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NMDARs in granule cells contribute to parallel fiber-Purkinje cell synaptic plasticity and motor learning. Proc Natl Acad Sci U S A 2021; 118:2102635118. [PMID: 34507990 PMCID: PMC8449340 DOI: 10.1073/pnas.2102635118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2021] [Indexed: 11/18/2022] Open
Abstract
Long-term synaptic plasticity is believed to be the cellular substrate of learning and memory. Synaptic plasticity rules are defined by the specific complement of receptors at the synapse and the associated downstream signaling mechanisms. In young rodents, at the cerebellar synapse between granule cells (GC) and Purkinje cells (PC), bidirectional plasticity is shaped by the balance between transcellular nitric oxide (NO) driven by presynaptic N-methyl-D-aspartate receptor (NMDAR) activation and postsynaptic calcium dynamics. However, the role and the location of NMDAR activation in these pathways is still debated in mature animals. Here, we show in adult rodents that NMDARs are present and functional in presynaptic terminals where their activation triggers NO signaling. In addition, we find that selective genetic deletion of presynaptic, but not postsynaptic, NMDARs prevents synaptic plasticity at parallel fiber-PC (PF-PC) synapses. Consistent with this finding, the selective deletion of GC NMDARs affects adaptation of the vestibulo-ocular reflex. Thus, NMDARs presynaptic to PCs are required for bidirectional synaptic plasticity and cerebellar motor learning.
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Pittaluga A. Presynaptic release-regulating NMDA receptors in isolated nerve terminals: A narrative review. Br J Pharmacol 2021; 178:1001-1017. [PMID: 33347605 PMCID: PMC9328659 DOI: 10.1111/bph.15349] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 12/03/2020] [Indexed: 02/02/2023] Open
Abstract
The existence of presynaptic, release‐regulating NMDA receptors in the CNS has been long matter of discussion. Most of the reviews dedicated to support this conclusion have preferentially focussed on the results from electrophysiological studies, paying little or no attention to the data obtained with purified synaptosomes, even though this experimental approach has been recognized as providing reliable information concerning the presence and the role of presynaptic release‐regulating receptors in the CNS. To fill the gap, this review is dedicated to summarising the results from studies with synaptosomes published during the last 40 years, which support the existence of auto and hetero NMDA receptors controlling the release of transmitters such as glutamate, GABA, dopamine, noradrenaline, 5‐HT, acetylcholine and peptides, in the CNS of mammals. The review also deals with the results from immunochemical studies in isolated nerve endings that confirm the functional observations.
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Affiliation(s)
- Anna Pittaluga
- Department of Pharmacology (DIFAR), School of Medical and Pharmaceutical Sciences, 3Rs Center, University of Genova, Italy.,San Martino Hospital IRCCS, Genova, Italy
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Zhang XY, Zhang YD, Cui BR, Jin R, Chu CP, Jin XH, Qiu DL. Propofol facilitates climbing fiber-Purkinje cell synaptic transmission via NMDA receptor in vitro in mice. Eur J Pharmacol 2020; 887:173474. [PMID: 32783960 DOI: 10.1016/j.ejphar.2020.173474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/07/2020] [Accepted: 08/07/2020] [Indexed: 11/19/2022]
Abstract
Propofol is generally used for the induction and maintenance of anesthesia in clinical procedures via activation of γ -aminobutyric acid A (GABAA) receptors. When administered at the clinical dose, propofol use is associated with movement disorders, including dystonia and ataxia, suggesting that propofol administration impacts the function of cerebellar neuronal circuitry. In this study, we investigated the effect of propofol on climbing fiber (CF)-Purkinje cell (PC) synaptic transmission in mouse cerebellar slices in the absence of GABAergic inhibition using a whole-cell recording technique and pharmacological methods. Our results showed that bath application of propofol enhanced CF-PC synaptic transmission, which was demonstrated by an increased amplitude and area under the curve (AUC) of the excitatory postsynaptic currents (EPSCs) accompanied by a decrease in the paired-pulse ratio (PPR). The propofol-induced increase in the amplitude of P1 was concentration-dependent with a half effective concentration (EC50) of 20.9 μM. The propofol-induced increases in the amplitude and AUC of CF-PC EPSCs were abolished by an N-Methyl-D-aspartate (NMDA) receptor blocker. Furthermore, the application of NMDA enhanced CF-PC EPSCs and overwhelmed the effect of propofol on CF-PC EPSCs. Moreover, intracellular blockade of NMDA receptors attenuated the propofol-induced enhancement of CF-PC synaptic transmission but strengthened the propofol-induced change in the PPR. These results indicate that propofol enhances CF-PC synaptic transmission by activation of NMDA receptors in the mouse cerebellar cortex, suggesting that propofol administration might be involved in propofol-induced dysfunction of the cerebellum via NMDA receptors.
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Affiliation(s)
- Xin-Yuan Zhang
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China
| | - Yi-Dan Zhang
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China
| | - Bai-Ri Cui
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Osteology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China
| | - Ri Jin
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Osteology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China
| | - Chun-Ping Chu
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China
| | - Xian-Hua Jin
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China.
| | - De-Lai Qiu
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China.
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Xu YH, Zhang GJ, Zhao JT, Chu CP, Li YZ, Qiu DL. Roles of N-methyl-d-aspartate receptors during the sensory stimulation-evoked field potential responses in mouse cerebellar cortical molecular layer. Neurosci Lett 2017; 660:135-139. [PMID: 28919538 DOI: 10.1016/j.neulet.2017.09.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 09/05/2017] [Accepted: 09/12/2017] [Indexed: 01/28/2023]
Abstract
The functions of N-methyl-d-aspartate receptors (NMDARs) in cerebellar cortex have been widely studied under in vitro condition, but their roles during the sensory stimulation-evoked responses in the cerebellar cortical molecular layer in living animals are currently unclear. We here investigated the roles of NMDARs during the air-puff stimulation on ipsilateral whisker pad-evoked field potential responses in cerebellar cortical molecular layer in urethane-anesthetized mice by electrophysiological recording and pharmacological methods. Our results showed that cerebellar surface administration of NMDA induced a dose-dependent decrease in amplitude of the facial stimulation-evoked inhibitory responses (P1) in the molecular layer, accompanied with decreases in decay time, half-width and area under curve (AUC) of P1. The IC50 of NMDA induced inhibition in amplitude of P1 was 46.5μM. In addition, application of NMDA induced significant increases in the decay time, half-width and AUC values of the facial stimulation-evoked excitatory responses (N1) in the molecular layer. Application of an NMDAR blocker, D-APV (250μM) abolished the facial stimulation-evoked P1 in the molecular layer. These results suggested that NMDARs play a critical role during the sensory information processing in cerebellar cortical molecular layer in vivo in mice.
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Affiliation(s)
- Yin-Hua Xu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China; Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China
| | - Guang-Jian Zhang
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Pain, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, China
| | - Jing-Tong Zhao
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Cardiology, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, 133000, China
| | - Chun-Ping Chu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China
| | - Yu-Zi Li
- Department of Cardiology, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, 133000, China.
| | - De-Lai Qiu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China.
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Curtice KJ, Leavitt LS, Chase K, Raghuraman S, Horvath MP, Olivera BM, Teichert RW. Classifying neuronal subclasses of the cerebellum through constellation pharmacology. J Neurophysiol 2015; 115:1031-42. [PMID: 26581874 DOI: 10.1152/jn.00894.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 11/12/2015] [Indexed: 11/22/2022] Open
Abstract
A pressing need in neurobiology is the comprehensive identification and characterization of neuronal subclasses within the mammalian nervous system. To this end, we used constellation pharmacology as a method to interrogate the neuronal and glial subclasses of the mouse cerebellum individually and simultaneously. We then evaluated the data obtained from constellation-pharmacology experiments by cluster analysis to classify cells into neuronal and glial subclasses, based on their functional expression of glutamate, acetylcholine, and GABA receptors, among other ion channels. Conantokin peptides were used to identify N-methyl-d-aspartate (NMDA) receptor subtypes, which revealed that neurons of the young mouse cerebellum expressed NR2A and NR2B NMDA receptor subunits. Additional pharmacological tools disclosed differential expression of α-amino-3-hydroxy-5-methyl-4-isoxazloepropionic, nicotinic acetylcholine, and muscarinic acetylcholine receptors in different neuronal and glial subclasses. Certain cell subclasses correlated with known attributes of granule cells, and we combined constellation pharmacology with genetically labeled neurons to identify and characterize Purkinje cells. This study illustrates the utility of applying constellation pharmacology to classify neuronal and glial subclasses in specific anatomical regions of the brain.
