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Analysis of Signal Transduction Pathways Downstream M2 Receptor Activation: Effects on Schwann Cell Migration and Morphology. Life (Basel) 2022; 12:life12020211. [PMID: 35207498 PMCID: PMC8875146 DOI: 10.3390/life12020211] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/25/2022] [Accepted: 01/27/2022] [Indexed: 01/14/2023] Open
Abstract
Background: Schwann cells (SCs) express cholinergic receptors, suggesting a role of cholinergic signaling in the control of SC proliferation, differentiation and/or myelination. Our previous studies largely demonstrated that the pharmacological activation of the M2 muscarinic receptor subtype caused an inhibition of cell proliferation and promoted the expression of pro-myelinating differentiation genes. In order to elucidate the molecular signaling activated downstream the M2 receptor activation, in the present study we investigated the signal transduction pathways activated by the M2 orthosteric agonist arecaidine propargyl ester (APE) in SCs. Methods: Using Western blot we analyzed some components of the noncanonical pathways involving β1-arrestin and PI3K/AKT/mTORC1 signaling. A wound healing assay was used to evaluate SC migration. Results: Our results demonstrated that M2 receptor activation negatively modulated the PI3K/Akt/mTORC1 axis, possibly through β1-arrestin downregulation. The involvement of the mTORC1 complex was also supported by the decreased expression of its specific target p-p70 S6KThr389. Then, we also analyzed the expression of p-AMPKαthr172, a negative regulator of myelination that resulted in reduced levels after M2 agonist treatment. The analysis of cell migration and morphology allowed us to demonstrate that M2 receptor activation caused an arrest of SC migration and modified cell morphology probably by the modulation of β1-arrestin/cofilin-1 and PKCα expression, respectively. Conclusions: The data obtained demonstrated that M2 receptor activation in addition to the canonical Gi protein-coupled pathway modulates noncanonical pathways involving the mTORC1 complex and other kinases whose activation may contribute to the inhibition of SC proliferation and migration and address SC differentiation.
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2
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Cristofaro I, Spinello Z, Matera C, Fiore M, Conti L, De Amici M, Dallanoce C, Tata AM. Activation of M2 muscarinic acetylcholine receptors by a hybrid agonist enhances cytotoxic effects in GB7 glioblastoma cancer stem cells. Neurochem Int 2018; 118:52-60. [DOI: 10.1016/j.neuint.2018.04.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 04/11/2018] [Accepted: 04/19/2018] [Indexed: 12/16/2022]
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3
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Hübsch M, Neuhuber WL, Raab M. Muscarinic acetylcholine receptors in the mouse esophagus: focus on intraganglionic laminar endings (IGLEs). Neurogastroenterol Motil 2013; 25:e560-73. [PMID: 23742744 DOI: 10.1111/nmo.12161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 05/04/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND IGLEs represent the only low-threshold vagal mechanosensory terminals in the tunica muscularis of the esophagus. Previously, close relationships of vesicular glutamate transporter 2 (VGLUT2) immunopositive IGLEs and cholinergic varicosities suggestive for direct contacts were described in almost all mouse esophageal myenteric ganglia. Possible cholinergic influence on IGLEs requires specific acetylcholine receptors. In particular, the occurrence and location of neuronal muscarinic acetylcholine receptors (mAChR) in the esophagus were not yet characterized. METHODS This study aimed at specifying relationships of VGLUT2 immunopositive IGLEs and vesicular acetylcholine transporter (VAChT)-immunopositive varicosities using pre-embedding electron microscopy and the location of mAChR1-3 (M1-3) within esophagus and nodose ganglia using multilabel immunofluorescence and retrograde tracing. KEY RESULTS Electron microscopy confirmed synaptic contacts between cholinergic varicosities and IGLEs. M1- and M2-immunoreactivities (-iry; -iries) were colocalized with VGLUT2-iry in subpopulations of IGLEs. Retrograde Fast Blue tracing from the esophagus showed nodose ganglion neurons colocalizing tracer and M2-iry. M1-3-iries were detected in about 80% of myenteric ganglia and in about 67% of myenteric neurons. M1- and M2-iry were present in many fibers and varicosities within myenteric ganglia. Presynaptic M2-iry was detected in all, presynaptic M3-iry in one-fifth of motor endplates of striated esophageal muscles. M1-iry could not be detected in motor endplates of the esophagus, but in sternomastoid muscle. CONCLUSIONS & INFERENCES Acetylcholine probably released from varicosities of both extrinsic and intrinsic origin may influence a subpopulation of esophageal IGLEs via M2 and M1-receptors.
