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Zhong M, Wang Y, Lin G, Liao FF, Zhou FM. Dopamine-independent development and maintenance of mouse striatal medium spiny neuron dendritic spines. Neurobiol Dis 2023; 181:106096. [PMID: 37001611 PMCID: PMC10864017 DOI: 10.1016/j.nbd.2023.106096] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/18/2023] [Accepted: 03/20/2023] [Indexed: 03/31/2023] Open
Abstract
Striatal medium spiny neurons (MSNs) and striatal dopamine (DA) innervation are profoundly important for brain function such as motor control and cognition. A widely accepted theory posits that striatal DA loss causes (or leads to) MSN dendritic atrophy. However, examination of the literature indicates that the data from Parkinson's disease (PD) patients and animal PD models were contradictory among studies and hard to interpret. Here we have re-examined the potential effects of DA activity on MSN morphology or lack thereof. We found that in 15-day, 4- and 12-month old Pitx3 null mutant mice that have severe DA denervation in the dorsal striatum while having substantial residual DA innervation in the ventral striatum, MSN dendrites and spine numbers were similar in dorsal and ventral striatum, and also similar to those in normal mice. In 15-day, 4- and 12-month old tyrosine hydroxylase knockout mice that cannot synthesize L-dopa and thus have no endogenous DA in the entire brain, MSN dendrites and spine numbers were also indistinguishable from age-matched wild-type (WT) mice. Furthermore, in adult WT mice, unilateral 6-OHDA lesion at 12 months of age caused an almost complete striatal DA denervation in the lesioned side, but MSN dendrites and spine numbers were similar in the lesioned and control sides. Taken together, our data indicate that in mice, the development and maintenance of MSN dendrites and spines are DA-independent such that DA depletion does not trigger MSN dendritic atrophy; our data also suggest that the reported MSN dendritic atrophy in PD may be a component of neurodegeneration in PD rather than a consequence of DA denervation.
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Affiliation(s)
- Manli Zhong
- College of Life and Health Sciences, Northeastern University, No.195, Chuangxin Road, Hunnan District, Shenyang 110169, China; Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA.
| | - Yuhan Wang
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA
| | - Geng Lin
- Teaching Center for Basic Medical Experiments, China Medical University, Shenyang 110122, China; Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA
| | - Francesca-Fang Liao
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA
| | - Fu-Ming Zhou
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA.
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2
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Dong J, Hawes S, Wu J, Le W, Cai H. Connectivity and Functionality of the Globus Pallidus Externa Under Normal Conditions and Parkinson's Disease. Front Neural Circuits 2021; 15:645287. [PMID: 33737869 PMCID: PMC7960779 DOI: 10.3389/fncir.2021.645287] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/05/2021] [Indexed: 12/18/2022] Open
Abstract
The globus pallidus externa (GPe) functions as a central hub in the basal ganglia for processing motor and non-motor information through the creation of complex connections with the other basal ganglia nuclei and brain regions. Recently, with the adoption of sophisticated genetic tools, substantial advances have been made in understanding the distinct molecular, anatomical, electrophysiological, and functional properties of GPe neurons and non-neuronal cells. Impairments in dopamine transmission in the basal ganglia contribute to Parkinson's disease (PD), the most common movement disorder that severely affects the patients' life quality. Altered GPe neuron activity and synaptic connections have also been found in both PD patients and pre-clinical models. In this review, we will summarize the main findings on the composition, connectivity and functionality of different GPe cell populations and the potential GPe-related mechanisms of PD symptoms to better understand the cell type and circuit-specific roles of GPe in both normal and PD conditions.
