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Harper KM, Knapp DJ, Todd CA, Balan I, Aurelian L, Criswell HE, Breese GR. Phenotyping CCL2 Containing Central Amygdala Neurons Controlling Alcohol Withdrawal-Induced Anxiety. Front Cell Neurosci 2020; 14:580583. [PMID: 33192326 PMCID: PMC7531233 DOI: 10.3389/fncel.2020.580583] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/24/2020] [Indexed: 11/30/2022] Open
Abstract
Chemokines such as chemokine (C-C motif) ligand 2 (CCL2) play a role in several behaviors, including anxiety-like behavior, but whether neurons are an important source of CCL2 for behavior and how neuronal CCL2 may work to affect behavior are still debated. When a herpes simplex virus (HSV) vector was used to knockdown CCL2 mRNA in neurons of the central nucleus of the amygdala (CeA) in rats experiencing multiple withdrawals from low dose ethanol, anxiety-like behavior appeared in the social interaction task. To examine this finding further Fractalkine (CX3CL1), a chemokine that is often found to have an opposing function to CCL2 was measured in these rats. Both alcohol withdrawal and CCL2 knockdown increased the levels of the anti-inflammatory protein CX3CL1. The combination of alcohol withdrawal and CCL2 knockdown decreased CX3CL1 and may alter pro-inflammatory/anti-inflammatory balance, and thus highlights the potential importance of CCL2 and CCL2/CX3CL1 balance in anxiety. To find a mechanism by which neuronal chemokines like CCL2 could affect behavior, retrograde tracing with fluorescent nanobeads was done in two brain regions associated with anxiety the bed nucleus of the stria terminalis (BNST) and the ventral periaqueductal gray (VPAG). These studies identified CeA projection neurons to these brain regions that contain CCL2. To demonstrate that CCL2 can be transported via axons to downstream brain regions, the axonal transport blocker, colchicine, was given and 24 h later, the accumulation of CCL2 in CeA neuronal cell bodies was found. Finally, CCL2 in CeA neurons was localized to the synapse using confocal microscopy with enhanced resolution following deconvolution and electron microscopy, which along with the other evidence suggests that CCL2 may be transported down axons in CeA neurons and released from nerve terminals perhaps into brain regions like the BNST and VPAG to affect behaviors such as anxiety. These results suggest that neurons are an important target for chemokine research related to behavior.
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Affiliation(s)
- Kathryn M Harper
- Department of Psychiatry, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States.,Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States
| | - Darin J Knapp
- Department of Psychiatry, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States.,Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States
| | - Caroline A Todd
- Department of Psychiatry, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States
| | - Irina Balan
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States.,Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Laure Aurelian
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, United States.,Stanford University School of Medicine, Stanford University, Stanford, CA, United States
| | - Hugh E Criswell
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States
| | - George R Breese
- Department of Psychiatry, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States.,Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States.,Department of Pharmacology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States
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Harper KM, Knapp DJ, Butler RK, Cook CA, Criswell HE, Stuber GD, Breese GR. Amygdala Arginine Vasopressin Modulates Chronic Ethanol Withdrawal Anxiety-Like Behavior in the Social Interaction Task. Alcohol Clin Exp Res 2019; 43:2134-2143. [PMID: 31386210 DOI: 10.1111/acer.14163] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/19/2019] [Indexed: 01/30/2023]
Abstract
BACKGROUND Chronic ethanol (EtOH) exposure induces neurobehavioral maladaptations in the brain though the precise changes have not been fully explored. The central nucleus of the amygdala (CEA) regulates anxiety-like behavior induced by withdrawal from chronic intermittent EtOH (CIE) exposure, and the arginine vasopressin (AVP) system within the CEA regulates many anxiety-like behaviors. Thus, adaptations occur in the CEA AVP system due to chronic EtOH exposure, which lead to anxiety-like behaviors in rats. METHODS Chronic exposure to a low-dose EtOH (4.5% wt/vol) induces anxiety-like behavior in rats. Wistar or Sprague Dawley rats were exposed to a modified CIE or CIE, while intra-CEA microinjections of AVP or a V1b receptor antagonist were used to elicit or block withdrawal-induced anxiety. Additionally, AVP microinjections into the CEA were given 24 hours following 15 days of continuous high-dose EtOH (7% wt/vol), a time period when rats no longer express anxiety. Chemogenetics was also used to activate the basolateral amygdala (BLA) or deactivate the dorsal periaqueductal gray=(dm/dlPAG) therefore PAG=periaqueductal gray to elicit or block withdrawal-induced anxiety. RESULTS AVP microinjected into the CEA in lieu of exposure to the first 2 cycles of CIE was sufficient to induce anxiety-like behavior in these commonly used rat strains. The V1b receptor antagonist, but not an oxytocin receptor agonist, into the CEA during the first 2 withdrawal cycles suppressed anxiety. However, activation of the BLA in lieu of exposure to the first 2 cycles of CIE was insufficient to induce anxiety-like behavior. AVP microinjection into the CEA 24 hours into withdrawal reelicited anxiety-like behavior, and deactivation of the dm/dlPAG reduced this effect of CEA AVP. CONCLUSIONS Taken together, this study demonstrates a role of CEA AVP and a CEA-dm/dlPAG circuit in the development of anxiety induced by CIE. Such information is valuable for identifying novel therapeutic targets for alcohol- and anxiety-associated disorders.
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Affiliation(s)
- Kathryn M Harper
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Darin J Knapp
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Ryan K Butler
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cory A Cook
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Hugh E Criswell
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Garret D Stuber
- Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Curriculum in Neurobiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - George R Breese
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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3
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Abstract
BACKGROUND Arginine vasopressin (VP) has been implicated in a number of neuropsychiatric disorders with an emphasis on situations where stress increased the severity of the disorder. Based on this hypothesized role for VP in neuropsychiatric disorders, much research is currently being undertaken in humans and animals to test VP as a target for treatment of a number of these disorders including alcohol abuse. OBJECTIVES To provide a summary of the literature regarding the role of VP in alcohol- and stress-related behaviors including the use of drugs that target VP in clinical trials. RESULTS Changes in various components of the VP system occur with alcohol and stress. Manipulating VP or its receptors can alter alcohol- and stress-related behaviors including tolerance to alcohol, alcohol drinking, and anxiety-like behavior. Finally, the hypothalamic-pituitary-adrenal axis response to alcohol is also altered by manipulating the VP system. However, clinical trials of VP antagonists have had mixed results. CONCLUSIONS A review of VP's involvement in alcohol's actions demonstrates that there is much to be learned about brain regions involved in VP-mediated effects on behavior. Thus, future work should focus on elucidating relevant brain regions. By using previous knowledge of the actions of VP and determining the brain regions and/or systems involved in its different behavioral effects, it may be possible to identify a specific receptor subtype target, drug treatment combination, or specific clinical contexts that may point toward a more successful treatment.
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Affiliation(s)
- Kathryn M Harper
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, CB #7178, Thurston Bowles Building, Chapel Hill, NC, 27599-7178, USA.
| | - Darin J Knapp
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, CB #7178, Thurston Bowles Building, Chapel Hill, NC, 27599-7178, USA
- Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7178, USA
| | - Hugh E Criswell
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, CB #7178, Thurston Bowles Building, Chapel Hill, NC, 27599-7178, USA
- Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7178, USA
| | - George R Breese
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, CB #7178, Thurston Bowles Building, Chapel Hill, NC, 27599-7178, USA
- Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7178, USA
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7178, USA
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Weinberg MS, Criswell HE, Powell SK, Bhatt AP, McCown TJ. Viral Vector Reprogramming of Adult Resident Striatal Oligodendrocytes into Functional Neurons. Mol Ther 2017; 25:928-934. [PMID: 28202388 DOI: 10.1016/j.ymthe.2017.01.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/06/2017] [Accepted: 01/11/2017] [Indexed: 11/18/2022] Open
Abstract
Recent advances suggest that in vivo reprogramming of endogenous cell populations provides a viable alternative for neuron replacement. Astrocytes and oligodendrocyte precursor cells can be induced to transdifferentiate into neurons in the CNS, but, in these instances, reprogramming requires either transgenic mice or retroviral-mediated gene expression. We developed a microRNA (miRNA)-GFP construct that in vitro significantly reduced the expression of polypyrimidine tract-binding protein, and, subsequently, we packaged this construct in a novel oligodendrocyte preferring adeno-associated virus vector. Ten days after rat striatal transduction, the vast majority of the GFP-positive cells were oligodendrocytes, but 6 weeks to 6 months later, the majority of GFP-positive cells exhibited neuronal morphology and co-localized with the neuronal marker NeuN. Patch-clamp studies on striatal slices established that the GFP-positive cells exhibited electrophysiological properties indicative of mature neurons, such as spontaneous action potentials and spontaneous inhibitory postsynaptic currents. Also, 3 months after striatal vector administration, GFP-positive terminals in the ipsilateral globus pallidus or substantia nigra retrogradely transported fluorescent beads back to GFP-positive striatal cell bodies, indicating the presence of functional presynaptic terminals. Thus, this viral vector approach provides a potential means to harness resident oligodendrocytes as an endogenous source for in vivo neuronal replacement.
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Affiliation(s)
- Marc S Weinberg
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Hugh E Criswell
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sara K Powell
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Aadra P Bhatt
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Thomas J McCown
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Ming Z, Criswell HE, Breese GR. Evidence for TNFα action on excitatory and inhibitory neurotransmission in the central amygdala: a brain site influenced by stress. Brain Behav Immun 2013; 33:102-11. [PMID: 23770090 PMCID: PMC3775850 DOI: 10.1016/j.bbi.2013.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 05/29/2013] [Accepted: 06/01/2013] [Indexed: 12/12/2022] Open
Abstract
Anxiety-like responses to stress are accompanied by elevation of brain cytokine-mRNAs. Because cytokines microinjected into central-amygdala (CeA) substitute for stress in a behavioral paradigm, the possibility was raised that cytokines increased by stress influence behavior by affecting CeA-neural activity. Previously, cytokines increased firing-rate of CeA-neurons comparable to that induced by corticotropin-releasing factor (CRF). In this investigation, tumor-necrosis-factor-α (TNFα) increased amplitude, but not frequency of mEPSCs from CeA-neurons. Additionally, TNFα decreased the threshold for triggering action potentials from CeA-neurons without altering membrane-properties during current-clamp recording. Glutamate-receptor-antagonist blockade of mEPSCs and the TNFα-induced reduction in firing threshold implicated glutamate in these changes. A phosphatidyl-inositol-3-kinase-antagonist prevented the TNFα-induced increased in amplitude of mEPSCs, documenting a TNFα intracellular influence. Additionally, TNFα increased frequency, but not amplitude of mIPSCs. CRF-receptor-antagonists were found to prevent the TNFα-induced increase in mIPSC-frequency, without altering the TNFα-induced amplitude increase in mEPSCs or the reduced threshold for action-potentials by TNFα. To clarify how TNFα was increasing CRF-release in the presence of tetrodotoxin, the possibility tested was whether preventing glial-activation would prevent this elevated mIPSC-frequency blocked by CRF-receptor antagonists. Minocycline, which blocks glial activation, prevented the TNFα-induced increase in mIPSC-frequency - a finding consistent with glia contributing to the CRF-involvement in this TNFα action. To fully understand the means by which a CRF1-receptor-antagonist and minocycline prevent TNFα from increasing mIPSC-frequency will require further clarification. Nonetheless, these data provide convincing evidence that release of TNFα by stress could alter neural activity of CeA-neurons by influencing GABA-and glutamate function.
