6 months, seizure frequency outcome according to Engel Scale was I 74.1% (20/27), II 7.4% (2/27), III 3.7% (1/27), and IV 14.8% (4/27). We found that 51.9% (14/27) and 40.8% (11/27) of patients without residual epileptiform discharges in postresective iECoG become seizure-free at 6 and 12 months of follow-up, respectively, compared with other postresective iECoG patterns. CONCLUSIONS Disregarding the presence of lack of residual epileptiform discharges (interictal epileptiform discharges) after resection, Engel I outcome was seen between 74.1% and 63% at 6- and 12-month postresection follow-up, suggesting the outcome might be in relation with other factors.
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Affiliation(s)
| | - Daniel San-Juan
- Epilepsy Clinic, National Institute of Neurology and Neurosurgery, Mexico City, México
| | - David Anschel
- St. Charles Epilepsy/New York University Comprehensive Epilepsy Center, St. Charles Hospital, Port Jefferson, New York, U.S.A.; and
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Blaine AT, van Rijn RM. Receptor expression and signaling properties in the brain, and structural ligand motifs that contribute to delta opioid receptor agonist-induced seizures. Neuropharmacology 2023; 232:109526. [PMID: 37004753 PMCID: PMC11078570 DOI: 10.1016/j.neuropharm.2023.109526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 03/10/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
The δ opioid receptor (δOR) is a therapeutic target for the treatment of various neurological disorders, such as migraines, chronic pain, alcohol use, and mood disorders. Relative to μ opioid receptor agonists, δOR agonists show lower abuse liability and may be potentially safer analgesic alternatives. However, currently no δOR agonists are approved for clinical use. A small number of δOR agonists reached Phase II trials, but ultimately failed to progress due to lack of efficacy. One side effect of δOR agonism that remains poorly understood is the ability of δOR agonists to produce seizures. The lack of a clear mechanism of action is partly driven by the fact that δOR agonists range in their propensity to induce seizure behavior, with multiple δOR agonists reportedly not causing seizures. There is a significant gap in our current understanding of why certain δOR agonists are more likely to induce seizures, and what signal-transduction pathway and/or brain area is engaged to produce these seizures. In this review we provide a comprehensive overview of the current state of knowledge of δOR agonist-mediated seizures. The review was structured to highlight which agonists produce seizures, which brain regions have been implicated and which signaling mediators have been examined in this behavior. Our hope is that this review will spur future studies that are carefully designed and aimed to solve the question why certain δOR agonists are seizurogenic. Obtaining such insight may expedite the development of novel δOR clinical candidates without the risk of inducing seizures. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".
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Affiliation(s)
- Arryn T Blaine
- Purdue University, Department of Medicinal Chemistry and Molecular Pharmacology, West Lafayette, IN, 47907, USA; Purdue University Interdisciplinary Life Science graduate program, West Lafayette, IN, 47907, USA
| | - Richard M van Rijn
- Purdue University, Department of Medicinal Chemistry and Molecular Pharmacology, West Lafayette, IN, 47907, USA; Purdue Institute for Integrative Neuroscience, West Lafayette, IN, 47907, USA; Purdue Institute for Drug Discovery, West Lafayette, IN, 47907, USA; Septerna Inc., South San Francisco, CA, 94080, USA.
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Lemos Duarte M, Devi LA. Post-translational Modifications of Opioid Receptors. Trends Neurosci 2020; 43:417-432. [PMID: 32459993 PMCID: PMC7323054 DOI: 10.1016/j.tins.2020.03.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/26/2020] [Accepted: 03/26/2020] [Indexed: 12/13/2022]
Abstract
Post-translational modifications (PTMs) are key events in signal transduction since they affect protein function by regulating their abundance and/or activity. PTMs involve the covalent attachment of functional groups to specific amino acids. Since they tend to be generally reversible, PTMs serve as regulators of signal transduction pathways. G-protein-coupled receptors (GPCRs) are major signaling proteins that undergo multiple types of PTMs. In this Review, we focus on the opioid receptors, members of GPCR family A, and highlight recent advances in the field that have underscored the importance of PTMs in the functional regulation of these receptors. Since opioid receptor activity plays a central role in the development of tolerance and addiction to morphine and other drugs of abuse, understanding the molecular mechanisms regulating receptor activity is of fundamental importance.
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Affiliation(s)
- Mariana Lemos Duarte
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lakshmi A Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Imam MZ, Kuo A, Ghassabian S, Cai Y, Qin Y, Li T, Smith MT. Intracerebroventricular administration of CYX-6, a potent μ-opioid receptor agonist, a δ- and κ-opioid receptor antagonist and a biased ligand at μ, δ & κ-opioid receptors, evokes antinociception with minimal constipation and respiratory depression in rats in contrast to morphine. Eur J Pharmacol 2020; 871:172918. [PMID: 31958457 DOI: 10.1016/j.ejphar.2020.172918] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 12/23/2019] [Accepted: 01/09/2020] [Indexed: 01/10/2023]
Abstract
Mu opioid receptor (MOPr) agonists are thought to produce analgesia via modulation of G-protein-coupled intracellular signalling pathways whereas the β-arrestin2 pathway is proposed to mediate opioid-related adverse effects. Here, we report the antinociception, constipation and respiratory depressant profile of CYX-6, a potent MOPr agonist that is also a delta and a kappa opioid receptor (DOPr/KOPr) antagonist and that lacks β-arrestin2 recruitment at each of the MOPr, DOPr and the KOPr. In anaesthetised male Sprague Dawley rats, an intracerebroventricular (i.c.v.) guide cannula was stereotaxically implanted. After 5-7 days post-surgical recovery, rats received a single i.c.v. bolus dose of CYX-6 (3-30 nmol), morphine (100 nmol) or vehicle. Antinociception was assessed using the warm water tail flick test (52.5 ± 0.5 °C). Constipation was assessed using the charcoal meal gut motility test and the castor oil-induced diarrhoea test. Respiratory depression was measured by whole-body plethysmography in awake, freely moving animals, upon exposure to a hypercapnic gas mixture (8% CO2, 21% O2 and 71% N2). The intrinsic pharmacology of CYX-6 given by the i.c.v. route in rats showed that it produced dose-dependent antinociception. It also produced respiratory stimulation rather than depression and it had a minimal effect on intestinal motility in contrast to the positive control, morphine. CYX-6 is an endomorphin-2 analogue that dissociates antinociception from constipation and respiratory depression in rats. Our findings provide useful insight to inform the discovery and development of novel opioid analgesics with a superior tolerability profile compared with morphine.
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MESH Headings
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/adverse effects
- Analgesics, Opioid/metabolism
- Analgesics, Opioid/pharmacology
- Animals
- Constipation/chemically induced
- Infusions, Intraventricular
- Ligands
- Male
- Morphine/adverse effects
- Morphine/pharmacology
- Opioid Peptides/drug effects
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Respiratory Insufficiency/chemically induced
- Nociceptin
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Affiliation(s)
- Mohammad Zafar Imam
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Andy Kuo
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Sussan Ghassabian
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Yunxin Cai
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yajuan Qin
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tingyou Li
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Maree T Smith
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia.
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Silvestro S, Mammana S, Cavalli E, Bramanti P, Mazzon E. Use of Cannabidiol in the Treatment of Epilepsy: Efficacy and Security in Clinical Trials. Molecules 2019; 24:E1459. [PMID: 31013866 PMCID: PMC6514832 DOI: 10.3390/molecules24081459] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/11/2019] [Accepted: 04/11/2019] [Indexed: 01/20/2023] Open
Abstract
Cannabidiol (CBD) is one of the cannabinoids with non-psychotropic action, extracted from Cannabis sativa. CBD is a terpenophenol and it has received a great scientific interest thanks to its medical applications. This compound showed efficacy as anti-seizure, antipsychotic, neuroprotective, antidepressant and anxiolytic. The neuroprotective activity appears linked to its excellent anti-inflammatory and antioxidant properties. The purpose of this paper is to evaluate the use of CBD, in addition to common anti-epileptic drugs, in the severe treatment-resistant epilepsy through an overview of recent literature and clinical trials aimed to study the effects of the CBD treatment in different forms of epilepsy. The results of scientific studies obtained so far the use of CBD in clinical applications could represent hope for patients who are resistant to all conventional anti-epileptic drugs.
