1
|
Mieling M, Meier H, Bunzeck N. Structural degeneration of the nucleus basalis of Meynert in mild cognitive impairment and Alzheimer's disease - Evidence from an MRI-based meta-analysis. Neurosci Biobehav Rev 2023; 154:105393. [PMID: 37717861 DOI: 10.1016/j.neubiorev.2023.105393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 07/17/2023] [Accepted: 09/14/2023] [Indexed: 09/19/2023]
Abstract
Recent models of Alzheimer's disease (AD) suggest that neuropathological changes of the medial temporal lobe, especially entorhinal cortex, are preceded by degenerations of the cholinergic Nucleus basalis of Meynert (NbM). Evidence from imaging studies in humans, however, is limited. Therefore, we performed an activation-likelihood estimation meta-analysis on whole brain voxel-based morphometry (VBM) MRI data from 54 experiments and 2581 subjects in total. It revealed, compared to healthy older controls, reduced gray matter in the bilateral NbM in AD, but only limited evidence for such an effect in patients with mild cognitive impairment (MCI), which typically precedes AD. Both patient groups showed less gray matter in the amygdala and hippocampus, with hints towards more pronounced amygdala effects in AD. We discuss our findings in the context of studies that highlight the importance of the cholinergic basal forebrain in learning and memory throughout the lifespan, and conclude that they are partly compatible with pathological staging models suggesting initial and pronounced structural degenerations within the NbM in the progression of AD.
Collapse
Affiliation(s)
- Marthe Mieling
- Department of Psychology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Hannah Meier
- Department of Psychology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Nico Bunzeck
- Department of Psychology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany; Center of Brain, Behavior and Metabolism, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany.
| |
Collapse
|
2
|
Ekmark-Lewén S, Aniszewska A, Molisak A, Gumucio A, Lindström V, Kahle P, Nordström E, Möller C, Fälting J, Lannfelt L, Bergström J, Ingelsson M. Reduction of brain stem pathology and transient amelioration of early cognitive symptoms in transgenic mice treated with a monoclonal antibody against α-synuclein oligomers/protofibrils. AGING BRAIN 2023; 4:100086. [PMID: 37559953 PMCID: PMC10407822 DOI: 10.1016/j.nbas.2023.100086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/05/2023] [Accepted: 07/08/2023] [Indexed: 08/11/2023] Open
Abstract
Immunotherapy against alpha-synuclein (α-syn) is a promising novel treatment strategy for Parkinson's disease (PD) and related α-synucleinopathies. We have previously shown that systemic treatment with the monoclonal oligomer/protofibril-selective antibody mAb47 targeting cytotoxic α-syn leads to reduced central nervous system levels of such species as well as an indication of reduced late-stage symptoms in aged (Thy-1)-h[A30P] α-syn transgenic mice. Here, we performed an early-onset long-term treatment study with this antibody to evaluate effects on brain pathology and behavioral outcomes in the same mouse model. Compared to the placebo group, the treatment strongly reduced phosphorylated α-syn (pS129 α-syn) pathology in the upper brain stem. Moreover, a preserved recognition memory and risk assessment behavior could be seen in antibody-treated mice at six months of age, even although these effects were no longer significant at eleven months of age. Importantly, no evidence of inflammatory responses or other potential toxic effects was seen with the treatment. Taken together, this study supports the strategy to target α-syn oligomers/protofibrils with monoclonal antibodies to counteract early symptoms and slow down the progression of PD and other α-synucleinopathies.
Collapse
Affiliation(s)
- S. Ekmark-Lewén
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - A. Aniszewska
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - A. Molisak
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - A. Gumucio
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - V. Lindström
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - P.J. Kahle
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research and German Center for Neurodegenerative Diseases, Tübingen, Germany
| | | | | | | | - L. Lannfelt
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
- BioArctic AB, Stockholm, Sweden
| | - J. Bergström
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - M. Ingelsson
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
- Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine and Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
3
|
Betts GD, Hynes TJ, Winstanley CA. Pharmacological evidence of a cholinergic contribution to elevated impulsivity and risky decision-making caused by adding win-paired cues to a rat gambling task. J Psychopharmacol 2021; 35:701-712. [PMID: 33573446 DOI: 10.1177/0269881120972421] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Pairing rewards with sensory stimulation, in the form of auditory and visual cues, increases risky decision-making in both rats and humans. Understanding the neurobiological basis of this effect could help explain why electronic gambling machines are so addictive, and inform treatment development for compulsive gambling and gaming. Numerous studies implicate the dopamine system in mediating the motivational influence of reward-paired cues; recent data suggest the cholinergic system also plays a critical role. Previous work also indicates that cholinergic drugs alter decision-making under uncertainty. AIMS We investigated whether the addition of reward-concurrent cues to the rat gambling task (crGT) altered the effects of peripherally administered cholinergic compounds. METHODS Muscarinic and nicotinic agonists and antagonists were administered to 16 male, Long-Evans rats trained on the crGT. Measures of optimal/risky decision-making and motor impulsivity were the main dependent variables of interest. RESULTS The muscarinic receptor antagonist scopolamine improved decision-making overall, decreasing selection of one of the risky options while increasing choice of the more advantageous options. The muscarinic agonist oxotremorine increased choice latency but did not significantly affect option preference. Neither the nicotinic antagonist mecamylamine nor the agonist nicotine affected choice patterns, but mecamylamine decreased premature responding, an index of motor impulsivity. CONCLUSIONS These results contrast sharply from those obtained previously using the uncued rGT, and suggest that the deleterious effects of win-paired cues on decision-making and impulse control may result from elevated cholinergic tone.
