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Ruszczak A, Poznański P, Leśniak A, Łazarczyk M, Skiba D, Nawrocka A, Gaweł K, Paszkiewicz J, Mickael ME, Sacharczuk M. Susceptibility to Pentylenetetrazole-Induced Seizures in Mice with Distinct Activity of the Endogenous Opioid System. Int J Mol Sci 2024; 25:6978. [PMID: 39000086 PMCID: PMC11241619 DOI: 10.3390/ijms25136978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 06/19/2024] [Accepted: 06/22/2024] [Indexed: 07/16/2024] Open
Abstract
Currently, pharmacotherapy provides successful seizure control in around 70% of patients with epilepsy; however, around 30% of cases are still resistant to available treatment. Therefore, effective anti-epileptic therapy still remains a challenge. In our study, we utilized two mouse lines selected for low (LA) and high (HA) endogenous opioid system activity to investigate the relationship between down- or upregulation of the opioid system and susceptibility to seizures. Pentylenetetrazole (PTZ) is a compound commonly used for kindling of generalized tonic-clonic convulsions in animal models. Our experiments revealed that in the LA mice, PTZ produced seizures of greater intensity and shorter latency than in HA mice. This observation suggests that proper opioid system tone is crucial for preventing the onset of generalized tonic-clonic seizures. Moreover, a combination of an opioid receptor antagonist-naloxone-and a GABA receptor agonist-diazepam (DZP)-facilitates a significant DZP-sparing effect. This is particularly important for the pharmacotherapy of neurological patients, since benzodiazepines display high addiction risk. In conclusion, our study shows a meaningful, protective role of the endogenous opioid system in the prevention of epileptic seizures and that disturbances in that balance may facilitate seizure occurrence.
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Affiliation(s)
- Anna Ruszczak
- Department of Small Animal Diseases with Clinic, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 166, 02-787 Warsaw, Poland
| | - Piotr Poznański
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec, Poland
- Laboratory of Host-Microbiota Interactions, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Anna Leśniak
- Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02-697 Warsaw, Poland
| | - Marzena Łazarczyk
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec, Poland
| | - Dominik Skiba
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec, Poland
| | - Agata Nawrocka
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec, Poland
| | - Kinga Gaweł
- Department of Experimental and Clinical Pharmacology, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland
| | - Justyna Paszkiewicz
- Department of Health, John Paul II University of Applied Sciences in Biala Podlaska, Sidorska 95/97, 21-500 Biała Podlaska, Poland
| | - Michel-Edwar Mickael
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec, Poland
| | - Mariusz Sacharczuk
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec, Poland
- Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02-697 Warsaw, Poland
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Lankhuijzen LM, Ridler T. Opioids, microglia, and temporal lobe epilepsy. Front Neurol 2024; 14:1298489. [PMID: 38249734 PMCID: PMC10796828 DOI: 10.3389/fneur.2023.1298489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/15/2023] [Indexed: 01/23/2024] Open
Abstract
A lack of treatment options for temporal lobe epilepsy (TLE) demands an urgent quest for new therapies to recover neuronal damage and reduce seizures, potentially interrupting the neurotoxic cascades that fuel hyper-excitability. Endogenous opioids, along with their respective receptors, particularly dynorphin and kappa-opioid-receptor, present as attractive candidates for controlling neuronal excitability and therapeutics in epilepsy. We perform a critical review of the literature to evaluate the role of opioids in modulating microglial function and morphology in epilepsy. We find that, in accordance with anticonvulsant effects, acute opioid receptor activation has unique abilities to modulate microglial activation through toll-like 4 receptors, regulating downstream secretion of cytokines. Abnormal activation of microglia is a dominant feature of neuroinflammation, and inflammatory cytokines are found to aggravate TLE, inspiring the challenge to alter microglial activation by opioids to suppress seizures. We further evaluate how opioids can modulate microglial activation in epilepsy to enhance neuroprotection and reduce seizures. With controlled application, opioids may interrupt inflammatory cycles in epilepsy, to protect neuronal function and reduce seizures. Research on opioid-microglia interactions has important implications for epilepsy and healthcare approaches. However, preclinical research on opioid modulation of microglia supports a new therapeutic pathway for TLE.