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Affiliation(s)
- Jie Dong
- Laboratory of Neurogenetics, Transgenic Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
| | - Sarah Hawes
- Laboratory of Neurogenetics, Transgenic Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
| | - Junbing Wu
- Child Health Institute of New Jersey, Rutgers University, New Brunswick, NJ, United States
| | - Weidong Le
- Liaoning Provincial Center for Clinical Research on Neurological Diseases & Liaoning Provincial Key Laboratory for Research on the Pathogenic Mechanisms of Neurological Diseases, The First Affiliated Hospital of Dalian Medical University, Dalian, China
- Medical School of University of Electronic Science and Technology of China, Institute of Neurology, Sichuan Provincial Hospital, Sichuan Academy of Medical Science, Chengdu, China
| | - Huaibin Cai
- Laboratory of Neurogenetics, Transgenic Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
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Augustin SM, Loewinger GC, O'Neal TJ, Kravitz AV, Lovinger DM. Dopamine D2 receptor signaling on iMSNs is required for initiation and vigor of learned actions. Neuropsychopharmacology 2020; 45:2087-2097. [PMID: 32811899 PMCID: PMC7547091 DOI: 10.1038/s41386-020-00799-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/30/2020] [Accepted: 08/05/2020] [Indexed: 12/15/2022]
Abstract
Striatal dopamine D2 receptors (D2Rs) are important for motor output. Selective deletion of D2Rs from indirect pathway-projecting medium spiny neurons (iMSNs) impairs locomotor activities in a task-specific manner. However, the role of D2Rs in the initiation of motor actions in reward seeking and taking is not fully understood, and there is little information about how receptors contribute under different task demands and with different outcome types. The iMSN-D2Rs modulate neuronal activity and synaptic transmission, exerting control on circuit functions that may play distinct roles in action learning and performance. Selective deletion of D2Rs on iMSNs resulted in slower action initiation and response rate in an instrumental conditioning task, but only when performance demand was increased. The iMSN-Drd2KO mice were also slower to initiate swimming in a T-maze procedural learning task but were unimpaired in cognitive function and behavioral flexibility. In contrast, in a Pavlovian discrimination learning task, iMSN-Drd2KO mice exhibited normal acquisition and extinction of rewarded responding. The iMSN-Drd2KO mice showed performance deficits at all phases of rotarod skill learning. These findings reveal that dopamine modulation through iMSN-D2Rs influences the ability to self-initiate actions, as well as the willingness and/or vigor with which these responses are performed. However, these receptors seem to have little influence on simple associative learning or on stimulus-driven responding. The loss of normal D2R roles may contribute to disorders in which impaired dopamine signaling leads to hypokinesia or impaired initiation of specific voluntary actions.
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Affiliation(s)
- Shana M Augustin
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, 20852, USA
| | - Gabriel C Loewinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, 20852, USA
- Department of Biostatistics, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA
| | - Timothy J O'Neal
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- Graduate Program in Neuroscience and Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, Washington, 98195, USA
| | - Alexxai V Kravitz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- Departments of Psychiatry, Anesthesiology, and Neuroscience, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, 20852, USA.
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McIver EL, Atherton JF, Chu HY, Cosgrove KE, Kondapalli J, Wokosin D, Surmeier DJ, Bevan MD. Maladaptive Downregulation of Autonomous Subthalamic Nucleus Activity following the Loss of Midbrain Dopamine Neurons. Cell Rep 2020; 28:992-1002.e4. [PMID: 31340159 PMCID: PMC6699776 DOI: 10.1016/j.celrep.2019.06.076] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 05/22/2019] [Accepted: 06/19/2019] [Indexed: 01/13/2023] Open
Abstract
Abnormal subthalamic nucleus (STN) activity is linked to impaired movement in Parkinson’s disease (PD). The autonomous firing of STN neurons, which contributes to their tonic excitation of the extrastriatal basal ganglia and shapes their integration of synaptic input, is downregulated in PD models. Using electrophysiological, chemogenetic, genetic, and optical approaches, we find that chemogenetic activation of indirect pathway striatopallidal neurons downregulates intrinsic STN activity in normal mice but this effect is occluded in Parkinsonian mice. Loss of autonomous spiking in PD mice is prevented by STN N-methyl-D-aspartate receptor (NMDAR) knockdown and reversed by reactive oxygen species breakdown or KATP channel inhibition. Chemogenetic activation of hM3D(Gq) in STN neurons in Parkinsonian mice rescues their intrinsic activity, modifies their synaptic integration, and ameliorates motor dysfunction. Together these data argue that in PD mice increased indirect pathway activity leads to disinhibition of the STN, which triggers maladaptive NMDAR-dependent downregulation of autonomous firing. McIver et al. describe the cellular and circuit mechanisms responsible for the loss of autonomous subthalamic nucleus (STN) spiking in dopamine-depleted mice and demonstrate that chemogenetic rescue of intrinsic STN activity reduces Parkinsonian motor dysfunction.
