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Witkin JM, Shafique H, Cerne R, Smith JL, Marini AM, Lipsky RH, Delery E. Mechanistic and therapeutic relationships of traumatic brain injury and γ-amino-butyric acid (GABA). Pharmacol Ther 2024; 256:108609. [PMID: 38369062 DOI: 10.1016/j.pharmthera.2024.108609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/18/2024] [Accepted: 02/01/2024] [Indexed: 02/20/2024]
Abstract
Traumatic brain injury (TBI) is a highly prevalent medical condition for which no medications specific for the prophylaxis or treatment of the condition as a whole exist. The spectrum of symptoms includes coma, headache, seizures, cognitive impairment, depression, and anxiety. Although it has been known for years that the inhibitory neurotransmitter γ-amino-butyric acid (GABA) is involved in TBI, no novel therapeutics based upon this mechanism have been introduced into clinical practice. We review the neuroanatomical, neurophysiological, neurochemical, and neuropharmacological relationships of GABA neurotransmission to TBI with a view toward new potential GABA-based medicines. The long-standing idea that excitatory and inhibitory (GABA and others) balances are disrupted by TBI is supported by the experimental data but has failed to invent novel methods of restoring this balance. The slow progress in advancing new treatments is due to the complexity of the disorder that encompasses multiple dynamically interacting biological processes including hemodynamic and metabolic systems, neurodegeneration and neurogenesis, major disruptions in neural networks and axons, frank brain lesions, and a multitude of symptoms that have differential neuronal and neurohormonal regulatory mechanisms. Although the current and ongoing clinical studies include GABAergic drugs, no novel GABA compounds are being explored. It is suggested that filling the gap in understanding the roles played by specific GABAA receptor configurations within specific neuronal circuits could help define new therapeutic approaches. Further research into the temporal and spatial delivery of GABA modulators should also be useful. Along with GABA modulation, research into the sequencing of GABA and non-GABA treatments will be needed.
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Affiliation(s)
- Jeffrey M Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA; Departments of Neuroscience and Trauma Research, Ascension St. Vincent Hospital, Indianapolis, IN, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA.
| | | | - Rok Cerne
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA; Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA
| | - Ann M Marini
- Department of Neurology, Program in Neuroscience, and Molecular and Cellular Biology Program, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Robert H Lipsky
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Elizabeth Delery
- College of Osteopathic Medicine, Marian University, Indianapolis, IN, USA.
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Cerne R, Lippa A, Poe MM, Smith JL, Jin X, Ping X, Golani LK, Cook JM, Witkin JM. GABAkines - Advances in the discovery, development, and commercialization of positive allosteric modulators of GABA A receptors. Pharmacol Ther 2022; 234:108035. [PMID: 34793859 PMCID: PMC9787737 DOI: 10.1016/j.pharmthera.2021.108035] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 11/08/2021] [Indexed: 12/25/2022]
Abstract
Positive allosteric modulators of γ-aminobutyric acid-A (GABAA) receptors or GABAkines have been widely used medicines for over 70 years for anxiety, epilepsy, sleep, and other disorders. Traditional GABAkines like diazepam have safety and tolerability concerns that include sedation, motor-impairment, respiratory depression, tolerance and dependence. Multiple GABAkines have entered clinical development but the issue of side-effects has not been fully solved. The compounds that are presently being developed and commercialized include several neuroactive steroids (an allopregnanolone formulation (brexanolone), an allopregnanolone prodrug (LYT-300), Sage-324, zuranolone, and ganaxolone), the α2/3-preferring GABAkine, KRM-II-81, and the α2/3/5-preferring GABAkine PF-06372865 (darigabat). The neuroactive steroids are in clinical development for post-partum depression, intractable epilepsy, tremor, status epilepticus, and genetic epilepsy disorders. Darigabat is in development for epilepsy and anxiety. The imidazodiazepine, KRM-II-81 is efficacious in animal models for the treatment of epilepsy and post-traumatic epilepsy, acute and chronic pain, as well as anxiety and depression. The efficacy of KRM-II-81 in models of pharmacoresistant epilepsy, preventing the development of seizure sensitization, and in brain tissue of intractable epileptic patients bodes well for improved therapeutics. Medicinal chemistry efforts are also ongoing to identify novel and improved GABAkines. The data document gaps in our understanding of the molecular pharmacology of GABAkines that drive differential pharmacological profiles, but emphasize advancements in the ability to successfully utilize GABAA receptor potentiation for therapeutic gain in neurology and psychiatry.