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Affiliation(s)
- Kigen J Curtice
- Department of Biology, University of Utah, Salt Lake City, Utah
| | - Lee S Leavitt
- Department of Biology, University of Utah, Salt Lake City, Utah
| | - Kevin Chase
- Department of Biology, University of Utah, Salt Lake City, Utah
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N-methyl-d-aspartate inhibits cerebellar Purkinje cell activity via the excitation of molecular layer interneurons under in vivo conditions in mice. Brain Res 2014; 1560:1-9. [PMID: 24642274 DOI: 10.1016/j.brainres.2014.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/06/2014] [Accepted: 03/07/2014] [Indexed: 11/20/2022]
Abstract
N-methyl-d-aspartate (NMDA) receptors play a key role in synaptic transmission, and are widely expressed on the membrane of granule cells, parallel fibers, and molecular layer interneurons (MLIs) in the cerebellar cortex of mammals. In cerebellar slices, activation of NMDA receptors increases inhibitory postsynaptic currents (IPSCs) of Purkinje cells (PCs). However, the effects of NMDA on the cerebellar network under in vivo conditions are currently unclear. In the present study, we examined the effects of NMDA on the spontaneous activity of PCs and MLIs in urethane-anesthetized mice by electrophysiological, pharmacological, and juxtacellular labeling methods. Our results revealed that cerebellar surface application of NMDA (5-200μM) reduced the PC simple spike (SS) firing rate in a dose-dependent manner. Application of GABAA receptor antagonist, SR95531 (20μM) abolished NMDA-induced inhibition of PCs spontaneous activity, and revealed NMDA-induced excitation of cerebellar PCs. NMDA receptor antagonist, DAP-V (250µM) did not affect the mean frequency of SS firing, but the SS firing rate of PCs became more regular than the control. In addition, NMDA increased the spike firing of both basket-type and stellate-type MLIs. Overall, these results indicated that NMDA-induced excitation of MLIs at the cerebellar surface may inhibit PC activity. Thus, NMDA receptors of MLIs may play a key role in regulating the spontaneous activity of PCs, and in information transmission and integration in cerebellar cortex.
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Quantification of the density of cooperative neighboring synapses required to evoke endocannabinoid signaling. Neuroscience 2013; 256:412-25. [PMID: 24183961 PMCID: PMC3928998 DOI: 10.1016/j.neuroscience.2013.10.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/07/2013] [Accepted: 10/22/2013] [Indexed: 11/23/2022]
Abstract
The spatial pattern of synapse activation may impact on synaptic plasticity. This applies to the synaptically-evoked endocannabinoid-mediated short-term depression at the parallel fiber (PF) to Purkinje cell synapse, the occurrence of which requires close proximity between the activated synapses. Here, we determine quantitatively this required proximity, helped by the geometrical organization of the cerebellar molecular layer. Transgenic mice expressing a calcium indicator selectively in granule cells enabled the imaging of action potential-evoked presynaptic calcium rise in isolated, single PFs. This measurement was used to derive the number of PFs activated within a beam of PFs stimulated in the molecular layer, from which the density of activated PFs (input density) was calculated. This density was on average 2.8 μm(-2) in sagittal slices and twice more in transverse slices. The synaptically-evoked endocannabinoid-mediated suppression of excitation (SSE) evoked by ten stimuli at 200 Hz was determined from the monitoring of either postsynaptic responses or presynaptic calcium rise. The SSE was significantly larger when recorded in transverse slices, where the input density is larger. The exponential description of the SSE plotted as a function of the input density suggests that the SSE is half reduced when the input density decreases from 6 to 2 μm(-2). We conclude that, although all PFs are truncated in an acute sagittal slice, half of them remain respondent to stimulation, and activated synapses need to be closer than 1.5 μm to synergize in endocannabinoid signaling.
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He Q, Titley H, Grasselli G, Piochon C, Hansel C. Ethanol affects NMDA receptor signaling at climbing fiber-Purkinje cell synapses in mice and impairs cerebellar LTD. J Neurophysiol 2012; 109:1333-42. [PMID: 23221414 DOI: 10.1152/jn.00350.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ethanol profoundly influences cerebellar circuit function and motor control. It has recently been demonstrated that functional N-methyl-(D)-aspartate (NMDA) receptors are postsynaptically expressed at climbing fiber (CF) to Purkinje cell synapses in the adult cerebellum. Using whole cell patch-clamp recordings from mouse cerebellar slices, we examined whether ethanol can affect NMDA receptor signaling in mature Purkinje cells. NMDA receptor-mediated currents were isolated by bath application of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoylbenzol[f]quinoxaline (NBQX). The remaining (D)-2-amino-5-phosphonovaleric acid ((D)-APV)-sensitive current was reduced by ethanol at concentrations as low as 10 mM. At a concentration of 50 mM ethanol, the blockade of (D)-APV-sensitive CF-excitatory postsynaptic currents was significantly stronger. Ethanol also altered the waveform of CF-evoked complex spikes by reducing the afterdepolarization. This effect was not seen when NMDA receptors were blocked by (D)-APV before ethanol wash-in. In contrast to CF synaptic transmission, parallel fiber (PF) synaptic inputs were not affected by ethanol. Finally, ethanol (10 mM) impaired long-term depression (LTD) at PF to Purkinje cell synapses as induced under control conditions by paired PF and CF activity. However, LTD induced by pairing PF stimulation with depolarizing voltage steps (substituting for CF activation) was not blocked by ethanol. These observations suggest that the sensitivity of cerebellar circuit function and plasticity to low concentrations of ethanol may be caused by an ethanol-mediated impairment of NMDA receptor signaling at CF synapses onto cerebellar Purkinje cells.
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Affiliation(s)
- Qionger He
- Department of Neurobiology, University of Chicago, Chicago, IL, USA
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Dougherty SE, Reeves JL, Lesort M, Detloff PJ, Cowell RM. Purkinje cell dysfunction and loss in a knock-in mouse model of Huntington disease. Exp Neurol 2012. [PMID: 23195593 DOI: 10.1016/j.expneurol.2012.11.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Huntington Disease (HD) is an autosomal dominant neurological disorder characterized by motor, psychiatric and cognitive disturbances. Recent evidence indicates that the viability and function of cerebellar Purkinje cells (PCs) are compromised in an aggressive mouse model of HD. Here we investigate whether this is also the case in the HdhQ200 knock-in mouse model of HD. Using quantitative-real time-PCR and immunofluorescence, we observed a loss of the PC marker and calcium buffer calbindin in 50week-old symptomatic mice. Reductions were also observed in parvalbumin and glutamic acid decarboxylase protein expression, most markedly in the molecular cell layer. Stereological analysis revealed an overall reduction in the PC population in HdhQ200/Q200 mice by nearly 40%, and loose patch electrophysiology of remaining PCs indicated a reduction in firing rate in HD mice compared to control littermates. Taken together, these data demonstrate that PC survival and function are compromised in a mouse model of adult-onset HD and suggest that further experiments should investigate the contribution of PC death and dysfunction to HD-associated motor impairment.