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Affiliation(s)
- Zhen Ming
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Hugh E. Criswell
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - George R. Breese
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC USA
- Department of Psychiatry, The University of North Carolina at Chapel Hill, Chapel Hill, NC USA
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC USA
- UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC USA
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6
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Knapp DJ, Whitman BA, Wills TA, Angel RA, Overstreet DH, Criswell HE, Ming Z, Breese GR. Cytokine involvement in stress may depend on corticotrophin releasing factor to sensitize ethanol withdrawal anxiety. Brain Behav Immun 2011; 25 Suppl 1:S146-54. [PMID: 21377524 PMCID: PMC3138123 DOI: 10.1016/j.bbi.2011.02.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 02/27/2011] [Accepted: 02/28/2011] [Indexed: 12/23/2022] Open
Abstract
Stress has been shown to facilitate ethanol withdrawal-induced anxiety. Defining neurobiological mechanisms through which stress has such actions is important given the associated risk of relapse. While CRF has long been implicated in the action of stress, current results show that stress elevates the cytokine TNFα in the rat brain and thereby implicates cytokines in stress effects. In support of this view, prior TNFα microinjection into the central amygdala (CeA) of rats facilitated ethanol withdrawal-induced anxiety-a response that could not be attributed to an increase in plasma corticosterone. To test for a possible interaction between cytokines and CRF, a CRF1-receptor antagonist (SSR125543) administered prior to the repeated administration of TNFα or MCP-1/CCL2 reduced the magnitude of the withdrawal-induced anxiety. This finding provided evidence for cytokine action being dependent upon CRF. Additionally, the sensitizing effect of stress on withdrawal-induced anxiety was reduced by treating the repeated stress exposure prior to ethanol with the MEK inhibitor SL327. Consistent with cytokines having a neuromediator function distinct from a neuroimmune action, TNFα increased firing rate and GABA release from CeA neurons. Thus, an interaction of glial and neuronal function is proposed to contribute to the interaction of stress and chronic ethanol. Interrupting this potential glial-neuronal interaction could provide a novel means by which to alter the development of emotional states induced by stress that predict relapse in the alcoholic.
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Affiliation(s)
- Darin J. Knapp
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Corresponding Author: Darin J. Knapp, PhD. CB 7178, University of North Carolina, Chapel Hill, NC 27599, ; Phone: 919-966-0505; Fax: 919-966-5679
| | - Buddy A. Whitman
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - Tiffany A. Wills
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - Robert A. Angel
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - David H. Overstreet
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - Hugh E. Criswell
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - Zhen Ming
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - George R. Breese
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599,Department of Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
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Werner DF, Kumar S, Criswell HE, Suryanarayanan A, Fetzer JA, Comerford CE, Morrow AL. PKCγ is required for ethanol-induced increases in GABA(A) receptor α4 subunit expression in cultured cerebral cortical neurons. J Neurochem 2011; 116:554-63. [PMID: 21155805 DOI: 10.1111/j.1471-4159.2010.07140.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ethanol exposure produces alterations in GABA(A) receptor function and expression associated with CNS hyperexcitability, but the mechanisms of these effects are unknown. Ethanol is known to increase both GABA(A) receptor α4 subunits and protein kinase C (PKC) isozymes in vivo and in vitro. Here, we investigated ethanol regulation of GABA(A) receptor α4 subunit expression in cultured cortical neurons to delineate the role of PKC. Cultured neurons were prepared from rat pups on postnatal day 0-1 and tested after 18 days. GABA(A) receptor α4 subunit surface expression was assessed using P2 fractionation and surface biotinylation following ethanol exposure for 4 h. Miniature inhibitory post-synaptic currents were measured using whole cell patch clamp recordings. Ethanol increased GABA(A) receptor α4 subunit expression in both the P2 and biotinylated fractions, while reducing the decay time constant in miniature inhibitory post-synaptic currents, with no effect on γ2 or δ subunits. PKC activation mimicked ethanol effects, while the PKC inhibitor calphostin C prevented ethanol-induced increases in GABA(A) receptor α4 subunit expression. PKCγ siRNA knockdown prevented ethanol-induced increases in GABA(A) receptor α4 subunit expression, but inhibition of the PKCβ isoform with PKCβ pseudosubstrate had no effect. We conclude that PKCγ regulates ethanol-induced alterations in α4-containing GABA(A) receptors.
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Affiliation(s)
- David F Werner
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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8
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Kelm MK, Criswell HE, Breese GR. Ethanol-enhanced GABA release: a focus on G protein-coupled receptors. Brain Res Rev 2011; 65:113-23. [PMID: 20837058 PMCID: PMC3005894 DOI: 10.1016/j.brainresrev.2010.09.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 09/01/2010] [Accepted: 09/02/2010] [Indexed: 12/20/2022]
Abstract
While research on the actions of ethanol at the GABAergic synapse has focused on postsynaptic mechanisms, recent data have demonstrated that ethanol also facilitates GABA release from presynaptic terminals in many, but not all, brain regions. The ability of ethanol to increase GABA release can be regulated by different G protein-coupled receptors (GPCRs), such as the cannabinoid-1 receptor, corticotropin-releasing factor 1 receptor, GABA(B) receptor, and the 5-hydroxytryptamine 2C receptor. The intracellular messengers linked to these GPCRs, including the calcium that is released from internal stores, also play a role in ethanol-enhanced GABA release. Hypotheses are proposed to explain how ethanol interacts with the GPCR pathways to increase GABA release and how this interaction contributes to the brain region specificity of ethanol-enhanced GABA release. Defining the mechanism of ethanol-facilitated GABA release will further our understanding of the GABAergic profile of ethanol and increase our knowledge of how GABAergic neurotransmission may contribute to the intoxicating effects of alcohol and to alcohol dependence.
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Affiliation(s)
- M Katherine Kelm
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, NC 27599-7178, USA.
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9
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Kelm MK, Weinberg RJ, Criswell HE, Breese GR. The PLC/IP 3 R/PKC pathway is required for ethanol-enhanced GABA release. Neuropharmacology 2010; 58:1179-86. [PMID: 20206640 DOI: 10.1016/j.neuropharm.2010.02.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/23/2010] [Accepted: 02/24/2010] [Indexed: 12/31/2022]
Abstract
Research on the actions of ethanol at the GABAergic synapse has traditionally focused on postsynaptic mechanisms, but recent data demonstrate that ethanol also increases both evoked and spontaneous GABA release in many brain regions. Using whole-cell voltage-clamp recordings, we previously showed that ethanol increases spontaneous GABA release at the rat interneuron-Purkinje cell synapse. This presynaptic ethanol effect is dependent on calcium release from internal stores, possibly through activation of inositol 1,4,5-trisphosphate receptors (IP(3)Rs). After confirming that ethanol targets vesicular GABA release, in the present study we used electron microscopic immunohistochemistry to demonstrate that IP(3)Rs are located in presynaptic terminals of cerebellar interneurons. Activation of IP(3)Rs requires binding of IP(3), generated through activation of phospholipase C (PLC). We find that the PLC antagonist edelfosine prevents ethanol from increasing spontaneous GABA release. Diacylglycerol generated by PLC and calcium released by activation of the IP(3)R activate protein kinase C (PKC). Ethanol-enhanced GABA release was blocked by two PKC antagonists, chelerythrine and calphostin C. When a membrane impermeable PKC antagonist, PKC (19-36), was delivered intracellularly to the postsynaptic neuron, ethanol continued to increase spontaneous GABA release. Overall, these results suggest that activation of the PLC/IP(3)R/PKC pathway is necessary for ethanol to increase spontaneous GABA release from presynaptic terminals onto Purkinje cells.
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Affiliation(s)
- M Katherine Kelm
- Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7365, USA.
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10
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Gray SJ, Blake BL, Criswell HE, Nicolson SC, Samulski RJ, McCown TJ, Li W. Directed evolution of a novel adeno-associated virus (AAV) vector that crosses the seizure-compromised blood-brain barrier (BBB). Mol Ther 2010; 18:570-8. [PMID: 20040913 PMCID: PMC2831133 DOI: 10.1038/mt.2009.292] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 11/30/2009] [Indexed: 12/11/2022] Open
Abstract
DNA shuffling and directed evolution were employed to develop a novel adeno-associated virus (AAV) vector capable of crossing the seizure-compromised blood-brain barrier (BBB) and transducing cells in the brain. Capsid DNA from AAV serotypes 1-6, 8, and 9 were shuffled and recombined to create a library of chimeric AAVs. One day after kainic acid-induced limbic seizure activity in rats, the virus library was infused intravenously (i.v.), and 3 days later, neuron-rich cells were mechanically dissociated from seizure-sensitive brain sites, collected and viral DNA extracted. After three cycles of selection, green fluorescent protein (GFP)-packaged clones were administered directly into brain or i.v. 1 day after kainic acid-induced seizures. Several clones that were effective after intracranial administration did not transduce brain cells after the i.v. administration. However, two clones (32 and 83) transduced the cells after direct brain infusion and after i.v. administration transduced the cells that were localized to the piriform cortex and ventral hippocampus, areas exhibiting a seizure-compromised BBB. No transduction occurred in areas devoid of BBB compromise. Only one parental serotype (AAV8) exhibited a similar expression profile, but the biodistribution of 32 and 83 diverged dramatically from this parental serotype. Thus, novel AAV vectors have been created that can selectively cross the seizure-compromised BBB and transduce cells.
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Affiliation(s)
- Steven J Gray
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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11
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Kelm MK, Criswell HE, Breese GR. The role of protein kinase A in the ethanol-induced increase in spontaneous GABA release onto cerebellar Purkinje neurons. J Neurophysiol 2008; 100:3417-28. [PMID: 18945815 DOI: 10.1152/jn.90970.2008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Ethanol increases miniature inhibitory postsynaptic current frequency and decreases the paired-pulse ratio, which suggests that ethanol increases both spontaneous and evoked GABA release, respectively. We have shown previously that ethanol increases GABA release at the rat interneuron-Purkinje cell synapse and that this ethanol effect involves calcium release from internal stores; however, further exploration of the mechanism responsible for ethanol-enhanced GABA release was needed. We found that a cannabinoid receptor 1 (CB1) agonist, WIN-55212, and a GABA(B) receptor agonist, baclofen, decreased baseline spontaneous GABA release and prevented ethanol from increasing spontaneous GABA release. The CB1 receptor and GABA(B) receptor are Galpha i-linked G protein-coupled receptors with common downstream messengers that include adenylate cyclase and protein kinase A (PKA). Adenylate cyclase and PKA antagonists blocked ethanol from increasing spontaneous GABA release, whereas a PKA antagonist limited to the postsynaptic neuron did not block ethanol from increasing spontaneous GABA release. These results suggest that presynaptic PKA plays an essential role in ethanol-enhanced spontaneous GABA release. Similar to ethanol, we found that the mechanism of the cannabinoid-mediated decrease in spontaneous GABA release involves internal calcium stores and PKA. A PKA antagonist decreased baseline spontaneous GABA release. This effect was reduced after incubating the slice with a calcium chelator, BAPTA-AM, but was unaffected when BAPTA was limited to the postsynaptic neuron. This suggests that the PKA antagonist is acting through a presynaptic, calcium-dependent mechanism to decrease spontaneous GABA release. Overall, these results suggest that PKA activation is necessary for ethanol to increase spontaneous GABA release.