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Affiliation(s)
- Rok Cerne
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN USA,Faculty of Medicine, University of Ljubljana, Zaloška cesta 4, Ljubljana, Slovenia.,RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA,Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Arnold Lippa
- RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA
| | | | - Jodi L. Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN USA
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Xingjie Ping
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Lalit K. Golani
- Department of Chemistry and Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - James M. Cook
- RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA,Department of Chemistry and Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jeffrey M. Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN USA,RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA,Department of Chemistry and Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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Abstract
GABAB receptors are implicated in numerous central nervous system-based behaviours and mechanisms, including cognitive processing in preclinical animal models. Homeostatic changes in the expression and function of these receptors across brain structures have been found to affect cognitive processing. Numerous preclinical studies have focused on the role of GABAB receptors in learning, memory and cognition per se with some interesting, although sometimes contradictory, findings. The majority of the existing clinical literature focuses on alterations in GABAB receptor function in conditions and disorders whose main symptomatology includes deficits in cognitive processing. The aim of this chapter is to delineate the role of GABAB receptors in cognitive processes in health and disease of animal models and human clinical populations. More specifically, this review aims to present literature on the role of GABAB receptors in animal models with cognitive deficits, especially those of learning and memory. Further, it aims to capture the progress and advances of research studies on the effects of GABAB receptor compounds in neurodevelopmental and neurodegenerative conditions with cognitive dysfunctions. The neurodevelopmental conditions covered include autism spectrum disorders, fragile X syndrome and Down's syndrome and the neurodegenerative conditions discussed are Alzheimer's disease, epilepsy and autoimmune anti-GABAB encephalitis. Although some findings are contradictory, results indicate a possible therapeutic role of GABAB receptor compounds for the treatment of cognitive dysfunction and learning/memory impairments for some of these conditions, especially in neurodegeneration. Moreover, future research efforts should aim to develop selective GABAB receptor compounds with minimal, if any, side effects.
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Shaye H, Stauch B, Gati C, Cherezov V. Molecular mechanisms of metabotropic GABA B receptor function. SCIENCE ADVANCES 2021; 7:7/22/eabg3362. [PMID: 34049877 PMCID: PMC8163086 DOI: 10.1126/sciadv.abg3362] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 04/14/2021] [Indexed: 05/06/2023]
Abstract
Metabotropic γ-aminobutyric acid G protein-coupled receptors (GABAB) represent one of the two main types of inhibitory neurotransmitter receptors in the brain. These receptors act both pre- and postsynaptically by modulating the transmission of neuronal signals and are involved in a range of neurological diseases, from alcohol addiction to epilepsy. A series of recent cryo-EM studies revealed critical details of the activation mechanism of GABAB Structures are now available for the receptor bound to ligands with different modes of action, including antagonists, agonists, and positive allosteric modulators, and captured in different conformational states from the inactive apo to the fully active state bound to a G protein. These discoveries provide comprehensive insights into the activation of the GABAB receptor, which not only broaden our understanding of its structure, pharmacology, and physiological effects but also will ultimately facilitate the discovery of new therapeutic drugs and neuromodulators.
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Affiliation(s)
- Hamidreza Shaye
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
| | - Benjamin Stauch
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
| | - Cornelius Gati
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Vadim Cherezov
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA.