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Affiliation(s)
- S E Dougherty
- Neuroscience Graduate Program, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Paul A, Cai Y, Atwal GS, Huang ZJ. Developmental Coordination of Gene Expression between Synaptic Partners During GABAergic Circuit Assembly in Cerebellar Cortex. Front Neural Circuits 2012; 6:37. [PMID: 22754500 PMCID: PMC3385560 DOI: 10.3389/fncir.2012.00037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/01/2012] [Indexed: 01/14/2023] Open
Abstract
The assembly of neural circuits involves multiple sequential steps such as the specification of cell-types, their migration to proper brain locations, morphological and physiological differentiation, and the formation and maturation of synaptic connections. This intricate and often prolonged process is guided by elaborate genetic mechanisms that regulate each step. Evidence from numerous systems suggests that each cell-type, once specified, is endowed with a genetic program that unfolds in response to, and is regulated by, extrinsic signals, including cell–cell and synaptic interactions. To a large extent, the execution of this intrinsic program is achieved by the expression of specific sets of genes that support distinct developmental processes. Therefore, a comprehensive analysis of the developmental progression of gene expression in synaptic partners of neurons may provide a basis for exploring the genetic mechanisms regulating circuit assembly. Here we examined the developmental gene expression profiles of well-defined cell-types in a stereotyped microcircuit of the cerebellar cortex. We found that the transcriptomes of Purkinje cell and stellate/basket cells are highly dynamic throughout postnatal development. We revealed “phasic expression” of transcription factors, ion channels, receptors, cell adhesion molecules, gap junction proteins, and identified distinct molecular pathways that might contribute to sequential steps of cerebellar inhibitory circuit formation. We further revealed a correlation between genomic clustering and developmental co-expression of hundreds of transcripts, suggesting the involvement of chromatin level gene regulation during circuit formation.
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Affiliation(s)
- Anirban Paul
- Cold Spring Harbor Laboratory, Neuroscience Cold Spring Harbor, New York, NY, USA
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Iseri PK, Karson A, Gullu KM, Akman O, Kokturk S, Yardýmoglu M, Erturk S, Ates N. The effect of memantine in harmaline-induced tremor and neurodegeneration. Neuropharmacology 2011; 61:715-23. [PMID: 21640732 DOI: 10.1016/j.neuropharm.2011.05.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 05/12/2011] [Accepted: 05/16/2011] [Indexed: 10/18/2022]
Abstract
Essential tremor (ET) is one of the most common and most disabling movement disorders among adults. The drug treatment of ET remains unsatisfactory. Additional therapies are required for patients with inadequate response or intolerable side effects. The current study aims to investigate the anti-tremogenic and neuroprotective effects of memantine (NMDA receptor antagonist) on the harmaline model of transient action tremor. The effects of memantine were further compared with ethanol. Three separate groups of male Wistar rats were injected either with saline, ethanol (1.5 gr/kg), or memantine (5 mg/kg) 15 min prior to a single intraperitoneal injection of harmaline (20 mg/kg). Tremor and locomotion were evaluated by a custom-built tremor and locomotion analysis system. After 24 h of harmaline injection, cellular viability, and apoptosis were assessed using crystal violet staining, and caspase-3 immunostaining, respectively. Harmaline caused neuronal cell loss and caspase-3 mediated apoptosis in cerebellar granular and purkinje cells as well as the inferior olivary neurons. Despite a reduction in tremor intensity and duration with ethanol, this compound resulted in cell loss in cerebellum and olivary nucleus. Memantine exhibited neuroprotective efficacy on cerebellar and inferior olivary neurons albeit weaker anti-tremor effect compared to ethanol. In conclusion, anti-tremogenic and neuroprotective effects do not necessarily overlap. Memantine is a potential treatment for ET particularly given its neuroprotective efficacy.
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Affiliation(s)
- Pervin K Iseri
- Department of Neurology, Kocaeli University Medical School, Kocaeli, Turkey.
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12
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Limitations of PET and lesion studies in defining the role of the human cerebellum in motor learning. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081899] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Eyeblink conditioning, motor control, and the analysis of limbic-cerebellar interactions. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081929] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Grasping cerebellar function depends on our understanding the principles of sensorimotor integration: The frame of reference hypothesis. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Dysmetria of thought: Correlations and conundrums in the relationship between the cerebellum, learning, and cognitive processing. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081851] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Q: Is the cerebellum an adaptive combiner of motor and mental/motor activities? A: Yes, maybe, certainly not, who can say? Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00082017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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What behavioral benefit does stiffness control have? An elaboration of Smith's proposal. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00081917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Schorge S, van de Leemput J, Singleton A, Houlden H, Hardy J. Human ataxias: a genetic dissection of inositol triphosphate receptor (ITPR1)-dependent signaling. Trends Neurosci 2010; 33:211-9. [PMID: 20226542 PMCID: PMC4684264 DOI: 10.1016/j.tins.2010.02.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 02/17/2010] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
Abstract
A persistent mystery about the ataxias has been why mutations in genes--many of which are expressed widely in the brain--primarily cause ataxia, and not, for example, epilepsy or dementia. Why should a polyglutamine stretch in the TATA-binding protein (that is important in all cells) particularly disrupt cerebellar coordination? We propose that advances in the genetics of cerebellar ataxias suggest a rational hypothesis for how so many different genes lead to predominantly cerebellar defects. We argue that the unifying feature of many genes involved in cerebellar ataxias is their impact on the signaling protein ITPR1 (inositiol 1,4,5-triphosphate receptor type 1), that underlies coincidence detection in Purkinje cells and could play an important role in cerebellar coordination.
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Affiliation(s)
- Stephanie Schorge
- Reta Lila Weston Laboratories and Department of Molecular Neuroscience, Institute of Neurology, University College London, London, WC1N 3BG, UK
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Glutamatergic and nonglutamatergic neurons of the ventral tegmental area establish local synaptic contacts with dopaminergic and nondopaminergic neurons. J Neurosci 2010; 30:218-29. [PMID: 20053904 DOI: 10.1523/jneurosci.3884-09.2010] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The ventral tegmental area (VTA) contributes to reward and motivation signaling. In addition to the well established populations of dopamine (DA) or GABA VTA neurons, glutamatergic neurons were recently discovered in the VTA. These glutamatergic neurons express the vesicular glutamate transporter 2, VGluT2. To investigate whether VTA glutamatergic neurons establish local synapses, we tagged axon terminals from resident VTA neurons by intra-VTA injection of Phaseolus vulgaris leucoagglutinin (PHA-L) or an adeno-associated virus encoding wheat germ agglutinin (WGA) and by immunoelectron microscopy determined the presence of VGluT2 in PHA-L- or WGA-positive terminals. We found that PHA-L- or WGA-positive terminals from tagged VTA cells made asymmetric or symmetric synapses within the VTA. VGluT2 immunoreactivity was detected in the vast majority of PHA-L- or WGA-positive terminals forming asymmetric synapses. These results indicate that both VTA glutamatergic and nonglutamatergic (likely GABAergic) neurons establish local synapses. To examine the possible DAergic nature of postsynaptic targets of VTA glutamatergic neurons, we did triple immunolabeling with antibodies against VGluT2, tyrosine hydroxylase (TH), and PHA-L. From triple-labeled tissue, we found that double-labeled PHA-L (+)/VGluT2 (+) axon terminals formed synaptic contacts on dendrites of both TH-positive and TH-negative cells. Consistent with these anatomical observations, in whole-cell slice recordings of VTA neurons we observed that blocking action potential activity significantly decreased the frequency of synaptic glutamatergic events in DAergic and non-DAergic neurons. These observations indicate that resident VTA glutamatergic neurons are likely to affect both DAergic and non-DAergic neurotransmission arising from the VTA.