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Affiliation(s)
- M Hübsch
- Institute of Anatomy I, University of Erlangen-Nuremberg, Erlangen, Germany
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4
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Salani M, Anelli T, Tocco GA, Lucarini E, Mozzetta C, Poiana G, Tata AM, Biagioni S. Acetylcholine-induced neuronal differentiation: muscarinic receptor activation regulates EGR-1 and REST expression in neuroblastoma cells. J Neurochem 2009; 108:821-34. [PMID: 19187099 DOI: 10.1111/j.1471-4159.2008.05829.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neurotransmitters are considered part of the signaling system active in nervous system development and we have previously reported that acetylcholine (ACh) is capable of enhancing neuronal differentiation in cultures of sensory neurons and N18TG2 neuroblastoma cells. To study the mechanism of ACh action, in this study, we demonstrate the ability of choline acetyltransferase-transfected N18TG2 clones (e.g. 2/4 clone) to release ACh. Analysis of muscarinic receptors showed the presence of M1-M4 subtypes and the activation of both IP(3) and cAMP signal transduction pathways. Muscarinic receptor activation increases early growth response factor-1 (EGR-1) levels and treatments with agonists, antagonists, and signal transduction enzyme inhibitors suggest a role for M3 subtype in EGR-1 induction. The role of EGR-1 in the enhancement of differentiation was investigated transfecting in N18TG2 cells a construct for EGR-1. EGR-1 clones show increased neurite extension and a decrease in Repressor Element-1 silencing transcription factor (REST) expression: both these features have also been observed for the 2/4 clone. Transfection of this latter with EGR zinc-finger domain, a dominant negative inhibitor of EGR-1 action, increases REST expression, and decreases fiber outgrowth. The data reported suggest that progression of the clone 2/4 in the developmental program is dependent on ACh release and the ensuing activation of muscarinic receptors, which in turn modulate the level of EGR-1 and REST transcription factors.
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Affiliation(s)
- Monica Salani
- Dipartimento di Biologia Cellulare e dello Sviluppo, Unità di Ricerca di Neurobiologia e Centro di Ricerca in Neurobiologia Daniel Bovet, Università La Sapienza, Piazzale Aldo Moro, Roma, Italy
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5
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Tata AM, De Stefano ME, Srubek Tomassy G, Vilaró MT, Levey AI, Biagioni S. Subpopulations of rat dorsal root ganglion neurons express active vesicular acetylcholine transporter. J Neurosci Res 2004; 75:194-202. [PMID: 14705140 DOI: 10.1002/jnr.10855] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The vesicular acetylcholine transporter (VAChT) is a transmembrane protein required, in cholinergic neurons, for selective storage of acetylcholine into synaptic vesicles. Although dorsal root ganglion (DRG) neurons utilize neuropeptides and amino acids for neurotransmission, we have previously demonstrated the presence of a cholinergic system. To investigate whether, in sensory neurons, the vesicular accumulation of acetylcholine relies on the same mechanisms active in classical cholinergic neurons, we investigated VAChT presence, subcellular distribution, and activity. RT-PCR and Western blot analysis demonstrated the presence of VAChT mRNA and protein product in DRG neurons and in the striatum and cortex, used as positive controls. Moreover, in situ hybridization and immunocytochemistry showed VAChT staining located mainly in the medium/large-sized subpopulation of the sensory neurons. A few small neurons were also faintly labeled by immunocytochemistry. In the electron microscope, immunolabeling was associated with vesicle-like elements distributed in the neuronal cytoplasm and in both myelinated and unmyelinated intraganglionic nerve fibers. Finally, [(3)H]acetylcholine active transport, evaluated either in the presence or in the absence of ATP, also demonstrated that, as previously reported, the uptake of acetylcholine by VAChT is ATP dependent. This study suggests that DRG neurons not only are able to synthesize and degrade ACh and to convey cholinergic stimuli but also are capable of accumulating and, possibly, releasing acetylcholine by the same mechanism used by the better known cholinergic neurons.