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Affiliation(s)
- Eileen L McIver
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Jeremy F Atherton
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Hong-Yuan Chu
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Kathleen E Cosgrove
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Jyothisri Kondapalli
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - David Wokosin
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - D James Surmeier
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | - Mark D Bevan
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago, IL 60611, USA.
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5
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Wang Y, Bouabid S, Darvas M, Zhou FM. The antiparkinson drug ropinirole inhibits movement in a Parkinson's disease mouse model with residual dopamine neurons. Exp Neurol 2020; 333:113427. [PMID: 32735872 DOI: 10.1016/j.expneurol.2020.113427] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 07/21/2020] [Accepted: 07/25/2020] [Indexed: 10/23/2022]
Abstract
The dopamine (DA) D2-like receptor (D2R) agonist ropinirole is often used for early and middle stage Parkinson's disease (PD). However, this D2-like agonism-based strategy has a complicating problem: D2-like agonism may activate D2 autoreceptors on the residual DA neurons in the PD brain, potentially inhibiting these residual DA neurons and motor function. We have examined this possibility by using systemic and local drug administration in transcription factor Pitx3 null mutant (Pitx3Null) mice that mimic the DA denervation in early and middle stage PD and in DA neuron tyrosine hydroxylase (TH) gene knockout (KO) mice that mimic the severe DA loss in late stage PD. We found that in Pitx3Null mice with residual DA neurons and normal mice with normal DA system, systemically injected ropinirole inhibited locomotion, whereas bilateral dorsal striatal-microinjected ropinirole stimulated movement in Pitx3Null mice; bilateral microinjection of ropinirole into the ventral tegmental area also inhibited movement in Pitx3Null mice; we further determined that ropinirole inhibited nigral DA neuron spike firing in WT mice. In contrast, both systemically and striatum-locally administered ropinirole increased movements in TH KO mice, but produced relatively more dyskinesia than L-dopa. Although requiring confirmation in non-human primates and PD patients, these data suggest that while activating D2-like receptors in striatal projection neurons and hence stimulating movements, D2-like agonists can inhibit residual DA neurons and cause akinesia when the residual DA neurons and motor functions are still substantial, and this motor-inhibitory effect disappears when almost all DA neurons are lost such as in late stage PD.
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Affiliation(s)
- Yuhan Wang
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA
| | - Safa Bouabid
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA
| | - Martin Darvas
- Department of Pathology, University of Washington, Seattle, WA 98104, USA
| | - Fu-Ming Zhou
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, University of Tennessee, Memphis, TN 38103, USA.
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Ciriachi C, Svane‐Petersen D, Rickhag M. Genetic tools to study complexity of striatal function. J Neurosci Res 2019; 97:1181-1193. [DOI: 10.1002/jnr.24479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 01/11/2023]
Affiliation(s)
- Chiara Ciriachi
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - David Svane‐Petersen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Mattias Rickhag
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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Runegaard AH, Fitzpatrick CM, Woldbye DPD, Andreasen JT, Sørensen AT, Gether U. Modulating Dopamine Signaling and Behavior with Chemogenetics: Concepts, Progress, and Challenges. Pharmacol Rev 2019; 71:123-156. [PMID: 30814274 DOI: 10.1124/pr.117.013995] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
For more than 60 years, dopamine (DA) has been known as a critical modulatory neurotransmitter regulating locomotion, reward-based motivation, and endocrine functions. Disturbances in DA signaling have been linked to an array of different neurologic and psychiatric disorders, including Parkinson's disease, schizophrenia, and addiction, but the underlying pathologic mechanisms have never been fully elucidated. One major obstacle limiting interpretation of standard pharmacological and transgenic interventions is the complexity of the DA system, which only appears to widen as research progresses. Nonetheless, development of new genetic tools, such as chemogenetics, has led to an entirely new era for functional studies of neuronal signaling. By exploiting receptors that are engineered to respond selectively to an otherwise inert ligand, so-called Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), chemogenetics enables pharmacological remote control of neuronal activity. Here we review the recent, extensive application of this technique to the DA field and how its use has advanced the study of the DA system and contributed to our general understanding of DA signaling and related behaviors. Moreover, we discuss the challenges and pitfalls associated with the chemogenetic technology, such as the metabolism of the DREADD ligand clozapine N-oxide (CNO) to the D2 receptor antagonist clozapine. We conclude that despite the recent concerns regarding CNO, the chemogenetic toolbox provides an exceptional approach to study neuronal function. The huge potential should promote continued investigations and additional refinements to further expound key mechanisms of DA signaling and circuitries in normal as well as maladaptive behaviors.