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Ohtsuki G, Piochon C, Hansel C. Climbing fiber signaling and cerebellar gain control. Front Cell Neurosci 2009; 3:4. [PMID: 19597563 PMCID: PMC2708967 DOI: 10.3389/neuro.03.004.2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 06/09/2009] [Indexed: 12/02/2022] Open
Abstract
The physiology of climbing fiber signals in cerebellar Purkinje cells has been studied since the early days of electrophysiology. Both the climbing fiber-evoked complex spike and the role of climbing fiber activity in the induction of long-term depression (LTD) at parallel fiber-Purkinje cell synapses have become hallmark features of cerebellar physiology. However, the key role of climbing fiber signaling in cerebellar motor learning has been challenged by recent reports of forms of synaptic and non-synaptic plasticity in the cerebellar cortex that do not involve climbing fiber activity, but might well play a role in cerebellar learning. Moreover, cerebellar LTD does not seem to strictly require climbing fiber activity. These observations make it necessary to re-evaluate the role of climbing fiber signaling in cerebellar function. Here, we argue that climbing fiber signaling is about adjusting relative probabilities for the induction of LTD and long-term potentiation (LTP) at parallel fiber synapses. Complex spike-associated, dendritic calcium transients control postsynaptic LTD and LTP induction. High calcium transients, provided by complex spike activity, do not only favor postsynaptic LTD induction, but simultaneously trigger retrograde cannabinoid signaling, which blocks the induction of presynaptic LTP. Plasticity of the climbing fiber input itself provides additional means to fine-tune complex spike associated calcium signaling and thus to adjust the gain of heterosynaptic climbing fiber control. In addition to dendritic calcium transients, climbing fiber activity leads to the release of the neuropeptide corticotropin-releasing factor (CRF), which facilitates LTD induction at both parallel fiber and climbing fiber synapses.
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Affiliation(s)
- Gen Ohtsuki
- Department of Neurobiology, University of Chicago Chicago, IL, USA
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Wee KSL, Zhang Y, Khanna S, Low CM. Immunolocalization of NMDA receptor subunit NR3B in selected structures in the rat forebrain, cerebellum, and lumbar spinal cord. J Comp Neurol 2008; 509:118-35. [PMID: 18425811 DOI: 10.1002/cne.21747] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
N-methyl-D-aspartate (NMDA) receptors have been implicated in many neurological disorders. Although NMDA receptors are best known for their high calcium permeability, the recently discovered NR3 subunits, NR3A and NR3B, have been shown to reduce the calcium permeability of the NMDA receptor. Thus, NR3 subunits may be important players in modulating synaptic plasticity in neurons. Although NR3B expression in the rodent and human brain has been studied, little is known about its distribution in different cell types. Here we used immunolabeling with a specific NR3B antibody together with antibodies against established neurochemical markers to determine the cellular and subcellular localization of NR3B. The nucleus was concurrently stained with NR3B immunolabeling to show that NR3B is widely expressed by many cells in each brain region. Our findings indicate that NR3B is widely expressed in the structures examined in the rat forebrain (hippocampus, cerebral cortex, caudoputamen, and nucleus accumbens), cerebellum, and lumbar sections of the spinal cord. Within these regions NR3B was found to be expressed in all the substructures of the hippocampus (CA1, CA3, dentate gyrus), the various layers of the cerebral cortex, projection neurons and interneurons of the striatum, different cell types of the cerebellum, and motor neurons of the spinal cord. Furthermore, when stained with NR1-the obligatory subunit responsible for forming functional NMDA receptors-the distribution of NR3B appears to be as ubiquitous as NR1. Taken together, our data suggest that there may be a population of NR3B-containing NMDA receptors conferring new functional roles in the mammalian central nervous system.
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Affiliation(s)
- Karen S-L Wee
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore
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Higley MJ, Sabatini BL. Calcium Signaling in Dendrites and Spines: Practical and Functional Considerations. Neuron 2008; 59:902-13. [DOI: 10.1016/j.neuron.2008.08.020] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 08/18/2008] [Accepted: 08/19/2008] [Indexed: 11/25/2022]
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Piochon C, Irinopoulou T, Brusciano D, Bailly Y, Mariani J, Levenes C. NMDA receptor contribution to the climbing fiber response in the adult mouse Purkinje cell. J Neurosci 2007; 27:10797-809. [PMID: 17913913 PMCID: PMC6672834 DOI: 10.1523/jneurosci.2422-07.2007] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Among integrative neurons displaying long-term synaptic plasticity, adult Purkinje cells seemed to be an exception by lacking functional NMDA receptors (NMDA-Rs). Although numerous anatomical studies have shown both NR1 and NR2 NMDA-R subunits in adult Purkinje cells, patch-clamp studies failed to detect any NMDA currents. Using more recent pharmacological and immunodetection tools, we demonstrate here that Purkinje cells from adult mice respond to exogenous NMDA application and that postsynaptic NMDA-Rs carry part of the climbing fiber-mediated EPSC (CF-EPSC), with undetectable contribution from presynaptic or polysynaptic NMDA currents. We also detect NR2-A/B subunits in adult Purkinje cells by immunohistochemistry. The NMDA-mediated CF-EPSC is barely detectable before 3 weeks postnatal. From the end of the third week, the number of cells displaying the NMDA-mediated CF-EPSC rapidly increases. Soon, this EPSC becomes detectable in all the Purkinje cells but is still very small. Its amplitude continues to increase until 12 weeks after birth. In mature Purkinje cells, we show that the NMDA-Rs contribute to the depolarizing plateau of complex spikes and increase their number of spikelets. Together, these observations demonstrate that mature Purkinje cells express functional NMDA receptors that become detectable in CF-EPSCs at approximately 21 d after birth and control the complex spike waveform.
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Affiliation(s)
- Claire Piochon
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche (UMR) 7102, Centre National de la Recherche Scientifique (CNRS), Laboratoire Neurobiologie des Processus Adaptifs, Équipe Développement et Vieillissement du Système Nerveux, 75005 Paris, France
| | - Theano Irinopoulou
- Unité 536/Unité 706, Inserm, Institut du Fer à Moulin, F-75005 Paris, France
| | - Daniel Brusciano
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche (UMR) 7102, Centre National de la Recherche Scientifique (CNRS), Laboratoire Neurobiologie des Processus Adaptifs, Équipe Développement et Vieillissement du Système Nerveux, 75005 Paris, France
| | - Yannick Bailly
- Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives UMR 7168, CNRS, Université Louis Pasteur, 67084 Strasbourg, France, and
| | - Jean Mariani
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche (UMR) 7102, Centre National de la Recherche Scientifique (CNRS), Laboratoire Neurobiologie des Processus Adaptifs, Équipe Développement et Vieillissement du Système Nerveux, 75005 Paris, France
- Hôpital Charles Foix, Assistance Publique–Hôpitaux de Paris, 94 Ivry sur Seine, France
| | - Carole Levenes
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche (UMR) 7102, Centre National de la Recherche Scientifique (CNRS), Laboratoire Neurobiologie des Processus Adaptifs, Équipe Développement et Vieillissement du Système Nerveux, 75005 Paris, France
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Renzi M, Farrant M, Cull-Candy SG. Climbing-fibre activation of NMDA receptors in Purkinje cells of adult mice. J Physiol 2007; 585:91-101. [PMID: 17901118 PMCID: PMC2327252 DOI: 10.1113/jphysiol.2007.141531] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Among principal neurons, adult Purkinje cells have long been considered unusual in lacking functional NMDA receptors. This view has emerged largely from studies on rats, where NMDA receptors are expressed in Purkinje cells of newborn animals, but are lost after 2 weeks. By contrast, immunolabelling data have shown that Purkinje cells from adult mice express multiple NMDA receptor subunits, suggesting a possible species difference. To investigate the presence of functional NMDA receptors in Purkinje cells of mice, and to explore the contribution of different receptor subunits, we made whole-cell and single-channel patch-clamp recordings from Purkinje cells of wild-type and NR2D-/- mice of different ages. Here we report that multiple NMDA receptor subtypes are indeed expressed in Purkinje cells of young and adult mice; in the adult, both NR2A- and NR2B-containing subtypes are present. Furthermore, we show that NMDA receptor-mediated EPSCs can be evoked by climbing fibre stimulation, and appear to be mediated mainly by NR2A-containing receptors.