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Affiliation(s)
| | - Thomas Ridler
- Hatherly Laboratories, Department of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
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Abstract
Temporal lobe epilepsy is considered to be one of the most common and severe forms of focal epilepsies. Patients frequently develop cognitive deficits and emotional blunting along progression of the disease. The high incidence of refractoriness to antiepileptic drugs and a frequent lack of admissibility to surgery pose an unmet medical challenge. In the urgent quest for novel treatment strategies, neuropeptides and their receptors are interesting candidates. However, their therapeutic potential has not yet been fully exploited. This chapter focuses on the functional role of the dynorphins (Dyns) and the kappa opioid receptor (KOR) system in temporal lobe epilepsy and the hippocampus.Genetic polymorphisms in the prepro-dynorphin (pDyn) gene causing lower levels of Dyns in humans and pDyn gene knockout in mice increase the risk to develop epilepsy. This suggests a role of Dyns and KOR as modulators of neuronal excitability. Indeed, KOR agonists induce inhibition of presynaptic neurotransmitter release, as well as postsynaptic hyperpolarization in glutamatergic neurons, both producing anticonvulsant effects.The development of new approaches to modulate the complex KOR signalling cascade (e.g. biased agonism and gene therapy) opens up new exciting therapeutic opportunities with regard to seizure control and epilepsy. Potential adverse side effects of KOR agonists may be minimized through functional selectivity or locally restricted treatment. Preclinical data suggest a high potential of such approaches to control seizures.
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Affiliation(s)
- Luca Zangrandi
- Institute of Virology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Freie Universität Berlin, Berlin, Germany
- Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria.
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4
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Liu L, Xu Y, Dai H, Tan S, Mao X, Chen Z. Dynorphin activation of kappa opioid receptor promotes microglial polarization toward M2 phenotype via TLR4/NF-κB pathway. Cell Biosci 2020; 10:42. [PMID: 32206297 PMCID: PMC7079364 DOI: 10.1186/s13578-020-00387-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/21/2020] [Indexed: 12/21/2022] Open
Abstract
Background Microglia-mediated neuroinflammation is associated with epilepsy. Switching microglial polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype represents a novel therapeutic strategy for mitigating epileptogenesis. We previously found that dynorphins protected against epilepsy via activation of kappa opioid receptor (KOR). Here, this study aims to investigate the role and the mechanism of dynorphin in regulating microglial polarization. Methods A pilocarpine-induced rat model of epilepsy was established and lipopolysaccharide (LPS)-activated BV-2 microglial cells were used as an inflammatory model to explore the mechanism of dynorphin regulating microglial polarization. Results Overexpression of the dynorphin precursor protein prodynorphin (PDYN) alleviated the pilocarpine-induced neuronal apoptosis, promoted microglial polarization to the M2 phenotype, and inhibited pilocarpine-induced Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway in the hippocampi of epileptic rats. Dynorphin activation of KOR promoted microglial M2 polarization via inhibiting TLR4/NF-κB pathway in LPS-stimulated BV-2 microglial cells. Moreover, dynorphin/KOR regulated microglial M2 polarization inhibited apoptosis of the primary mouse hippocampal neurons. Conclusion In conclusion, dynorphin activation of KOR promotes microglia polarization toward M2 phenotype via inhibiting TLR4/NF-κB pathway.