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MESH Headings
- Acetylcholine/metabolism
- Adenosine Triphosphate/metabolism
- Animals
- Biological Transport, Active/physiology
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cell Size
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/ultrastructure
- Membrane Transport Proteins
- Microscopy, Electron
- Nerve Fibers, Myelinated/metabolism
- Nerve Fibers, Myelinated/ultrastructure
- Nerve Fibers, Unmyelinated/metabolism
- Nerve Fibers, Unmyelinated/ultrastructure
- Neurons, Afferent/metabolism
- Neurons, Afferent/ultrastructure
- Presynaptic Terminals/metabolism
- Presynaptic Terminals/ultrastructure
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Synaptic Transmission/physiology
- Synaptic Vesicles/metabolism
- Synaptic Vesicles/ultrastructure
- Transport Vesicles/metabolism
- Transport Vesicles/ultrastructure
- Vesicular Acetylcholine Transport Proteins
- Vesicular Transport Proteins
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Affiliation(s)
- Ada Maria Tata
- Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy
| | - M Egle De Stefano
- Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy
| | - Giulio Srubek Tomassy
- Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy
| | - M Teresa Vilaró
- Department of Neurochemistry, CSIC-IDIBAPS, Barcelona, Spain
| | - Allan I Levey
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia
| | - Stefano Biagioni
- Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy
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6
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Pannese E. Perikaryal surface specializations of neurons in sensory ganglia. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 220:1-34. [PMID: 12224547 DOI: 10.1016/s0074-7696(02)20002-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Slender projections, similar to microvilli, are the main specialization of the perikaryal surface of sensory ganglion neurons. The extent of these projections correlates closely with the volume of the corresponding nerve cell body. It is likely that the role of perikaryal projections of sensory ganglion neurons, which lack dendrites, is to maintain the surface-to-volume ratio of the nerve cell body above some critical level for adequate metabolic exchange. Satellite cells probably have the ability to promote, or provide a permissive environment for, the outgrowth of these projections. It is not yet known whether the effect of satellite cells is mediated by molecules associated with their plasma membrane or by diffusible factors. Furthermore, receptor molecules for numerous chemical agonists are located on the nerve cell body surface, but it is not known whether certain molecules are located exclusively on perikaryal projections or are also present on the smooth surface between these projections. Further study of the nerve cell body surface and of the influence that satellite cells exert on it will improve our understanding of the interactions between sensory ganglion neurons and satellite neuroglial cells.
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Affiliation(s)
- Ennio Pannese
- Institute of Histology, Embryology, and Neurocytology, University of Milan, Italy
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7
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De Jaco A, Augusti-Tocco G, Biagioni S. Muscarinic acetylcholine receptors induce neurite outgrowth and activate the synapsin I gene promoter in neuroblastoma clones. Neuroscience 2002; 113:331-8. [PMID: 12127090 DOI: 10.1016/s0306-4522(02)00179-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The possible role of acetylcholine as a modulator of neuronal differentiation has been tested using a neuroblastoma cell line (N18TG2), which does not synthesize any neurotransmitter. Acetylcholine synthesis has been activated in this line by transfection with a construct containing a choline acetyltransferase (ChAT) cDNA; ChAT-positive clones share a higher ability to grow fibers and an activation of synapsin I expression compared to the parental cells. Atropine, a muscarinic antagonist, abolishes the higher ability to grow fibers of ChAT-positive transfected clones, and the cholinergic agonist carbachol induces higher neurite outgrowth in the parental line. In transient transfections of ChAT-positive clones, the expression of a reporter gene under the control of synapsin I promoter is considerably reduced by atropine, while it is not modified by carbachol; in contrast, in the parental cells, which do not synthesize acetylcholine, the reporter gene expression is induced by carbachol and this effect is abolished by atropine. The data presented provide evidence for the existence of a direct modulation of fiber outgrowth and synapsin I expression by muscarinic receptor activation, which may be related to early growth response gene-1 (EGR-1) levels.