Collapse
Affiliation(s)
- Graeme D Betts
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada
| | - Tristan J Hynes
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada
| | | |
Collapse
|
4
|
Satoh Y, Tsuji K. Suppressive effect of the swallowing reflex by stimulation of the pedunculopontine tegmental nucleus. Neurosci Res 2020; 169:40-47. [PMID: 32649975 DOI: 10.1016/j.neures.2020.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 10/23/2022]
Abstract
This study investigates whether the swallowing reflex is modulated by stimulation of the pedunculopontine tegmental nucleus (PTg). Sprague-Dawley rats under urethane anesthesia were used. The swallowing reflex was induced by electrical stimulation of the superior laryngeal nerve and was identified by the electromyographic activities from the mylohyoid muscle. The number of swallows was reduced by electrical stimulation of the PTg. The latency of the onset of the first swallow was increased during stimulation of the PTg. The duration of electromyogram bursts of the mylohyoid muscle was significantly shorter during the PTg stimulation than with no stimulation. The number of swallows was reduced, latency of onset of the first swallow increased, the duration of electromyogram bursts of the mylohyoid muscle was significantly shorter and the peak-to-peak amplitude of electromyogram bursts of the mylohyoid muscle was significantly suppressed after microinjection of glutamate into the PTg. These results suggest that the PTg is involved in the control of swallowing.
Collapse
Affiliation(s)
- Yoshihide Satoh
- Department of Physiology, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-cho, Chuo-ku, Niigata, 951-8580, Japan.
| | - Kojun Tsuji
- Department of Physiology, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-cho, Chuo-ku, Niigata, 951-8580, Japan
| |
Collapse
|
5
|
Ettaro R, Markovic T, Daniels D, MacLaren DA, Clark SD. Microinjection of urotensin II into the pedunculopontine tegmentum leads to an increase in the consumption of sweet tastants. Physiol Behav 2020; 215:112775. [PMID: 31843472 DOI: 10.1016/j.physbeh.2019.112775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/02/2019] [Accepted: 12/11/2019] [Indexed: 11/29/2022]
Abstract
The pedunculopontine tegmentum (PPTg) plays a role in processing multiple sensory inputs and innervates brain regions associated with reward-related behaviors. The urotensin II receptor, activated by the urotensin II peptide (UII), is selectively expressed by the cholinergic neurons of the PPTg. Although the exact function of cholinergic neurons of the PPTg is unknown, they are thought to contribute to the perception of reward magnitude or salience detection. We hypothesized that the activation of PPTg cholinergic neurons would alter sensory processing across multiple modalities (ex. taste and hearing). Here we had three aims: first, determine if cholinergic activation is involved in consumption behavior of palatable solutions (sucrose). Second, if so, distinguish the impact of the caloric value by using saccharin, a zero calorie sweetener. Lastly, we tested the UII-mediated effects on perception of acoustic stimuli by measuring acoustic startle reflex (ASR). Male Sprague-Dawley rats were bilaterally cannulated into the PPTg, then placed under food restriction lasting the entire consumption experiment (water ad lib.). Treatment consisted of a microinjection of either 1 μL of aCSF or 1 μL of 10 μM UII into the PPTg, and the rats were immediately given access to either sucrose or saccharin. For the remaining five days, rats were allowed one hour access per day to the same sweet solution without any further treatments. During the saccharin experiment rats were tested in a contact lickometer which recorded each individual lick to give insight into the microstructure of the consumption behavior. ASR testing consisted of a baseline (no treatment), treatment day, and two additional days (no treatment). Immediately following the microinjection of UII, consumption of both saccharin and sucrose increased compared to controls. This significant increase persisted for days after the single administration of UII, but there was no generalized arousal or increase in water consumption between testing sessions. The effects on ASR were not significant. Activating cholinergic PPTg neurons may lead to a miscalculation of the salience of external stimuli, implicating the importance of cholinergic input in modulating a variety of behaviors. The long-lasting effects seen after UII treatment support further research into the role of sensory processing on reward related-behaviors at the level of the PPTg cholinergic neurons.