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Affiliation(s)
- Lin Liu
- 1Department of Pediatrics, The Third Xiangya Hospital, Central South University, No. 138 Tongzipo Road, Yuelu District, ChangshaHunan, 410013 China
| | - Yingtong Xu
- 1Department of Pediatrics, The Third Xiangya Hospital, Central South University, No. 138 Tongzipo Road, Yuelu District, ChangshaHunan, 410013 China
| | - Hongmei Dai
- 1Department of Pediatrics, The Third Xiangya Hospital, Central South University, No. 138 Tongzipo Road, Yuelu District, ChangshaHunan, 410013 China
| | - Shan Tan
- 1Department of Pediatrics, The Third Xiangya Hospital, Central South University, No. 138 Tongzipo Road, Yuelu District, ChangshaHunan, 410013 China
| | - Xiao Mao
- Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, ChangshaHunan, 410008 China
| | - Zhiheng Chen
- 1Department of Pediatrics, The Third Xiangya Hospital, Central South University, No. 138 Tongzipo Road, Yuelu District, ChangshaHunan, 410013 China
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5
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Dai H, Wang P, Mao H, Mao X, Tan S, Chen Z. Dynorphin activation of kappa opioid receptor protects against epilepsy and seizure-induced brain injury via PI3K/Akt/Nrf2/HO-1 pathway. Cell Cycle 2019; 18:226-237. [PMID: 30595095 PMCID: PMC6343729 DOI: 10.1080/15384101.2018.1562286] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 11/28/2018] [Accepted: 12/01/2018] [Indexed: 12/25/2022] Open
Abstract
Dynorphins act as endogenous anticonvulsants via activation of kappa opioid receptor (KOR). However, the mechanism underlying the anticonvulsant role remains elusive. This study aims to investigate whether the potential protection of KOR activation by dynorphin against epilepsy was associated with the regulation of PI3K/Akt/Nrf2/HO-1 pathway. Here, a pilocarpine-induced rat model of epilepsy and Mg2+-free-induced epileptiform hippocampal neurons were established. Decreased prodynorphin (PDYN) expression, suppressed PI3K/Akt pathway, and activated Nrf2/HO-1 pathway were observed in rat epileptiform hippocampal tissues and in vitro neurons. Furthermore, dynorphin activation of KOR alleviated in vitro seizure-like neuron injury via activation of PI3K/Akt/Nrf2/HO-1 pathway. Further in vivo investigation revealed that PDYN overexpression by intra-hippocampus injection of PDYN-overexpressing lentiviruses decreased hippocampal neuronal apoptosis and serum levels of inflammatory cytokines and malondialdehyde (MDA) content, and increased serum superoxide dismutase (SOD) level, in pilocarpine-induced epileptic rats. The protection of PDYN in vivo was associated with the activation of PI3K/Akt/Nrf2/HO-1 pathway. In conclusion, dynorphin activation of KOR protects against epilepsy and seizure-induced brain injury, which is associated with activation of the PI3K/Akt/Nrf2/HO-1 pathway.
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Affiliation(s)
- Hongmei Dai
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Peipei Wang
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Huafang Mao
- Department of Child Hygiene, Maternal and Child Health Hospital of Longhua District of Shenzhen City, ShenZhen, China
| | - Xiao Mao
- Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, Changsha, China
| | - Shan Tan
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Zhiheng Chen
- Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China
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6
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Burtscher J, Schwarzer C. The Opioid System in Temporal Lobe Epilepsy: Functional Role and Therapeutic Potential. Front Mol Neurosci 2017; 10:245. [PMID: 28824375 PMCID: PMC5545604 DOI: 10.3389/fnmol.2017.00245] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/24/2017] [Indexed: 12/13/2022] Open
Abstract
Temporal lobe epilepsy is considered to be one of the most common and severe forms of focal epilepsies. Patients often develop cognitive deficits and emotional blunting along the progression of the disease. The high incidence of resistance to antiepileptic drugs and a frequent lack of admissibility to surgery poses an unmet medical challenge. In the urgent quest of novel treatment strategies, neuropeptides are interesting candidates, however, their therapeutic potential has not yet been exploited. This review focuses on the functional role of the endogenous opioid system with respect to temporal lobe epilepsy, specifically in the hippocampus. The role of dynorphins and kappa opioid receptors (KOPr) as modulators of neuronal excitability is well understood: both the reduced release of glutamate as well of postsynaptic hyperpolarization were shown in glutamatergic neurons. In line with this, low levels of dynorphin in humans and mice increase the risk of epilepsy development. The role of enkephalins is not understood so well. On one hand, some agonists of the delta opioid receptors (DOPr) display pro-convulsant properties probably through inhibition of GABAergic interneurons. On the other hand, enkephalins play a neuro-protective role under hypoxic or anoxic conditions, most probably through positive effects on mitochondrial function. Despite the supposed absence of endorphins in the hippocampus, exogenous activation of the mu opioid receptors (MOPr) induces pro-convulsant effects. Recently-expanded knowledge of the complex ways opioid receptors ligands elicit their effects (including biased agonism, mixed binding, and opioid receptor heteromers), opens up exciting new therapeutic potentials with regards to seizures and epilepsy. Potential adverse side effects of KOPr agonists may be minimized through functional selectivity. Preclinical data suggest a high potential of such compounds to control seizures, with a strong predictive validity toward human patients. The discovery of DOPr-agonists without proconvulsant potential stimulates the research on the therapeutic use of neuroprotective potential of the enkephalin/DOPr system.