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Affiliation(s)
- A De Jaco
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università La Sapienza, Piazzale A. Moro 5, 00185, Rome, Italy
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8
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Allen DD, Cárdenas AM, Arriagada C, Bennett LB, García CJ, Caviedes R, Rapoport SI, Caviedes P. A dorsal root ganglia cell line derived from trisomy 16 fetal mice, a model for Down syndrome. Neuroreport 2002; 13:491-6. [PMID: 11930168 DOI: 10.1097/00001756-200203250-00027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have established two immortalized cell lines from dorsal root ganglia of normal (G4b) and trisomy 16 mice (GT1), a model for Down syndrome. By immunohistochemistry, both cell lines exhibit neuronal traits and lack glial markers. GTl cells exhibited greater [3H]choline uptake than G4b cells. K+ and nicotine-mediated acetylcholine release was greater in GT1 cells. Basal intracellular Ca2+ concentration ([Ca2+]i) was significantly lower in GTl cells. More GTl cells responded to neurotransmitters with a transient [Ca2+]i increase compared to G4b cells, but both cell types showed similar amplitudes of [Ca2+]i responses. The results show that both cell lines retain neuronal characteristics and respond to specific neurotransmitter stimuli. Altered GT1 cell responses could be related to neuronal pathophysiology in Down's syndrome.
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Affiliation(s)
- David D Allen
- Department of Pharmaceutical Sciences, Texas Tech University HSC, Amarillo, Texas, USA
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9
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Guo J, Chiappinelli VA. Distinct muscarinic receptors enhance spontaneous GABA release and inhibit electrically evoked GABAergic synaptic transmission in the chick lateral spiriform nucleus. Neuroscience 2001; 104:1057-66. [PMID: 11457590 DOI: 10.1016/s0306-4522(01)00152-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effects of muscarinic agonists on GABAergic synaptic transmission were examined using whole-cell patch-clamp recording in chick brain slices containing the lateral spiriform nucleus. Bath application of muscarine (10 microM) both increased the frequency of spontaneous GABAergic postsynaptic currents and reduced the amplitude of evoked GABAergic polysynaptic postsynaptic currents elicited by focal afferent fiber electrical stimulation. Both of these muscarinic actions were reversible and dose-dependent. Two M(1) antagonists, telenzepine and pirenzipine, and to a lesser extent the M(2) antagonist methoctramine, protected against muscarine's inhibition of the evoked polysynaptic currents. Other M(2) antagonists (tripitramine and gallamine) as well as the M(3) antagonist 4-DAMP mustard (4-diphenylacetoxy-N-(2-chloroethyl)-piperidine hydrochloride) and an M(4) antagonist (tropicamide) provided little or no protection against muscarine in this assay. In contrast, 4-diphenylacetoxy-N-(2-chloroethyl)-piperidine hydrochloride, tropicamide and telenzepine, but not pirenzepine, methoctramine, tripitramine and gallamine, blocked muscarine's enhancement of spontaneous GABAergic currents. McN-A-343 [(4-hydroxy-2-butynyl)-1-trimethylammonium-m-chlorocarbanilate chloride] and CDD-0097 (5-propargyloxycarbonyl-1,4,5,6-tetrahydropyrimidine hydrochloride), two M(1) agonists, mimicked muscarine's inhibition of the evoked polysynaptic GABAergic currents but did not mimic muscarine's enhancement of spontaneous GABAergic currents. Both actions of muscarine persisted when slices were pretreated with pertussis toxin or N-ethylmaleimide, which inactivate G-proteins coupled to M(2) and M(4) receptors while leaving G-proteins coupled to M(1), M(3) and M(5) receptors intact. Muscarine had no significant effect on the amplitude of the direct postsynaptic current elicited by exogenous GABA in the presence of tetrodotoxin. The results demonstrate that distinct muscarinic receptors oppositely modulate GABAergic transmission in the lateral spiriform nucleus. The receptor mediating the inhibition of evoked GABAergic polysynaptic currents is pharmacologically similar to an M(1) receptor, while the enhancement of spontaneous GABAergic currents appears to be mediated by an M(3) receptor.