Collapse
Affiliation(s)
- Robert Ettaro
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY 14214, United States
| | - Tamara Markovic
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY 14214, United States
| | - Derek Daniels
- Department of Psychology and the Center for Ingestive Behavior Research, University at Buffalo, Buffalo, NY 14214, United States
| | - Duncan Aa MacLaren
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY 14214, United States
| | - Stewart D Clark
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY 14214, United States
| |
Collapse
|
6
|
Complex Control of Striatal Neurotransmission by Nicotinic Acetylcholine Receptors via Excitatory Inputs onto Medium Spiny Neurons. J Neurosci 2018; 38:6597-6607. [PMID: 29941445 DOI: 10.1523/jneurosci.0071-18.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 04/06/2018] [Accepted: 05/10/2018] [Indexed: 01/12/2023] Open
Abstract
The prevalence of nicotine dependence is higher than that for any other substance abuse disorder; still, the underlying mechanisms are not fully established. To this end, we studied acute effects by nicotine on neurotransmission in the dorsolateral striatum, a key brain region with respect to the formation of habits. Electrophysiological recordings in acutely isolated brain slices from rodent showed that nicotine (10 nm to 10 μm) produced an LTD of evoked field potentials. Current-clamp recordings revealed no significant effect by nicotine on membrane voltage or action potential frequency, indicating that the effect by nicotine is primarily synaptic. Nicotine did not modulate sIPSCs, or the connectivity between fast-spiking interneurons and medium spiny neurons, as assessed by whole-cell recordings combined with optogenetics. However, the frequency of sEPSCs was significantly depressed by nicotine. The effect by nicotine was mimicked by agonists targeting α7- or α4-containing nAChRs and blocked in slices pretreated with a mixture of antagonists targeting these receptor subtypes. Nicotine-induced LTD was furthermore inhibited by dopamine D2 receptor antagonist and occluded by D2 receptor agonist. In addition, modulation of cholinergic neurotransmission suppressed the responding to nicotine, which might reflect upon the postulated role for nAChRs as a presynaptic filter to differentially govern dopamine release depending on neuronal activity. Nicotine-induced suppression of excitatory inputs onto medium spiny neurons may promote nicotine-induced locomotor stimulation and putatively initiate neuroadaptations that could contribute to the transition toward compulsive drug taking.SIGNIFICANCE STATEMENT To decrease smoking, prevalence factors that may contribute to the development of nicotine addiction need to be identified. The data presented here show that nicotine suppresses striatal neurotransmission by selectively reducing the frequency of excitatory inputs to medium spiny neurons (MSNs) while rendering excitability, inhibitory neurotransmission, and fast-spiking interneuron-MSN connectivity unaltered. In addition, we show that the effect displayed by nicotine outlasts the presence of the drug, which could be fundamental for the addictive properties of nicotine. Considering the inhibitory tone displayed by MSNs on dopaminergic cell bodies and local terminals, nicotine-induced long-lasting depression of striatal output could play a role in behavioral transformations associated with nicotine use, and putatively elicit neuroadaptations underlying compulsive drug-seeking habits.
Collapse
|
7
|
Kim LH, Sharma S, Sharples SA, Mayr KA, Kwok CHT, Whelan PJ. Integration of Descending Command Systems for the Generation of Context-Specific Locomotor Behaviors. Front Neurosci 2017; 11:581. [PMID: 29093660 PMCID: PMC5651258 DOI: 10.3389/fnins.2017.00581] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 10/04/2017] [Indexed: 11/23/2022] Open
Abstract
Over the past decade there has been a renaissance in our understanding of spinal cord circuits; new technologies are beginning to provide key insights into descending circuits which project onto spinal cord central pattern generators. By integrating work from both the locomotor and animal behavioral fields, we can now examine context-specific control of locomotion, with an emphasis on descending modulation arising from various regions of the brainstem. Here we examine approach and avoidance behaviors and the circuits that lead to the production and arrest of locomotion.
Collapse
Affiliation(s)
- Linda H Kim
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Sandeep Sharma
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Simon A Sharples
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Kyle A Mayr
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Charlie H T Kwok
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Patrick J Whelan
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| |
Collapse
|
8
|
Mori F, Okada KI, Nomura T, Kobayashi Y. The Pedunculopontine Tegmental Nucleus as a Motor and Cognitive Interface between the Cerebellum and Basal Ganglia. Front Neuroanat 2016; 10:109. [PMID: 27872585 PMCID: PMC5097925 DOI: 10.3389/fnana.2016.00109] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/24/2016] [Indexed: 11/13/2022] Open
Abstract
As an important component of ascending activating systems, brainstem cholinergic neurons in the pedunculopontine tegmental nucleus (PPTg) are involved in the regulation of motor control (locomotion, posture and gaze) and cognitive processes (attention, learning and memory). The PPTg is highly interconnected with several regions of the basal ganglia, and one of its key functions is to regulate and relay activity from the basal ganglia. Together, they have been implicated in the motor control system (such as voluntary movement initiation or inhibition), and modulate aspects of executive function (such as motivation). In addition to its intimate connection with the basal ganglia, projections from the PPTg to the cerebellum have been recently reported to synaptically activate the deep cerebellar nuclei. Classically, the cerebellum and basal ganglia were regarded as forming separated anatomical loops that play a distinct functional role in motor and cognitive behavioral control. Here, we suggest that the PPTg may also act as an interface device between the basal ganglia and cerebellum. As such, part of the therapeutic effect of PPTg deep brain stimulation (DBS) to relieve gait freezing and postural instability in advanced Parkinson’s disease (PD) patients might also involve modulation of the cerebellum. We review the anatomical position and role of the PPTg in the pathway of basal ganglia and cerebellum in relation to motor control, cognitive function and PD.