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Affiliation(s)
- M Katherine Kelm
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7178, USA.
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Criswell HE, Ming Z, Kelm MK, Breese GR. Brain regional differences in the effect of ethanol on GABA release from presynaptic terminals. J Pharmacol Exp Ther 2008; 326:596-603. [PMID: 18502983 DOI: 10.1124/jpet.107.135418] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Whereas ethanol has behavioral actions consistent with increased GABAergic function, attempts to demonstrate a direct enhancement of GABA-gated currents by ethanol have produced mixed results. Recent work has suggested that a part of the GABAergic profile of ethanol may result from enhanced GABA release from presynaptic terminals. The present study examines the effect of ethanol on GABA release in several brain regions to assess the regional nature of ethanol-induced GABA release. Whole-cell voltage clamp recording of spontaneous inhibitory postsynaptic currents (sIPSCs) from mechanically dissociated neurons and miniature inhibitory postsynaptic currents (mIPSCs) and paired-pulse ratio (PPR) from a slice preparation were used to quantify GABA release. Ethanol produced a concentration-dependent increase in the frequency of sIPSCs recorded from mechanically dissociated cerebellar Purkinje neurons and mIPSCs from substantia nigra neurons without having an effect on sIPSCs recorded from lateral septal or cerebrocortical neurons. This regional difference in the effect of ethanol on GABA release was confirmed with PPR recording from brain slices. These data indicate that ethanol can act on presynaptic terminals to increase GABA release in some brain regions while having little or no effect on GABA release in others. This regional difference is consistent with earlier in vivo studies in which ethanol affected neural activity and sensitivity to GABA in some, but not all, brain sites.
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Affiliation(s)
- Hugh E Criswell
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC 27599, USA.
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Kelm MK, Criswell HE, Breese GR. Calcium Release from Presynaptic Internal Stores Is Required for Ethanol to Increase Spontaneous γ-Aminobutyric Acid Release onto Cerebellum Purkinje Neurons. J Pharmacol Exp Ther 2007; 323:356-64. [PMID: 17652632 DOI: 10.1124/jpet.107.126144] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent data have demonstrated that ethanol increases gamma-aminobutyric acid (GABA) release in many brain regions, but little is known about the mechanism responsible for this action. Consistent with previous results, ethanol increased miniature inhibitory postsynaptic current (mIPSC) frequency at the interneuron-Purkinje cell synapse in the slice and in mechanically dissociated neurons. These data suggest that ethanol is increasing spontaneous GABA release at this synapse. It is generally accepted that ethanol increases levels of intracellular calcium and that changes in intracellular calcium can alter neurotransmitter release. Therefore, we examined the contribution of calcium-dependent pathways to the effect of ethanol on spontaneous GABA release at the interneuron-Purkinje cell synapse. Ethanol continued to increase mIPSC frequency in a nominally calcium-free extracellular solution and in the presence of a voltage-dependent calcium channel inhibitor, cadmium chloride. These data suggest that influx of extracellular calcium does not play a critical role in the mechanism of ethanol-enhanced spontaneous GABA release. However, a sarco/endoplasmic-reticulum calcium ATPase pump inhibitor (thapsigargin), an inositol 1,4,5-trisphosphate receptor antagonist (2-aminoethoxydiphenylborate) and a ryanodine receptor antagonist (ryanodine) significantly reduced the ability of ethanol to increase mIPSC frequency. In addition, ethanol was still able to increase mIPSC frequency in the presence of intracellular 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and a cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM-251); thus, retrograde messengers are not involved in ethanol-enhanced spontaneous GABA release. Overall, these data suggest that calcium release from presynaptic internal stores plays a vital role in the mechanism of ethanol-enhanced spontaneous GABA release at the interneuron-Purkinje cell synapse.
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Affiliation(s)
- M Katherine Kelm
- Bowles Center for Alcohol Studies, CB 7178, Thurston-Bowles Building, Chapel Hill, NC 27599-7178, USA.
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Abstract
BACKGROUND Ethanol has actions on cerebellar Purkinje neurons that can result either in a net excitation or in inhibition of neuronal activity. The present study examines the interplay of presynaptic and postsynaptic mechanisms to determine the net effect of ethanol on the neuronal firing rate of cerebellar Purkinje neurons. METHODS Whole-cell voltage-clamp recording of miniature inhibitory postsynaptic currents (mIPSCs) from Purkinje neurons in cerebellar slices was used to examine the effect of ethanol on presynapticsynaptic release of gamma-aminobutyric acid (GABA) and glutamate. Extracellular recording was used to examine the net action of both presynaptic and postsynaptic effects of ethanol on the firing rate of Purkinje neurons. RESULTS Under whole-cell voltage clamp, the frequency of bicuculline-sensitive miniature postsynaptic currents (mIPSCs) was increased dose-dependently by 25, 50, and 100 mM ethanol without any change in amplitude or decay time. Despite this evidence of increased release of GABA by ethanol, application of 50 mM ethanol caused an increase in firing in some neurons and a decrease in firing in others with a nonrandom distribution. When both glutamatergic and GABAergic influences were removed by simultaneous application of 6-cyano-7-nitroquinoxaline-2,3-dione and picrotoxin, respectively, ethanol caused only an increase in firing rate. CONCLUSIONS These data are consistent with a dual action of ethanol on cerebellar Purkinje neuron activity. Specifically, ethanol acts presynaptically to increase inhibition by release of GABA, while simultaneously acting postsynaptically to increase intrinsic excitatory drive.
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Affiliation(s)
- Zhen Ming
- Department of Psychiatry, Center for Alcohol Studies, UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7178, USA
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Breese GR, Criswell HE, Carta M, Dodson PD, Hanchar HJ, Khisti RT, Mameli M, Ming Z, Morrow AL, Olsen RW, Otis TS, Parsons LH, Penland SN, Roberto M, Siggins GR, Valenzuela CF, Wallner M. Basis of the gabamimetic profile of ethanol. Alcohol Clin Exp Res 2006; 30:731-44. [PMID: 16573592 PMCID: PMC2958095 DOI: 10.1111/j.0145-6008.2006.00086.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This article summarizes the proceedings of a symposium held at the 2005 Research Society on Alcoholism meeting. The initial presentation by Dr. Wallner provided evidence that selected GABA(A) receptors containing the delta subunit display sensitivity to low intoxicating ethanol concentrations and this sensitivity is further increased by a mutation in the cerebellar alpha6 subunit, found in alcohol-hypersensitive rats. Dr. Mameli reported that ethanol affects gamma-aminobutyric acid (GABA) function by affecting neural circuits that influence GABA release. Dr. Parsons presented data from electrophysiological and microdialysis investigations that ethanol is capable of releasing GABA from presynaptic terminals. Dr. Morrow demonstrated that systemic ethanol increases neuroactive steroids in brain, the absence of which alters various functional responses to ethanol. Dr. Criswell presented evidence that the ability of ethanol to increase GABA was apparent in some, but not all, brain regions indicative of regional specificity. Further, Dr. Criswell demonstrated that neurosteroids alone and when synthesized locally by ethanol act postsynaptically to enhance the effect of GABA released by ethanol in a region specific manner. Collectively, this series of reports support the GABAmimetic profile of acutely administered ethanol being dependent on several specific mechanisms distinct from a direct effect on the major synaptic isoforms of GABA(A) receptors.
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Affiliation(s)
- G R Breese
- Bowles Center for Alcohol Studies, UNC School of Medicine, Chapel Hill, North Carolina 27599, USA.
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Abstract
Early behavioral investigations supported the contention that systemic ethanol displays a GABAmimetic profile. Microinjection of GABA agonists into brain and in vivo electrophysiological studies implicated a regionally specific action of ethanol on GABA function. While selectivity of ethanol to enhance the effect of GABA was initially attributed an effect on type-I-benzodiazepine (BZD)-GABA(A) receptors, a lack of ethanol's effect on GABA responsiveness from isolated neurons with this receptor subtype discounted this contention. Nonetheless, subsequent work identified GABA(A) receptor subtypes, with limited distribution in brain, sensitive to enhancement of GABA at relevant ethanol concentrations. In view of these data, it is hypothesized that the GABAmimetic profile for ethanol is due to activation of mechanisms associated with GABA function, distinct from a direct action on the majority of postsynaptic GABA(A) receptors. The primary action proposed to account for ethanol's regional specificity on GABA transmission is its ability to release GABA from some, but not all, presynaptic GABAergic terminals. As systemic administration of ethanol increases neuroactive steroids, which can enhance GABA responsiveness, this elevated level of neurosteroids is proposed to magnify the effect of GABA released by ethanol. Additional factors contributing to the degree to which ethanol interacts with GABA function include an involvement of GABA(B) and other receptors that influence ethanol-induced GABA release, an effect of phosphorylation on GABA responsiveness, and a regional reduction of glutamatergic tone. Thus, an integration of these consequences induced by ethanol is proposed to provide a logical basis for its in vivo GABAmimetic profile.
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Affiliation(s)
- Hugh E Criswell
- Center For Alcohol Studies, UNC Neuroscience Center, Department of Psychiatry, University of North Carolina, School of Medicine, Chapel Hill, NC 27599-7178, USA.
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Breese GR, Knapp DJ, Criswell HE, Moy SS, Papadeas ST, Blake BL. The neonate-6-hydroxydopamine-lesioned rat: a model for clinical neuroscience and neurobiological principles. ACTA ACUST UNITED AC 2005; 48:57-73. [PMID: 15708628 DOI: 10.1016/j.brainresrev.2004.08.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2004] [Indexed: 01/08/2023]
Abstract
In 1973, a technique of administering 6-hydroxydopamine (2,4,5-trihydroxyphenylethylamine) intracisternally to neonate rats was introduced to selectively reduce brain dopamine (neonate-lesioned rat). This neonate treatment proved unique when compared to rats lesioned as adults with 6-hydroxydopamine--prompting the discovery of differing functional characteristics resulting from the age at which brain dopamine is reduced. A realization was that neonate-lesioned rats modeled the loss of central dopamine and the increased susceptibility for self-injury in Lesch-Nyhan disease, which allowed identification of drugs useful in treating self-injury in mentally retarded patients. The neonate-lesioned rat has also been proposed to model the hyperactivity observed in attention-deficit hyperactivity disorder. Because the neonate-lesioned rat exhibits enhanced sensitization to repeated NMDA receptor antagonist administration and has functional changes characteristic of schizophrenia, the neonate lesioning is believed to emulate the hypothesized NMDA hypofunction in this psychiatric disorder. Besides modeling features of neurological and psychiatric disorders, important neurobiological concepts emerged from pharmacological studies in the neonate-lesioned rats. One was the discovery of coupling of D1/D2-dopamine receptor function. Another was the progressive increase in responsiveness to repeated D1-dopamine agonist administration referred to as "priming" of D1-dopamine receptor function. Additionally, a unique profile of signaling protein expression related to neonate reduction of dopamine has been identified. Thus, from modeling characteristics of disease to defining adaptive mechanisms related to neonatal loss of dopamine, the neonate-lesioned rat has had a persisting influence on neuroscience. Despite an extraordinary legacy from studies of the neurobiology of this treatment, a host of unknowns remain that will inspire future investigations.
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Affiliation(s)
- George R Breese
- Department of Psychiatry, UNC School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7178, USA.