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
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Bruni O, Ferini-Strambi L, Giacomoni E, Pellegrino P. Herbal Remedies and Their Possible Effect on the GABAergic System and Sleep. Nutrients 2021; 13:nu13020530. [PMID: 33561990 PMCID: PMC7914492 DOI: 10.3390/nu13020530] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 01/22/2023] Open
Abstract
Sleep is an essential component of physical and emotional well-being, and lack, or disruption, of sleep due to insomnia is a highly prevalent problem. The interest in complementary and alternative medicines for treating or preventing insomnia has increased recently. Centuries-old herbal treatments, popular for their safety and effectiveness, include valerian, passionflower, lemon balm, lavender, and Californian poppy. These herbal medicines have been shown to reduce sleep latency and increase subjective and objective measures of sleep quality. Research into their molecular components revealed that their sedative and sleep-promoting properties rely on interactions with various neurotransmitter systems in the brain. Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that plays a major role in controlling different vigilance states. GABA receptors are the targets of many pharmacological treatments for insomnia, such as benzodiazepines. Here, we perform a systematic analysis of studies assessing the mechanisms of action of various herbal medicines on different subtypes of GABA receptors in the context of sleep control. Currently available evidence suggests that herbal extracts may exert some of their hypnotic and anxiolytic activity through interacting with GABA receptors and modulating GABAergic signaling in the brain, but their mechanism of action in the treatment of insomnia is not completely understood.
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Affiliation(s)
- Oliviero Bruni
- Department of Developmental and Social Psychology, Sapienza University, 00185 Rome, Italy
- Correspondence: ; Tel.: +39-33-5607-8964; Fax: +39-06-3377-5941
| | - Luigi Ferini-Strambi
- Department of Neurology, Ospedale San Raffaele Turro, 20127 Milan, Italy;
- Sleep Disorders Center, Vita-Salute San Raffaele University, 20132 Milan, Italy
| | - Elena Giacomoni
- Department of Medical Affairs, Sanofi Consumer HealthCare, 20158 Milan, Italy; (E.G.); (P.P.)
| | - Paolo Pellegrino
- Department of Medical Affairs, Sanofi Consumer HealthCare, 20158 Milan, Italy; (E.G.); (P.P.)
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Evenseth LSM, Gabrielsen M, Sylte I. The GABA B Receptor-Structure, Ligand Binding and Drug Development. Molecules 2020; 25:molecules25133093. [PMID: 32646032 PMCID: PMC7411975 DOI: 10.3390/molecules25133093] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 11/17/2022] Open
Abstract
The γ-aminobutyric acid (GABA) type B receptor (GABAB-R) belongs to class C of the G-protein coupled receptors (GPCRs). Together with the GABAA receptor, the receptor mediates the neurotransmission of GABA, the main inhibitory neurotransmitter in the central nervous system (CNS). In recent decades, the receptor has been extensively studied with the intention being to understand pathophysiological roles, structural mechanisms and develop drugs. The dysfunction of the receptor is linked to a broad variety of disorders, including anxiety, depression, alcohol addiction, memory and cancer. Despite extensive efforts, few compounds are known to target the receptor, and only the agonist baclofen is approved for clinical use. The receptor is a mandatory heterodimer of the GABAB1 and GABAB2 subunits, and each subunit is composed of an extracellular Venus Flytrap domain (VFT) and a transmembrane domain of seven α-helices (7TM domain). In this review, we briefly present the existing knowledge about the receptor structure, activation and compounds targeting the receptor, emphasizing the role of the receptor in previous and future drug design and discovery efforts.