Collapse
Affiliation(s)
- Fumika Mori
- Laboratories for Neuroscience Visual Neuroscience Group, Graduate School of Frontier Biosciences, Osaka UniversityOsaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology and Osaka UniversityOsaka, Japan
| | - Ken-Ichi Okada
- Laboratories for Neuroscience Visual Neuroscience Group, Graduate School of Frontier Biosciences, Osaka UniversityOsaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology and Osaka UniversityOsaka, Japan
| | - Taishin Nomura
- Bio-Dynamics Group, Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University Osaka, Japan
| | - Yasushi Kobayashi
- Laboratories for Neuroscience Visual Neuroscience Group, Graduate School of Frontier Biosciences, Osaka UniversityOsaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology and Osaka UniversityOsaka, Japan; Research Center for Behavioral Economics, Osaka UniversityOsaka, Japan
| |
Collapse
|
9
|
Garzón M, Pickel VM. Electron microscopic localization of M2-muscarinic receptors in cholinergic and noncholinergic neurons of the laterodorsal tegmental and pedunculopontine nuclei of the rat mesopontine tegmentum. J Comp Neurol 2016; 524:3084-103. [PMID: 27038330 DOI: 10.1002/cne.24010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 03/02/2016] [Accepted: 03/28/2016] [Indexed: 01/01/2023]
Abstract
Muscarinic m2 receptors (M2Rs) are implicated in autoregulatory control of cholinergic output neurons located within the pedunculopontine (PPT) and laterodorsal tegmental (LTD) nuclei of the mesopontine tegmentum (MPT). However, these nuclei contain many noncholinergic neurons in which activation of M2R heteroceptors may contribute significantly to the decisive role of the LTD and PPT in sleep-wakefulness. We examined the electron microscopic dual immunolabeling of M2Rs and the vesicular acetylcholine transporter (VAchT) in the MPT of rat brain to identify the potential sites for M2R activation. M2R immunogold labeling was predominately seen in somatodendritic profiles throughout the PPT/LTD complex. In somata, M2R immunogold particles were often associated with Golgi lamellae and cytoplasmic endomembrannes, but were rarely in contact with the plasma membrane, as was commonly seen in dendrites. Approximately 36% of the M2R-labeled somata and 16% of the more numerous M2R-labeled dendrites coexpressed VAchT. M2R and M2R/VAchT-labeled dendritic profiles received synapses from inhibitory- and excitatory-type axon terminals, over 88% of which were unlabeled and others contained exclusively M2R or VAchT immunoreactivity. In axonal profiles M2R immunogold was localized to plasmalemmal and cytoplasmic regions and showed a similar distribution in many VAchT-negative glial profiles. These results provide ultrastructural evidence suggestive of somatic endomembrane trafficking of M2Rs, whose activation serves to regulate the postsynaptic excitatory and inhibitory responses in dendrites of cholinergic and noncholinergic neurons in the MPT. They also suggest the possibility that M2Rs in this brain region mediate the effects of acetylcholine on the release of other neurotransmitters and on glial signaling. J. Comp. Neurol. 524:3084-3103, 2016. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Miguel Garzón
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina UAM, Madrid, Spain.,Instituto de Investigación Hospital Universitario La Paz (IDIPAZ), Madrid, Spain.,Department of Neuroscience, Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Virginia M Pickel
- Department of Neuroscience, Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York, USA
| |
Collapse
|
10
|
Bunzeck N, Thiel C. Neurochemical modulation of repetition suppression and novelty signals in the human brain. Cortex 2015; 80:161-73. [PMID: 26625882 DOI: 10.1016/j.cortex.2015.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/22/2015] [Accepted: 10/15/2015] [Indexed: 12/11/2022]
Abstract
The repeated processing of a sensory stimulus, such as a picture or sound, leads to a decrement in response in neurons that fired to the initial presentation. These effects are well known from single cell recordings in the inferior temporal cortex in monkeys, and functional neuroimaging in humans on large-scale neural activity could show similar effects in extrastriate, frontal and medial temporal lobe (MTL) regions. The role of specific neurotransmitters in repeated processing of information is, however, less clear. In the first part of this article, we will introduce the two concepts of repetition suppression and novelty signals, which is followed by a brief overview of pharmacological neuroimaging in humans. We will then summarize human studies suggesting that gamma-aminobutyric-acid (GABA) and acetylcholine (ACh) play an important role in modulating behavioral priming and associated repetition suppression in extrastriate and frontal brain regions. Finally, we review studies on neural novelty signals in the dopaminergic mesolimbic system, and conclude that dopamine (DA) regulates the temporal aspects of novelty processing and closely relates to long-term memory encoding rather than behavioral priming. As such, this review describes differential roles of GABA, ACh and DA in repeated stimulus processing, and further suggests that repetition suppression and neural novelty signals may not be two sides of the same coin but rather independent processes.
Collapse
Affiliation(s)
- Nico Bunzeck
- Department of Psychology, University of Lübeck, Lübeck, Germany; Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Christiane Thiel
- Biological Psychology, Department of Psychology, European Medical School, Carl von Ossietzky University Oldenburg, Oldenburg, Germany; Cluster of Excellence "Hearing4all" and Research Center Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| |
Collapse
|
11
|
Nilsson MKL, Carlsson ML. The monoaminergic stabilizer (-)-OSU6162 reverses delay-dependent natural forgetting and improves memory impairment induced by scopolamine in mice. Neuropharmacology 2013; 75:399-406. [PMID: 23994443 DOI: 10.1016/j.neuropharm.2013.08.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 08/05/2013] [Accepted: 08/18/2013] [Indexed: 12/14/2022]
Abstract
The aim of the present study was to evaluate the effect of the monoaminergic stabilizer (-)-OSU6162 on spatial recognition memory. Male NMRI mice were tested in the object location model which is based on the animals' inherent interest to examine changes in their environment: The animals' propensity to explore relocated objects in relation to unaltered objects, presented in two different sessions (sample and trial), was studied. In a first series of experiments the effect of (-)-OSU6162 on natural forgetting was evaluated. With an inter-session interval (ISI) of 30 min or an hour, untreated mice spent longer time exploring the displaced object, but when the time between sessions was as long as 6 h, the mice did not identify the displaced object. However, using the 6 h ISI design we found that (-)-OSU6162 in doses up to 30 μmol/kg, given directly after the sample session, caused an increased interest for the displaced object. Twenty-four hours after administration, (-)-OSU6162 was still effective in facilitating identification of the displaced object. We also evaluated the effect of (-)-OSU6162 on scopolamine-induced memory deficits in this model - the two agents were given 30 min before the sample session and the ISI was one hour. Under these conditions scopolamine induced a deficit in object location memory and this effect was counteracted by (-)-OSU6162. The data from the present study suggest that (-)-OSU6162 prolongs object location memory in normal mice and reverses scopolamine-induced memory deficits. (-)-OSU6162 might be a valuable drug candidate for memory deficits and other cognitive impairments.