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Affiliation(s)
- J Guo
- Department of Pharmacology, School of Medicine and Health Sciences, The George Washington University, 2300 Eye Street N.W., Washington, DC 20037, USA.
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10
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Tata AM. An in situ hybridization protocol to detect rare mRNA expressed in neural tissue using biotin-labelled oligonucleotide probes. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 2001; 6:178-84. [PMID: 11223418 DOI: 10.1016/s1385-299x(00)00053-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of the non-radioactive in situ hybridization protocols has allowed in general to obtain a better resolution of different transcripts at histological and cytological levels with a shortening of the developmental time. The common protocols using digoxigenin and biotin-labelled probes share a considerable limitation depending on the amount of the transcripts present in the tissues. This problem becomes more evident when oligonucleotide probes are used, because of their small size and lower ability to give sufficient signal amplification. The protocol reported here allows to localize rare mRNA expressed in a tissue, using a combination of two biotin-labelled oligonucleotide probes followed by streptavidin-peroxidase and biotinyl tyramide amplification system.
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Affiliation(s)
- A M Tata
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università La Sapienza, P.le Aldo Moro, 5, 00185 Rome, Italy.
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11
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Biagioni S, Tata AM, Agrati C, Cianfarani F, Augusti-Tocco G. Modulation of cholinergic marker expression by nerve growth factor in dorsal root ganglia. J Neurosci Res 2000; 62:591-9. [PMID: 11070503 DOI: 10.1002/1097-4547(20001115)62:4<591::aid-jnr14>3.0.co;2-s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The presence of cholinergic markers in sensory ganglia has suggested a possible functional role of acetylcholine both as a cofactor of morphogenesis in embryonic life and in sensory transduction during adult life. Acetylcholine, in fact, is able to excite cutaneous nociceptors and to modulate noxious stimuli. Nerve growth factor (NGF) overexpression induces the survival of nociceptive neurons, the expression of their specific markers, and hyperalgesia. On the other hand, NGF modulate the levels of cholinergic markers in several area of nervous system. Considering these observations, the present work aims to investigate whether NGF is able also to control the expression of cholinergic markers in chick sensory neurons in culture. We selected three developmental stages (E8, E12, and E18) representative of different phases of chick embryo development and performed observations on culture in which NGF was omitted at the plating time, withdrawn after the initial 24 hr of culture or maintained for 48 hr. In the experimental protocol devised, NGF did not significantly affect cell survival. At E12 a 48 hr treatment with NGF causes a significant but limited increase in acetylcholinesterase activity; activity increase was not observed when NGF was removed after 24 hr. No changes in acetylcholinesterase activity were observed at E8 and E18 stages. NGF appears to be more effective in the modulation of choline acetyltransferase activity. At E12, in fact, about a doubling of enzyme activity was measured after 24 or 48 hr of treatment with NGF. A response was also found at E18, when a 50% increase in choline acetyltransferase activity was observed just after 24 hr treatment. The behavior of muscarinic receptors in response to NGF differs compared to the two cholinergic enzymes. At E8 and E12 a profound increase in muscarinic receptor expression was observed. Conversely, at E18 NGF produces a 50% reduction of receptors. Considering these observations and the demonstrated role of muscarinic receptors in the desensitization of nociceptors, the reduction of muscarinic receptors in DRG after NGF treatment is in agreement with the proposed algogenic action of NGF in the skin.
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MESH Headings
- Acetylcholine/metabolism
- Acetylcholinesterase/drug effects
- Acetylcholinesterase/metabolism
- Animals
- Biomarkers/analysis
- Cell Survival/drug effects
- Cell Survival/physiology
- Cells, Cultured/cytology
- Cells, Cultured/drug effects
- Cells, Cultured/enzymology
- Chick Embryo
- Choline O-Acetyltransferase/drug effects
- Choline O-Acetyltransferase/metabolism
- Ganglia, Spinal/cytology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/embryology
- Ganglia, Spinal/enzymology
- Nerve Growth Factor/metabolism
- Nerve Growth Factor/pharmacology
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/enzymology
- Nociceptors/cytology
- Nociceptors/drug effects
- Nociceptors/enzymology
- Pain/physiopathology
- Receptors, Muscarinic/drug effects
- Receptors, Muscarinic/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- S Biagioni
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy.