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Affiliation(s)
- Serena Silvestro
- IRCCS Centro Neurolesi "Bonino-Pulejo", Via Provinciale Palermo, Contrada Casazza, 98124 Messina, Italy.
| | - Santa Mammana
- IRCCS Centro Neurolesi "Bonino-Pulejo", Via Provinciale Palermo, Contrada Casazza, 98124 Messina, Italy.
| | - Eugenio Cavalli
- IRCCS Centro Neurolesi "Bonino-Pulejo", Via Provinciale Palermo, Contrada Casazza, 98124 Messina, Italy.
| | - Placido Bramanti
- IRCCS Centro Neurolesi "Bonino-Pulejo", Via Provinciale Palermo, Contrada Casazza, 98124 Messina, Italy.
| | - Emanuela Mazzon
- IRCCS Centro Neurolesi "Bonino-Pulejo", Via Provinciale Palermo, Contrada Casazza, 98124 Messina, Italy.
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Koletar MM, Dorr A, Brown ME, McLaurin J, Stefanovic B. Refinement of a chronic cranial window implant in the rat for longitudinal in vivo two-photon fluorescence microscopy of neurovascular function. Sci Rep 2019; 9:5499. [PMID: 30940849 PMCID: PMC6445076 DOI: 10.1038/s41598-019-41966-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 03/19/2019] [Indexed: 12/13/2022] Open
Abstract
Longitudinal studies using two–photon fluorescence microscopy (TPFM) are critical for facilitating cellular scale imaging of brain morphology and function. Studies have been conducted in the mouse due to their relatively higher transparency and long term patency of a chronic cranial window. Increasing availability of transgenic rat models, and the range of established behavioural paradigms, necessitates development of a chronic preparation for the rat. However, surgical craniotomies in the rat present challenges due to craniotomy closure by wound healing and diminished image quality due to inflammation, restricting most rat TPFM experiments to acute preparations. Long-term patency is enabled by employing sterile surgical technique, minimization of trauma with precise tissue handling during surgery, judicious selection of the size and placement of the craniotomy, diligent monitoring of animal physiology and support throughout the surgery, and modification of the home cage for long-term preservation of cranial implants. Immunohistochemical analysis employing the glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule-1 (Iba-1) showed activation and recruitment of astrocytes and microglia/macrophages directly inferior to the cranial window at one week after surgery, with more diffuse response in deeper cortical layers at two weeks, and amelioration around four weeks post craniotomy. TPFM was conducted up to 14 weeks post craniotomy, reaching cortical depths of 400 µm to 600 µm at most time-points. The rate of signal decay with increasing depth and maximum cortical depth attained had greater variation between individual rats at a single time-point than within a rat across time.
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Affiliation(s)
- Margaret M Koletar
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
| | - Adrienne Dorr
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Mary E Brown
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - JoAnne McLaurin
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A1, Canada
| | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada.,Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
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Ibeas Bih C, Chen T, Nunn AVW, Bazelot M, Dallas M, Whalley BJ. Molecular Targets of Cannabidiol in Neurological Disorders. Neurotherapeutics 2015; 12:699-730. [PMID: 26264914 PMCID: PMC4604182 DOI: 10.1007/s13311-015-0377-3] [Citation(s) in RCA: 349] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Cannabis has a long history of anecdotal medicinal use and limited licensed medicinal use. Until recently, alleged clinical effects from anecdotal reports and the use of licensed cannabinoid medicines are most likely mediated by tetrahydrocannabinol by virtue of: 1) this cannabinoid being present in the most significant quantities in these preparations; and b) the proportion:potency relationship between tetrahydrocannabinol and other plant cannabinoids derived from cannabis. However, there has recently been considerable interest in the therapeutic potential for the plant cannabinoid, cannabidiol (CBD), in neurological disorders but the current evidence suggests that CBD does not directly interact with the endocannabinoid system except in vitro at supraphysiological concentrations. Thus, as further evidence for CBD's beneficial effects in neurological disease emerges, there remains an urgent need to establish the molecular targets through which it exerts its therapeutic effects. Here, we conducted a systematic search of the extant literature for original articles describing the molecular pharmacology of CBD. We critically appraised the results for the validity of the molecular targets proposed. Thereafter, we considered whether the molecular targets of CBD identified hold therapeutic potential in relevant neurological diseases. The molecular targets identified include numerous classical ion channels, receptors, transporters, and enzymes. Some CBD effects at these targets in in vitro assays only manifest at high concentrations, which may be difficult to achieve in vivo, particularly given CBD's relatively poor bioavailability. Moreover, several targets were asserted through experimental designs that demonstrate only correlation with a given target rather than a causal proof. When the molecular targets of CBD that were physiologically plausible were considered for their potential for exploitation in neurological therapeutics, the results were variable. In some cases, the targets identified had little or no established link to the diseases considered. In others, molecular targets of CBD were entirely consistent with those already actively exploited in relevant, clinically used, neurological treatments. Finally, CBD was found to act upon a number of targets that are linked to neurological therapeutics but that its actions were not consistent withmodulation of such targets that would derive a therapeutically beneficial outcome. Overall, we find that while >65 discrete molecular targets have been reported in the literature for CBD, a relatively limited number represent plausible targets for the drug's action in neurological disorders when judged by the criteria we set. We conclude that CBD is very unlikely to exert effects in neurological diseases through modulation of the endocannabinoid system. Moreover, a number of other molecular targets of CBD reported in the literature are unlikely to be of relevance owing to effects only being observed at supraphysiological concentrations. Of interest and after excluding unlikely and implausible targets, the remaining molecular targets of CBD with plausible evidence for involvement in therapeutic effects in neurological disorders (e.g., voltage-dependent anion channel 1, G protein-coupled receptor 55, CaV3.x, etc.) are associated with either the regulation of, or responses to changes in, intracellular calcium levels. While no causal proof yet exists for CBD's effects at these targets, they represent the most probable for such investigations and should be prioritized in further studies of CBD's therapeutic mechanism of action.
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Affiliation(s)
- Clementino Ibeas Bih
- School of Chemistry, Food and Nutritional Sciences, and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AP, UK
| | - Tong Chen
- School of Chemistry, Food and Nutritional Sciences, and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AP, UK
| | | | - Michaël Bazelot
- School of Chemistry, Food and Nutritional Sciences, and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AP, UK
- GW Pharmaceuticals Ltd, Sovereign House, Vision Park, Chivers Way, Histon, Cambridge, CB24 9BZ, UK
| | - Mark Dallas
- School of Chemistry, Food and Nutritional Sciences, and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AP, UK
| | - Benjamin J Whalley
- School of Chemistry, Food and Nutritional Sciences, and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AP, UK.
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The prognostic role of electrocorticography in tailored temporal lobe surgery. Seizure 2011; 20:564-9. [PMID: 21616682 DOI: 10.1016/j.seizure.2011.04.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 04/04/2011] [Accepted: 04/22/2011] [Indexed: 11/23/2022] Open
Abstract
UNLABELLED Intraoperative electrocorticography (ECoG) has been in clinical use for many decades, yet the validity of this procedure in guiding resective surgery for temporal lobe epilepsy (TLE) is still uncertain, especially in tailored temporal lobectomies in cases of TLE with hippocampal sclerosis. METHODOLOGY Using a case-control design combined with descriptive and comparative analyses we retrospectively evaluated two groups of patients: patients (n=20) who had tailored temporal lobectomies guided by intraoperative ECoG and patients (n=19) who had standard temporal lobectomies without ECoG. Clinical and neuroimaging data, pre- and post-resection ECoG recordings, and seizure-free outcomes were reviewed. RESULTS Of the 20 patients who underwent epilepsy surgery guided by ECoG, pre-resection ECoG studies found spikes both in mesial temporal lobe (MTL) and lateral temporal lobe (LTL) in 10 patients, and restricted to the LTL or MTL in 7 and 3 patients respectively. Postsurgical ECoG captured residual epileptiform activity in only 3 patients, all of whom had MTL and LTL spikes prior to surgery. Postsurgical follow-up at 16.3 (±6.7) months found 15 (75%) patients were seizure free (1A), while 5 (25%) had other outcomes. Analysis found no difference in the proportion of seizure-free outcomes between patients with residual epileptiform activity compared to those without residual epileptiform activity, or between patients who had a tailored resection guided by ECoG and patients who had standard resections without ECoG monitoring. CONCLUSION The patients who underwent tailored temporal lobe epilepsy surgery guided by ECoG had similar outcome compared with the patients with epilepsy surgery not guided by ECoG.