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Kralic JE, Criswell HE, Osterman JL, O'Buckley TK, Wilkie ME, Matthews DB, Hamre K, Breese GR, Homanics GE, Morrow AL. Genetic essential tremor in gamma-aminobutyric acidA receptor alpha1 subunit knockout mice. J Clin Invest 2005; 115:774-9. [PMID: 15765150 PMCID: PMC1052003 DOI: 10.1172/jci23625] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 12/21/2004] [Indexed: 12/16/2022] Open
Abstract
Essential tremor is the most common movement disorder and has an unknown etiology. Here we report that gamma-aminobutyric acidA (GABA(A)) receptor alpha1-/- mice exhibit postural and kinetic tremor and motor incoordination that is characteristic of essential tremor disease. We tested mice with essential-like tremor using current drug therapies that alleviate symptoms in essential tremor patients (primidone, propranolol, and gabapentin) and several candidates hypothesized to reduce tremor, including ethanol; the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801; the adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA); the GABA(A) receptor modulators diazepam, allopregnanolone, and Ro15-4513; and the L-type Ca2+ channel antagonist nitrendipine. Primidone, propranolol, and gabapentin reduced the amplitude (power) of the pathologic tremor. Nonsedative doses of ethanol eliminated tremor in mice. Diazepam, allopregnanolone, Ro15-4513, and nitrendipine had no effect or enhanced tremor, whereas MK-801 and CCPA reduced tremor. To understand the etiology of tremor in these mice, we studied the electrophysiological properties of cerebellar Purkinje cells. Cerebellar Purkinje cells in GABA(A) receptor alpha1-/- mice exhibited a profound loss of all responses to synaptic or exogenous GABA, but no differences in abundance, gross morphology, or spontaneous synaptic activity were observed. This genetic animal model elucidates a mechanism of GABAergic dysfunction in the major motor pathway and potential targets for pharmacotherapy of essential tremor.
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Affiliation(s)
- Jason E Kralic
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7178, USA
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Kralic JE, Criswell HE, Osterman JL, O’Buckley TK, Wilkie ME, Matthews DB, Hamre K, Breese GR, Homanics GE, Morrow AL. Genetic essential tremor in γ-aminobutyric acidA receptor α1 subunit knockout mice. J Clin Invest 2005. [DOI: 10.1172/jci200523625] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Criswell HE, Ming Z, Pleasant N, Griffith BL, Mueller RA, Breese GR. Macrokinetic analysis of blockade of NMDA-gated currents by substituted alcohols, alkanes and ethers. Brain Res 2004; 1015:107-13. [PMID: 15223373 DOI: 10.1016/j.brainres.2004.04.050] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2004] [Indexed: 12/21/2022]
Abstract
Volatile hydrocarbon based CNS depressants including short chain alcohols and anesthetics act, in part, by inhibition of the excitatory effect of glutamate at the NMDA receptor. While effects of several of these volatile agents on NMDA-gated currents have been demonstrated, there has been no direct comparison of different chemical classes of CNS depressant drugs on NMDA-gated currents. Here, whole-cell voltage clamp measurements of currents gated by 100 microM NMDA from cultured cerebrocortical neurons were examined in the presence of varying concentrations of the alcohols ethanol and hexanol, the halogenated alcohol trichloroethanol, the halogenated alkane halothane and the halogenated ethers isoflurane and sevoflurane. All drugs tested showed concentration-dependent inhibition of NMDA-gated currents with anesthetic concentrations of each agent producing approximately 30% inhibition of the NMDA-gated current. A rapid-translation perfusion system was used to study the onset and offset kinetics of each of the volatile agents. Onset kinetics for the CNS depressants was similar with tau values near 100 ms. Offset kinetics was more variable with tau ranging from 88.2 ms for ethanol to 221.4 ms for trichloroethanol. These data indicate that a wide variety of volatile hydrocarbon based CNS depressants produce a similar inhibition of NMDA-gated currents and that the kinetics for these agents are inconsistent with an open channel block.
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Affiliation(s)
- Hugh E Criswell
- Department of Anesthesiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7178, USA.
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Ji X, Xu Z, Criswell HE, Boysen PG. Propyl paraben inhibits voltage-dependent sodium channels and protects cardiomyocytes from ischemia-reperfusion injury. Life Sci 2004; 74:3043-52. [PMID: 15051427 DOI: 10.1016/j.lfs.2003.11.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Accepted: 11/20/2003] [Indexed: 11/19/2022]
Abstract
The effects of propyl paraben, an antimicrobial preservative, on voltage-dependent sodium current and myocardial ischemia-reperfusion injury were investigated in isolated adult rat cardiomyocytes. Whole cell voltage-clamp recording showed that propyl paraben reversibly blocked the voltage-gated sodium channel both in concentration- and voltage-dependent manners. Propyl paraben (500 microM but not 100 microM) significantly shifted the steady-state inactivation of the sodium channel toward the hyperpolarizing direction at the V(1/2) point. Consistent with the above result, the propidium iodide (PI) uptake test revealed that pretreatment with 500 microM but not 100 microM of propyl paraben significantly reduced cell death induced by 45 min of sustained ischemia followed by 15 h of reperfusion (42.37 +/- 7.01% of cell viability in control and 71.05 +/- 7.06% in the propyl paraben group), suggesting that propyl paraben can protect myocytes from ischemia-reperfusion injury. These results indicate a possible correlation between the inhibition of sodium current and cardioprotection against ischemia-reperfusion injury.
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Affiliation(s)
- Xiang Ji
- Department of Anesthesiology, CB# 7010, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Criswell HE, Ming Z, Griffith BL, Breese GR. Comparison of effect of ethanol on N-methyl-D-aspartate- and GABA-gated currents from acutely dissociated neurons: absence of regional differences in sensitivity to ethanol. J Pharmacol Exp Ther 2003; 304:192-9. [PMID: 12490591 DOI: 10.1124/jpet.102.041590] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In vivo, ethanol alters the effect of N-methyl-D-aspartate (NMDA) and GABA in some brain regions but is without effect in others. To determine whether these regional differences were due to differences in the effect of ethanol on postsynaptic NMDA or GABAA receptors, we examined the effect of ethanol on NMDA- and GABA-gated currents from neurons acutely dissociated from the lateral septal nucleus, substantia nigra, thalamus, hippocampus, and cerebellum. Ethanol decreased the effect of NMDA similarly in all brain areas tested and had similar effects on Chinese hamster ovary cells expressing NR2A or NR2B subunits with an NR1-1a subunit. However, ifenprodil reduced the inhibition by ethanol of NMDA-gated currents from neurons isolated from the lateral septum without affecting neurons from the substantia nigra. In contrast to the robust effect of ethanol on NMDA-gated currents, ethanol (25-300 mM) was without effect on GABA-gated currents at all brain sites tested or on Ltk- cells stably expressing the alpha1, beta2, and gamma2L or gamma2S subunits. The neuroactive steroid alphaxalone profoundly enhanced GABA-gated currents in all brain areas and cell types tested, indicating a similar sensitivity to allosteric modulation; however, there was no interaction of alphaxalone with ethanol at any site tested. These data suggest that the regional differences in the effect of ethanol observed in vivo are not due to a differential action of ethanol at the postsynaptic NMDA or GABAA receptor subtypes.
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Affiliation(s)
- Hugh E Criswell
- Bowles Center for Alcohol Studies, Chapel Hill, North Carolina 27599-7178, USA.
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Haberman RP, Criswell HE, Snowdy S, Ming Z, Breese GR, Samulski RJ, McCown TJ. Therapeutic liabilities of in vivo viral vector tropism: adeno-associated virus vectors, NMDAR1 antisense, and focal seizure sensitivity. Mol Ther 2002; 6:495-500. [PMID: 12377191 PMCID: PMC3213639 DOI: 10.1006/mthe.2002.0701] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The N-methyl-D-aspartic acid (NMDA) receptor provides a potential target for gene therapy of focal seizure disorders. To test this approach, we cloned a 729-bp NMDA receptor (NMDAR1) cDNA fragment in the antisense orientation into adeno-associated virus (AAV) vectors, where expression was driven by either a tetracycline-off regulatable promoter (AAV-tTAK-NR1A) or a cytomegalovirus (CMV) promoter (AAV-CMV-NR1A). After infection of primary cultured cortical neurons with recombinant AAV-tTAK-NR1A, patch clamp studies found a significant decrease in maximal NMDA-evoked currents, indicative of a decrease in the number of NMDA receptors. Similarly, infusion of AAV-tTAK-NR1A (1 microl) into the rat temporal cortex significantly decreased NMDAR1-like immunoreactivity in layer V pyramidal cells. When AAV-tTAK-NR1A vectors were infused into the seizure-sensitive site of the rat inferior collicular cortex, the seizure sensitivity increased significantly over a period of 4 weeks. However, collicular infusion of AAV-CMV-NR1A vectors caused the opposite effect, a significant decrease in seizure sensitivity. Subsequent collicular coinfusion of vector encoding green fluorescent protein (GFP) driven by the tetracyclineoff promoter (AAV-tTAK-GFP) and vector encoding beta-galactosidase driven by the CMV promoter (AAV-CMV-LacZ) transduced distinct neuronal populations with only partial overlap. Thus, differing transduction ratios of inhibitory interneurons to primary output neurons likely account for the divergent seizure influences. Although AAV vector-derived NMDAR1 antisense can influence NMDA receptor function both in vitro and in vivo, promoter-related tropic differences dramatically alter the physiological outcome of this receptor-based gene therapy.
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Affiliation(s)
- Rebecca P. Haberman
- UNC Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Hugh E. Criswell
- Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Anesthesiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Stephen Snowdy
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Zhen Ming
- Department of Anesthesiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - George R. Breese
- Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - R. Jude Samulski
- UNC Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Thomas J. McCown
- UNC Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- To whom correspondence and reprint requests should be addressed. Fax: (919) 966-0907.
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Ming Z, Griffith BL, Breese GR, Mueller RA, Criswell HE. Changes in the effect of isoflurane on N-methyl-D-aspartic acid-gated currents in cultured cerebral cortical neurons with time in culture: evidence for subunit specificity. Anesthesiology 2002; 97:856-67. [PMID: 12357151 DOI: 10.1097/00000542-200210000-00017] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Developmental changes in NR1 splice variants and NR2 subunits of the N-methyl-D-aspartate (NMDA) receptor have been associated with changes in the sensitivity of NMDA receptors to agonists, antagonists, and pharmacologic modulators. The authors have investigated changes in the effect of isoflurane on NMDA-gated currents from cultured cortical neurons with time in culture and related these changes to the subunit composition of the NMDA receptors. METHODS N-methyl-D-aspartate-gated currents were measured using whole-cell voltage clamp recording in cortical neurons cultured for 1-4 weeks and HEK 293 cells transiently expressing NR1-1a + NR2A or NR1-1a + NR2B subunit-containing receptors. NMDA alone or NMDA with treatment agents (isoflurane or ifenprodil) was applied to cells using a U tube. RESULTS The effect of isoflurane and the NR2B selective antagonist ifenprodil on NMDA-gated currents from cortical neurons decreased significantly with time in culture. NMDA-gated currents mediated by NR2A-containing receptors were less sensitive to isoflurane than those mediated by NR2B-containing receptors. Tachyphylaxis to repeated application of isoflurane was found in cortical neurons and HEK 293 cells with recombinant NMDA receptors. Hooked tail currents were induced by isoflurane in cultured cortical neurons and HEK 293 cells with expressed NMDA receptors. CONCLUSIONS Isoflurane inhibits NMDA-gated currents at concentrations well below 1 minimum alveolar concentration (MAC). This effect of isoflurane was subunit dependent with the NR2B-containing receptors more sensitive to isoflurane than the NR2A-containing receptors. A potent tachyphylaxis occurred after brief exposure to isoflurane.