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Affiliation(s)
- Massimiliano Renzi
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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Mansouri B, Henne WM, Oomman SK, Bliss R, Attridge J, Finckbone V, Zeitouni T, Hoffman T, Bahr BA, Strahlendorf HK, Strahlendorf JC. Involvement of calpain in AMPA-induced toxicity to rat cerebellar Purkinje neurons. Eur J Pharmacol 2006; 557:106-14. [PMID: 17188264 DOI: 10.1016/j.ejphar.2006.11.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 11/09/2006] [Accepted: 11/13/2006] [Indexed: 02/06/2023]
Abstract
AMPA receptor-elicited excitotoxicity is manifested as both a type of programmed cell death termed dark cell degeneration and edematous necrosis, both of which are linked to increased intracellular Ca2+ concentration. The appearance of marked cytoskeletal changes in response to abusive AMPA receptor activation, coupled with increased intracellular Ca2+ concentration suggests activation of various destructive enzymes such as calpains, a family of Ca2+-dependent cysteine proteases. Since calpains and AMPA have been linked to both necrotic cell death and programmed cell death, we sought to determine the role of calpains in mediating both types of AMPA-mediated toxicity in Purkinje neurons of the cerebellum. These studies employed immunohistochemistry for cytoskeletal breakdown products of calpain activity coupled with confocal microscopy and pharmacological interventions with calpain and AMPA receptor antagonists. The present study identifies an early involvement of calpains in mediating AMPA-induced dark cell degeneration, but not edematous necrosis, based upon the effectiveness of AMPA to generate calpain-derived alpha-spectrin cleavage products in cerebellar Purkinje neurons that express dark cell degeneration, and the effectiveness of calpain antagonists, PD150606 and MDL28170, to attenuate AMPA-induced dark cell degeneration. Moreover, the AMPA receptor antagonist CNQX, a proven inhibitor of AMPA-elicited dark cell degeneration, also blocked AMPA-induced increases in alpha-spectrin, further suggesting interplay between abusive AMPA receptor activation, calpain activation and dark cell degeneration. Since AMPA-induced dark cell degeneration possesses morphological changes that resemble those that occur following brain ischemia in vivo, hypoglycemia, or extended seizure episodes, the involvement of calpains as mediators of cell death is potentially far reaching and has widespread therapeutic implications in numerous CNS disorders.
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Affiliation(s)
- Bobbak Mansouri
- Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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Goto JI, Inoue T, Kuruma A, Mikoshiba K. Short-term potentiation at the parallel fiber–Purkinje cell synapse. Neurosci Res 2006; 55:28-33. [PMID: 16472880 DOI: 10.1016/j.neures.2006.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 01/10/2006] [Accepted: 01/12/2006] [Indexed: 11/22/2022]
Abstract
Changes in synaptic efficacy at the parallel fiber (PF)-Purkinje cell (PC) synapse are postulated to be a cellular basis for motor learning. Although long-term efficacy changes lasting more than an hour at this synapse, i.e., long-term potentiation and depression, have been extensively studied, relatively short lasting synaptic efficacy changes, namely short-term potentiation (STP) lasting for tens of minutes, have not been discussed to date. Here we report that this synapse shows an apparent STP reliably by a periodic burst pattern of homosynaptic stimulation. This STP is presynaptically expressed, since it accompanies with a reduced paired-pulse facilitation and is resistant to postsynaptic Ca(2+) reduction by BAPTA injection or in P/Q-type Ca channel knockout cerebella. This novel type of synaptic plasticity at the PF-PC synapse would be a clue for understanding the presynaptic mechanisms of plasticity at this synapse.
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Affiliation(s)
- Jun-Ichi Goto
- Division of Molecular Neurobiology, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639 Japan
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Kakegawa W, Yuzaki M. A mechanism underlying AMPA receptor trafficking during cerebellar long-term potentiation. Proc Natl Acad Sci U S A 2005; 102:17846-51. [PMID: 16303868 PMCID: PMC1308917 DOI: 10.1073/pnas.0508910102] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Long-term potentiation (LTP) is mediated by the activity-driven delivery of GluR1 glutamate receptors via Ca2+/calmodulin-dependent protein kinase II activity in various brain regions. Recently, postsynaptic LTP was shown to be induced at parallel fiber-Purkinje cell synapses by stimulating the parallel fibers at 1 Hz or applying a NO donor. Here, we demonstrate that NO-evoked postsynaptic LTP in mice cerebellum was blocked by botulinum toxin and enhanced by prior treatment with phorbol ester, which is known to induce GluR2 endocytosis. Interestingly, such LTP was not affected by a Ca2+/calmodulin-dependent protein kinase II inhibitor or a peptide binding to a protein interacting with C kinase 1, but was blocked by a peptide binding to N-ethylmaleimide-sensitive factor, which specifically binds to GluR2. Therefore, although the synaptic incorporation of GluR2 has been reported to be a constitutive pathway, NO-induced postsynaptic LTP in Purkinje cells is likely mediated by a pathway involving N-ethylmaleimide-sensitive factor-dependent GluR2 trafficking.
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Affiliation(s)
- Wataru Kakegawa
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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Huang H, Bordey A. Glial glutamate transporters limit spillover activation of presynaptic NMDA receptors and influence synaptic inhibition of Purkinje neurons. J Neurosci 2004; 24:5659-69. [PMID: 15215288 PMCID: PMC6729224 DOI: 10.1523/jneurosci.1338-04.2004] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Glutamate transporters limit cross talk between excitatory synapses by removing synaptically released glutamate. However, the role of glutamate transporters in limiting the action of synaptically released glutamate at inhibitory synapses remains unknown. Single and paired whole-cell patch-clamp recordings were obtained from Purkinje neurons and Bergmann glia in mouse cerebellar slices to determine the function of neuronal and glial glutamate transporters at GABAergic synapses onto Purkinje neurons. NMDA and inhibition of glutamate transporters with DL-threo-beta-benzyloxyaspartic acid (TBOA) increased the frequency of miniature IPSCs (mIPSCs) by enhancing presynaptic NMDA receptor (NMDAR) activation, whereas inhibition of cystine-glutamate antiporters had no effect on mIPSCs. Selective inhibition of glutamate transporters in an individual Bergmann glial cell enhanced mIPSC frequency recorded in an adjacent Purkinje neuron significantly more than did postsynaptic transporter inhibition. TBOA did not change the frequency of spontaneous IPSCs (sIPSCs) but decreased their amplitude, as well as that of evoked IPSCs (eIPSCs), and enhanced the paired-pulse ratio. The action of NMDAR activation on eIPSCs but not that on mIPSCs was prevented by 100 microm ryanodine. Repetitive stimulations of climbing fibers resulted in a NMDAR-dependent reduction of sIPSC amplitude, and this effect was enhanced by TBOA even when postsynaptic glutamate transporters were blocked. These data indicate that glial glutamate transporters limit glutamate spillover from excitatory to inhibitory synapses and strongly influence synaptic inhibition of Purkinje neurons by controlling NMDAR activation on GABAergic terminals.
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Affiliation(s)
- Hao Huang
- Department of Neurosurgery, Yale University, New Haven, Connecticut 06520-8082, USA
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36
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Abstract
Neuronal circuits are shaped by experience during critical periods of early postnatal life. The ability to control the timing, duration, and closure of these heightened levels of brain plasticity has recently become experimentally accessible, especially in the developing visual system. This review summarizes our current understanding of known critical periods across several systems and species. It delineates a number of emerging principles: functional competition between inputs, role for electrical activity, structural consolidation, regulation by experience (not simply age), special role for inhibition in the CNS, potent influence of attention and motivation, unique timing and duration, as well as use of distinct molecular mechanisms across brain regions and the potential for reactivation in adulthood. A deeper understanding of critical periods will open new avenues to "nurture the brain"-from international efforts to link brain science and education to improving recovery from injury and devising new strategies for therapy and lifelong learning.