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Validation of a preclinical spinal safety model: effects of intrathecal morphine in the neonatal rat. Anesthesiology 2010; 113:183-99. [PMID: 20526189 DOI: 10.1097/aln.0b013e3181dcd6ec] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Preclinical studies demonstrate increased neuroapoptosis after general anesthesia in early life. Neuraxial techniques may minimize potential risks, but there has been no systematic evaluation of spinal analgesic safety in developmental models. We aimed to validate a preclinical model for evaluating dose-dependent efficacy, spinal cord toxicity, and long-term function after intrathecal morphine in the neonatal rat. METHODS Lumbar intrathecal injections were performed in anesthetized rats aged postnatal day (P) 3, 10, and 21. The relationship between injectate volume and segmental spread was assessed postmortem and by in vivo imaging. To determine the antinociceptive dose, mechanical withdrawal thresholds were measured at baseline and 30 min after intrathecal morphine. To evaluate toxicity, doses up to the maximum tolerated were administered, and spinal cord histopathology, apoptosis, and glial response were evaluated 1 and 7 days after P3 or P21 injection. Sensory thresholds and gait analysis were evaluated at P35. RESULTS Intrathecal injection can be reliably performed at all postnatal ages and injectate volume influences segmental spread. Intrathecal morphine produced spinally mediated analgesia at all ages with lower dose requirements in younger pups. High-dose intrathecal morphine did not produce signs of spinal cord toxicity or alter long-term function. CONCLUSIONS The therapeutic ratio for intrathecal morphine (toxic dose/antinociceptive dose) was at least 300 at P3 and at least 20 at P21 (latter doses limited by side effects). These data provide relative efficacy and safety for comparison with other analgesic preparations and contribute supporting evidence for the validity of this preclinical neonatal safety model.
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Rocha L, Suchomelová L, Mares P, Kubová H. Effects of LiCl/pilocarpine-induced status epilepticus on rat brain mu and benzodiazepine receptor binding: regional and ontogenetic studies. Brain Res 2007; 1181:104-17. [PMID: 17919468 DOI: 10.1016/j.brainres.2007.08.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 08/13/2007] [Accepted: 08/25/2007] [Indexed: 10/22/2022]
Abstract
Neurochemical studies document involvement of benzodiazepine (BDZ) and mu opioid receptors in seizure development and their possible age-related role during epileptogenesis. To study developmental changes of this role LiCl/pilocarpine status epilepticus (SE) was induced in P12, P25 and/or adult rats. This SE leads to epilepsy in all adult and subpopulation of immature rats. Using in vitro autoradiography, benzodiazepine (BDZ) and mu opioid receptor binding was evaluated 1 week (early phase of epileptogenesis) and 3 months (chronic phase) after SE in 27 brain structures involved in seizure generation and spread (amygdala, hippocampus, basal ganglia and thalamic nuclei). The pattern of receptor binding changes was related to the age at SE, interval after SE and to brain structures. Enhanced BDZ binding was found 1 week after SE in many cortical areas in P12 and also in the amygdala complex and dentate gyrus in both P12 and P25. No changes of BDZ binding occurred in adults at that time, but 3 months after SE a decrease of binding appeared in all evaluated areas in both adult and P25 but not P12 rats. This decrease did not reflect neuronal loss. mu opioid receptors were less significantly affected but clear tendency to decrease binding occurred in adult rats in various cortical, amygdala and thalamic regions early after SE. Changes were less expressed in immature rats. Our data support the hypothesis that age-related changes of receptor properties may participate in different functional consequences of SE including epileptogenesis (more common in older age groups) and behavioral changes.
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Affiliation(s)
- Luisa Rocha
- Department of Pharmacobiology, Center of Research and Advanced Studies, Mexico.
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Peters JWB, Anderson BJ, Simons SHP, Uges DRA, Tibboel D. Morphine metabolite pharmacokinetics during venoarterial extra corporeal membrane oxygenation in neonates. Clin Pharmacokinet 2006; 45:705-14. [PMID: 16802851 DOI: 10.2165/00003088-200645070-00005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
OBJECTIVE To examine morphine metabolite serum concentrations in neonates undergoing venoarterial extra corporeal membrane oxygenation (ECMO) and to quantify clearance differences between these neonates and those subjected to noncardiac major surgery. PATIENTS AND METHODS This was an observational study in level III referral centre. Fourteen neonates (< 7 days old) undergoing ECMO were included. Morphine and concomitant medications were given by protocol, adapted to the clinical conditions of the neonates. Pharmacokinetic findings were compared with those from a previous study in infants after noncardiac major surgery. Nonlinear mixed-effect modelling was used. Parameter estimates were standardised to a 70 kg person using allometric modeling RESULTS Morphine-3-glucuronide (M3G) was the predominant metabolite. Formation clearance to M3G at the start of ECMO on day 1 was lower than those in postoperative children, but matured more rapidly. After 10 days formation clearances of M3G in neonates on ECMO equalled those of postoperative children. Higher ECMO flows were associated with reduced formation clearances. Elimination clearances of M3G, but not morphine-6-glucuronide (M6G), were lower in the ECMO neonates; this was attributable to reduced renal clearance. These elimination clearances were correlated positively with ECMO flow and negatively with dopamine dose. Haemofiltration cleared M3G and M6G, but not morphine. CONCLUSION Formation clearance to M3G, the predominant metabolite, is reduced during the first 10 days of ECMO. Elimination clearance of M3G and M6G is related to creatinine clearance. ECMO flow had a small effect on metabolite clearance. Higher flows were associated with decreased formation clearances, possibly reflecting illness severity. Dopamine dose reflected decreased renal clearance.
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Affiliation(s)
- Jeroen W B Peters
- Department of Pediatric Surgery, Erasmus MC-Sophia, Rotterdam, The Netherlands.
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Jutkiewicz EM, Baladi MG, Folk JE, Rice KC, Woods JH. The convulsive and electroencephalographic changes produced by nonpeptidic delta-opioid agonists in rats: comparison with pentylenetetrazol. J Pharmacol Exp Ther 2006; 317:1337-48. [PMID: 16537798 DOI: 10.1124/jpet.105.095810] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
delta-Opioid agonists produce convulsions and antidepressant-like effects in rats. It has been suggested that the antidepressant-like effects are produced through a convulsant mechanism of action either through overt convulsions or nonconvulsive seizures. This study evaluated the convulsive and seizurogenic effects of nonpeptidic delta-opioid agonists at doses that previously were reported to produce antidepressant-like effects. In addition, delta-opioid agonist-induced electroencephalographic (EEG) and behavioral changes were compared with those produced by the chemical convulsant pentylenetetrazol (PTZ). For these studies, EEG changes were recorded using a telemetry system before and after injections of the delta-opioid agonists [(+)-4-[(alphaR)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)methyl]-N,N-diethylbenz (SNC80) and [(+)-4-[alpha(R)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide [(+)-BW373U86]. Acute administration of nonpeptidic delta-opioid agonists produced bilateral ictal and paroxysmal spike and/or sharp wave discharges. delta-Opioid agonists produced brief changes in EEG recordings, and tolerance rapidly developed to these effects; however, PTZ produced longer-lasting EEG changes that were exacerbated after repeated administration. Studies with antiepileptic drugs demonstrated that compounds used to treat absence epilepsy blocked the convulsive effects of nonpeptidic delta-opioid agonists. Overall, these data suggest that delta-opioid agonist-induced EEG changes are not required for the antidepressant-like effects of these compounds and that neural circuitry involved in absence epilepsy may be related to delta-opioid agonist-induced convulsions. In terms of therapeutic development, these data suggest that it may be possible to develop delta-opioid agonists devoid of convulsive properties.
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Affiliation(s)
- Emily M Jutkiewicz
- Department of Pharmacology, 1301 Medical Science Research Bldg. III, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA.