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12
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Tata AM, Vilaró MT, Mengod G. Muscarinic receptor subtypes expression in rat and chick dorsal root ganglia. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 82:1-10. [PMID: 11042353 DOI: 10.1016/s0169-328x(00)00165-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In the present work we have analyzed by Northern blot, RT-PCR and in situ hybridization the expression of muscarinic receptor subtype mRNAs in rat and chick dorsal root ganglia. Northern blot analysis performed on rat total RNA revealed a strong signal for M(2) while a faint band was observed for M(3) and M(4) subtypes; no signal was evident for M(1) and M(5), while in chick total RNA no signal was detected for any of the analyzed subtypes (M(2), M(3), M(4)). On the other hand, RT-PCR revealed that all muscarinic subtype mRNAs were present both in rat and chick DRG, although the level of their expression may be different. In chick DRG, the presence of various muscarinic subtypes was confirmed by competition binding experiments. In situ hybridization in rat DRG showed that M(3) and M(4) transcripts, similarly to what has been previously described for M(2) mRNA, were preferentially localized in medium-small neurons. Large neurons were usually negative or faintly labelled. No hybridization signal was detected in rat DRG with probes for M(1) and M(5) muscarinic subtypes. The presence of various muscarinic receptors in DRG and their preferential expression in the medium-small sensory neurons suggest their possible involvement in the modulation of nociceptive stimuli transduction.
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MESH Headings
- Animals
- Binding, Competitive
- Blotting, Northern
- Chickens
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Hippocampus/metabolism
- In Situ Hybridization
- Kinetics
- Muscarinic Agonists/pharmacokinetics
- Neurons/cytology
- Neurons/metabolism
- RNA, Messenger/genetics
- Rats
- Receptor, Muscarinic M2
- Receptor, Muscarinic M3
- Receptor, Muscarinic M4
- Receptors, Muscarinic/genetics
- Receptors, Muscarinic/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic
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Affiliation(s)
- A M Tata
- Department of Cell and Developmental Biology, Università 'La Sapienza', P.le A. Moro, 5, 00185, Roma, Italy.
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13
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De Jaco A, Ajmone-Cat MA, Baldelli P, Carbone E, Augusti-Tocco G, Biagioni S. Modulation of acetylcholinesterase and voltage-gated Na(+) channels in choline acetyltransferase- transfected neuroblastoma clones. J Neurochem 2000; 75:1123-31. [PMID: 10936194 DOI: 10.1046/j.1471-4159.2000.0751123.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neurotransmitters appear early in the developing embryo and may play a role in the regulation of neuronal differentiation. To study potential effects of acetylcholine production in neuronal differentiation, we used the FB5 subclone of N18TG2 murine neuroblastoma cells stably transfected with cDNA for choline acetyltransferase. We tested whether the forced acetylcholine production can modify the expression or the cellular localization of different neuronal markers. We studied the activity, localization, and secretion of acetylcholinesterase in view of its possible role in the modulation of the morphogenetic action of acetylcholine and of its proposed role of a regulator of neurite outgrowth. FB5 cells are characterized by a high level of acetylcholinesterase, predominantly released into the culture medium. Acetylcholinesterase secretion into the medium was lower in choline acetyltransferase-transfected clones than in nontransfected and antisense-transfected controls. Moreover, sequential extraction of acetylcholinesterase revealed that detergent-extracted, i.e., membrane-associated, activity was higher in the transfected clones expressing choline acetyltransferase activity than in both control groups. These observations suggest that a shift occurs in the utilization of acetylcholinesterase in choline acetyltransferase-transfected clones from a secretion pathway to a pathway leading to membrane localization. In addition, the choline acetyltransferase-positive clones showed higher densities of voltage-gated Na(+) channels and enhanced high-affinity choline uptake, suggesting the accomplishment of a more advanced differentiated neuronal phenotype. Finally, binding experiments demonstrated the presence of muscarinic acetylcholine receptors in all examined clones. This observation is consistent with the proposed existence of an autocrine loop, which may be important for the enhancement in the expression of neurospecific traits.