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Affiliation(s)
- Takao K Hensch
- Laboratory for Neuronal Circuit Development, Critical Period Mechanisms Research Group, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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37
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Santamaria F, Bower JM. Background synaptic activity modulates the response of a modeled purkinje cell to paired afferent input. J Neurophysiol 2004; 93:237-50. [PMID: 15306625 DOI: 10.1152/jn.00458.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We studied the possible effects of background excitatory and inhibitory synaptic activity on Purkinje cell responses to paired pulse inputs using a morphologically and physiologically detailed compartmental model. Paired-pulse inputs were provided via synapses associated with the ascending segment of the granule cell axon in the presence of variable amounts of background synaptic input provided by parallel fibers and inhibitory interneurons. The results predict the amplitude and dynamics of the somatic and dendritic responses to paired ascending segment inputs are modulated by the level of background synaptic activity, the basal somatic firing rate of the Purkinje cell model does not indicate the type or degree of modulation, and the modulatory effects are mediated through dendritic calcium and calcium-activated potassium currents. These results have important consequences for the functional organization of cerebellar cortex as well as the more general issue of the modulatory as distinct from driving effects of synapses now also being considered in other regions of the mammalian brain including the cerebral cortex.
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Affiliation(s)
- Fidel Santamaria
- Duke University Medical Center, P. O. Box 3209, Durham, NC 27710, USA.
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Blitz DM, Foster KA, Regehr WG. Short-term synaptic plasticity: a comparison of two synapses. Nat Rev Neurosci 2004; 5:630-40. [PMID: 15263893 DOI: 10.1038/nrn1475] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dawn M Blitz
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
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Dunbar RL, Chen G, Gao W, Reinert KC, Feddersen R, Ebner TJ. Imaging parallel fiber and climbing fiber responses and their short-term interactions in the mouse cerebellar cortex in vivo. Neuroscience 2004; 126:213-27. [PMID: 15145087 DOI: 10.1016/j.neuroscience.2004.02.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 11/25/2022]
Abstract
A major question in the study of cerebellar cortical function is how parallel fiber and climbing fiber inputs interact to shape information processing. Emphasis has been placed on the long-term effects due to conjunctive stimulation of climbing fibers and parallel fibers. Much less emphasis has been placed on short-term interactions and their spatial nature. To address this question the responses to parallel fiber and climbing fiber inputs and their short-term interaction were characterized using optical imaging with Neutral Red in the anesthetized mouse in vivo. Electrical stimulation of the cerebellar surface evoked an increase in fluorescence consisting of a transverse optical beam. The linear relationship between the optical responses and stimulus parameters, high spatial resolution and close coupling to the electrophysiological recordings show the utility of this imaging methodology. The majority of the optical response was due to activation of postsynaptic alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate (AMPA) and metabotropic glutamate receptors with a minor contribution from the presynaptic parallel fibers. Stimulation of the inferior olive evoked parasagittal bands that were abolished by blocking AMPA glutamate receptors. Conjunctive stimulation of the cerebellar surface and inferior olive resulted in inhibition of the climbing fiber evoked optical responses. This lateral inhibition of the parasagittal bands extended out from both sides of an activated parallel fiber beam and was mediated by GABA(A) but not GABA(B) receptors. One hypothesized role for lateral inhibition of this type is to spatially focus the interactions between parallel fiber and climbing fiber input on Purkinje cells. In summary optical imaging with Neutral Red permitted visualization of cerebellar cortical responses to parallel fiber and climbing fiber activation. The GABA(A) dependent lateral inhibition of the climbing fiber evoked parasagittal bands by parallel fiber stimulation shows that cerebellar interneurons play a short-term role in shaping the responses of Purkinje cells to climbing fiber input.
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Affiliation(s)
- R L Dunbar
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street Southeast, Minneapolis, MN 55455, USA
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O'Hearn E, Molliver ME. Administration of a non-NMDA antagonist, gyki 52466, increases excitotoxic Purkinje cell degeneration caused by ibogaine. Neuroscience 2004; 127:373-83. [PMID: 15262328 DOI: 10.1016/j.neuroscience.2004.04.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2004] [Indexed: 12/01/2022]
Abstract
Ibogaine is a tremorigenic hallucinogen that has been proposed for clinical use in treating addiction. We previously reported that ibogaine, administered systemically, produces degeneration of a subset of Purkinje cells in the cerebellum, primarily within the vermis. Ablation of the inferior olive affords protection against ibogaine-induced neurotoxicity leading to the interpretation that ibogaine itself is not directly toxic to Purkinje cells. We postulated that ibogaine produces sustained excitation of inferior olivary neurons that leads to excessive glutamate release at climbing fiber terminals, causing subsequent excitotoxic injury to Purkinje cells. The neuronal degeneration induced by ibogaine provides an animal model for studying excitotoxic injury in order to analyze the contribution of glutamate receptors to this injury and to evaluate neuroprotective strategies. Since non-N-methyl-D-aspartate (NMDA) receptors mediate Purkinje cell excitation by climbing fibers, we hypothesized that 1-4-aminophenyl-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI-52466), which antagonizes non-NMDA receptors, may have a neuroprotective effect by blocking glutamatergic excitation at climbing fiber synapses. To test this hypothesis, rats were administered systemic ibogaine plus GYKI-52466 and the degree of neuronal injury was analyzed in cerebellar sections. The results indicate that the AMPA antagonist GYKI-52466 (10 mg/kg i.p. x 3) does not protect against Purkinje cell injury at the doses used. Rather, co-administration of GYKI-52466 with ibogaine produces increased toxicity evidenced by more extensive Purkinje cell degeneration. Several hypotheses that may underlie this result are discussed. Although the reason for the increased toxicity found in this study is not fully explained, the present results show that a non-NMDA antagonist can produce increased excitotoxic injury under some conditions. Therefore, caution should be exercised before employing glutamate antagonists to reduce the risk of neuronal damage in human clinical disorders. Moreover, the contribution of different glutamate receptors to excitotoxic injury is complex and merits further analysis.
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Affiliation(s)
- E O'Hearn
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Pisu MB, Guioli S, Conforti E, Bernocchi G. Signal molecules and receptors in the differential development of cerebellum lobules. Acute effects of cisplatin on nitric oxide and glutamate systems in Purkinje cell population. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 145:229-40. [PMID: 14604763 DOI: 10.1016/j.devbrainres.2003.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three functionally correlated parameters, nitric oxide (NO), glutamate and NMDA receptors were analyzed through enzymehistochemical and immunohistochemical reactions. A single injection of cisplatin (cisPt) was administered to 10-day-old rats in order to study how Purkinje cells differentiation may be early changed by a mild injury due to the drug during postnatal cerebellar histogenesis. In comparison with age-matched control rats, a correlated decreasing expression of nitric oxide synthase (NOS), glutamate and NMDAR1 was observed in the Purkinje cells of lobules VI-VIII 6 h after the treatment. Moreover, at 24 h after cisPt, the expression of glutamate, NMDAR1 and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHd) reactivity was further decreased. In the same period, the ionotropic receptor GluR2 evidenced a less developed dendrite of Purkinje neurons in the top of lobules. In addition, the metabotropic receptor mGluR1alpha revealed unstained areas in the molecular layer, which was entirely stained in control rats; on PD11 this altered pattern was observed in all the lobules and in both the outer and the inner parts. Findings show the importance of NO-glutamate interactions via NMDAR1 in the crucial phases of Purkinje cells differentiation and their involvement on Purkinje neurons dendrite branching as demonstrated by the patterns of the other glutamate receptors. Changes were discussed in relation to an important critical event of Purkinje cell differentiation, i.e. regression of perisomatic spines and elimination of climbing fiber synapses on the somata. Finally, lobules VI-VIII appear to be the most vulnerable ones when cisplatin treatment is administered at 10 days of life, which demonstrates that at this stage some critical developmental changes occur in these lobules and that slower/damaged dendritic tree development is different in the outer versus the inner regions of the lobules.