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Gardell LR, King T, Ossipov MH, Rice KC, Lai J, Vanderah TW, Porreca F. Opioid receptor-mediated hyperalgesia and antinociceptive tolerance induced by sustained opiate delivery. Neurosci Lett 2006; 396:44-9. [PMID: 16343768 DOI: 10.1016/j.neulet.2005.11.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 11/04/2005] [Accepted: 11/04/2005] [Indexed: 10/25/2022]
Abstract
Opiates are commonly used to treat moderate to severe pain and can be used over prolonged periods in states of chronic pain such as those associated with cancer. In addition, to analgesic actions, studies show that opiate administration can paradoxically induce hyperalgesia. At the pre-clinical level, such hyperalgesia is associated with numerous pronociceptive neuroplastic changes within the primary afferent fibers and the spinal cord. In rodents, sustained opiate administration also induces antinociceptive tolerance. The mechanisms by which prolonged opiate exposure induces hyperalgesia and the relationship of this state to antinociceptive tolerance remain unclear. The present study was aimed at determining whether sustained opiate-induced hyperalgesia, associated neuroplasticity and antinociceptive tolerance are the result of specific opiate interaction at opiate receptors. Enantiomers of oxymorphone, a mu opioid receptor agonist, were administered to rats by spinal infusion across 7 days. Sustained spinal administration of (-)-oxymorphone, but not its inactive enantiomer (+)-oxymorphone or vehicle, upregulated spinal dynorphin content, produced thermal and tactile hypersensitivity, and produced antinociceptive tolerance. These results indicate that these pronociceptive actions of sustained opiate administration require specific interaction with opiate receptors and are unlikely to be the result of accumulation of potentially excitatory metabolic products. While the precise mechanisms, which may account for these pronociceptive changes remain to be unraveled, the present data point to plasticity initiated by opiate receptor interaction.
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Affiliation(s)
- Luis R Gardell
- Department of Pharmacology, College of Medicine, University of Arizona Health Sciences Center, 1501 N. Campbell Avenue, Tucson, AZ 85724, USA
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Jutkiewicz EM, Torregrossa MM, Sobczyk-Kojiro K, Mosberg HI, Folk JE, Rice KC, Watson SJ, Woods JH. Behavioral and neurobiological effects of the enkephalinase inhibitor RB101 relative to its antidepressant effects. Eur J Pharmacol 2006; 531:151-9. [PMID: 16442521 PMCID: PMC1828120 DOI: 10.1016/j.ejphar.2005.12.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 12/08/2005] [Accepted: 12/12/2005] [Indexed: 10/25/2022]
Abstract
Nonpeptidic delta-opioid receptor agonists produce antidepressant-like effects in rodents, and compounds that inhibit the breakdown of endogenous opioid peptides have antidepressant-like effects in animal models. In this study, the behavioral effects of the enkephalinase inhibitor, RB101 (N-[(R, S)-2-benzyl-3-[(S)(2-amino-4-methyl-thio)-butyldithio]-1-oxopropyl]-l-phenylalanine benzyl ester), were examined. Specifically, the effects of RB101 on convulsive activity, locomotor activity, and antidepressant-like effects in the forced swim test were studied in Sprague-Dawley rats, and the opioid receptor types mediating these effects were examined by antagonist studies. In addition, the effects of RB101 on brain-derived neurotrophic factor (BDNF) mRNA expression were evaluated in relation to its antidepressant effects. RB101 produced delta-opioid receptor-mediated antidepressant effects (32 mg/kg i.v. and 100 mg/kg i.p.) and increased locomotor activity (32 mg/kg i.v.) in rats. RB101 did not produce convulsions or seizures and did not alter BDNF mRNA expression. In conclusion, RB101 has the potential to produce antidepressant effects without convulsions.
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Affiliation(s)
- Emily M Jutkiewicz
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA.
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15
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Klein M, Rudich Z, Gurevich B, Lifshitz M, Brill S, Lottan M, Weksler N. Controlled-release oxycodone-induced seizures. Clin Ther 2005; 27:1815-8. [PMID: 16368452 DOI: 10.1016/j.clinthera.2005.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2005] [Indexed: 11/30/2022]
Abstract
BACKGROUND The use of the opioid oxycodone hydrochloride in the management of chronic pain is gaining popularity principally because of its tolerability. However, opioid-related seizure in patients with epilepsy or other conditions that may decrease seizure threshold has been described in the literature; in particular, oxycodone has been associated with seizure in a patient with acute renal failure. OBJECTIVE The aim of this article was to report a patient with a history of seizures but normal renal and hepatic function who developed seizure on 2 occasions after oxycodone ingestion. METHODS A 54-year-old male patient presented with a history of tonic-clonic seizures that developed immediately after intracranial surgery. Long-term treatment with carbamazepine 400 mg QD was started, and the patient was free of convulsions for approximately 7 years. The patient presented to us with severe headache that was nonresponsive to an NSAID and the opiate agonist tramadol. Treatment with controlled-release (CR) oxycodone and tramadol drops (50 mg QID if necessary) was started, and tonic-clonic seizures developed 3 days later. RESULTS Based on laboratory analysis, the patient had normal renal and hepatic function. On discontinuation of oxycodone treatment, the seizures resolved. However, due to effective pain relief with oxycodone, the patient decided to continue treatment, and seizures recurred. Carbamazepine was then administered 4 hours before oxycodone dosing, which allowed continuation of treatment without seizure. CONCLUSIONS A patient with a history of seizures controlled with long-term carbamazepine therapy developed seizures when he started treatment with oxycodone CR at recommended doses. Oxycodone CR should be used with extreme caution in patients with epilepsy or other conditions that may decrease seizure threshold.
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Affiliation(s)
- Moti Klein
- Division of Anesthesiology and Critical Care Medicine, Soroka Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
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16
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Bausch SB, Garland JP, Yamada J. The delta opioid receptor agonist, SNC80, has complex, dose-dependent effects on pilocarpine-induced seizures in Sprague-Dawley rats. Brain Res 2005; 1045:38-44. [PMID: 15910761 DOI: 10.1016/j.brainres.2005.03.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 02/28/2005] [Accepted: 03/02/2005] [Indexed: 11/17/2022]
Abstract
Delta opioid receptor (DOR) selective agonists hold promise clinically as analgesics, but their effects on seizures remain controversial. In this study we examined the effects of the DOR agonist, (+)-4-[(alpha R)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethyl-benzamide (SNC80), on behavioral seizures and hippocampal histopathology in the pilocarpine model of temporal lobe epilepsy. Systemic administration of SNC80 (30 or 60 mg/kg) alone elicited brief seizures within minutes of injection in about half of all rats. When SNC80 (30 or 60 mg/kg) was given prior to pilocarpine administration, trends toward increased latencies to first seizure and status epilepticus (SE) were seen, which correlated with the incidence of a prior, brief SNC80-induced seizure. Significant dose-dependent effects of SNC80 also were observed. Prior administration of SNC80 (30 mg/kg) significantly decreased the number of rats exhibiting acute pilocarpine-induced seizures and overall seizure severity compared to rats given pilocarpine alone, suggesting that SNC80 was anticonvulsant. SNC80 (60 mg/kg) also decreased overall seizure severity. However, SNC80 (60 mg/kg) doubled the total seizure time and the number of rats exhibiting prolonged SE compared to pilocarpine alone, further suggesting that SNC80 has pro-convulsant properties. Significant effects of SNC80 on pilocarpine-induced seizures did not correlate with the occurrence of a prior SNC80-induced seizure. The degree of hilar neuron loss and mossy fiber sprouting correlated strongly with prolonged SE rather than dose of SNC80 (> or =60 min), suggesting that SNC80 did not dramatically alter pilocarpine-induced seizures in the absence of behavioral modifications. Our results demonstrate that the DOR agonist, SNC80, has complex, dose-dependent effects on pilocarpine-induced seizures.
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MESH Headings
- Animals
- Anticonvulsants/administration & dosage
- Benzamides/administration & dosage
- Convulsants/administration & dosage
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drug Interactions/physiology
- Epilepsy, Temporal Lobe/chemically induced
- Epilepsy, Temporal Lobe/drug therapy
- Epilepsy, Temporal Lobe/physiopathology
- Hippocampus/drug effects
- Hippocampus/physiopathology
- Male
- Mossy Fibers, Hippocampal/drug effects
- Mossy Fibers, Hippocampal/physiopathology
- Muscarinic Agonists/pharmacology
- Narcotics/adverse effects
- Pilocarpine
- Piperazines/administration & dosage
- Rats
- Rats, Sprague-Dawley
- Reaction Time/drug effects
- Reaction Time/physiology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/metabolism
- Seizures/chemically induced
- Seizures/drug therapy
- Seizures/physiopathology
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Affiliation(s)
- Suzanne B Bausch
- Department of Pharmacology, Uniformed Services University, Bethesda, MD 20814, USA.