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Affiliation(s)
- Annika Højrup Runegaard
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience (A.H.R., D.P.D.W., A.T.S., U.G.) and Department of Drug Design and Pharmacology (C.M.F., J.T.A.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ciarán Martin Fitzpatrick
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience (A.H.R., D.P.D.W., A.T.S., U.G.) and Department of Drug Design and Pharmacology (C.M.F., J.T.A.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - David Paul Drucker Woldbye
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience (A.H.R., D.P.D.W., A.T.S., U.G.) and Department of Drug Design and Pharmacology (C.M.F., J.T.A.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Tobias Andreasen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience (A.H.R., D.P.D.W., A.T.S., U.G.) and Department of Drug Design and Pharmacology (C.M.F., J.T.A.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Toft Sørensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience (A.H.R., D.P.D.W., A.T.S., U.G.) and Department of Drug Design and Pharmacology (C.M.F., J.T.A.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience (A.H.R., D.P.D.W., A.T.S., U.G.) and Department of Drug Design and Pharmacology (C.M.F., J.T.A.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Chemogenetic Targeting of Dorsomedial Direct-pathway Striatal Projection Neurons Selectively Elicits Rotational Behavior in Mice. Neuroscience 2019; 401:106-116. [PMID: 30668973 DOI: 10.1016/j.neuroscience.2019.01.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/16/2018] [Accepted: 01/11/2019] [Indexed: 01/11/2023]
Abstract
The striatum of the basal ganglia is pivotal for voluntary movements and is implicated in debilitating movement disorders such as Parkinsonism and dystonia. Striatum projects to downstream nuclei through direct (dSPN) and indirect (iSPN) pathway projection neurons thought to exert opposite effects on movement. In rodent models of striatal function, unilateral dopamine deprivation induces ipsiversive rotational behavior. The dSPNs of the dorsal striatum are believed to engage distinct motor programs but underlying mechanisms remain unclear. Here, we show by employing chemogenetics [Designer Receptors Exclusively Activated by Designer Drugs (DREADDs)] that unilateral inhibition of dorsomedial dSPNs is sufficient to selectively impair contraversive movement and elicit ipsiversive rotational behavior in mice. Adeno-associated virus (AAV) encoding Cre-dependent Gi-coupled DREADD was injected unilaterally into the dorsomedial striatum of Drd1-Cre mice, resulting in expression of the modified human M4 muscarinic receptor (hM4Di) in ∼20% of dorsostriatal dSPNs. Upon hM4Di activation, a striking positive linear correlation was found between turn ratio and viral expression, which corroborates a relationship between unilateral inhibition of dorsomedial dSPNs and rotational behavior. Bursts of ipsiversive rotations were interspersed with normal ambulation. However, partial unilateral inhibition of ∼20% of dorsostriatal dSPNs did not affect horizontal and vertical locomotion or forelimb use preference. Overall, our results substantiate a unique role of dSPNs in promoting response bias in rotational behavior and show this to be a highly sensitive measure of dSPN performance.