Collapse
Affiliation(s)
- Marie K L Nilsson
- Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska Science Park, Medicinaregatan 8A, 413 46 Gothenburg, Sweden.
| | - Maria L Carlsson
- Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska Science Park, Medicinaregatan 8A, 413 46 Gothenburg, Sweden
| |
Collapse
|
12
|
Eckart C, Bunzeck N. Dopamine modulates processing speed in the human mesolimbic system. Neuroimage 2013; 66:293-300. [DOI: 10.1016/j.neuroimage.2012.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 10/30/2012] [Accepted: 11/01/2012] [Indexed: 12/01/2022] Open
|
13
|
Bunzeck N, Guitart-Masip M, Dolan RJ, Duzel E. Pharmacological dissociation of novelty responses in the human brain. ACTA ACUST UNITED AC 2013; 24:1351-60. [PMID: 23307638 PMCID: PMC3977623 DOI: 10.1093/cercor/bhs420] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Repeated processing of the same information is associated with decreased neuronal responses, termed repetition suppression (RS). Although RS effects (i.e., the difference in activity between novel and repeated stimuli) have been demonstrated within several brain regions, such as the medial temporal lobe, their precise neural mechanisms still remain unclear. Here, we used functional magnetic resonance imaging together with psychopharmacology in 48 healthy human subjects, demonstrating that RS effects within the mesolimbic system are differentially modulated by cholinergic and dopaminergic stimulation. The dopamine precursor levodopa (100 mg) attenuated RS within the hippocampus, parahippocampal cortex, and substantia nigra/ventral tegmental area, and the degree of this reduction correlated with recognition memory performance 24 h later. The acetylcholinesterase inhibitor galantamine (8 mg), in contrast, reversed RS into repetition enhancement, showing no relationship to subsequent recognition memory. This suggests that novelty sensitive neural populations of the mesolimbic system can dynamically shift their responses depending on the balance of cholinergic and dopaminergic neurotransmission, and these shifts can influence memory retention.
Collapse
Affiliation(s)
- Nico Bunzeck
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | | | | | | |
Collapse
|
14
|
References. Anal Chem 2012. [DOI: 10.1201/b11478-14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
15
|
A neural correlate of predicted and actual reward-value information in monkey pedunculopontine tegmental and dorsal raphe nucleus during saccade tasks. Neural Plast 2011; 2011:579840. [PMID: 22013541 PMCID: PMC3195531 DOI: 10.1155/2011/579840] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 07/13/2011] [Accepted: 08/04/2011] [Indexed: 11/28/2022] Open
Abstract
Dopamine, acetylcholine, and serotonin, the main modulators of the central nervous system, have been proposed to play important roles in the execution of movement, control of several forms of attentional behavior, and reinforcement learning. While the response pattern of midbrain dopaminergic neurons and its specific role in reinforcement learning have been revealed, the role of the other neuromodulators remains rather elusive. Here, we review our recent studies using extracellular recording from neurons in the pedunculopontine tegmental nucleus, where many cholinergic neurons exist, and the dorsal raphe nucleus, where many serotonergic neurons exist, while monkeys performed eye movement tasks to obtain different reward values. The firing patterns of these neurons are often tonic throughout the task period, while dopaminergic neurons exhibited a phasic activity pattern to the task event. The different modulation patterns, together with the activity of dopaminergic neurons, reveal dynamic information processing between these different neuromodulator systems.
Collapse
|
16
|
Lester DB, Rogers TD, Blaha CD. Acetylcholine-dopamine interactions in the pathophysiology and treatment of CNS disorders. CNS Neurosci Ther 2010; 16:137-62. [PMID: 20370804 PMCID: PMC6493877 DOI: 10.1111/j.1755-5949.2010.00142.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dopaminergic neurons in the substantia nigra pars compacta and ventral tegmental area of the midbrain form the nigrostriatal and mesocorticolimbic dopaminergic pathways that, respectively, project to dorsal and ventral striatum (including prefrontal cortex). These midbrain dopaminergic nuclei and their respective forebrain and cortical target areas are well established as serving a critical role in mediating voluntary motor control, as evidenced in Parkinson's disease, and incentive-motivated behaviors and cognitive functions, as exhibited in drug addiction and schizophrenia, respectively. Although it cannot be disputed that excitatory and inhibitory amino acid-based neurotransmitters, such as glutamate and GABA, play a vital role in modulating activity of midbrain dopaminergic neurons, recent evidence suggests that acetylcholine may be as important in regulating dopaminergic transmission. Midbrain dopaminergic cell tonic and phasic activity is closely dependent upon projections from hindbrain pedunculopontine and the laterodorsal tegmental nuclei, which comprises the only known cholinergic inputs to these neurons. In close coordination with glutamatergic and GABAergic activity, these excitatory cholinergic projections activate nicotinic and muscarinic acetylcholine receptors within the substantia nigra and ventral tegmental area to modulate dopamine transmission in the dorsal/ventral striatum and prefrontal cortex. Additionally, acetylcholine-containing interneurons in the striatum also constitute an important neural substrate to provide further cholinergic modulation of forebrain striatal dopaminergic transmission. In this review, we examine neurological and psychopathological conditions associated with dysfunctions in the interaction of acetylcholine and dopamine and conventional and new pharmacological approaches to treat these disorders.