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17
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Kahn L, Alonso G, Normand E, Manzoni OJ. Repeated morphine treatment alters polysialylated neural cell adhesion molecule, glutamate decarboxylase-67 expression and cell proliferation in the adult rat hippocampus. Eur J Neurosci 2005; 21:493-500. [PMID: 15673448 DOI: 10.1111/j.1460-9568.2005.03883.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Altered synaptic transmission and plasticity in brain areas involved in reward and learning are thought to underlie the long-lasting effects of addictive drugs. In support of this idea, opiates reduce neurogenesis [A.J. Eisch et al. (2000) Proceedings of the National Academy of Sciences USA, 97, 7579-7584] and enhance long-term potentiation in adult rodent hippocampus [J.M. Harrison et al. (2002) Journal of Neurophysiology, 87, 2464-2470], a key structure of learning and memory processes. Here we studied how repeated morphine treatment and withdrawal affect cell proliferation and neuronal phenotypes in the dentate gyrus-CA3 region of the adult rat hippocampus. Our data showed a strong reduction of cellular proliferation in morphine-dependent animals (54% of control) that was followed by a rebound increase after 1 week withdrawal and a return to normal after 2 weeks withdrawal. Morphine dependence was also associated with a drastic reduction in the expression levels of the polysialylated form of neural cell adhesion molecule (68% of control), an adhesion molecule expressed by newly generated neurons and involved in cell migration and structural plasticity. Polysialylated neural cell adhesion molecule levels quickly returned to normal following withdrawal. In morphine-dependent rats, we found a significant increase of glutamate decarboxylase-67 mRNA transcription (170% of control) in dentate gyrus granular cells which was followed by a marked rebound decrease after 1 week withdrawal and a return to normal after 4 weeks withdrawal. Together, the results show, for the first time, that, in addition to reducing cell proliferation and neurogenesis, chronic exposure to morphine dramatically alters neuronal phenotypes in the dentate gyrus-CA3 region of the adult rat hippocampus.
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Affiliation(s)
- Laëtitia Kahn
- INSERM Equipe Avenir 'Plasticité synaptique: Maturation & Addiction', Bordeaux Cedex, France
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18
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Andersen G, Christrup L, Sjøgren P. Relationships among morphine metabolism, pain and side effects during long-term treatment: an update. J Pain Symptom Manage 2003; 25:74-91. [PMID: 12565191 DOI: 10.1016/s0885-3924(02)00531-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The two metabolites of morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), have been studied intensively in animals and humans during the past 30 years in order to elucidate their precise action and possible contribution to the desired effects and side effects seen after morphine administration. M3G and M6G are formed by morphine glucuronidation, mainly in the liver, and are excreted by the kidneys. The metabolites are found in the cerebrospinal fluid after single as well as multiple doses of morphine. M6G binds to opioid receptors, and animal studies have demonstrated that M6G may be a more potent analgesic than morphine. Results from human studies regarding the analgesic effect of M6G are not unanimous. The potency ratio between systemic M6G and morphine in humans has not been settled, but is probably lower than previously assumed. Hitherto, only a few studies have found evidence for a contributory effect of M6G to the overall effects observed after morphine administration. Several studies have demonstrated that administration of M6G is accompanied by fewer and a milder degree of opioid-like side effects than observed after morphine administration, but most of the studies have used lower doses of M6G than of morphine. M3G displays very low affinity for opioid receptors and has no analgesic activity. Animal studies have shown that M3G may antagonize the analgesic effect of morphine and M6G, but no human studies have demonstrated this. M3G has also been connected to certain neurotoxic symptoms, such as hyperalgesia, allodynia and myoclonus, which have been observed after administration of M3G or high doses of morphine in animals. The symptoms have been reported sporadically in humans treated primarily with high doses of morphine, but the role of M3G in eliciting the symptoms is not fully elucidated.
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Affiliation(s)
- Gertrud Andersen
- Multidisciplinary Pain Center, Herlev University Hospital, Herlev, Denmark
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19
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Spector S, Munjal I, Schmidt DE. Endogenous morphine and codeine. Possible role as endogenous anticonvulsants. Brain Res 2001; 915:155-60. [PMID: 11595204 DOI: 10.1016/s0006-8993(01)02837-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exogenously administered morphine can have both convulsive or anticonvulsive effects, depending on the dose and species. The levels of the endogenous opiate alkaloids morphine and codeine were significantly elevated in specific rat brain regions by the convulsive drug, pentylenetetrazole, as well as by the anticonvulsant drugs, carbamazepine and phenytoin. Morphine and codeine levels in peripheral tissues (heart, lung, spleen and adrenal) were unaffected by these drugs. Maximal increases in morphine levels were seen in the hypothalamus and striatum (2-10-fold), while lesser increases occurred in the midbrain and brain stem (2-4-fold). Codeine levels were also markedly increased in hypothalamus (5-10 fold), In contrast to morphine, codeine levels were also increased in the hippocampus (2-10-fold), but were unchanged in the striatum. These studies suggest that the endogenous alkaloids morphine and codeine are involved in the modulation of convulsions and that morphine and/or codeine may act as an endogenous anticonvulsant.
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Affiliation(s)
- S Spector
- Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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20
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Vathy I. Prenatal morphine exposure induces age- and sex-dependent changes in seizure susceptibility. Prog Neuropsychopharmacol Biol Psychiatry 2001; 25:1203-26. [PMID: 11474841 DOI: 10.1016/s0278-5846(01)00187-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
1. Prenatal exposure to morphine induces long-term alterations in seizure susceptibility, which are age-, sex-, and seizure model-specific. 2. Adult male and female rats exposed prenatally to morphine show decreased susceptibility to GABA-regulated seizures. 3. Prenatally morphine-exposed, adult male rats are more sensitive to excitatory amino acid receptor-mediated seizures than control males, control females, or morphine-exposed females.
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Affiliation(s)
- I Vathy
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx 10461, NY, USA.
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21
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Brown BS, Yu SP. Modulation and genetic identification of the M channel. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2001; 73:135-66. [PMID: 10958929 DOI: 10.1016/s0079-6107(00)00004-3] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Potassium channels constitute a superfamily of the most diversified ion channels, acting in delicate and accurate ways to control or modify many physiological and pathological functions including membrane excitability, transmitter release, cell proliferation and cell degeneration. The M-type channel is a unique ligand-regulated and voltage-gated K(+) channel showing distinct physiological and pharmacological characteristics. This review will cover some important progress in the study of M channel modulation, particularly focusing on membrane transduction mechanisms. The K(+) channel genes corresponding to the M channel have been identified and will be reviewed in detail. It has been a long journey since the discovery of M current in 1980 to our present understanding of the mysterious mechanisms for M channel modulation; a journey which exemplifies tremendous achievements in ion channel research and exciting discoveries of elaborate modulatory systems linked to these channels. While substantial evidence has accumulated, challenging questions remain to be answered.
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Affiliation(s)
- B S Brown
- General Pharmacology Department, DuPont Pharmaceuticals Company, Wilmington, DE 19880-0400, USA
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22
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Abstract
The pathophysiology of convulsive and non-convulsive epilepsies is discussed in its primary generalised forms. Focal, clinical and experimental epilepsies, with emphasis placed on the temporal lobe epilepsies (TLE) and their pathophysiologies are also reviewed. Neurotransmitters and neuromodulators and between them, the second messenger systems are considered in the generation, maintenance or inhibition of the epileptic discharge. Action mechanisms of the more classic antiepileptic drugs are briefly summarized along with the therapeutic strategies that might achieve the final control of abnormal discharges, including genetic control as a promising alternative in the current state of research. We emphasized the study of all type of glutamate and GABA receptors and their relation with mRNA editing in the brain. Some of the genetic studies which have been so fruitful during the last ten years and which have brought new insights regarding the understanding of epileptic syndromes are summarized in this article.