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Affiliation(s)
- Linn Samira Mari Evenseth
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Mari Gabrielsen
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Ingebrigt Sylte
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
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Abstract
GABA (γ-aminobutyric acid) stimulation of the metabotropic GABAB receptor results in prolonged inhibition of neurotransmission that is central to brain physiology1. GABAB belongs to the Family C of G protein-coupled receptors (GPCRs), which operate as dimers to relay synaptic neurotransmitter signals into a cellular response through the binding and activation of heterotrimeric G proteins2,3. GABAB, however, is unique in its function as an obligate heterodimer in which agonist binding and G protein activation take place on distinct subunits4,5. Here we show structures of heterodimeric and homodimeric full-length GABAB receptors. Complemented by cellular signaling assays and atomistic simulations, the structures reveal an essential role for the GABAB extracellular loop 2 (ECL2) in relaying structural transitions by ordering the linker connecting the extracellular ligand-binding domain to the transmembrane region. Furthermore, the ECL2 of both GABAB subunits caps and interacts with the hydrophilic head of a phospholipid occupying the extracellular half of the transmembrane domain, thereby providing a potentially crucial link between ligand binding and the receptor core that engages G protein. These results provide a starting framework to decipher mechanistic modes of signal transduction mediated by GABAB dimers and have important implications for rational drug design targeting these receptors.
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Lima Neto JX, Bezerra KS, Barbosa ED, Oliveira JIN, Manzoni V, Soares-Rachetti VP, Albuquerque EL, Fulco UL. Exploring the Binding Mechanism of GABAB Receptor Agonists and Antagonists through in Silico Simulations. J Chem Inf Model 2019; 60:1005-1018. [DOI: 10.1021/acs.jcim.9b01025] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- José X. Lima Neto
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Katyanna S. Bezerra
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Emmanuel D. Barbosa
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Jonas I. N. Oliveira
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Vinícius Manzoni
- Instituto de Física, Universidade Federal do Alagoas, 57072-970 Maceió-AL, Brazil
| | - Vanessa P. Soares-Rachetti
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Eudenilson L. Albuquerque
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Umberto L. Fulco
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
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Trombley TA, Capstick RA, Lindsley CW. DARK Classics in Chemical Neuroscience: Gamma-Hydroxybutyrate (GHB). ACS Chem Neurosci 2019; 11:3850-3859. [PMID: 31287661 DOI: 10.1021/acschemneuro.9b00336] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gamma-hydroxybutyrate (GHB) is a naturally occurring short-chain fatty acid that rose to prominence as a popular club drug in the 1990s. Originally developed as an anesthetic in the early 1960s, it was later sold as an over-the-counter dietary supplement before becoming a rising substance of abuse in the following decades as one of the "date rape" drugs. Despite its abuse potential, there has been a recent surge in therapeutic interest in the drug due to its clinical viability in the treatment of narcolepsy and alcohol abuse/withdrawal. Its interactions with the GABAergic framework of higher mammals has made it the prototypical example for the study of the chief inhibitory mechanism in the human central nervous system. Though relatively obscure in terms of popular culture, it has a storied history with widespread usage in therapeutic, recreational ("Chemsex"), and some disturbingly nefarious contexts. This Review aims to capture its legacy through review of the history, synthesis, pharmacology, drug metabolism, and societal impact of this DARK classic in chemical neuroscience.
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Affiliation(s)
- Trevor A. Trombley
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Rory A. Capstick
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
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10
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GABAergic mediation of hippocampal theta rhythm induced by stimulation of the vagal nerve. Brain Res Bull 2019; 147:110-123. [DOI: 10.1016/j.brainresbull.2019.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 02/18/2019] [Indexed: 12/22/2022]
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Bell RL, Hauser S, Rodd ZA, Liang T, Sari Y, McClintick J, Rahman S, Engleman EA. A Genetic Animal Model of Alcoholism for Screening Medications to Treat Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 126:179-261. [PMID: 27055615 PMCID: PMC4851471 DOI: 10.1016/bs.irn.2016.02.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The purpose of this review is to present up-to-date pharmacological, genetic, and behavioral findings from the alcohol-preferring P rat and summarize similar past work. Behaviorally, the focus will be on how the P rat meets criteria put forth for a valid animal model of alcoholism with a highlight on its use as an animal model of polysubstance abuse, including alcohol, nicotine, and psychostimulants. Pharmacologically and genetically, the focus will be on the neurotransmitter and neuropeptide systems that have received the most attention: cholinergic, dopaminergic, GABAergic, glutamatergic, serotonergic, noradrenergic, corticotrophin releasing hormone, opioid, and neuropeptide Y. Herein, we sought to place the P rat's behavioral and neurochemical phenotypes, and to some extent its genotype, in the context of the clinical literature. After reviewing the findings thus far, this chapter discusses future directions for expanding the use of this genetic animal model of alcoholism to identify molecular targets for treating drug addiction in general.