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Affiliation(s)
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of InnsbruckInnsbruck, Austria
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7
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Long HY, Feng L, Kang J, Luo ZH, Xiao WB, Long LL, Yan XX, Zhou L, Xiao B. Blood DNA methylation pattern is altered in mesial temporal lobe epilepsy. Sci Rep 2017; 7:43810. [PMID: 28276448 PMCID: PMC5343463 DOI: 10.1038/srep43810] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/31/2017] [Indexed: 12/28/2022] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) is a common epileptic disorder; little is known whether it is associated with peripheral epigenetic changes. Here we compared blood whole genomic DNA methylation pattern in MTLE patients (n = 30) relative to controls (n = 30) with the Human Methylation 450 K BeadChip assay, and explored genes and pathways that were differentially methylated using bioinformatics profiling. The MTLE and control groups showed significantly different (P < 1.03e-07) DNA methylation at 216 sites, with 164 sites involved hyper- and 52 sites hypo- methylation. Two hyper- and 32 hypo-methylated sites were associated with promoters, while 87 hyper- and 43 hypo-methylated sites corresponded to coding regions. The differentially methylated genes were largely related to pathways predicted to participate in anion binding, oxidoreductant activity, growth regulation, skeletal development and drug metabolism, with the most distinct ones included SLC34A2, CLCN6, CLCA4, CYP3A43, CYP3A4 and CYP2C9. Among the MTLE patients, panels of genes also appeared to be differentially methylated relative to disease duration, resistance to anti-epileptics and MRI alterations of hippocampal sclerosis. The peripheral epigenetic changes observed in MTLE could be involved in certain disease-related modulations and warrant further translational investigations.
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Affiliation(s)
- Hong-Yu Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Li Feng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Jin Kang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Zhao-Hui Luo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Wen-Biao Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Li-Li Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Xiao-Xin Yan
- Department of Anatomy and Neurobiology, Central South University School of Basic Medicine, Changsha, Hunan 410013, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Changsha, Hunan 410008, China
| | - Luo Zhou
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
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8
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Dixit AB, Banerjee J, Srivastava A, Tripathi M, Sarkar C, Kakkar A, Jain M, Chandra PS. RNA-seq analysis of hippocampal tissues reveals novel candidate genes for drug refractory epilepsy in patients with MTLE-HS. Genomics 2016; 107:178-88. [DOI: 10.1016/j.ygeno.2016.04.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 01/12/2016] [Accepted: 04/05/2016] [Indexed: 12/13/2022]
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9
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Zangrandi L, Burtscher J, MacKay JP, Colmers WF, Schwarzer C. The G-protein biased partial κ opioid receptor agonist 6'-GNTI blocks hippocampal paroxysmal discharges without inducing aversion. Br J Pharmacol 2016; 173:1756-67. [PMID: 26928671 PMCID: PMC4867738 DOI: 10.1111/bph.13474] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 02/05/2016] [Accepted: 02/09/2016] [Indexed: 11/29/2022] Open
Abstract
Background and Purpose With a prevalence of 1–2%, epilepsies belong to the most frequent neurological diseases worldwide. Although antiepileptic drugs are available since several decades, the incidence of patients that are refractory to medication is still over 30%. Antiepileptic effects of κ opioid receptor (κ receptor) agonists have been proposed since the 1980s. However, their clinical use was hampered by dysphoric side effects. Recently, G‐protein biased κ receptor agonists were developed, suggesting reduced aversive effects. Experimental Approach We investigated the effects of the κ receptor agonist U‐50488H and the G‐protein biased partial κ receptor agonist 6′‐GNTI in models of acute seizures and drug‐resistant temporal lobe epilepsy and in the conditioned place avoidance (CPA) test. Moreover, we performed slice electrophysiology to understand the functional mechanisms of 6′‐GNTI. Key Results As previously shown for U‐50488H, 6′‐GNTI markedly increased the threshold for pentylenetetrazole‐induced seizures. All treated mice displayed reduced paroxysmal activity in response to U‐50488H (20 mg·kg−1) or 6′‐GNTI (10–30 nmoles) treatment in the mouse model of intra‐hippocampal injection of kainic acid. Single cell recordings on hippocampal pyramidal cells revealed enhanced inhibitory signalling as potential mechanisms causing the reduction of paroxysmal activity. Effects of 6′‐GNTI were blocked in both seizure models by the κ receptor antagonist 5′‐GNTI. Moreover, 6′‐GNTI did not induce CPA, a measure of aversive effects, while U‐50488H did. Conclusions and Implications Our data provide the proof of principle that anticonvulsant/antiseizure and aversive effects of κ receptor activation can be pharmacologically separated in vivo.