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Affiliation(s)
- A De Jaco
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Roma, Italy
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14
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Tata AM, Tripiciano A, Filippini A, Biagioni S, Augusti-Tocco G. Muscarinic receptors modulate intracellular calcium level in chick sensory neurons. Brain Res 2000; 866:65-72. [PMID: 10825481 DOI: 10.1016/s0006-8993(00)02225-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present work we have studied the variation of intracellular calcium levels induced by muscarinic agonists in chick dorsal root ganglia neurons. Muscarinic agonists such as muscarine and oxotremorine cause an increase of intracellular calcium levels in fura-2AM-loaded DRG neurons of E18 chick embryos. This increase was abolished following treatment with 1 microM atropine but not by 1 microM mecamylamine, indicating that the observed intracellular calcium increase, was dependent on muscarinic receptor activation. Stimulation in absence of external calcium or pre-incubation of the DRG cultures with thapsigargin or Mn(2+) demonstrated that [Ca(2+)](i) increase is mainly due to its release from intracellular stores. The use of selective antagonists of muscarinic receptor subtypes also indicated that M(1) and to a lesser extent M(3) receptor subtypes are responsible for the observed intracellular calcium mobilization. Finally pre-treatment of DRG cultures with pertussis toxin showed that the variation of [Ca(2+)](i) levels was dependent on PTX-insensitive G-protein. Moreover muscarinic agonists induce in DRG also the increase of IPs level, suggesting that the variations of intracellular calcium levels may be due at least in part to the activation of the phosphoinositide transduction pathway. In conclusion the reported observations demonstrate the activity of muscarinic receptors in sensory neurons, suggesting a functional role for acetylcholine in sensory transduction.
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Affiliation(s)
- A M Tata
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università 'La Sapienza', P. le Aldo Moro 5, 00185, Rome, Italy
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16
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Tata AM, Vilaró MT, Agrati C, Biagioni S, Mengod G, Augusti-Tocco G. Expression of muscarinic m2 receptor mRNA in dorsal root ganglia of neonatal rat. Brain Res 1999; 824:63-70. [PMID: 10095043 DOI: 10.1016/s0006-8993(99)01109-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The expression of mRNA coding for m2 subtype of muscarinic cholinergic receptors was assessed in dorsal root ganglia (DRG) of 15-day post-natal rats. Northern blot analysis on total RNA using a mixture of two different oligonucleotide probes, indicated the presence of a single prominent band of approximately 6.5 kb in rat DRG; a band of the same size was observed both in brainstem and cortex taken as positive controls. Analysis by RT-PCR of the mRNA coding for a region of the third cytoplasmic loop of m2 receptor showed a single signal both in rat DRG and hippocampus. In situ hybridization was then used to identify the neuronal subpopulations expressing the mRNA for M2. The transcripts were preferentially localized in medium-small neurons of the ganglion as well as in satellite cells surrounding the neuron cell body. Large neurons were usually negative. Finally, competition binding experiments, performed in the presence of [3H]-quinuclidinyl benzilate (QNB) and methoctramine (a selective competitor for M2 receptors), demonstrated the presence of M2 receptor protein (Ki=100 nM), as previously observed in chick DRG. The preferential localization of M2 in medium-small neurons of the ganglion suggests the involvement of this receptor subtype in the transduction of nociceptive stimuli.