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MESH Headings
- Animals
- Anticonvulsants/pharmacology
- Anticonvulsants/therapeutic use
- Epilepsy, Generalized/drug therapy
- Epilepsy, Generalized/genetics
- Epilepsy, Generalized/physiopathology
- Epilepsy, Temporal Lobe/drug therapy
- Epilepsy, Temporal Lobe/genetics
- Epilepsy, Temporal Lobe/physiopathology
- Epilepsy, Tonic-Clonic/drug therapy
- Epilepsy, Tonic-Clonic/genetics
- Epilepsy, Tonic-Clonic/physiopathology
- Humans
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Receptors, GABA/drug effects
- Receptors, GABA/physiology
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- J A Ure
- Department of Neurology, Borda Hospital, Buenos Aires, Argentina.
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23
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Ragazzo PC, Galanopoulou AS. Alfentanil-induced activation: a promising tool in the presurgical evaluation of temporal lobe epilepsy patients. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2000; 32:316-27. [PMID: 10751680 DOI: 10.1016/s0165-0173(99)00098-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Pharmacologic activation of epileptic foci has been used experimentally with the hope that it may accelerate the presurgical evaluation of patients with medically intractable epilepsy. In this article, we will review the existing literature on these activating tests giving emphasis on the opioid analogs, and particularly alfentanil. Alfentanil is an opioid analog with rapid anesthetic effect, which has been known to trigger epileptiform discharges in epilepsy patients. 58 temporal lobe epilepsy (TLE) patients were studied with alfentanil activation during electrocorticography, at the Epilepsy Surgery Unit (ING, Brazil). An increase of the interictal epileptiform discharges was observed originating from hippocampal and parahippocampal regions (96.5%). To a lesser extent, alfentanil activated the basal and lateral temporal regions. Electrographic seizures were observed in 38%. In addition, we performed continuous video-EEG (VT/EEG) monitoring, with scalp and bilateral foramen ovale electrodes, in 12 TLE patients. The results of spontaneously observed seizures were compared with the electrographic changes following alfentanil activation (50-75 microg/kg, i.v.). In seven cases, alfentanil triggered focal electrographic seizures, ipsilaterally to the side generating the spontaneous seizures and in two patients it produced bilateral sequential activation of the temporal lobes. Ictal SPECTs during the alfentanil test showed hyperperfusion at the lateral temporal regions, ipsilaterally to the activated area or bilaterally. In summary, our study confirms the activating effect of alfentanil, and provides a strong evidence for its selective activating effect on the temporal lobes of TLE patients. The ictal SPECT during alfentanil activation did not offer any additional advantage for the localization of the ictal onset.
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Affiliation(s)
- P C Ragazzo
- Epilepsy Surgery Unit, Instituto de Neurologia de Goiania, Goias, 74, 000, Brazil.
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24
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Manninen PH, Burke SJ, Wennberg R, Lozano AM, El Beheiry H. Intraoperative Localization of an Epileptogenic Focus with Alfentanil and Fentanyl. Anesth Analg 1999. [DOI: 10.1213/00000539-199905000-00025] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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25
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Manninen PH, Burke SJ, Wennberg R, Lozano AM, El Beheiry H. Intraoperative localization of an epileptogenic focus with alfentanil and fentanyl. Anesth Analg 1999; 88:1101-6. [PMID: 10320177 DOI: 10.1097/00000539-199905000-00025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
UNLABELLED We evaluated the effectiveness of alfentanil and fentanyl in stimulating epileptogenic activity during surgery for intractable temporal lobe epilepsy under general anesthesia. Ten patients received a standardized anesthetic induction with i.v. fentanyl 5 microg/kg, propofol 3-5 mg/kg, and atracurium 0.5 mg/kg. Maintenance was with isoflurane, 70% N2O/30% O2, and an atracurium infusion. After dural opening, droperidol 0.02 mg/kg was administered i.v.. Both inhaled anesthetics were discontinued and verified to be at 0 end-tidal concentration before the study. Baseline electrocorticography over the surface of the temporal lobe and depth electrode recordings in the amygdala and hippocampus were obtained, followed by 10 min of recording before and after the i.v. administration of both alfentanil 50 microg/kg and fentanyl 10 microg/kg. Any changes in cardiovascular variables were documented. The number of interictal epileptiform spikes at the most active site for each patient was tabulated before and after the administration of each drug. Both alfentanil and fentanyl induced an increase in spike activity in all patients. Alfentanil was more potent, increasing the median number of spikes per epoch from 18 to 58, compared with fentanyl (20 to 42 spikes) (P < 0.05). Alfentanil had a shorter duration of action (4.9+/-1.3 min) compared with fentanyl (8.5+/-2 min) (P < 0.009). In nine patients, the most active site was the hippocampus or amygdala. There was a decrease in mean blood pressure, but only after the administration of alfentanil (P < 0.05). Two patients had electrographic evidence of seizure activity. These opioids can be used to assist in the localization of the epileptogenic focus during surgery. IMPLICATIONS Both alfentanil and fentanyl activate epileptiform activity in patients with temporal lobe epilepsy. These opioids can be used to assist in the localization of the epileptogenic focus during surgery.
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Affiliation(s)
- P H Manninen
- Department of Anaesthesia, University of Toronto, The Toronto Hospital, Ontario, Canada
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26
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Negus SS, Picker MJ. BW373U86: A Non-Peptidic, Systemically-Active ? Opioid Agonist. CNS DRUG REVIEWS 1996. [DOI: 10.1111/j.1527-3458.1996.tb00290.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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27
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Abstract
Several factors may contribute to the propensity for the developing brain to have seizures and develop epilepsy. Hypersynchrony of neuronal circuits contributes to the seizure potential and several neurobiological features of the immature brain may support synchronized neuronal firing. The immature cerebral cortex and hippocampus have an increased density of synapses compared to adults and also a higher density of gap junctions and of excitatory amino acid receptors. Enhanced regenerative responses to injury in the developing brain may also contribute to the formation of abnormal hippocampal connections that support epilepsy. Molecular mechanisms that contribute to enhanced synaptic plasticity in the child's brain can also contribute to epileptogenesis in certain circumstances. The phenomenon of kindling, where repeated electrical stimulation of neuronal circuits leads to the development of epileptic seizures, is easily elicited in young animals. Long-term potentiation (LTP), where repeated synaptic stimulation leads to a reduced threshold for activation of that pathway and enhanced postsynaptic potentials, is much more robust in the immature cerebral cortex and may contribute to kindling and epileptogenesis. Age related enhancement of N-methyl-D-aspartate-type glutamate receptors, which are important for the activity dependent plasticity in the developing brain, appears to participate in LTP. This information suggests that normal developmental features of synaptic development make the immature brain more excitable than the adult brain and may contribute to epileptogenesis.
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Affiliation(s)
- M V Johnston
- Department of Neurology and Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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28
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Simmons ML, Chavkin C. Endogenous opioid regulation of hippocampal function. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1996; 39:145-96. [PMID: 8894847 DOI: 10.1016/s0074-7742(08)60666-2] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Endogenous opioid peptides modulate neural transmission in the hippocampus. Procnkephalin-derived peptides have been demonstrated to act at mu and delta opioid receptors to inhibit GABA release from inhibitory interneurons, resulting in increased excitability of hippocampal pyramidal cells and dentate gyrus granule cells. Prodynorphin-derived peptides primarily act at presynaptic kappa opioid receptors to inhibit excitatory amino acid release from perforant path and mossy fiber terminals. Opioid receptors reduce membrane excitability by modulating ion conductances, and in this way they may decrease voltage-dependent calcium influx and transmitter release. Synaptic plasticity in the hippocampus also is modulated by endogenous opioids. Enkephalins facilitate long-term potentiation, whereas dynorphins inhibit the induction of this type of neuroplasticity. Further, opioids may play important roles in hippocampal epilepsy. Recurrent seizures induce changes in the expression of opioid peptides and receptors. Also, enkephalins have proconvulsant effects in the epileptic hippocampus, whereas dynorphins may function as endogenous anticonvulsants.