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Affiliation(s)
- R L Bell
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - S Hauser
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Z A Rodd
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - T Liang
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - Y Sari
- University of Toledo, Toledo, OH, United States
| | - J McClintick
- Center for Medical Genomics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - S Rahman
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, United States
| | - E A Engleman
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
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Enna SJ, Reisman SA, Stanford JA. CGP 56999A, a GABA(B) receptor antagonist, enhances expression of brain-derived neurotrophic factor and attenuates dopamine depletion in the rat corpus striatum following a 6-hydroxydopamine lesion of the nigrostriatal pathway. Neurosci Lett 2006; 406:102-6. [PMID: 16890350 DOI: 10.1016/j.neulet.2006.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 05/19/2006] [Accepted: 07/10/2006] [Indexed: 01/11/2023]
Abstract
Rats were injected (i.p.) once daily with either 1 mg/kg CGP 56999A, a gamma-aminobutyric acid(B) (GABA(B)) receptor antagonist, or an equivalent volume of saline beginning 7 days prior to, and continuing for 7 days following, a unilateral 6-hydroxydopamine lesion of the nigrostriatal dopamine (DA) pathway. At the end of the CGP 56999A treatment period the concentrations of DA and dihydroxyphenylacetic acid (DOPAC), as well as the expression of brain-derived neurotrophic factor (BDNF), were analyzed in corpus striatum ipsilateral and contralateral to the lesioning. No significant differences in these parameters were noted in the contralateral striatum between saline- and CGP 56999A-treated subjects. In contrast, as compared to animals receiving saline only, daily treatment with the GABA(B) receptor antagonist significantly attenuated the 6-hydroxydopamine-induced decline in DA and increased the expression of BDNF in the ipsilateral striatum. The results indicate that CGP 56999A enhances BDNF gene expression in the rat corpus striatum and prevents the decline in DA content that is a characteristic sequela of 6-hydroxydopapmine lesions of the nigrostraital dopamine pathway. These findings suggest that GABA(B) receptor antagonists may be of value in the treatment of Parkinson's disease and other conditions that would benefit from an enhanced production of neurotrophic factors in brain.
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Affiliation(s)
- S J Enna
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA
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Gupta S, Jain S, Brahmachari SK, Kukreti R. Pharmacogenomics: a path to predictive medicine for schizophrenia. Pharmacogenomics 2006; 7:31-47. [PMID: 16354123 DOI: 10.2217/14622416.7.1.31] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A significant variability is observed among patients in response to antipsychotics, and is caused by a variety of factors. This review summarizes the available knowledge of associations between pharmacogenetics and drug response in schizophrenia. The multifactorial etiology of schizophrenia makes it a complex interaction of symptoms. Adopting a pharmacogenomics approach represents a unique opportunity for the prediction of response to antipsychotic drugs by investigating genes implicated with specific symptoms and side effects. A network model of the interaction/crosstalk between the neurotransmitter signaling systems is presented to emphasize the importance of the genes associated with the molecular mechanisms of the disease and drug response. These genes may serve as potential susceptibility genes and drug targets for schizophrenia. The crucial point for the identification of a significant biologic marker(s) will include not only the experimental validation of the genes involved in the neurotransmitter signaling systems, but also the availability of large exactly comparable phenotyped patients samples. Coupling our knowledge of genetic polymorphisms with clinical response data promises a bright future for rapid advances in personalized medicine.