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Affiliation(s)
- Zhen Ming
- Anesthesiology, Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, 27599, USA
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Criswell HE, Ming Z, Griffith BL, Mueller RA, Breese GR. Comparison of Concentration-Response and Macrokinetic Variables across Anesthetics and Alcohols. Anesthesiology 2002. [DOI: 10.1097/00000542-200209002-00771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ming Z, Knapp DJ, Mueller RA, Breese GR, Criswell HE. Differential modulation of GABA- and NMDA-gated currents by ethanol and isoflurane in cultured rat cerebral cortical neurons. Brain Res 2001; 920:117-24. [PMID: 11716817 DOI: 10.1016/s0006-8993(01)03044-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Ethanol and the volatile anesthetics share many features including effects on both GABA and NMDA receptors. To determine the degree of similarity between these compounds, we examined the concentration-response curves for ethanol and isoflurane on currents gated by GABA or NMDA. The effects of isoflurane and ethanol on the righting reflex of rats were also observed. The concentration of ethanol causing loss of the righting reflex of rats was 82.3+/-2.9 mM, whereas median concentration of isoflurane exerting that effect was 0.125 mM. Both isoflurane and ethanol inhibited NMDA-gated currents in cultured cerebral cortical neurons at concentrations well below those associated with loss of the righting reflex or anesthesia. However, the effect of isoflurane was greater than that of ethanol and the slope of the concentration-response curve for isoflurane less steep than that for ethanol. Isoflurane enhanced GABA-gated currents at anesthetic concentrations but there was a sharp concentration-response curve with only minimal effects of isoflurane on GABA-gated currents at concentrations associated with loss of the righting reflex. In contrast, ethanol had no effect on GABA-gated currents even at lethal concentrations, i.e. 300 mM or 1.2%. Comparison of the concentration-response curves for the effects of isoflurane on NMDA- and GABA-gated currents has revealed both EC50 and Hill slope for the potentiation of GABA-gated currents were significantly greater than those for inhibition of NMDA-gated currents. These results support the hypothesis that isoflurane has actions on both the GABA and NMDA systems that are not shared by ethanol.
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Affiliation(s)
- Z Ming
- Department of Anesthesiology, University of North Carolina, Chapel Hill, NC 27599-7178, USA
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Matthews DB, Criswell HE, Grobin AC, Morrow AL. Chronic Ethanol Consumption Alters Recovery of Spontaneously Active Medial Septal/Diagonal Band of Broca Neurons From GABA-Microiontophoresis. Alcohol Clin Exp Res 2000. [DOI: 10.1111/j.1530-0277.2000.tb02113.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Matthews DB, Criswell HE, Grobin AC, Morrow AL. Chronic ethanol consumption alters recovery of spontaneously active medial septal/diagonal band of broca neurons from GABA-microiontophoresis. Alcohol Clin Exp Res 2000; 24:1427-32. [PMID: 11003210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
BACKGROUND Acute ethanol administration increases GABA-mediated inhibition in a variety of cerebral cortical preparations. Furthermore, chronic ethanol administration blunts ethanol-induced increases in GABA-mediated inhibition and alters GABA A receptor subunit mRNA and peptide expression in the cerebral cortex. The sedative hypnotic effects of ethanol are believed to be modulated by GABA-induced inhibition in medial septum/diagonal band of Broca (MS/DB) neurons, a brain region where acute ethanol administration increases GABA-mediated inhibition of spontaneously active neurons. Chronic ethanol administration produces tolerance to the sedative effects of ethanol. However, it is unknown if chronic ethanol consumption produces alterations in GABA-mediated inhibition in the MS/DB in a manner similar to that found in the cerebral cortex. METHODS Animals either consumed ethanol chronically for 14 days via a liquid diet or were pair-fed an equicaloric dextrose-containing control diet. Spontaneously active MS/DB neurons were recorded using multibarrel glass micropipettes while the effect of GABA-microiontophoresis was investigated. The total amount of GABA-mediated inhibition at four ejection currents was analyzed, as was the recovery to spontaneous neural firing rates following GABA inhibition. In a separate group of animals, the medial septum was microdissected, and the relative expression of GABA A receptor alpha1 and alpha4 subunit peptide were analyzed via Western blot analysis. RESULTS Chronic ethanol consumption altered recovery of spontaneous neural activity of MS/DB neurons following GABA-microiontophoresis compared to premicroiontophoresis levels. Specifically, the recovery of spontaneous neural activity of MS/DB neurons recorded from animals that chronically consumed ethanol was slower following GABA-microiontophoresis compared to neurons recorded from control animals. This effect was temporary and reversible. Furthermore, the alteration in recovery of spontaneous neural activity was not due to changes in the total amount of inhibition produced by GABA. Finally, there was no significant change in GABA A receptor alpha1 and alpha4 subunit peptide levels in the MS/DB. CONCLUSIONS Chronic ethanol consumption alters the frequency of spontaneous MS/DB neural activity following GABA microiontophoresis compared to premicroiontophoresis levels. These data suggest that the kinetics of GABA A receptors in the MS/DB are altered by chronic ethanol consumption independent of changes in the total amount of inhibition or alterations in GABA A receptor alpha1 and alpha4 subunit peptide expression.
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Affiliation(s)
- D B Matthews
- Skipper Bowles Center for Alcohol Studies, Department of Psychiatry, University of North Carolina at Chapel Hill, USA.
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Yang X, Criswell HE, Breese GR. Ethanol Modulation of gamma-Aminobutyric Acid (GABA)-Mediated Inhibition of Cerebellar Purkinje Neurons: Relationship to GABAb Receptor Input. Alcohol Clin Exp Res 2000. [DOI: 10.1111/j.1530-0277.2000.tb02040.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Yang X, Criswell HE, Breese GR. Ethanol modulation of gamma-aminobutyric acid (GABA)-mediated inhibition of cerebellar Purkinje neurons: relationship to GABAb receptor input. Alcohol Clin Exp Res 2000; 24:682-90. [PMID: 10832910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
BACKGROUND Electrophysiological recording reveals that only a portion of cerebellar Purkinje neurons are sensitive to ethanol enhancement of gamma-aminobutyric acid (GABA) responses. Although activation of beta-adrenergic receptors permits ethanol enhancement of GABA function from some cerebellar Purkinje neurons, other neurons remain insensitive to ethanol. These findings are consistent with the finding that other external neural inputs are required to allow ethanol enhancement of GABA responses from Purkinje neurons. Because of a high expression of GABA(B) receptors on Purkinje cells, we tested whether activation of GABA(B) receptors might modulate the action of ethanol on GABA responsiveness. METHODS Extracellular single-unit electrophysiological recording was used to investigate the effects of ethanol on responses to GABA and muscimol (a GABA(A) agonist) from cerebellar Purkinje neurons. Drugs tested were baclophen (a GABA(B) agonist) and CGP35348 (a GABA(B) antagonist). RESULTS Ethanol did not enhance responses to GABA and muscimol from all Purkinje neurons. Systemic administration of the GABA(B) agonist, baclophen (3 mg/kg intravenously), permitted ethanol to enhance GABA inhibition from approximately 75% of cerebellar Purkinje neurons not initially enhanced by ethanol. Local iontophoretic application of baclophen to Purkinje neurons also allowed ethanol to enhance GABA and muscimol responsiveness from a portion of neurons in which ethanol initially did not affect their actions. An inhibitory action of ethanol on responses to GABA and muscimol, which was also influenced by baclophen, was observed from some Purkinje neurons. From Purkinje neurons initially sensitive to ethanol enhancement of GABA and muscimol function, administration of CGP35348, a GABA(B) antagonist, diminished the effect of ethanol on the responsiveness of these agonists from the majority (9/15) of neurons. CONCLUSIONS The present findings demonstrated that baclophen allows ethanol enhancement of GABA and muscimol responsiveness from some, but not all, cerebellar Purkinje neurons initially not sensitive to ethanol. Likewise, a GABA(B) antagonist can diminish ethanol enhancement of GABA and muscimol responses from some ethanol-sensitive neurons. Thus, these results emphasize that GABA(B) receptors on a portion of Purkinje neurons act as an auxiliary neural input that allows ethanol enhancement of GABA responses. Consequently, receptor structure alone does not account for the action of ethanol on GABA(A) receptor function on this cell type.
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Affiliation(s)
- X Yang
- School of Medicine, University of North Carolina at Chapel Hill, 27599, USA
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Criswell HE, McCown TJ, Ming Z, Mueller RA, Breese GR. Interactive role for neurosteroids in ethanol enhancement of gamma-aminobutyric acid-gated currents from dissociated substantia nigra reticulata neurons. J Pharmacol Exp Ther 1999; 291:1054-9. [PMID: 10565824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Although previous in vivo electrophysiological studies demonstrated a consistent ethanol enhancement of gamma-aminobutyric acid (GABA) responsiveness from substantia nigra reticulata (SNR) neurons, ethanol applied in vitro to dissociated neurons from the SNR had an inconsistent effect on GABA function. One source for the disparity between these contrasting in vivo and in vitro results could be an endogenous factor (acting on an auxiliary site on GABA(A) receptors) that was not available to the isolated SNR neurons. Because neurosteroids are present in vivo and act on an auxiliary site, it was hypothesized that the presence of a neurosteroid was important for a consistent effect of ethanol on GABA responsiveness from neurons studied in vitro. Alone, the neurosteroid analog alphaxalone produced a significant, concentration-related enhancement of GABA responsiveness from isolated SNR neurons. In contrast to an inconsistent action of 100 mM ethanol on GABA responsiveness in the absence of alphaxalone, the presence of 30 and 100 nM alphaxalone resulted in the majority of isolated neurons responding to this ethanol level. At a concentration of alphaxalone as low as 30 nM, ethanol produced a robust concentration-related increase in GABA-gated currents from this cell type. The neurosteroid 3alpha, 5alpha-tetrahydrodeoxycorticosterone (100 nM) also permitted a reliable concentration-dependent ethanol enhancement of responses to GABA from SNR cells, indicative that the effects of alphaxalone were not unique. This consistent neurosteroid-induced ethanol enhancement of GABA responsiveness from dissociated SNR neurons supports the view that neurosteroids may play a key role in the action of ethanol on postsynaptic GABA(A) receptor function.
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Affiliation(s)
- H E Criswell
- Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7178, USA.