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cAMP-producing chemogenetic and adenosine A2a receptor activation inhibits the inwardly rectifying potassium current in striatal projection neurons. Neuropharmacology 2019; 148:229-243. [PMID: 30659840 DOI: 10.1016/j.neuropharm.2019.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 01/14/2019] [Accepted: 01/14/2019] [Indexed: 12/29/2022]
Abstract
Adenosine A2a receptors (A2aRs) are highly and selectively expressed in D2-medium spiny neurons (D2-MSNs) that also express a high level of dopamine D2 receptors (D2Rs). However, it was not established how A2aR activity affects D2-MSN excitability, let alone the ion channels involved. We have performed two sets of experiments to determine the potential A2aR agonistic effects on D2-MSN intrinsic excitability and the underlying ion channel mechanism. First, we have used the cAMP-producing, Gαs/olf coupled designer receptors exclusively activated by designer drug (Gs-DREADDs) to phenocopy cAMP-stimulating A2aR activation. We found that activation of Gs-DREADD inhibited the inwardly rectifying potassium current (Kir)-a key regulator of MSN excitability, caused a depolarization, increased input resistance, and substantially increased the intrinsic excitability of MSNs such that depolarizing inputs evoked many more action potentials. Second, we have determined that A2aR agonism produced these same excitatory effects on D2-MSN intrinsic excitability and spike firing, although at lower magnitudes than those induced by Gs-DREADD activation; furthermore, these A2aR-triggered excitatory effects were intact in the presence of a D2R antagonist. Taken together, these results clearly establish that in striatal D2-MSNs, A2aR activation can independently inhibit Kir and increase intrinsic excitability and spike and neurotransmitter output; our results also indicate that Gs-DREADD can serve as a broadly useful positive control for neurotransmitter receptors that increase intracellular cAMP levels and hence facilitate the determination of the cellular effects of these neurotransmitter receptors.
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Morales-Figueroa GE, Rivera-Ramírez N, González-Pantoja R, Escamilla-Sánchez J, García-Hernández U, Galván EJ, Arias-Montaño JA. Adenosine A 2A and histamine H 3 receptors interact at the cAMP/PKA pathway to modulate depolarization-evoked [ 3H]-GABA release from rat striato-pallidal terminals. Purinergic Signal 2018; 15:85-93. [PMID: 30565027 DOI: 10.1007/s11302-018-9638-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/20/2018] [Indexed: 02/06/2023] Open
Abstract
We previously reported that the activation of histamine H3 receptors (H3Rs) selectively counteracts the facilitatory action of adenosine A2A receptors (A2ARs) on GABA release from rat globus pallidus (GP) isolated nerve terminals (synaptosomes). In this work, we examined the mechanisms likely to underlie this functional interaction. Three possibilities were explored: (a) changes in receptor affinity for agonists induced by physical A2AR/H3R interaction, (b) opposite actions of A2ARs and H3Rs on depolarization-induced Ca2+ entry, and (c) an A2AR/H3R interaction at the level of adenosine 3',5'-cyclic monophosphate (cAMP) formation. In GP synaptosomal membranes, H3R activation with immepip reduced A2AR affinity for the agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride hydrate (CGS-21680) (Ki control 4.53 nM; + immepip 9.32 nM), whereas A2AR activation increased H3R affinity for immepip (Ki control 0.63 nM; + CGS-21680 0.26 nM). Neither A2AR activation nor H3R stimulation modified calcium entry through voltage-gated calcium channels in GP synaptosomes, as evaluated by microfluorometry. A2AR-mediated facilitation of depolarization-evoked [2,3-3H]-γ-aminobutyric acid ([3H]-GABA) release from GP synaptosomes (130.4 ± 3.6% of control values) was prevented by the PKA inhibitor H-89 and mimicked by the adenylyl cyclase activator forskolin or by 8-Bromo-cAMP, a membrane permeant cAMP analogue (169.5 ± 17.3 and 149.5 ± 14.5% of controls). H3R activation failed to reduce the facilitation of [3H]-GABA release induced by 8-Bromo-cAMP. In GP slices, A2AR activation stimulated cAMP accumulation (290% of basal) and this effect was reduced (- 75%) by H3R activation. These results indicate that in striato-pallidal nerve terminals, A2ARs and H3Rs interact at the level of cAMP formation to modulate PKA activity and thus GABA release.
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Affiliation(s)
- Guadalupe-Elide Morales-Figueroa
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Nayeli Rivera-Ramírez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Raúl González-Pantoja
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Juan Escamilla-Sánchez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Ubaldo García-Hernández
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, 07360, MÉXICO, México
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México.
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