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Affiliation(s)
- Maria Bonaria Pisu
- Dipartimento di Biologia Animale, Istituto di Genetica Molecolare del CNR-Sezione di Istochimica e Citometria, Università di Pavia, Piazza Botta 10, I-27100 Pavia, Italy
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Kuruma A, Inoue T, Mikoshiba K. Dynamics of Ca2+ and Na+ in the dendrites of mouse cerebellar Purkinje cells evoked by parallel fibre stimulation. Eur J Neurosci 2003; 18:2677-89. [PMID: 14656316 DOI: 10.1111/j.1460-9568.2003.02977.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Ca2+ and Na+ play important roles in neurons, such as in synaptic plasticity. Their concentrations in neurons change dynamically in response to synaptic inputs, but their kinetics have not been compared directly. Here, we show the mechanisms and dynamics of Ca2+ and Na+ transients by simultaneous monitoring in Purkinje cell dendrites in mouse cerebellar slices. High frequency parallel fibre stimulation (50 Hz, 3-50-times) depolarized Purkinje cells, and Ca2+ transients were observed at the anatomically expected sites. The magnitude of the Ca2+ transients increased linearly with increasing numbers of parallel fibre inputs. With 50 stimuli, Ca2+ transients lasted for seconds, and the peak [Ca2+] reached approximately 100 microm, which was much higher than that reported previously, although it was still confined to a part of the dendrite. In contrast, Na+ transients were sustained for tens of seconds and diffused away from the stimulated site. Pharmacological interventions revealed that Na+ influx through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and Ca2+ influx through P-type Ca channels were essential players, that AMPA receptors did not operate as a Ca2+ influx pathway and that Ca2+ release from intracellular stores through inositol trisphosphate receptors or ryanodine receptors did not contribute greatly to the large Ca2+ transients.
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Affiliation(s)
- Akinori Kuruma
- Laboratory for Developmental Neurobiology, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan
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Momiyama A, Silver RA, Hausser M, Notomi T, Wu Y, Shigemoto R, Cull-Candy SG. The density of AMPA receptors activated by a transmitter quantum at the climbing fibre-Purkinje cell synapse in immature rats. J Physiol 2003; 549:75-92. [PMID: 12665613 PMCID: PMC2342931 DOI: 10.1113/jphysiol.2002.033472] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We aimed to estimate the number of AMPA receptors (AMPARs) bound by the quantal transmitter packet, their single-channel conductance and their density in the postsynaptic membrane at cerebellar Purkinje cell synapses. The synaptic and extrasynaptic AMPARs were examined in Purkinje cells in 2- to 4-day-old rats, when they receive synaptic inputs solely from climbing fibres (CFs). Evoked CF EPSCs and whole-cell AMPA currents displayed roughly linear current-voltage relationships, consistent with the presence of GluR2 subunits in synaptic and extrasynaptic AMPARs. The mean quantal size, estimated from the miniature EPSCs (MEPSCs), was approximately 300 pS. Peak-scaled non-stationary fluctuation analysis of spontaneous EPSCs and MEPSCs gave a weighted-mean synaptic channel conductance of approximately 5 pS (approximately 7 pS when corrected for filtering). By applying non-stationary fluctuation analysis to extrasynaptic currents activated by brief glutamate pulses (5 mM), we also obtained a small single-channel conductance estimate for extrasynaptic AMPARs (approximately 11 pS). This approach allowed us to obtain a maximum open probability (Po,max) value for the extrasynaptic receptors (Po,max = 0.72). Directly resolved extrasynaptic channel openings in the continued presence of glutamate exhibited clear multiple-conductance levels. The mean area of the postsynaptic density (PSD) of these synapses was 0.074 microm2, measured by reconstructing electron-microscopic (EM) serial sections. Postembedding immunogold labelling by anti-GluR2/3 antibody revealed that AMPARs are localised in PSDs. From these data and by simulating error factors, we estimate that at least 66 AMPARs are bound by a quantal transmitter packet at CF-Purkinje cell synapses, and the receptors are packed at a minimum density of approximately 900 microm-2 in the postsynaptic membrane.
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Affiliation(s)
- Akiko Momiyama
- Department of Pharmacology, University College London, UK.
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Kakegawa W, Tsuzuki K, Iino M, Ozawa S. Functional NMDA receptor channels generated by NMDAR2B gene transfer in rat cerebellar Purkinje cells. Eur J Neurosci 2003; 17:887-91. [PMID: 12603279 DOI: 10.1046/j.1460-9568.2003.02498.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The adult cerebellar Purkinje cell is an exceptional neuron in the central nervous system in that it expresses high levels of NMDAR1 (NR1) mRNA without expressing any NMDAR2 (NR2) mRNAs. It has no functional NMDA receptor (NMDAR) channels, although it receives enormous numbers of excitatory inputs. Despite the high level of NR1 mRNA expression, the presence and localization of NR1 protein in mature Purkinje cells are controversial. To examine the presence of NR1 protein and its ability to form functional NMDARs, we expressed the NR2B subunit in rat mature Purkinje neurons by Sindbis viral-mediated gene transfer. The recombinant virus encoding both the NR2B and enhanced green fluorescent protein (GFP) genes (designated as SIN-EG-NR2B) infected Purkinje cells without infecting glial cells. GFP fluorescence was detected in the soma and throughout dendrites of Purkinje cells 18-24 h postinfection. In most of GFP-positive cells, the expression of NR2B protein was detected by immunostaining with NR2B-specific antibodies. In Purkinje cells infected with SIN-EG-NR2B, the iontophoretic application of NMDA induced prominent NMDAR-mediated current responses, indicating that the exogenous NR2B was assembled with endogenous NR1 to form functional NMDARs. Furthermore, NMDAR-mediated synaptic currents were detected at both the climbing fibre and parallel fibre synapses in infected Purkinje cells. Thus, the mature Purkinje cell produces NR1 protein that is ready to combine with NR2 to form functional NMDARs in excitatory synapses.
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Affiliation(s)
- Wataru Kakegawa
- Department of Physiology, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
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Brockhaus J, Deitmer JW. Long-lasting modulation of synaptic input to Purkinje neurons by Bergmann glia stimulation in rat brain slices. J Physiol 2002; 545:581-93. [PMID: 12456836 PMCID: PMC2290679 DOI: 10.1113/jphysiol.2002.028423] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Information processing in the nervous system is achieved primarily at chemical synapses between neurons. Recent evidence suggests that glia-neuron interactions contribute in multiple ways to the synaptic process. In the present study we used the frequency of spontaneous postsynaptic currents (sPSC) in Purkinje neurons in acute cerebellar brain slices from juvenile rats (13-19 days old) as a measure of synaptic activity. Following 50 depolarizing pulses to an adjacent Bergmann glial cell (50 mV; duration 0.5 s; 1 Hz) the sPSC frequency of the Purkinje neuron was reduced to 65 +/- 7 % of control values within 10 min after glial stimulation and remained depressed for at least 40 min. Depolarizing pulses to 0 mV had a comparable effect (70 +/- 5 % of control). The frequency of miniature PSCs, as recorded in 300 nM TTX, was not modulated after glial stimulation. Blockade of ionotropic glutamate receptors (iGluRs) with kynurenic acid (1 mM) or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5 microM) suppressed the reduction of neuronal activity induced by glial depolarization, whereas the glial modulation of synaptic activity was not inhibited by a block of N-methyl-D-aspartate iGluRs, metabotropic glutamate receptors, cannabinoid receptors or GABA(B) receptors. Fluorometric measurements of the intraglial Ca(2+) concentration revealed no glial Ca(2+) transients during the depolarization series, and glial cell stimulation reduced the neuronal sPSC frequency even after loading the glial cell with 20 mM of the Ca(2+) chelator BAPTA. Our results indicate a glia-induced long-lasting depression of neuronal communication mediated by iGluRs.
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Affiliation(s)
- Johannes Brockhaus
- Abteilung Allgemeine Zoologie, Fachbereich Biologie, Universität Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663 Kaiserslautern, Germany.