Collapse
Affiliation(s)
- Deranda B Lester
- Department of Psychology, The University of Memphis, Memphis, TN, USA
| | - Tiffany D. Rogers
- Department of Psychology, The University of Memphis, Memphis, TN, USA
| | - Charles D. Blaha
- Department of Psychology, The University of Memphis, Memphis, TN, USA
| |
Collapse
|
17
|
English BA, Hahn MK, Gizer IR, Mazei-Robison M, Steele A, Kurnik DM, Stein MA, Waldman ID, Blakely RD. Choline transporter gene variation is associated with attention-deficit hyperactivity disorder. J Neurodev Disord 2009; 1:252-63. [PMID: 21547719 PMCID: PMC3164006 DOI: 10.1007/s11689-009-9033-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 08/12/2009] [Indexed: 01/06/2023] Open
Abstract
The neurotransmitter acetylcholine (ACh) plays a critical role in brain circuits mediating motor control, attention, learning and memory. Cholinergic dysfunction is associated with multiple brain disorders including Alzheimer’s Disease, addiction, schizophrenia and Attention-Deficit Hyperactivity Disorder (ADHD). The presynaptic choline transporter (CHT, SLC5A7) is the major, rate-limiting determinant of ACh production in the brain and periphery and is consequently upregulated during tasks that require sustained attention. Given the contribution of central cholinergic circuits to the control of movement and attention, we hypothesized that functional CHT gene variants might impact risk for ADHD. We performed a case-control study, followed by family-based association tests on a separate cohort, of two purportedly functional CHT polymorphisms (coding variant Ile89Val (rs1013940) and a genomic SNP 3’ of the CHT gene (rs333229), affording both a replication sample and opportunities to reduce potential population stratification biases. Initial genotyping of pediatric ADHD subjects for two purportedly functional CHT alleles revealed a 2–3 fold elevation of the Val89 allele (n = 100; P = 0.02) relative to healthy controls, as well as a significant decrease of the 3’SNP minor allele in Caucasian male subjects (n = 60; P = 0.004). In family based association tests, we found significant overtransmission of the Val89 variant to children with a Combined subtype diagnosis (OR = 3.16; P = 0.01), with an increased Odds Ratio for a haplotype comprising both minor alleles. These studies show evidence of cholinergic deficits in ADHD, particularly for subjects with the Combined subtype, and, if replicated, may encourage further consideration of cholinergic agonist therapy in the disorder.
Collapse
Affiliation(s)
- Brett A English
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, 37232-8548, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Di Giovanni G, Shi WX. Effects of scopolamine on dopamine neurons in the substantia nigra: role of the pedunculopontine tegmental nucleus. Synapse 2009; 63:673-80. [PMID: 19360852 DOI: 10.1002/syn.20650] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Previous neurochemical and behavioral studies suggest that muscarinic receptor antagonism has an excitatory effect on the nigrostriatal dopamine (DA) system. Using in vivo extracellular single unit recording, this study examined whether blockade of the muscarinic receptor by scopolamine alters the firing properties of DA neurons in the substantia nigra (SN). Scopolamine was administered either systemically or locally to DA neurons using microiontophoresis. Surprisingly, scopolamine did not cause any significant change in either the firing rate or pattern of the spontaneously active DA neurons. However, systemic injection of scopolamine significantly increased the number of active DA neurons in the SN. Local infusion of scopolamine into the pedunculopontine tegmental nucleus (PPT) mimicked the effect induced by systemically administered scopolamine, significantly increasing the number of active DA neurons without altering the firing rate and pattern. These results suggest that the reported increase in striatal DA release induced by scopolamine is in part mediated by activation of silent nigral DA neurons. The experiments with PPT local infusion further suggest that part of the effect of scopolamine may be due to its blockade of the inhibitory muscarinic autoreceptors on PPT cholinergic cells. The latter effect may lead to activation of quiescent DA neurons by increasing acetylcholine (ACh) release in the SN or in other brain areas providing inputs to DA neurons. Further understanding of the mechanism of action of scopolamine may help us further understand the role of ACh in both the pathophysiology and treatment of DA-related disorders including schizophrenia and Parkinson's disease.