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Affiliation(s)
- M L Simmons
- Department of Pharmacology, University of Washington, Seattle 98195, USA
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29
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Gioanni Y, Greco B, Prevost J. Search for the structures initiating seizures triggered by intraventricular injection of the mu opioid agonist dermorphin in rats. Epilepsia 1995; 36:922-8. [PMID: 7649132 DOI: 10.1111/j.1528-1157.1995.tb01636.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Free-moving rats received intraventricular (i.c.v.) or intravenous (i.v.) injections of the mu opioid agonist dermorphin (DRM). The EEG activity of the cortex and of several structures near the injected lateral ventricle was recorded. The intravenous injections of DRM did not induce epileptiform activity. The intracerebroventricular injections of DRM triggered several types of electrical seizures and interictal spikes. With the aim of determining which structure gave rise to the epileptiform discharges, we compared the time relationships of epileptiform phenomena occurring in different structures. Epileptiform discharges, at once generalized, appeared first in the CA3 area of the ventral hippocampus, with involvement of the CA1 area of ventral hippocampus, the entorhinal cortex and the amygdala following immediately. We conclude that, after intracerebroventricular injection of a mu opiate agonist, epileptiform activity originates in the CA3 area of the ventral hippocampus.
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Affiliation(s)
- Y Gioanni
- INSERM, Centre Paul Broca, Paris, France
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30
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Katz Y, Weizman A, Pick CG, Pasternak GW, Liu L, Fonia O, Gavish M. Interactions between laudanosine, GABA, and opioid subtype receptors: implication for laudanosine seizure activity. Brain Res 1994; 646:235-41. [PMID: 8069669 DOI: 10.1016/0006-8993(94)90084-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We examined the interactions of D,L-laudanosine, a potentially epileptogenic metabolite of the neuromuscular relaxant atracurium besylate, with gamma-aminobutyric acid (GABA) and opioid binding sites, all of which have been implicated in seizure activity. Laudanosine was almost ineffective at [3H]muscimol binding to high-affinity GABA receptors (IC50 = 100 microM). However, laudanosine displayed an inhibitory effect at the low-affinity GABA receptors labeled by [3H]bicuculline methochloride, with an IC50 value of 10 microM. At the opioid receptor subtype, laudanosine lowered radiolabeled opioid binding at the mu 1, mu 2, delta, kappa 1, and kappa 3 receptors with Ki values of 2.7, 13, 5.5, 21, and 24 microM, respectively, concentrations seen clinically in blood and approaching those measured in cerebrospinal fluid. Saturation studies of mu 1, mu 2, delta, and kappa 3 sites in the presence of laudanosine revealed competitive interactions, with increases in the apparent Kd values but without significant changes in the maximal numbers of binding sites. In addition, we investigated whether the in vitro laudanosine-opioid receptor interaction would also be expressed by analgesic physiologic effects. We found that laudanosine elicited a dose-dependent analgesia in mouse tail-flick assay that was attenuated by coadministration of beta-funaltrexamine (mu 1- and mu 2-selective antagonist) and of naloxonazine (mu 1 antagonist), but not by nor-binaltorphimine (kappa 1-selective antagonist) or naltrindole (delta-selective antagonist), indicating a mu 1 mechanism for analgesia-mediated property of laudanosine. There is evidence suggesting mu 2 activity as well, but this is due to the ability of laudanosine to elicit analgesia when given intrathecally. We also observed cross-tolerance between laudanosine and morphine, as well as a partial effect of laudanosine on gastrointestinal transit. These results suggest an interaction between laudanosine and the low-affinity GABA receptor, as well as opioid mu 1 and mu 2 receptors.
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MESH Headings
- Animals
- Bicuculline/analogs & derivatives
- Bicuculline/metabolism
- Binding, Competitive
- Brain/drug effects
- Brain/metabolism
- Cell Membrane/metabolism
- Cerebral Ventricles/drug effects
- Cerebral Ventricles/physiology
- GABA Antagonists
- Injections, Intraventricular
- Injections, Spinal
- Isoquinolines/administration & dosage
- Isoquinolines/pharmacology
- Isoquinolines/toxicity
- Kinetics
- Male
- Mice
- Mice, Inbred Strains
- Muscimol/metabolism
- Narcotic Antagonists
- Pain
- Rats
- Rats, Sprague-Dawley
- Receptors, GABA/metabolism
- Receptors, Opioid/physiology
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, mu/antagonists & inhibitors
- Seizures/chemically induced
- Spinal Cord/drug effects
- Spinal Cord/physiology
- Substance Withdrawal Syndrome
- gamma-Aminobutyric Acid/pharmacology
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Affiliation(s)
- Y Katz
- Department of Pharmacology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa
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31
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Gomar MD, Fernández B, Castillo JL, del Aguila CM, Acuña-Castroviejo D. Melatonin counteracts pinealectomy-dependent decreases in rat brain [3H]flunitrazepam binding through an opioid mechanism. Neurosci Lett 1993; 164:149-53. [PMID: 8152591 DOI: 10.1016/0304-3940(93)90879-p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effect of intracerebroventricular (i.c.v.) injection of melatonin and/or beta-endorphin on the [3H]flunitrazepam binding sites in the cerebral cortex of pinealectomized or superior cervical ganglionectomized rats was studied. Pinealectomy decreased the maximum concentration of benzodiazepine receptors (Bmax) without affecting the dissociation constant (KD), while melatonin, ineffective in control animals, counteracted the effect of pinealectomy. Intracerebroventricular injection of beta-endorphin increases Bmax in both control and pinealectomized animals, the effect being significantly higher in the latter. Simultaneous i.c.v. injection of melatonin + beta-endorphin did not further increase Bmax in any group, whereas i.c.v. injection of naloxone significantly blocked the effects of melatonin and/or beta-endorphin administration. Pineal sympathetic denervation produced a significant increase in Bmax and KD, whereas i.c.v. injection of melatonin further increased the former, restoring KD to control values. Neither i.c.v. administration of beta-endorphin or melatonin + beta-endorphin significantly modified the ganglionectomy-dependent increase in Bmax, although both treatments restored KD to control values. Naloxone administration had no effect on beta-endorphin- and melatonin + beta-endorphin-treated ganglionectomized groups, but counteracted the increased effect of melatonin on Bmax in ganglionectomized animals.
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Affiliation(s)
- M D Gomar
- Departamento de Fisiología, F. de Medicina, Universidad de Granada, Spain
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32
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Kearse LA, Koski G, Husain MV, Philbin DM, McPeck K. Epileptiform activity during opioid anesthesia. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1993; 87:374-9. [PMID: 7508369 DOI: 10.1016/0013-4694(93)90150-t] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The proconvulsant properties of exogenously administered opioids in man are not established. We prospectively evaluated relationships between epileptiform activity and opioid dose in 20 patients undergoing coronary artery revascularization. Baseline electroencephalograms were performed before surgery. Ten subjects were given fentanyl and 10 sufentanil, at 100 micrograms/kg and 10 micrograms/kg, respectively, in 4 divided doses, 3 min apart. Midazolam (4 mg) was given 3 min after the last dose of narcotic. Serum opioid concentrations were measured by radioimmunoassay. Within 3 min of the first opioid dose, 19 of 20 patients developed epileptiform activity, characterized by generalized single and multiphasic, low-to-moderate voltage spike discharges, similar in appearance to benign epileptiform transients of sleep (BETS). Despite continuously increasing serum concentrations of opioid, the number of spike discharges initially increased during the first and second dose intervals and then declined during the third and fourth dose intervals. This dissociation between epileptiform discharges and measured serum opioid concentration was unexpected and remained unexplained. Spike activity was consistently attenuated (P = 0.000003) within 20 sec of midazolam administration. Abrupt cessation of discharges after administration of the anticonvulsant, midazolam, suggests an epileptogenic mechanism for the opioid-induced activity.
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Affiliation(s)
- L A Kearse
- Department of Anesthesia, Massachusetts General Hospital, Harvard Medical School, Boston 02114
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33
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Hong JS, McGinty JF, Lee PH, Xie CW, Mitchell CL. Relationship between hippocampal opioid peptides and seizures. Prog Neurobiol 1993; 40:507-28. [PMID: 8446760 DOI: 10.1016/0301-0082(93)90020-s] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J S Hong
- Laboratory of Molecular and Integrative Neuroscience, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709
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34
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van Praag H, Frenk H. The effects of systemic morphine on behavior and EEG in newborn rats. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1992; 67:19-26. [PMID: 1638740 DOI: 10.1016/0165-3806(92)90021-n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Early studies suggested that newborn animals are far more susceptible to the convulsant effect of systemic morphine than adult animals. The present study reassessed morphine's (0, 6, 12.5, 25, 50, 100 and 300 mg/kg) toxic effects, making use of electroencephalographic (EEG) recordings, behavioral observations and the specific opiate antagonist naloxone in immature rats (postnatal days 1, 3, 6, 12 and 24). Although morphine had opiate-specific effects (such as inhibition of activity at low doses), non-specific effects (such as hyperactivity) elicited by the highest doses, predominated in the 3 youngest age groups. At day 12 high doses of morphine first produced Straub tail and catatonia. At this age morphine produced EEG spikes that were not reversed by naloxone. Only at day 24 were electrographic spikes temporarily inhibited by naloxone. Behavioral convulsions were never observed, at any age. These findings indicate that morphine is less toxic in newborns than suggested previously.