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Activity-dependent recruitment of extrasynaptic NMDA receptor activation at an AMPA receptor-only synapse. J Neurosci 2002. [PMID: 12040050 DOI: 10.1523/jneurosci.22-11-04428.2002] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have identified an excitatory synapse in cerebellar molecular layer interneurons at which the level of presynaptic activity determines the receptor type involved in the postsynaptic response. When small numbers of parallel fibers are activated, EPSCs are mediated solely by AMPA receptors (AMPARs), despite our finding that NMDA receptors (NMDARs) are present in the dendrites of these cells. The EPSC kinetics are fast (tau decay = 0.82 +/- 0.05 msec at room temperature), consistent with the role these interneurons are thought to play in precisely timed inhibitory control of Purkinje cells. NMDARs are activated only when glutamate release is increased either by facilitation with brief high-frequency trains or by recruiting more presynaptic fibers with higher stimulus intensities. Under these conditions, EPSCs consist of a fast-rising AMPAR-mediated current followed by a slow component mediated by both NMDARs and AMPARs. Inhibitors of glutamate transport increase the amplitude and prolong the time course of the compound EPSCs. In contrast, the properties of fast AMPAR EPSCs resulting from the activation of few inputs remain unchanged when glutamate uptake is blocked. Our results suggest that, at these synapses, the postsynaptic density contains AMPARs alone. It is only when transmitter release is high enough for glutamate to diffuse to the extrasynaptic space and to reach concentrations sufficient to activate extrasynaptic receptors that NMDARs are involved in the postsynaptic response. We suggest that such a spatial separation of receptor types may provide a mechanism for rapid changes in EPSC properties, depending on the amount of synaptic activity.
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Role of calcium, glutamate neurotransmission, and nitric oxide in spreading acidification and depression in the cerebellar cortex. J Neurosci 2002. [PMID: 11739595 DOI: 10.1523/jneurosci.21-24-09877.2001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This study investigated the mechanisms underlying the recently reported fast spreading acidification and transient depression in the cerebellar cortex in vivo. Spreading acidification was evoked by surface stimulation in the rat and mouse cerebellar cortex stained with the pH-sensitive dye neutral red and monitored using epifluorescent imaging. The probability of evoking spreading acidification was dependent on stimulation parameters; greater frequency and/or greater amplitude were more effective. Although activation of the parallel fibers defined the geometry of the spread, their activation alone was not sufficient, because blocking synaptic transmission with low Ca(2+) prevented spreading acidification. Increased postsynaptic excitability was also a major factor. Application of either AMPA or metabotropic glutamate receptor antagonists reduced the likelihood of evoking spreading acidification, but stronger stimulation intensities were still effective. Conversely, superfusion with GABA receptor antagonists decreased the threshold for evoking spreading acidification. Blocking nitric oxide synthase (NOS) increased the threshold for spreading acidification, and nitric oxide donors lowered the threshold. However, spreading acidification could be evoked in neuronal NOS-deficient mice (B6;129S-Nos1(tm1plh)). The depression in cortical excitability that accompanies spreading acidification occurred in the presence of AMPA and metabotropic glutamate receptor antagonists and NOS inhibitors. These findings suggest that spreading acidification is dependent on extracellular Ca(2+) and glutamate neurotransmission with a contribution from both AMPA and metabotropic glutamate receptors and is modulated by nitric oxide. Therefore, spreading acidification involves both presynaptic and postsynaptic mechanisms. We hypothesize that a regenerative process, i.e., a nonpassive process, is operative that uses the cortical architecture to account for the high speed of propagation.
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Casado M, Isope P, Ascher P. Involvement of presynaptic N-methyl-D-aspartate receptors in cerebellar long-term depression. Neuron 2002; 33:123-30. [PMID: 11779485 DOI: 10.1016/s0896-6273(01)00568-2] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
At the cerebellar synapses between parallel fibers (PFs) and Purkinje cells (PCs), long-term depression (LTD) of the excitatory synaptic current has been assumed to be independent of the N-methyl-D-aspartate (NMDA) receptor activation because PCs lack NMDA receptors. However, we now report that LTD is suppressed by NMDA receptor antagonists that act on presynaptic NMDA receptors of the PFs. This effect is still observed when the input is restricted to a single fiber. Therefore, LTD does not require the spatial integration of multiple inputs. In contrast, it involves a temporal integration, since reliable LTD induction requires the PFs to fire two action potentials in close succession. This implies that LTD will selectively depress the response to a burst of presynaptic action potentials.
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Affiliation(s)
- Mariano Casado
- Laboratoire de Neurobiologie, CNRS UMR 8544, Ecole Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France.
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Tomomura M, Rice DS, Morgan JI, Yuzaki M. Purification of Purkinje cells by fluorescence-activated cell sorting from transgenic mice that express green fluorescent protein. Eur J Neurosci 2001; 14:57-63. [PMID: 11488949 DOI: 10.1046/j.0953-816x.2001.01624.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cerebellar Purkinje cell has been the focus of numerous studies involving the analysis of development and information processing in the nervous system. Purkinje cells represent less than 0.1% of the total cell content of the cerebellum. To facilitate studies of molecules that are expressed in such a small proportion of neurons, we have established procedures for the purification of these cells. Transgenic mice were developed in which the expression of green fluorescent protein (GFP) was controlled by the L7 promoter. In adult cerebellum, GFP fluorescence was only detected in Purkinje cells, where it filled dendrites, soma and axons. GFP fluorescence was detected in Purkinje cells as early as embryonic day 17 and increased during development in vivo and in dissociated cerebellar culture. Mirroring endogenous L7 expression, high levels of GFP were observed in retinal rod bipolar cells. Lower levels of GFP were seen in olfactory periglomerular cells, neurons in the interpeduncular nucleus, and superior colliculus neurons. Cerebella from transgenic mice were dissociated by mild enzymatic treatment and Purkinje cells were isolated by fluorescence-activated cell sorting (FACS). By selecting optimal parameters, a fraction of viable Purkinje cells that was 94% pure was obtained. These results indicate that FACS is a powerful tool for isolating Purkinje cells from postnatal L7-GFP transgenic mice. GFP-positive neurons will also be useful in the real-time observation of dendritic morphogenesis and axonal outgrowth during development, or after neuronal activity in vitro.
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Affiliation(s)
- M Tomomura
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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Yamada K, Fukaya M, Shimizu H, Sakimura K, Watanabe M. NMDA receptor subunits GluRepsilon1, GluRepsilon3 and GluRzeta1 are enriched at the mossy fibre-granule cell synapse in the adult mouse cerebellum. Eur J Neurosci 2001; 13:2025-36. [PMID: 11422443 DOI: 10.1046/j.0953-816x.2001.01580.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cerebellar N-methyl-D-aspartate (NMDA) receptors are concentrated in the granular layer and are involved in motor coordination and the induction of long-term potentiation at mossy fibre-granule cell synapses. In the present study, we used immunohistochemistry to examine the distribution of NMDA receptor subunits in the adult mouse cerebellum. We found that appropriate pepsin pretreatment of sections greatly enhanced the sensitivity and specificity of immunohistochemical detection. As a result, intense immunolabelling for GluRepsilon1 (NR2A), GluRepsilon3 (NR2C), and GluRzeta1 (NR1) all appeared in synaptic glomeruli of the granular layer. Double immunofluorescence showed that these subunits were colocalized in individual synaptic glomeruli. Within the glomerulus, NMDA receptor subunits were located between centrally-located huge mossy fibre terminals and peripherally-located tiny Golgi axon terminals. By immunoelectron microscopy, all three subunits were detected at the postsynaptic junction in granule cell dendrites, forming synapses with mossy fibre terminals. Consistent with the known functional localization, GluRepsilon1, GluRepsilon3, and GluRzeta1 are, thus, anatomically concentrated at the mossy fibre-granule cell synapse. By contrast, immunohistochemical signals were very low in Purkinje cell somata and dendrites in the molecular layer. The lack of GluRzeta1 immunolabelling in Purkinje cells was unexpected because the cells express GluRzeta1 mRNA at high levels and high levels of GluRzeta1 protein in the molecular layer were revealed by immunoblot. As Purkinje cells are exceptionally lacking GluRepsilon expression, the discrepant result may provide in vivo evidence suggesting the importance of accompanying GluRepsilon subunits in synaptic localization of GluRzeta1.
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Affiliation(s)
- K Yamada
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
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