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Yang X, Criswell HE, Breese GR. Action of ethanol on responses to nicotine from cerebellar Purkinje neurons: relationship to methyllycaconitine (MLA) inhibition of nicotine responses. Neurochem Int 1999; 35:185-94. [PMID: 10406002 DOI: 10.1016/s0197-0186(99)00060-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effect of ethanol on responses to nicotine from rat cerebellar Purkinje neurons was investigated using extracellular single-unit recording. Systemic administration of ethanol initially enhanced the nicotine-induced inhibition from 50% of the Purkinje neurons. However, irrespective of whether there was an initial enhancement, systemic administration of ethanol antagonized the response to nicotine from the majority of Purkinje neurons. When varying ethanol concentrations were electro-osmotically applied to this neuronal cell type, the responses to nicotine (6/8) were enhanced when a low concentration of ethanol (40 mM) was in the pipette, whereas the majority of nicotine responses (10/11) were antagonized when a higher concentration of ethanol (160 mM) was applied to Purkinje neurons. Thus, the concentration of ethanol presented to the neuron seemed to explain the biphasic consequence of systemically administered ethanol on responses to nicotine. In order to determine whether ethanol affected a specific nACh receptor subtype containing the alpha-7 subunit, it was initially established that the nicotinic antagonists, alpha-bungarotoxin (alpha-BTX) and methyllycaconitine (MLA), which are associated with this subunit, had identical actions on responses to nicotine from Purkinje neurons. When MLA was tested against responses to nicotine from this cell type, MLA antagonized the response to nicotine from 45% (9/20) of the neurons tested. In a direct comparison of the action of ethanol to inhibit responses to nicotine with the action of MLA on the same Purkinje neuron, ethanol inhibited responses to nicotine on all neurons sensitive to MLA. However, ethanol also affected nicotine-induced neural changes from some Purkinje neurons not sensitive to MLA antagonism of nicotine. These data support the supposition that ethanol affects a nACh receptor subtype which has an alpha-7 subunit as well as other nACh receptor subtypes without this specific subunit.
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Affiliation(s)
- X Yang
- North Carolina Neurosciences Center, School of Medicine, University of North Carolina at Chapel Hill 27599-7178, USA
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Yang X, Criswell HE, Breese GR. Action of ethanol on responses to nicotine from cerebellar interneurons and medial septal neurons: relationship to methyllycaconitine inhibition of nicotine responses. Alcohol Clin Exp Res 1999; 23:983-90. [PMID: 10397282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND A majority of alcoholics also smoke, suggesting that alcohol and nicotine share a common action on nicotinic cholinergic receptors. METHODS Extracellular single-unit recording was used to investigate the effects of ethanol on responses to nicotine from rat cerebellar interneurons and medial septal neurons. RESULTS Nicotine produced inhibition from medial septal neurons, but increased neural activity of cerebellar interneurons. When ethanol was applied locally to cerebellar interneurons, the excitatory response to nicotine was enhanced in a dose-related manner. Nicotine-induced inhibition from medial septal neurons was reduced by ethanol from the majority of neurons, but a dose relationship for this inhibition by ethanol was not observed. Ethanol affected responses to nicotine from over 90% of all neurons investigated at these sites. Initially, it was established that the nicotinic antagonists, methyllycaconitine (MLA) and alpha-bungarotoxin, which affect a nicotinic cholinergic (nACh) receptor with an alpha7 subunit, had similar actions on responses to nicotine from individual medial septal cells and cerebellar interneurons. When MLA was tested against responses to nicotine from neurons in the two brain regions, MLA antagonized responses to nicotine from only 27% of the neurons rather than the 90% found for ethanol. This latter observation provided evidence that ethanol was affecting neurons with MLA-insensitive receptors. When the actions of ethanol on responses to nicotine were compared directly with the action of MLA on the same medial septal neurons, both ethanol and MLA caused a greater than 50% antagonism of the response to nicotine, indicative that nACh receptors with the alpha7 subunit were sensitive to ethanol. CONCLUSIONS Collectively, these data provide evidence that ethanol affects responses to nicotine not only from nACh receptors on medial septal cells and cerebellar interneurons containing an alpha7 subunit (i.e., MLA-sensitive receptors), but also from nACh receptor subtypes without this specific nACh receptor subunit (i.e., MLA-insensitive receptors).
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Affiliation(s)
- X Yang
- Department of Psychiatry and Anesthesiology, North Carolina Neurosciences Center, School of Medicine, University of North Carolina at Chapel Hill, 27599-7178, USA
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Yang X, Criswell HE, Breese GR. Action of Ethanol on Responses to Nicotine From Cerebellar Interneurons and Medial Septal Neurons: Relationship to Methyllycaconitine Inhibition of Nicotine Responses. Alcohol Clin Exp Res 1999. [DOI: 10.1111/j.1530-0277.1999.tb04216.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Yang X, Knapp DJ, Criswell HE, Breese GR. Action of ethanol and zolpidem on gamma-aminobutyric acid responses from cerebellar Purkinje neurons: relationship to beta-adrenergic receptor input. Alcohol Clin Exp Res 1998; 22:1655-61. [PMID: 9835278 PMCID: PMC3025704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The observation that cerebellar Purkinje cells contain type-I benzodiazepine-sensitive GABA(A) receptors is consistent with findings in the present work that the majority of Purkinje neurons are sensitive to enhancement of GABA by the type-1 benzodiazepine agonist, zolpidem. Previous work has demonstrated a relation between zolpidem and ethanol enhancement of GABA responses in several brain regions, but had not tested Purkinje neurons. Therefore, given that a majority of Purkinje neurons were found to be sensitive to zolpidem, ethanol would have been expected to enhance GABA responses from this cell type. However, in agreement with earlier electrophysiological studies, ethanol enhanced GABA inhibitory responses from only a small proportion of these cerebellar Purkinje neurons. Rather than enhancement of GABA, local application of ethanol either inhibited or did not affect responses to GABA from a majority of cerebellar-Purkinje neurons. Nonetheless, as previously reported, a portion of the Purkinje neurons initially insensitive to ethanol enhancement of GABA became sensitive to this action of ethanol with co-application of the beta-adrenergic agonist, isoproterenol. Thus, these results collectively implicate a beta-adrenergic input dependency for ethanol enhancement of GABA from some, but not all, cerebellar Purkinje neurons sensitive to zolpidem. Because a beta-adrenergic input did not allow ethanol enhancement of GABA from all Purkinje neurons, future studies should explore the possibility that other auxiliary neural inputs to zolpidem-sensitive cerebellar Purkinje neurons may be required for ethanol enhancement of GABA responsiveness when a beta-adrenergic input does not have this action. Likewise, knowing that the action of zolpidem can predict ethanol enhancement of GABA in other brain regions, the present findings suggest that a future determination be made concerning whether zolpidem-sensitive neurons in these other regions of brain require a beta-adrenergic or an alternative neural input for ethanol enhancement of GABA responses.
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Affiliation(s)
- X Yang
- Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill, 27599, USA
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Yang X, Knapp DJ, Criswell HE, Breese GR. Action of Ethanol and Zolpidem on gamma-Aminobutyric Acid Responses from Cerebellar Purkinje Neurons: Relationship to beta-Adrenergic Receptor Input. Alcohol Clin Exp Res 1998. [DOI: 10.1111/j.1530-0277.1998.tb03963.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Criswell HE, McCown TJ, Moy SS, Oxford GS, Mueller RA, Morrow AL, Breese GR. Action of zolpidem on responses to GABA in relation to mRNAs for GABA(A) receptor alpha subunits within single cells: evidence for multiple functional GABA(A) isoreceptors on individual neurons. Neuropharmacology 1997; 36:1641-52. [PMID: 9517435 DOI: 10.1016/s0028-3908(97)00169-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The relationship between zolpidem sensitivity and GABA(A) receptor alpha subunits was studied in individual dissociated neurons from rat brain. Using whole-cell recording, similar EC50 values were demonstrated for the effect of gamma-aminobutyric acid (GABA) on gated-chloride currents from substantia nigra reticulata (SNR) and lateral septal neurons. Subsequently, many neurons from both the SNR or lateral septum were found to exhibit enhanced GABA-gated chloride currents across concentrations of zolpidem ranging from 10 to 300 nM. Some neurons exhibited a greater than 20% increase in responsiveness to GABA at 30 nM of zolpidem without further increase at higher concentrations of zolpidem. Conversely, zolpidem enhancement of GABA from another group of neurons was not observed at 30 nM zolpidem, but between 100 and 300 nM the response to GABA increased greater than 20%. Finally, a third group of neurons reached both of these criteria for zolpidem enhancement of GABA. This latter spectrum of responses to GABA after varying concentrations of zolpidem was consistent with the presence of either two GABA(A) receptors or a single receptor with differing affinities for zolpidem on an individual neuron. Following determination of the sensitivity of neurons from SNR or lateral septum to zolpidem, cytoplasm was extracted from some individual cells to allow identification of cellular mRNAs for the alpha1, alpha2 and alpha3 GABA(A) receptor subunits with RT-PCR. Those neurons that responded to the 30 nM zolpidem concentration invariably expressed the alpha1-GABA(A) receptor subunit. This result is consistent with the GABA(A) alpha1-receptor subunit being an integral part of a functional high-affinity zolpidem type 1-BZD receptor complex on neurons in brain. Those neurons which showed enhancement of GABA from 100 to 300 nM zolpidem contained mRNAs for the alpha2 and/or the alpha3 receptor subunits, a finding consistent with these alpha subunits forming type 2-BZD receptors. Some individual dissociated SNR neurons were sensitive to both low and high concentrations of zolpidem and contained mRNAs for all three alpha-receptor subunits. These latter individual neurons are proposed to have at least two functional GABA(A) receptor subtypes. Thus, the present investigation emphasizes the importance of characterizing the relationship between endogenous GABA(A) receptor function and the presence of specific structural components forming GABA(A) receptor subtypes on neurons.
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Affiliation(s)
- H E Criswell
- UNC Neuroscience Center, University of North Carolina, School of Medicine, Chapel Hill 27599, USA.
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Abstract
Both Lesch-Nyhan syndrome and Parkinson's disease are associated with decreased brain dopamine, yet each disorder is characterized by a different set of motor symptoms. Lesch-Nyhan syndrome is manifested in early childhood, while parkinsonism usually does not appear until adulthood, suggesting that age at the time of dopamine loss is one determinant of the effects of neurotransmitter deficiency. Support for this view is found in studies of animals given dopamine-depleting lesions at different ages and then tested in adulthood. Animals lesioned as neonates show a supersensitivity to dopamine agonists, especially D1-dopamine receptor agonists, and to MK-801, an NMDA receptor antagonist. In addition, neonatally treated animals show a 'priming' effect following repeated exposure to D1-dopamine agonists. Animals depleted of dopamine as adults are more supersensitive to agonists acting on the D2-dopamine receptor, and do not evidence priming to dopamine agonists or an enhanced response to MK-801. These differential pharmacological profiles suggest that the changes in neurotransmitter systems following dopamine depletion are, at least in part, determined by age at the time of the lesion.
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Affiliation(s)
- S S Moy
- Department of Anesthesiology, University of North Carolina at Chapel Hill 27599, USA
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Abstract
In previous research, the drug flumazenil has been categorized both as a pure benzodiazepine antagonist and as a benzodiazepine partial agonist. The following studies used an elevated plus maze to test whether flumazenil would exert any antianxiety action in rats. While chlordiazepoxide (3.0 mg/kg), ethanol (0.75 g/kg), and the atypical benzodiazepine zolpidem (1.0 mg/kg) all significantly increased time spent on the open arms and percent open arm entries, flumazenil (1-10 mg/kg) alone did not produce any anxiolytic effects on the maze. Withdrawal from chronic ethanol treatment led to a decrease in open arm time and percent open arm entries. Flumazenil (3.0 mg/kg) blocked these changes, suggesting that the effects of flumaxenil are at least partially dependent upon the levels of stress or anxiety in the subjects. An anxiolytic action of flumazenil was not seen following the central administration of the neuropeptide corticotropin-releasing factor (CRF), which reduced open arm time on the elevated plus maze. These results support the hypothesis that the mechanism of action for flumazenil effects on the anxiety observed during ethanol withdrawal involves antagonism of an endogenous benzodiazepine inverse agonist, rather than activity as a partial agonist or blockade of CRF-mediated effects.