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Affiliation(s)
- H van Praag
- Department of Psychology, Tel-Aviv University, Ramat-Aviv, Israel
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35
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Bansinath M, Ramabadran K, Turndorf H, Shukla VK. Intracerebroventricular administration of kappa-agonists induces convulsions in mice. Brain Res Bull 1991; 27:75-9. [PMID: 1657321 DOI: 10.1016/0361-9230(91)90283-p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Intracerebroventricular (ICV) administration of kappa-agonists (PD 117302, U-50488H and U-69593) induced convulsions in a dose-related manner in mice. The dose at which 50% of animals convulsed (CD50) was in nmol ranges for all opioids. Among the opioids used, PD 117302 was the most potent convulsant. ICV administration of either vehicle alone or U-53445E, a non-kappa-opioid (+) enantiomer of U-50488H did not induce convulsions. The convulsive response of kappa-agonists was differentially susceptible for antagonism by naloxone and/or MR 2266. Collectively, these findings support the view that convulsions induced by kappa-agonists in mice involve stereospecific opioid receptor mechanisms. Furthermore, the convulsant effect of kappa-agonists could not be modified by pretreatment with MK-801, ketamine, muscimol or baclofen. It is concluded that kappa-opioid but not NMDA or GABA receptor mechanisms are involved in convulsions induced by kappa-agonists. These results are the first experimental evidence implicating stereospecific kappa-receptor mechanisms in opioid-induced convulsions in mice.
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Affiliation(s)
- M Bansinath
- Department of Anesthesiology, School of Medicine, New York University Medical Center, NY 10016
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36
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Liu L, Katz Y, Weizman R, Rosenberg B, Pasternak GW, Gavish M. Interactions of chloroquine with benzodiazepine, gamma-aminobutyric acid and opiate receptors. Biochem Pharmacol 1991; 41:1534-6. [PMID: 1850280 DOI: 10.1016/0006-2952(91)90574-o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- L Liu
- Cotzias Laboratory of Neuro-Oncology Memorial Sloan-Kettering Cancer Center, New York, NY
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37
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Abstract
D-Tyr-Ser-Gly-Phe-Leu-Thr (DSLET), beta-endorphin, morphiceptin and morphine were microinjected at 48-h intervals into the amygdala or hippocampus of awake rats in an attempt to identify the opiate receptor types involved in opioid kindling. DSLET, beta-endorphin, morphiceptin and morphine were injected into the lateral ventricle to assess the possibility of kindling seizures by this route. The delta-receptor agonist DSLET effectively kindled convulsions when microinjected into amygdala or ventral hippocampus. The convulsions were suppressed or strongly attenuated by ICI 174,864, a specific antagonist of the delta-receptor, microinjected into the same brain site, but were not affected by ICI 174,864 administered peripherally. When microinjected into amygdala or hippocampus, beta-endorphin and morphiceptin also kindled convulsions, which were antagonized by naloxone but not by ICI 174,864. Morphine evoked EEG epileptiform activity but did not kindle convulsions from limbic brain sites. DSLET occasionally evoked epileptiform spiking and submaximal convulsions when injected into ventricle, and morphiceptin evoked epileptiform spiking only, but tolerance to these effects occurred after repetition of the injections. Thus, convulsions can be kindled by activation of either mu-, delta- or epsilon-receptors when opioids are injected directly into limbic tissue. However, the ability of these compounds to kindle seizures is markedly reduced when they are administered into ventricle. The striking differences between the present results and previous results obtained by peripheral or intraventricular administration of opioid peptides suggest that the route of administration, among other variables, is a crucial factor in assessing the epileptogenic properties of opioid peptides.
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Affiliation(s)
- D P Cain
- Department of Psychology, University of Western Ontario, London, Canada
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38
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Zagon IS, Zagon E, McLaughlin PJ. Opioids and the developing organism: a comprehensive bibliography, 1984-1988. Neurosci Biobehav Rev 1989; 13:207-35. [PMID: 2691928 DOI: 10.1016/s0149-7634(89)80055-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A comprehensive bibliography of the literature concerned with opioids and the developing organism for 1984-1988 is presented. Utilized with companion papers (Neurosci. Biobehav. Rev. 6:439-479; 1982; 8:387-403; 1984), these articles cover the clinical and laboratory references beginning in 1875. For the years 1984, 1985, 1986, 1987, and 1988, a total of 877 citations were recorded. A series of indexes accompanies the citations in order to make the literature more accessible. These indexes are divided into clinical and laboratory topics, and subdivided into such topics as the type of opioid explored and the general area of biological interest (e.g., physiology).
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Affiliation(s)
- I S Zagon
- Department of Anatomy, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033
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39
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Lason W, Simpson JN, McGinty JF. Mu but not delta opioid receptor stimulation intensifies kainic acid-induced neurotoxicity in rat hippocampus. Neuropeptides 1988; 12:89-94. [PMID: 2847074 DOI: 10.1016/0143-4179(88)90036-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the present study, we compared the effects of the selective mu agonist, [D-Ala2-N-methyl-pHe4-Gly-ol]-enkephalon (DAGO), and the selective delta agonist, [D-Pen2,5]-enkephalin (DPDPE), on kainic acid-induced neurotoxicity in rats. Infusion of kainic acid (0.5 ug/1.5 ul, ic.v.) alone caused pyramidal cell loss predominantly in hippocampal field CA3 with minimal involvement of the CA1 field. Coadministration of DAGO plus kainic acid into the lateral ventricle intensified the extent of degeneration of hippocampal pyramidal cells in the CA1 field. The potentiating effect of DAGO was completely blocked by naltrexone. In contrast, DPDPE had no significant effect on kainic acid-induced neurotoxicity. Thus, activation of mu but not delta receptors intensifies the neurotoxic effects of kainic acid in the hippocampus.
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MESH Headings
- Analgesics/pharmacology
- Animals
- Drug Synergism
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/antagonists & inhibitors
- Enkephalins/pharmacology
- Hippocampus/drug effects
- Hippocampus/pathology
- Injections, Intraventricular
- Kainic Acid/administration & dosage
- Kainic Acid/toxicity
- Male
- Naltrexone/pharmacology
- Rats
- Rats, Inbred Strains
- Receptors, Opioid/drug effects
- Receptors, Opioid, delta
- Receptors, Opioid, mu
- Seizures/chemically induced
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Affiliation(s)
- W Lason
- Department of Anatomy and Biology, School of Medicine, East Carolina University, Greenville, NC 27858-4354
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40
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Laorden ML, Miralles FS, Puig MM. High doses of L-naloxone but neither D-naloxone nor beta-funaltrexamine prevent hyperthermia-induced seizures in rat pups. J Pharm Pharmacol 1988; 40:223-4. [PMID: 2899160 DOI: 10.1111/j.2042-7158.1988.tb05229.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effects of the non-specific opiate antagonist L-naloxone and the inactive isomer D-naloxone, as well as the specific mu receptor antagonist beta-funaltrexamine, have been examined on hyperthermia-induced seizures in unrestrained 15 days old rats. Saline-injected animals exposed to an ambient temperature of 40 degrees C showed a gradual increase in body temperature reaching a maximum of 42 +/- 0.1 degrees C at 50 min exposure. At this time all the pups had seizures and died. Similar results were obtained when the animals were pretreated with different doses of D-naloxone and beta-funaltrexamine. Rats pretreated with L-naloxone also showed an increase in rectal temperature; but the temperature was lower than in saline-injected animals. Only high doses of L-naloxone prevented seizures and deaths. These data indicate that endogenous opioid peptides may play a role in seizures induced by hyperthermia and that receptors other than mu receptors could be involved in hyperthermia-induced seizures.
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Affiliation(s)
- M L Laorden
- Department of Pharmacology, Murcia University School of Medicine, Espinardo, Spain
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