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Affiliation(s)
- Luca Zangrandi
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Johannes Burtscher
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - James P MacKay
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - William F Colmers
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
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Jagirdar R, Drexel M, Bukovac A, Tasan RO, Sperk G. Expression of class II histone deacetylases in two mouse models of temporal lobe epilepsy. J Neurochem 2015; 136:717-730. [PMID: 26603269 PMCID: PMC4738395 DOI: 10.1111/jnc.13440] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 11/10/2015] [Indexed: 11/04/2022]
Abstract
Epigenetic mechanisms like altered histone acetylation may have a crucial role in epileptogenesis. In two mouse models of temporal lobe epilepsy, we investigated changes in the expression of class II histone deacetylases (HDAC), a group of signal transducers that shuttle between nucleus and cytoplasm. Intrahippocampal injection of kainic acid (KA) induced a status epilepticus, development of spontaneous seizures (after 3 days), and finally chronic epilepsy and granule cell dispersion. Expression of class II HDAC mRNAs was investigated at different time intervals after KA injection in the granule cell layers and in sectors CA1 and CA3 contralateral to the site of KA injection lacking neurodegeneration. Increased expression of HDAC5 and 9 mRNAs coincided with pronounced granule cell dispersion in the KA‐injected hippocampus at late intervals (14–28 days after KA) and equally affected both HDAC9 splice variants. In contrast, in the pilocarpine model (showing no granule cell dispersion), we observed decreases in the expression of HDAC5 and 9 at the same time intervals. Beyond this, striking similarities between both temporal lobe epilepsy models such as fast decreases in HDAC7 and 10 mRNAs during the acute status epilepticus were observed, notably also in the contralateral hippocampus not affected by neurodegeneration. The particular patterns of HDAC mRNA expression suggest a role in epileptogenesis and granule cell dispersion. Reduced expression of HDACs may result in increased expression of pro‐ and anticonvulsive proteins. On the other hand, export of HDACs from the nucleus into the cytoplasm could allow for deacetylation of cytoplasmatic proteins involved in axonal and dendritic remodeling, like granule cell dispersion. HDAC 5 and HDAC 9 expression is highly increased in granule cells of the KA‐injected hippocampus and parallels granule cell dispersion. Both HDACs are thought to be targeted to the cytoplasm and to act there by deacetylating cytoplasmatic (e.g. cytosceleton‐related) proteins.
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Affiliation(s)
- Rohan Jagirdar
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Meinrad Drexel
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Anneliese Bukovac
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Ramon O Tasan
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Günther Sperk
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
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Crowley NA, Kash TL. Kappa opioid receptor signaling in the brain: Circuitry and implications for treatment. Prog Neuropsychopharmacol Biol Psychiatry 2015; 62:51-60. [PMID: 25592680 PMCID: PMC4465498 DOI: 10.1016/j.pnpbp.2015.01.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/20/2014] [Accepted: 01/04/2015] [Indexed: 12/15/2022]
Abstract
Kappa opioid receptors (KORs) in the central nervous system have been known to be important regulators of a variety of psychiatry illnesses, including anxiety and addiction, but their precise involvement in these disorders is complex and has yet to be fully elucidated. Here, we briefly review the pharmacology of KORs in the brain, including KOR's involvement in anxiety, depression, and drug addiction. We also review the known neuronal circuitry impacted by KOR signaling, and interactions with corticotrophin-releasing factor (CRF), another key peptide in anxiety-related illnesses, as well as the role of glucocorticoids. We suggest that KORs are a promising therapeutic target for a host of neuropsychiatric conditions.