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Affiliation(s)
- S S Moy
- UNC Neuroscience Center, UNC School of Medicine, Chapel Hill 27599, USA
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Yang X, Criswell HE, Simson P, Moy S, Breese GR. Evidence for a selective effect of ethanol on N-methyl-d-aspartate responses: ethanol affects a subtype of the ifenprodil-sensitive N-methyl-d-aspartate receptors. J Pharmacol Exp Ther 1996; 278:114-24. [PMID: 8764342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
An extracellular electrophysiological approach was used to determine the effect of ethanol on responses to N-methyl-D-aspartate (NMDA) across several brain regions in urethane-anesthetized rats. The results indicated that, in most brain regions, ethanol inhibited the NMDA-induced increases in firing rate for some, but not all, spontaneously active neurons. Ethanol functioned as an NMDA antagonist for some neurons in the medial septum, red nucleus, deep mesencephalic nucleus, substantia nigra reticulata, ventral tegmental area and cerebellum. In the hippocampus, ethanol inhibited NMDA responses from all neurons. However, ethanol was not found to be active against NMDA responses in the lateral septum, suggesting that there is a degree of regional specificity for ethanol inhibition of NMDA responses. It was then established in unanesthetized rats that ethanol also antagonized responses to NMDA in some, but not all, neurons in the medial septum and cortex, indicating that the differential action of ethanol on NMDA responses obtained in the urethane-anesthetized rats was not due to the anesthetic. Based on an earlier study showing that the effects of ifenprodil and ethanol on NMDA responses were correlated, the ability of ethanol to inhibit NMDA responses was compared with changes produced by ifenprodil on the same neurons, where ethanol did or did not affect NMDA responses. In the several brain regions investigated, ethanol inhibited NMDA responses in a subgroup of neurons in which ifenprodil inhibited NMDA-induced increases in firing. For all neurons investigated, if a cell was insensitive to ifenprodil antagonism of NMDA responses then ethanol also was ineffective against the response to NMDA. These results suggest that ethanol acts on an ifenprodil-sensitive NMDA receptor subtype. Given that previous investigations have suggested that the NMDA receptor type 2B subunit is essential for the action of ifenprodil, the positive relationship between the actions of ifenprodil and ethanol on responses to NMDA is consistent with the hypothesis that the combination of specific receptor subunits forming an NMDA receptor on a neuron determines the ability of ethanol to antagonize an NMDA response.
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Affiliation(s)
- X Yang
- UNC Neuroscience Center, University of North Carolina School of Medicine at Chapel Hill, North Carolina, USA
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Overstreet DH, Lee YW, Rezvani AH, Pei YH, Criswell HE, Janowsky DS. Suppression of alcohol intake after administration of the Chinese herbal medicine, NPI-028, and its derivatives. Alcohol Clin Exp Res 1996; 20:221-7. [PMID: 8730211 DOI: 10.1111/j.1530-0277.1996.tb01633.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The Chinese herbal medicine, NPI-028, has been used for centuries in China to counteract alcohol intoxication. The present study used a number of different experimental conditions to determine whether NPI-028 and its derivatives might selectively influence alcohol intake in rodents that naturally exhibit high alcohol intakes. It was determined that intraperitoneal (i.p.) injections of NPI-028 (0.5, 0.75, and 1.0 g/kg) suppressed alcohol intake by up to 30% in both alcohol-preferring P and Fawn-Hooded (FH) rats during a continuous access schedule. These injections did not significantly affect food or water intakes, nor did the highest dose of NPI-028 (1 g/kg) alter blood ethanol levels after an i.p. injection of 2.5 g/kg of ethanol. In P rats, it was found that NPI-028 was orally active with the dose of 1.5 g/kg having a greater effect on ethanol intake than the 1.0 g/kg dose; once again, food and water intakes were not significantly altered. In FH rats maintained on a limited access schedule (1 hr/day), alcohol intake was completely abolished by 1.5 g/kg of NPI-028. Chronic i.p. administration of NPI-028 (0.75 g/kg) for four consecutive days in FH rats maintained on a continuous access schedule did not lead to any diminution of its alcohol-suppressant effects. Thus, NPI-028 has significant effects on alcohol intake without much effect on water and food intake, and tolerance does not readily develop to these effects. The i.p. administration of a partially purified extract (NPI-031) of NPI-028, obtained by countercurrent chromatography, also dose-dependently suppressed ethanol intake in FH rats, but the highest dose 200 mg/kg) also significantly decreased food intake. Finally, the i.p. administration of puerarin (NPI-31G), an isoflavone isolated from NPI-031 by countercurrent chromatography, significantly reduced ethanol intake in FH rats without affecting food or water intake. Therefore, NPI-028 and one of its pure components, NPI-031G, selectively reduced ethanol intake in alcohol-preferring rats.
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Affiliation(s)
- D H Overstreet
- Skipper Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill 27599-7178, USA
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Yang X, Criswell HE, Breese GR. Nicotine-induced inhibition in medial septum involves activation of presynaptic nicotinic cholinergic receptors on gamma-aminobutyric acid-containing neurons. J Pharmacol Exp Ther 1996; 276:482-9. [PMID: 8632313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Neuronal responses to drugs acting on nicotinic cholinergic receptors (nAChRs) were examined in the rat medial septal area by using an in vivo extracellular single-unit recording technique. In the medial septal area, iontophorectically applied nicotine inhibited neuronal activity in 45% of the neurons, but had no effect on the remaining neurons. Dihydro-beta-erythroidine application to neurons in the medial septal area not only blocked nicotine-induced inhibition, but also reduced spontaneous neuronal activity of the neurons. When Mg++ was applied iontophoretically to block presynaptic neurotransmitter release, a significant reduction in spontaneous neural activity also was observed. No further reduction of spontaneous activity by dihydro-beta-erythroidine occurred in the presence of Mg++, suggesting an apparent tonic excitatory input to the majority of neurons in the medial septal area under the control of presynaptic nAChRs. Mg++ abolished the nicotine-induced inhibition in the medial septal area without having an effect on nicotine-induced inhibition in the cerebellum. Thus, these data provide evidence that the inhibitory effects of nicotine in the medial septum are due to an action on presynaptic nAChRs, controlling the release of an inhibitory neurotransmitter. Of the medial septal neurons which showed no response to nicotine, nicotine produced excitation in 21% of the cells after Mg++ application, indicating that nicotine can have a direct action on postsynaptic nAChRs, in addition to its presynaptic action, in the medial septum. Finally, application of the gamma-aminobutyric acid antagonist bicuculline reduced the nicotine-induced inhibition on the majority of medial septal neurons tested, but was without effect on the inhibition produced by nicotine on cerebellar Purkinje neurons. Consequently, it can be concluded that the nicotine-induced inhibition in the medial septum is the result of gamma-aminobutyric acid release due to its action on presynaptic nAChRs present on gamma-aminobutyric acid-containing terminals.
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Affiliation(s)
- X Yang
- Brain and Development Research Center, School of Medicine, University of North Carolina at Chapel Hill, USA
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Devaud LL, Morrow AL, Criswell HE, Breese GR, Duncan GE. Regional differences in the effects of chronic ethanol administration on [3H]zolpidem binding in rat brain. Alcohol Clin Exp Res 1995; 19:910-4. [PMID: 7485838 DOI: 10.1111/j.1530-0277.1995.tb00966.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A strong association has been observed between [3H]zolpidem binding and the presence of gamma-aminobutyric acid (GABAA) receptor mRNA for alpha 1-, beta 2-, and gamma 2-subunits in specific brain regions. This correlates with observed sensitivity of individual neurons to zolpidem and ethanol in these same regions. Previous studies using homogenate binding approaches showed small alterations in [3H]zolpidem binding levels after chronic ethanol exposure. This study was undertaken to ascertain if there is regional specificity of the effects of chronic ethanol administration on [3H]zolpidem binding levels. Chronic ethanol administration induced small, but significant alterations in [3H]zolpidem (5 nM) binding in the inferior colliculus, substantia nigra, and the medial septum. [3H]Zolpidem binding was increased in the inferior colliculus and substantia nigra, and decreased in the medial septum. No significant differences in [3H]zolpidem binding were noted in any other brain area analyzed, including the cortex and cerebellum. These findings show that chronic ethanol administration has small effects on [3H]zolpidem binding, although they occur in a site-specific and bidirectional manner. Moreover, there is no correlation between changes in [3H]zolpidem binding and alterations in GABAA receptor subunit expression.
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Affiliation(s)
- L L Devaud
- Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill 27599-7178, USA
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Criswell HE, Simson PE, Knapp DJ, Devaud LL, McCown TJ, Duncan GE, Morrow AL, Breese GR. Effect of zolpidem on gamma-aminobutyric acid (GABA)-induced inhibition predicts the interaction of ethanol with GABA on individual neurons in several rat brain regions. J Pharmacol Exp Ther 1995; 273:526-36. [PMID: 7714808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Previous investigations have suggested a relationship between zolpidem binding within specific brain regions and the ability of ethanol or zolpidem to enhance gamma-aminobutyric acid (GABA)-induced inhibition. The purpose of the present study was to extend our electrophysiological analysis to additional brain sites with high levels of zolpidem binding. In the brain regions chosen, red nucleus and globus pallidus, GABA-induced inhibition was shown to be enhanced by either ethanol or zolpidem on some, but not all, neurons. These findings led to the hypothesis that the effect of zolpidem on GABA-induced inhibition would predict the action of ethanol on responses to GABA for that neuron. When zolpidem and ethanol were applied individually to the same neurons in the red nucleus and globus pallidus, those neurons sensitive to zolpidem enhancement of GABA also were sensitive to ethanol. Conversely, if zolpidem did not enhance responses to GABA, ethanol did not enhance responses to GABA at these brain sites. A similar relationship between the abilities of zolpidem and ethanol to enhance GABA-induced inhibition was obtained in 90% of the neurons studied in the medial septum/diagonal band and ventral pallidum. These studies provide further support for the contention that the zolpidem-sensitive GABAA-benzodiazepine isoreceptor also responds to ethanol. Finally, the expression of GABAA subunit mRNAs was analyzed by polymerase chain reaction from micropunches of several brain regions that contain zolpidem binding sites and exhibit sensitivity to ethanol. Polymerase chain reaction analysis proved more sensitive than in situ hybridization in the detection of receptor subunit mRNAs. Several subunits (alpha 1, alpha 2, alpha 3, beta 2, beta 3 and gamma 2) were common to all brain regions in which ethanol and zolpidem enhanced GABA responses. GABAA receptor alpha 4/5, alpha 6, beta 1, gamma 1, gamma 3 and delta subunits were not consistently expressed in association with the presence of zolpidem binding. These data are consistent with the view that one native GABAA receptor to which zolpidem binds, and on which ethanol acts, contains the GABAA receptor subunits alpha 1, beta 2 and gamma 2; however, the present investigation did not preclude the possibility that other subunit combinations can contribute to ethanol and zolpidem enhancement of responses to GABA.