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Affiliation(s)
- Simone Gupta
- Institute of Genomics and Integrative Biology (CSIR), Delhi University Campus, Delhi 110007, India
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14
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Abstract
A great deal of effort has been expended in attempting to define the role of GABA in mediating the transmission and perception of pain. Pursuit of this question has been stimulated by the fact that GABAergic neurons are widely distributed throughout the central nervous system, including regions of the spinal cord dorsal horn known to be important for transmitting pain impulses to the brain. In addition, GABA neurons and receptors are found in supraspinal sites known to coordinate the perception and response to painful stimuli and this neurotransmitter system has been shown to regulate control of sensory information processing in the spinal cord. The discovery that GABA receptor agonists display antinociceptive properties in a variety of animal models of pain has provided an impetus for developing such agents for this purpose. It has been shown that GABA receptor agonists, as well as inhibitors of GABA uptake or metabolism, are clinically effective in treating this symptom. However, even with an enhanced understanding of the relationship between GABAergic transmission and pain, it has proven difficult to exploit these findings in designing novel analgesics that can be employed for the routine management of pain. Work in this area has revealed a host of reasons why GABAergic drugs have, to date, been of limited utility in the management of pain. Chief among these are the side effects associated with such agents, in particular sedation. These limitations are likely due to the simultaneous activation of GABA receptors throughout the neuraxis, most of which are not involved in the transmission or perception of pain. This makes it difficult to fully exploit the antinociceptive properties of GABAergic drugs before untoward effects intervene. The discovery of molecularly and pharmacologically distinct GABAA receptors may open the way to developing subtype selective agents that target those receptors most intimately involved in the transmission and perception of pain. The more limited repertoire of GABAB receptor subunits makes it more difficult to develop subtype selective agents for this site. Nonetheless, a GABAB agonist, CGP 35024, has been identified that induces antinociceptive responses at doses well below those that cause sedation (Patel et al., 2001). It has also been reported that, unlike baclofen, tolerance to antinociceptive responses is not observed with CGP 44532, a more potent GABAB receptor agonist (Enna et al., 1998). While the reasons for these differences in responses to members of the same class remain unknown, these findings suggest it may be possible to design a GABAB agonist with a superior clinical profile than existing agents. Besides the challenges associated with identifying subtype selective GABAA and GABAB receptor agonists, the development of GABA analgesics has been hindered by the fact that the responsiveness of these receptor systems appear to vary with the type and duration of pain being treated and the mode of drug administration. Further studies are necessary to more precisely define the types of pain most amenable to treatment with GABAergic drugs. Inasmuch as the antinociceptive responses to these agents in laboratory animals are mediated, at least in part, through activation or inhibition of other neurotransmitter and neuromodulator systems, it is conceivable that GABA agonists will be most efficacious as analgesics when administered in combination with other agents. The results of anatomical, biochemical, molecular, and pharmacological studies support the notion that generalized activation of GABA receptor systems dampens the response to painful stimuli. The data leave little doubt that, under certain circumstances, stimulation of neuroanatomically discreet GABA receptor sites could be of benefit in the management of pain. Continued research in this area is warranted given the limited choices, and clinical difficulties, associated with conventional analgesics.
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Affiliation(s)
- S J Enna
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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15
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Abstract
Arginine plays an important role in many physiologic and biologic processes beyond its role as a protein-incorporated amino acid. Dietary supplementation of arginine can enhance wound healing, regulate endocrine activity and potentiate immune activity. Under normal unstressed conditions the arginine requirement of adult humans is fulfilled by endogenous sources, however this is compromised during times of stress, especially in critical illness. These finding have led to use of arginine supplementation as part of an immune-enhancing dietary regimen to help combat the immune suppression seen in such patients. Though the results from studies examining the use of this type of immunonutrition in critically ill patients are far from definitive, they are promising that this mode of therapy may be of some advantage. A better understanding of the in vivo biology of arginine and its metabolism is necessary to truly define a benefit from arginine supplementation.
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Affiliation(s)
- D Efron
- Department of Surgery, Sinai Hospital of Baltimore, MD 21215, USA
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