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Affiliation(s)
- Nicole A. Crowley
- Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA,Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Thomas L. Kash
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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12
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Clynen E, Swijsen A, Raijmakers M, Hoogland G, Rigo JM. Neuropeptides as targets for the development of anticonvulsant drugs. Mol Neurobiol 2014; 50:626-46. [PMID: 24705860 PMCID: PMC4182642 DOI: 10.1007/s12035-014-8669-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 02/27/2014] [Indexed: 11/04/2022]
Abstract
Epilepsy is a common neurological disorder characterized by recurrent seizures. These seizures are due to abnormal excessive and synchronous neuronal activity in the brain caused by a disruption of the delicate balance between excitation and inhibition. Neuropeptides can contribute to such misbalance by modulating the effect of classical excitatory and inhibitory neurotransmitters. In this review, we discuss 21 different neuropeptides that have been linked to seizure disorders. These neuropeptides show an aberrant expression and/or release in animal seizure models and/or epilepsy patients. Many of these endogenous peptides, like adrenocorticotropic hormone, angiotensin, cholecystokinin, cortistatin, dynorphin, galanin, ghrelin, neuropeptide Y, neurotensin, somatostatin, and thyrotropin-releasing hormone, are able to suppress seizures in the brain. Other neuropeptides, such as arginine-vasopressine peptide, corticotropin-releasing hormone, enkephalin, β-endorphin, pituitary adenylate cyclase-activating polypeptide, and tachykinins have proconvulsive properties. For oxytocin and melanin-concentrating hormone both pro- and anticonvulsive effects have been reported, and this seems to be dose or time dependent. All these neuropeptides and their receptors are interesting targets for the development of new antiepileptic drugs. Other neuropeptides such as nesfatin-1 and vasoactive intestinal peptide have been less studied in this field; however, as nesfatin-1 levels change over the course of epilepsy, this can be considered as an interesting marker to diagnose patients who have suffered a recent epileptic seizure.
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Affiliation(s)
- Elke Clynen
- Biomedical Research Institute BIOMED, Hasselt University, Martelarenlaan 42, 3500, Hasselt, Belgium,
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13
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McGinnity CJ, Shidahara M, Feldmann M, Keihaninejad S, Riaño Barros DA, Gousias IS, Duncan JS, Brooks DJ, Heckemann RA, Turkheimer FE, Hammers A, Koepp MJ. Quantification of opioid receptor availability following spontaneous epileptic seizures: correction of [11C]diprenorphine PET data for the partial-volume effect. Neuroimage 2013; 79:72-80. [PMID: 23597934 DOI: 10.1016/j.neuroimage.2013.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 04/03/2013] [Accepted: 04/05/2013] [Indexed: 10/27/2022] Open
Abstract
Previous positron emission tomography (PET) studies in refractory temporal lobe epilepsy (TLE) using the non-selective opioid receptor antagonist [(11)C]diprenorphine (DPN) did not detect any changes in mesial temporal structures, despite known involvement of the hippocampus in seizure generation. Normal binding in smaller hippocampi is suggestive of increased receptor concentration in the remaining grey matter. Correction for partial-volume effect (PVE) has not been used in previous DPN PET studies. Here, we present PVE-corrected DPN-PET data quantifying post-ictal and interictal opioid receptor availability in humans with mTLE. Eight paired datasets of post-ictal and interictal DPN PET scans and eleven test/retest control datasets were available from a previously published study on opioid receptor changes in TLE following seizures (Hammers et al., 2007a). Five of the eight participants with TLE had documented hippocampal sclerosis. Data were re-analyzed using regions of interest and a novel PVE correction method (structural functional synergistic-resolution recovery (SFS-RR); (Shidahara et al., 2012)). Data were denoised, followed by application of SFS-RR, with anatomical information derived via precise anatomical segmentation of the participants' MRI (MAPER; (Heckemann et al., 2010)). [(11)C]diprenorphine volume-of-distribution (VT) was quantified in six regions of interest. Post-ictal increases were observed in the ipsilateral fusiform gyri and lateral temporal pole. A novel finding was a post-ictal increase in [(11)C]DPN VT relative to the interictal state in the ipsilateral parahippocampal gyrus, not observed in uncorrected datasets. As for voxel-based (SPM) analyses, correction for global VT values was essential in order to demonstrate focal post-ictal increases in [(11)C]DPN VT. This study provides further direct human in vivo evidence for changes in opioid receptor availability in TLE following seizures, including changes that were not evident without PVE correction. Denoising, resolution recovery and precise anatomical segmentation can extract valuable information from PET studies that would be missed with conventional post-processing procedures.