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Affiliation(s)
- H E Criswell
- Department of Psychiatry, University of North Carolina at Chapel Hill, USA
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Duncan GE, Breese GR, Criswell HE, McCown TJ, Herbert JS, Devaud LL, Morrow AL. Distribution of [3H]zolpidem binding sites in relation to messenger RNA encoding the alpha 1, beta 2 and gamma 2 subunits of GABAA receptors in rat brain. Neuroscience 1995; 64:1113-28. [PMID: 7753379 DOI: 10.1016/0306-4522(94)00433-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Localization of the messenger RNAs that encode the alpha 1, beta 2 and gamma 2 subunits of GABAA showed a distinct topographic pattern in rat brain which corresponded with [3H]zolpidem binding in most brain regions. The close topographic correspondence between the specific receptor subunits examined and the distribution of [3H]zolpidem binding sites provides support for the hypothesis that this benzodiazepine type 1 selective ligand binds to a GABAA receptor that consists of alpha 1, beta 2 and gamma 2 subunits in the rat brain. Brain regions with relatively high densities of alpha 1, beta 2 and gamma 2 subunits of GABAA and [3H]zolpidem binding included olfactory bulb, medial septum, ventral pallidum, diagonal band, inferior colliculus, substantia nigra pars reticulata and specific layers of the cortex. Two areas with low [3H]zolpidem binding and a virtual absence of these GABAA receptor subunit messenger RNAs were the lateral septum and the striatum. In contrast to the discrete pattern observed for alpha 1 and beta 2 subunit messenger RNAs, the gamma 2 subunit messenger RNA was distributed more diffusely in brain. Only the hippocampus, layer 2 of the piriform cortex and the cerebellum showed a strong concentration of the gamma 2 subunit messenger RNA. It was determined with a polymerase chain reaction assay that both long and short variants of the gamma 2 subunit messenger RNAs were present within several of the brain sites selected for examination. Sites with high densities of [3H]zolpidem binding sites had a greater relative abundance of the gamma 2 long splice variant, compared to the gamma 2 short variant. There were some regions that expressed high levels of alpha 1, beta 2 and gamma 2S subunit messenger RNAs but low [3H]zolpidem binding, suggesting that gamma 2 splice variant expression may modulate high-affinity [3H]zolpidem binding. To determine relationships between in vitro [3H]zolpidem binding and functional sensitivity in vivo, interactions between zolpidem and GABA were assessed in brain regions that contained high and low densities of [3H]zolpidem binding sites. In the medial septum, a brain region with a high concentration of [3H]zolpidem binding sites, iontophoretic application of zolpidem enhanced the inhibitory effect of GABA responses on 70% of the neurons examined. In the lateral septum, which contains very low densities of [3H]zolpidem binding sites, neurons were not sensitive to zolpidem enhancement of GABA-induced inhibition. These electrophysiological results demonstrate a correspondence between the regional distribution of [3H]zolpidem binding in vitro and functional sensitivity to the drug in vivo.
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Affiliation(s)
- G E Duncan
- Department of Psychiatry, University of North Carolina at Chapel Hill 27599, USA
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Breese GR, Criswell HE, Duncan GE, Moy SS, Johnson KB, Wong DF, Mueller RA. Model for reduced brain dopamine in Lesch-Nyhan syndrome and the mentally retarded: Neurobiology of neonatal-6-hydroxydopamine-lesioned rats. ACTA ACUST UNITED AC 1995. [DOI: 10.1002/mrdd.1410010207] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Criswell HE, Overstreet DH, Rezvani AH, Johnson KB, Simson PE, Knapp DJ, Moy SS, Breese GR. Effects of ethanol, MK-801, and chlordiazepoxide on locomotor activity in different rat lines: dissociation of locomotor stimulation from ethanol preference. Alcohol Clin Exp Res 1994; 18:917-23. [PMID: 7978104 DOI: 10.1111/j.1530-0277.1994.tb00060.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Several lines of research have suggested a link between the reward value of a drug and its ability to stimulate locomotion. One goal of the present study was to determine whether ethanol preferentially stimulates locomotor activity in lines of rat that show a preference for ethanol. A secondary goal was to determine the extent to which the benzodiazepine-like and NMDA antagonistic action of ethanol accounted for its effect on locomotor activity. To meet these goals, the effects of varying doses of ethanol (0.125-1.0 g/kg), MK-801 (0.1-0.3 mg/kg), and chlordiazepoxide (0.3-3 mg/kg) on locomotor activity were studied in several lines of rats that had been habituated to the testing procedure. The effect of low doses of ethanol on motor activity in the Alcohol-Preferring (P) and Fawn-Hooded rats, which show a strong ethanol preference, were similar to those of the alcohol-nonpreferring (NP), Flinders Sensitive Line, and Flinders Resistant Line rats. Only the Flinder Resistant Line rats showed a small, but significant increase in locomotor activity after the administration of ethanol. The highest dose of ethanol (1.0 g/kg) produced locomotor depression in all lines except the P and NP lines, which were not tested at this dose. These findings do not support a link between locomotor stimulation by ethanol and ethanol preference. In contrast, all lines exhibited locomotor stimulation after moderate (0.1-0.3 mg/kg) doses of MK-801, but did not exhibit increases in activity following any dose of chlordiazepoxide. These data indicate that the profiles of activity after MK-801 and chlordiazepoxide were distinct from that of ethanol in the various rat lines.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H E Criswell
- Brain and Development Research Center, University of North Carolina School of Medicine, Chapel Hill 27599-7250
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Criswell HE, Knapp DJ, Overstreet DH, Breese GR. Effects of ethanol, chlordiazepoxide, and MK-801 on performance in the elevated-plus maze and on locomotor activity. Alcohol Clin Exp Res 1994; 18:596-601. [PMID: 7943661 DOI: 10.1111/j.1530-0277.1994.tb00916.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of ethanol, chlordiazepoxide, and MK-801 on performance in the elevated-plus maze and on activity measured in a circular activity monitor were compared in Sprague-Dawley rats to determine whether these effects of ethanol could be explained by its action on either GABAA or NMDA receptors. Both ethanol and chlordiazepoxide produced an increase in the time spent in the open arms of the elevated-plus maze and in the ratio of open arm to total arm entries, indicative of an anxiolytic action of these drugs. MK-801 did not alter either the time spent in the open arms or the ratio of open to total arm entries. Chlordiazepoxide and MK-801 produced an increase in total arm entries that suggested that these compounds were increasing locomotor activity. Ethanol also increased total arm entries, but the effect was not statistically reliable. Following habituation to an activity monitor, neither ethanol nor chlordiazepoxide increased activity in this task, whereas MK-801 produced a robust increase in locomotion. Additionally, neither ethanol nor chlordiazepoxide blocked the MK-801-induced locomotor stimulation. The latter finding suggests that the effects of ethanol on GABAA receptors was not blocking an increased activity level produced by its antagonism of NMDA. Additionally, these results indicate that the anxiolytic and locomotor action of ethanol in rats parallel the effects of a benzodiazepine and not those of an NMDA antagonist. Finally, these results suggest that the consequence of ethanol's antagonism of NMDA receptor function is more restricted than that produced by MK-801.
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Affiliation(s)
- H E Criswell
- Brain and Development Research Center, University of North Carolina School of Medicine, Chapel Hill 27599-7250
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Duncan GE, Breese GR, Criswell HE, Johnson KB, Schambra UB, Mueller RA, Caron MG, Fremeau RT. D1 dopamine receptor binding and mRNA levels are not altered after neonatal 6-hydroxydopamine treatment: evidence against dopamine-mediated induction of D1 dopamine receptors during postnatal development. J Neurochem 1993; 61:1255-62. [PMID: 8376983 DOI: 10.1111/j.1471-4159.1993.tb13616.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The role of dopaminergic innervation on the postnatal developmental expression of D1 dopamine receptors was investigated. Bilateral destruction of dopamine-containing neurons was achieved by treating rats intracisternally with 6-hydroxydopamine (6-OHDA) on postnatal day 3, and rats were killed on day 21. To ensure effective reduction of D1 receptor activation by residual dopamine, a group of 6-OHDA-lesioned rats was given twice daily injections of the D1 receptor antagonist SCH-23390, from day 4 to 20. D1 dopamine receptor binding was assessed in the caudate-putamen, nucleus accumbens, and olfactory tubercle by quantitative autoradiographic analysis of [3H]SCH-23390 binding. In addition, the relative amount of D1A receptor mRNA was assessed by in situ hybridization of a 35S-labeled riboprobe. In the developing rats, neither the amount of [3H]SCH-23390 binding nor the amount of D1A receptor mRNA was altered by 6-OHDA lesioning followed by chronic treatment with SCH-23390. Thus, bilateral destruction of dopamine-containing neurons and treatment with SCH-23390 in neonatal rats did not interfere with the developmental expression of D1 receptors or alter the levels of mRNA that code for this receptor protein. Treatment of intact rats with SCH-23390 from postnatal day 4 to 20 also did not alter [3H]SCH-23390 binding or levels of D1 receptor mRNA. However, adult rats treated chronically with SCH-23390 exhibited increased [3H]SCH-23390 binding but did not show a significant change in D1 receptor mRNA levels.
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Affiliation(s)
- G E Duncan
- Brain and Development Research Center, University of North Carolina at Chapel Hill 27599
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Criswell HE, Simson PE, Duncan GE, McCown TJ, Herbert JS, Morrow AL, Breese GR. Molecular basis for regionally specific action of ethanol on gamma-aminobutyric acidA receptors: generalization to other ligand-gated ion channels. J Pharmacol Exp Ther 1993; 267:522-37. [PMID: 8229784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The present investigation provides evidence that there is neuroanatomical specificity for ethanol enhancement of gamma-aminobutyric acid (GABA)-induced inhibition in mammalian brain and that the expression of a specific GABAA isoreceptor is associated with this regional action of ethanol. Ethanol enhanced responses to iontophoretically applied GABA in the medial septum, inferior colliculus, substantia nigra reticulata, ventral pallidum and the diagonal band of Broca. In contrast to these results, responses to GABA applied to cells in the lateral septum, ventral tegmental area and the hippocampus were not affected by ethanol. In those brain regions where ethanol enhanced responses to GABA, a high concentration of zolpidem binding was found, whereas zolpidem binding was much lower or absent in brain regions where ethanol did not enhance GABA. These observations support the hypothesis that ethanol enhances GABA within specific regions of brain by affecting a GABAA receptor with specific structural components. From data obtained with in situ hybridization, there was a strong relationship between the regional distribution of zolpidem binding and the expression of specific mRNAs for the alpha-1, beta-2 and gamma-2 GABAA receptor subunits at sites where ethanol enhanced responses to GABA. The mRNA for the long and short variants of the gamma-2 subunit were found in brain regions both sensitive and insensitive to the action of ethanol on GABA-induced inhibition. These data were not able to address whether the gamma-2 long variant in combination with the alpha-1 and beta-2 subunits is essential for ethanol enhancement of responses to GABA. However, the observation that the long version of the gamma-2 subunit is present in brain areas where ethanol did not affect GABA function suggests that the presence of the long variant of the gamma-2 subunit alone is not sufficient for ethanol's action to enhance responses to GABA. Rather it is concluded that the appropriate combination of GABAA receptor subunits is critical for this action of ethanol. Because the GABAA receptor belongs to a superfamily of ligand-gated ion channels, the action of ethanol was examined on responses to agonists acting on receptors linked to other ion channels. As noted for GABA, local application of ethanol altered responses to NMDA, nicotine and glycine when applied to some, but not all, neurons.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- H E Criswell
- Brain and Development Research Center, School of Medicine, University of North Carolina at Chapel Hill
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