Collapse
Affiliation(s)
- Giuseppe Di Giovanni
- Dipartimento di Medicina Sperimentale, Sezione di Fisiologia Umana G Pagano, Università degli Studi di Palermo, Palermo, Italy.
| | | |
Collapse
|
19
|
Lee KW, Tian YH, You IJ, Kwon SH, Ha RR, Lee SY, Kim HC, Jang CG. Blockade of M1 muscarinic acetylcholine receptors modulates the methamphetamine-induced psychomotor stimulant effect. Neuroscience 2008; 153:1235-44. [DOI: 10.1016/j.neuroscience.2008.02.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 02/12/2008] [Accepted: 02/16/2008] [Indexed: 11/27/2022]
|
20
|
Apostolov EO, Wang X, Shah SV, Basnakian AG. Role of EndoG in development and cell injury. Cell Death Differ 2007; 14:1971-4. [PMID: 17762883 DOI: 10.1038/sj.cdd.4402217] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
|
21
|
Price DA, Owens WA, Gould GG, Frazer A, Roberts JL, Daws LC, Giuffrida A. CB1-independent inhibition of dopamine transporter activity by cannabinoids in mouse dorsal striatum. J Neurochem 2007; 101:389-96. [PMID: 17250681 DOI: 10.1111/j.1471-4159.2006.04383.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cannabinoid drugs are known to affect dopaminergic neurotransmission in the basal ganglia circuitry. In this study, we used in vitro and in vivo techniques to investigate whether cannabinoid agonists and antagonist could affect dopaminergic transmission in the striatum by acting at the dopamine transporter. Incubation of striatal synaptosomes with the cannabinoid agonists WIN55,212-2 or methanandamide decreased dopamine uptake (IC(50) = 2.0 micromol/L and 3.1 micromol/L, respectively). A similar inhibitory effect was observed after application of the inactive WIN55,212-2 isomer, S(-)WIN55,212-3. The CB(1) antagonist AM251 did not reverse WIN55,212-2 effect but rather mimicked it. WIN55,212-2 and AM251 partially displaced the binding of the cocaine analog [(3)H]WIN35,428, thus acting as dopamine transporter pseudo-substrates in the high micromolar range. High-speed chronoamperometry measurements showed that WIN55,212-2 (4 mg/kg, i.p.) caused significant release of endogenous dopamine via activation of CB(1) receptors, followed by a reduction of dopamine clearance. This reduction was CB(1)-independent, as it was mimicked by S(-)WIN55,212-3. Administration of AM251 (1 and 4 mg/kg, i.p.) increased the signal amplitude and reduced the clearance of dopamine pressure ejected into the striatum. These results indicate that both cannabinoid agonists and antagonists inhibit dopamine transporter activity via molecular targets other than CB(1) receptors.
Collapse
Affiliation(s)
- David A Price
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
| | | | | | | | | | | | | |
Collapse
|
22
|
Gomez-Gallego M, Fernandez-Villalba E, Fernandez-Barreiro A, Herrero MT. Changes in the neuronal activity in the pedunculopontine nucleus in chronic MPTP-treated primates: an in situ hybridization study of cytochrome oxidase subunit I, choline acetyl transferase and substance P mRNA expression. J Neural Transm (Vienna) 2006; 114:319-26. [PMID: 16988796 DOI: 10.1007/s00702-006-0547-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Accepted: 06/23/2006] [Indexed: 10/24/2022]
Abstract
The pedunculopontine nucleus is a mesencephalic nucleus that has widespread and reciprocal connections with the basal ganglia. It has been implicated in the physiopathology of akinesia, rigidity, gait failure and sleep disorders associated with Parkinson's disease. In this study, in situ hybridization was used to examine the changes in neuronal metabolic activity (measuring cytochrome oxidase subunit I) and in the level of acetylcholine and Substance P synthesis in the pedunculopontine nucleus of monkeys chronically treated with MPTP. Significant reductions were observed in cytochrome oxidase subunit I (p = 0.001), choline acetyl transferase (p = 0.003) and substance P (p = 0.006) mRNA expression in parkinsonian animals compared with controls, indicating that pedunculopontine cholinergic neurons activity decreases with parkinsonism.
Collapse
Affiliation(s)
- M Gomez-Gallego
- Department of Neurology, Virgen de la Arrixaca University Hospital, Murcia, Spain.
| | | | | | | |
Collapse
|
23
|
Chen J, Nakamura M, Kawamura T, Takahashi T, Nakahara D. Roles of pedunculopontine tegmental cholinergic receptors in brain stimulation reward in the rat. Psychopharmacology (Berl) 2006; 184:514-22. [PMID: 16385418 DOI: 10.1007/s00213-005-0252-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 10/31/2005] [Indexed: 12/24/2022]
Abstract
RATIONALE The brainstem pedunculopontine tegmental nucleus (PPTg) is proposed to mediate hypothalamic self-stimulation reward via cholinergic activation of the ventral tegmental area (VTA). However, to date there is little direct evidence to support this hypothesis. OBJECTIVES To further study the role of PPTg in hypothalamic self-stimulation reward. METHODS By using in vivo microdialysis, the levels of extracellular acetylcholine (ACh) in the PPTg and VTA were detected during lateral hypothalamic (LH) self-stimulation in rats. Rate-frequency curve shift procedure was used to evaluate the effects of nonselective muscarinic antagonist scopolamine (1 approximately 100 microg/microl) and nicotinic antagonist mecamylamine (5 approximately 100 microg/microl) microinjected into the PPTg on the rewarding efficacy of LH self-stimulation. Subsequently, the drugs were injected into the PPTg, and the extracellular ACh in the VTA was measured. RESULTS LH self-stimulation produced a concurrent ACh release in the PPTg and VTA. Intra-PPTg injection of scopolamine (100 microg/microl) significantly reduced the frequency threshold for LH self-stimulation reward, but nicotinic antagonist mecamylamine did not shift the threshold. However, mecamylamine (10, 25 microg/microl) injected into the PPTg robustly diminished the nicotine-potentiated LH self-stimulation reward. The extracellular ACh in the VTA was dramatically increased by intra-PPTg scopolamine (10, 100 microg/microl), but not by mecamylamine. CONCLUSIONS Results confirm that PPTg plays an important role in brain stimulation reward by modulating the cholinergic activity of the VTA. The PPTg muscarinic receptors contribute to an inhibitory modulation of reward effects by self-stimulation, whereas nicotinic receptors seem to be more involved in nicotine potentiation of brain stimulation reward.