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Affiliation(s)
- A M Tata
- Department of Cell and Developmental Biology, Università 'La Sapienza', P. le Aldo Moro, 5, 00185, Rome, Italy
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Bernardini N, de Stefano ME, Tata AM, Biagioni S, Augusti-Tocco G. Neuronal and non-neuronal cell populations of the avian dorsal root ganglia express muscarinic acetylcholine receptors. Int J Dev Neurosci 1998; 16:365-77. [PMID: 9829173 DOI: 10.1016/s0736-5748(98)00038-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The distribution of muscarinic acetylcholine receptors was investigated by immuno-light and electron microscopy in the chick dorsal root ganglion during embryonic development (E12 and E18) and after hatching. The monoclonal antibody we used recognizes the acetylcholine binding site shared by all five muscarinic acetylcholine receptor subtypes. At E12, light microscopy reveals several immunopositive neurons with variable degrees of immunolabeling, heterogeneously distributed throughout the ganglion. Later in development and after hatching, the intensity of immunolabeling seems to decrease and the immunopositive neurons, of the small-medium-sized type, are located mostly in the medio-dorsal region of the ganglion. Under the electron microscope, the immunoreaction is associated with the Nissl bodies, budding Golgi cisterns and, especially at E12, with discrete loci along the neuronal plasma membrane. Unmyelinated nerve fibers, in both central and peripheral branches, are also immunopositive, suggesting that muscarinic acetylcholine receptors are transported towards the spinal cord and the periphery, respectively. A large number of perineuronal satellite cells and both myelinating and unmyelinating Schwann cells are intensely labeled. These observations, combined with previous data on the pharmacological and functional characterization of muscarinic acetylcholine receptors in the avian dorsal root ganglion, suggest that both sensory neurons and non-neuronal cells are able to respond to acetylcholine stimuli. Since muscarinic acetylcholine receptor-immunoreactivity is restricted to the small-medium-sized neurons and their unmyelinated fibers, of the nociceptive type, we suggest that these receptors are involved in modulating the transduction of noxious stimuli from the periphery.
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Affiliation(s)
- N Bernardini
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università La Sapienza, Rome, Italy
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Koenigsberger C, Hammond P, Brimijoin S. Developmental expression of acetyl- and butyrylcholinesterase in the rat: enzyme and mRNA levels in embryonic dorsal root ganglia. Brain Res 1998; 787:248-58. [PMID: 9518638 DOI: 10.1016/s0006-8993(97)01507-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dorsal root ganglia (DRG) in the adult rat contain acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes implicated in neural morphogenesis. We used quantitative histochemistry, reverse transcription-PCR (RT-PCR), and in situ hybridization histochemistry to study cholinesterase expression during embryogenesis. Longitudinal sections of rat embryos, embryonic day 9 (E9), E11-E17, and E19, were studied by video microscopy of the stained enzyme reaction products. Both enzymes were detectable in the early DRG (E11-E12), with BChE being most prominent. There was a spatiotemporal change in expression of each cholinesterase within the DRG. From E13 on, AChE expression predominated, especially in the neuronal cell bodies, while BChE was more highly expressed in the surrounding neuropil and the ganglionic roots. This distribution resembled the pattern in adult DRG. AChE mRNA levels, as determined by RT-PCR from DRG collected at days E12-E17, and E19, varied in parallel with the intensity of enzyme stain in the DRG. Overall, these results demonstrate temporally regulated ganglionic expression of cholinesterases, which may be important in the development of the sensory nervous system.
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Affiliation(s)
- C Koenigsberger
- Department of Pharmacology, Mayo Clinic, Rochester, MN 55905, USA
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Senba E, Kashiba H. Sensory afferent processing in multi-responsive DRG neurons. PROGRESS IN BRAIN RESEARCH 1996; 113:387-410. [PMID: 9009747 DOI: 10.1016/s0079-6123(08)61100-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The recent advance in molecular and neurobiological techniques disclosed the multi-responsive nature of DRG neurons. The survival, phenotype expression and electrical properties of these neurons are under the control of a variety of substances through their specific receptors. In pathological conditions, such as tissue inflammation or nerve injury, DRG neurons change their responsiveness through the dynamic reconstruction of their receptor system. This reconstruction is initiated by environmental stimuli. Thus the properties of polymodal nociceptors can be altered according to the environmental conditions. The whole story of this mechanism is not disclosed yet. In order to understand this mechanism, it is basically important to identify various receptor mRNAs in DRG neurons, precise localization of receptor proteins, site of synthesis and route of supply of ligands for these receptors.
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Affiliation(s)
- E Senba
- Department of Anatomy and Neurobiology, Wakayama Medical College, Japan.
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