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Affiliation(s)
- Colm J McGinnity
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
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Houser CR, Zhang N, Peng Z, Huang CS, Cetina Y. Neuroanatomical clues to altered neuronal activity in epilepsy: from ultrastructure to signaling pathways of dentate granule cells. Epilepsia 2012; 53 Suppl 1:67-77. [PMID: 22612811 DOI: 10.1111/j.1528-1167.2012.03477.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The dynamic aspects of epilepsy, in which seizures occur sporadically and are interspersed with periods of relatively normal brain function, present special challenges for neuroanatomical studies. Although numerous morphologic changes can be identified during the chronic period, the relationship of many of these changes to seizure generation and propagation remains unclear. Mossy fiber sprouting is an example of a frequently observed morphologic change for which a functional role in epilepsy continues to be debated. This review focuses on neuroanatomically identified changes that would support high levels of activity in reorganized mossy fibers and potentially associated granule cell activation. Early ultrastructural studies of reorganized mossy fiber terminals in human temporal lobe epilepsy tissue have identified morphologic substrates for highly efficacious excitatory connections among granule cells. If similar connections in animal models contribute to seizure activity, activation of granule cells would be expected. Increased labeling with two activity-related markers, Fos and phosphorylated extracellular signal-regulated kinase, has suggested increased activity of dentate granule cells at the time of spontaneous seizures in a mouse model of epilepsy. However, neuroanatomical support for a direct link between activation of reorganized mossy fiber terminals and increased granule cell activity remains elusive. As novel activity-related markers are developed, it may yet be possible to demonstrate such functional links and allow mapping of seizure activity throughout the brain. Relating patterns of neuronal activity during seizures to the underlying morphologic changes could provide important new insights into the basic mechanisms of epilepsy and seizure generation.
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Affiliation(s)
- Carolyn R Houser
- Department of Neurobiology, David Geffen School of Medicine at the University of California-Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095-1763, U.S.A.
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15
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Sperk G, Wieselthaler-Hölzl A, Pirker S, Tasan R, Strasser SS, Drexel M, Pifl C, Marschalek J, Ortler M, Trinka E, Heitmair-Wietzorrek K, Ciofi P, Feucht M, Baumgartner C, Czech T. Glutamate decarboxylase 67 is expressed in hippocampal mossy fibers of temporal lobe epilepsy patients. Hippocampus 2011; 22:590-603. [PMID: 21509853 DOI: 10.1002/hipo.20923] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2010] [Indexed: 11/12/2022]
Abstract
Recently, expression of glutamate decarboxylase-67 (GAD67), a key enzyme of GABA synthesis, was detected in the otherwise glutamatergic mossy fibers of the rat hippocampus. Synthesis of the enzyme was markedly enhanced after experimentally induced status epilepticus. Here, we investigated the expression of GAD67 protein and mRNA in 44 hippocampal specimens from patients with mesial temporal lobe epilepsy (TLE) using double immunofluorescence histochemistry, immunoblotting, and in situ hybridization. Both in specimens with (n = 37) and without (n = 7) hippocampal sclerosis, GAD67 was highly coexpressed with dynorphin in terminal areas of mossy fibers, including the dentate hilus and the stratum lucidum of sector CA3. In the cases with Ammon's horn sclerosis, also the inner molecular layer of the dentate gyrus contained strong staining for GAD67 immunoreactivity, indicating labeling of mossy fiber terminals that specifically sprout into this area. Double immunofluorescence revealed the colocalization of GAD67 immunoreactivity with the mossy fiber marker dynorphin. The extent of colabeling correlated with the number of seizures experienced by the patients. Furthermore, GAD67 mRNA was found in granule cells of the dentate gyrus. Levels, both of GAD67 mRNA and of GAD67 immunoreactivity were similar in sclerotic and nonsclerotic specimens and appeared to be increased compared to post mortem controls. Provided that the strong expression of GAD67 results in synthesis of GABA in hippocampal mossy fibers this may represent a self-protecting mechanism in TLE. In addition GAD67 expression also may result in conversion of excessive intracellular glutamate to nontoxic GABA within mossy fiber terminals.
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Affiliation(s)
- Günther Sperk
- Department of Pharmacology, Medical University Innsbruck, Austria.
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Abstract
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).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Sperk G, Drexel M, Pirker S. Neuronal plasticity in animal models and the epileptic human hippocampus. Epilepsia 2010; 50 Suppl 12:29-31. [PMID: 19941518 DOI: 10.1111/j.1528-1167.2009.02365.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Gunther Sperk
- Department of Pharmacology, Medical University Innsbruck, Austria.
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