Collapse
Affiliation(s)
- J Chen
- Department of Psychology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431-3192, Japan
| | | | | | | | | |
Collapse
|
24
|
Miller AD, Blaha CD. Midbrain muscarinic receptor mechanisms underlying regulation of mesoaccumbens and nigrostriatal dopaminergic transmission in the rat. Eur J Neurosci 2005; 21:1837-46. [PMID: 15869479 DOI: 10.1111/j.1460-9568.2005.04017.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Laterodorsal (LDT) and pedunculopontine (PPT) tegmental nuclei in the mesopontine project cholinergic inputs to the midbrain ventral tegmental area (VTA) and substantia nigra pars compacta (SNc), respectively, to directly and indirectly influence the activity of dopamine neuronal cells via actions on muscarinic and nicotinic receptors. The present study investigated the role of midbrain muscarinic receptors in the functional modulation of VTA and SNc dopamine cell activity as reflected by alterations in, respectively, nucleus accumbens (NAc) and striataldopamine efflux. In vivo chronoamperometry was used to measure changes in basal dopamine efflux via stearate-graphite paste electrodes implanted unilaterally in the NAc or striatum of urethane-anaesthetized rats, following blockade or activation of, respectively, VTA or SNc muscarinic receptors. Intra-VTA or -SNc infusion of the muscarinic antagonist scopolamine (200 microg/microL) reduced, respectively, NAc and striatal dopamine efflux while infusion of the muscarinic and nicotinic agonist carbachol (0.5 microg/microL) or the prototypical muscarinic agonist muscarine (0.5 microg/microL) increased NAc and striatal dopamine efflux. Transient decreases in dopamine efflux preceded these increases selectively in the striatum, suggesting a reduction in excitatory or increase in inhibitory drive to the SNc by preferential activation of M3 muscarinic receptors on GABA interneurons and glutamatergic inputs. This was confirmed by showing that selective blockade of M3 receptors with p-F-HHSiD (0.5 microg/microL) increased striatal, but not NAc, dopamine efflux. Together, these findings suggest that midbrain muscarinic receptors, probably M5 subtypes on VTA and SNc dopamine neurons, contribute to the tonic excitatory regulation of forebrain basal dopamine transmission whereas presynaptic M3 receptors serve to counter excessive excitation of nigral dopamine cell activity.
Collapse
Affiliation(s)
- Anthony D Miller
- Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia
| | | |
Collapse
|
25
|
Miller AD, Forster GL, Yeomans JS, Blaha CD. Midbrain muscarinic receptors modulate morphine-induced accumbal and striatal dopamine efflux in the rat. Neuroscience 2005; 136:531-8. [PMID: 16216430 DOI: 10.1016/j.neuroscience.2005.08.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 07/20/2005] [Accepted: 08/15/2005] [Indexed: 10/25/2022]
Abstract
Midbrain dopamine neurons are critical in mediating the rewarding effects of opiates in dependent rats, as well as modulating some manifestations of opiate withdrawal. Morphine is known to excite dopamine neurons and thereby facilitate forebrain dopamine transmission through inhibition of GABA neurons. Cholinergic neurons in the mesopontine laterodorsal and pedunculopontine tegmental nuclei provide the principal source of excitatory cholinergic input to ventral tegmental area and substantia nigra pars compacta dopamine-containing neurons, via actions on midbrain muscarinic and nicotinic acetylcholine receptors. The present study hypothesized that a reduction in tonic cholinergic input via blockade of midbrain muscarinic receptors would reduce the pharmacological effects of morphine on forebrain dopamine release. Using in vivo chronoamperometry, alterations in morphine-evoked dopamine efflux were monitored at stearate-graphite paste electrodes implanted unilaterally in the nucleus accumbens and striatum of urethane (1.5 g/kg) anesthetized rats, following the pharmacological inhibition of ventral tegmental area/substantia nigra pars compacta muscarinic receptors. The facilitatory effects of morphine (2.0 mg/kg, i.v.) on accumbens and striatal dopamine efflux were markedly reduced by prior infusion of the non-selective muscarinic receptor antagonist scopolamine (200 microg/microl) into the ventral tegmental area or substantia nigra pars compacta, respectively. These findings demonstrate that decreased activation of midbrain muscarinic receptors attenuates the excitatory effects of morphine on mesoaccumbens and nigrostriatal dopaminergic transmission.
Collapse
Affiliation(s)
- A D Miller
- Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia
| | | | | | | |
Collapse
|