The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Takashi Suzuki - One of the best experts on this subject based on the ideXlab platform.
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endothelin 1 induced depolarization and hyperpolarization in Submandibular Ganglion neurons
The Bulletin of Tokyo Dental College, 2004Co-Authors: Takashi SuzukiAbstract:The effects of endothelin-1 were studied in vitro on neurons in the hamster Submandibular Ganglion, using the intracellular microelectrode technique. Endothelin (1M) caused a depolarization (5.51.2 mV) followed by a hyperpolarization (8.52.8 mV) of the membrane potential. Membrane conductance was increased during the endothelininduced depolarization and was decreased during the endothelin-induced hyperpolarization. The endothelin-induced depolarization was depressed (mean 43.6%) in a Krebs solution containing zero calcium and high magnesium. The results suggested that the predominant component of the depolarization was mediated by calcium ions. The calciuminsensitive component of depolarization was carried by chloride ions. Endothelin-induced slow rhythmic hyperpolarizations were probably induced by a decrease in chloride ion conductance.
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multiple signal pathways coupling vip and pacap receptors to calcium channels in hamster Submandibular Ganglion neurons
Autonomic Neuroscience: Basic and Clinical, 2004Co-Authors: Hideaki Kamaishi, Takayuki Endoh, Takashi SuzukiAbstract:Abstract The Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are two novel neuropeptides which produce particular biological effects caused by interaction with G-protein-coupled receptors. We have shown in a previous study where VIP and PACAP 38 inhibit voltage-dependent calcium channel (VDCC) currents (I Ca ) via G-proteins in hamster Submandibular Ganglion (SMG) neurons. In this study, we attempt to further characterize the signal transduction pathways of VIP-and PACAP 38-induced modulation of I Ca . Application of 1 μM VIP and PACAP 38 inhibited I Ca by 33.0±3.1% and 36.8±2.6%, respectively (mean±S.E.M., n =8). Application of strong voltage prepulse attenuated PACAP 38-induced inhibition of I Ca . Pretreatment of cAMP dependent protein kinase (PKA) activator attenuated VIP-induced inhibition, but not the PACAP 38-induced inhibition. Intracellular dialysis of the PKA inhibitor attenuated the VIP-induced inhibition, but not the PACAP 38-induced inhibition. Pretreatment of protein kinase C (PKC) activator and inhibitor attenuated VIP-induced inhibition, but not the PACAP 38-induced inhibition. Pretreatment of cholera toxin (CTX) attenuated PACAP 38-induced inhibition of I Ca . These findings indicate that there are multiple signaling pathways in VIP and PACAP 38-induced inhibitions of I Ca : one pathway would be the VPAC 1 /VPAC 2 receptors-induced inhibition involving both the PKA and PKC, and another one concerns the PAC 1 receptor-induced inhibition via G s -protein βγ subunits. The VIP-and PACAP 38-induced facilitation of I Ca can be observed in the SMG neurons in addition to inhibiting of I Ca .
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angiotensin ii induced ionic currents and signalling pathways in Submandibular Ganglion neurons
Archives of Oral Biology, 2003Co-Authors: Minako Abe, Takayuki Endoh, Takashi SuzukiAbstract:Abstract Angiotensin II (Ang II) is one of the most important vasoconstrictive hormones but is also known to act as a neuromodulator and a neurotransmitter in the central and peripheral nervous system. The Submandibular Ganglion (SMG) neuron is a parasympathetic Ganglion which receives inputs from preGanglionic cholinergic neurons, and innervates the Submandibular salivary gland to control saliva secretion. In this study, the effects of Ang II on SMG neurons were investigated using the whole-cell patch clamp technique. Membrane currents evoked by a ramp pulse from +50 to −100 mV (−150 mV/500 ms) were compared in both the absence and presence of Ang II. In eight neurons tested, 1 μM Ang II increased inward currents by 42.0±8.2%. The reversal potentials of the Ang II-induced current were 0.2±0.6 mV. These increase of inward currents by Ang II were antagonized by losartan, a selective antagonist of AT 1 receptors. Intracellular dialysis with 0.1 mM guanosin 5′- O -(2-thiodiphosphate) (GDP-β-S), a G-proteins blocker, and anti-G q/11 antibody attenuated Ang II-induced ionic current. In addition, pretreatment of neurons with 10 μM staurosporine (stauro), a protein kinase C (PKC) inhibitor, 0.5 μM PMA, a PKC activator, and 10 μM KN-93, a Ca 2+ /calmodulin-dependent protein kinase II (CaM K II) inhibitor, attenuated Ang II-induced ionic current in SMG neurons. The data presented here demonstrated that Ang II-induced ionic current via G q/11 -proteins involving both PKC and CaM K II pathways in SMG neurons.
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extracellular atp induced calcium channel inhibition mediated by p1 p2y purinoceptors in hamster Submandibular Ganglion neurons
British Journal of Pharmacology, 2003Co-Authors: Mitsuhiro Abe, Takayuki Endoh, Takashi SuzukiAbstract:1. The presence and profile of purinoceptors in neurons of the hamster Submandibular Ganglion (SMG) have been studied using the whole-cell configuration of the patch-clamp technique. 2. Extracellular application of adenosine 5'-triphosphate (ATP) reversibly inhibited voltage-dependent Ca(2+) channel (VDCC) currents (I(Ca)) via G(i/o)-protein in a voltage-dependent manner. 3. Extracellular application of uridine 5'-triphosphate (UTP), 2-methylthioATP (2-MeSATP), alpha,beta-methylene ATP (alpha,beta-MeATP) and adenosine 5'-diphosphate (ADP) also inhibited I(Ca). The rank order of potency was ATP=UTP>ADP>2-MeSATP=alpha,beta-MeATP. 4. The P2 purinoceptor antagonists, suramin and pyridoxal-5-phosphate-6-azophenyl-2', 4'-disulfonic acid (PPADS), partially antagonized the ATP-induced inhibition of I(Ca), while coapplication of suramin and the P1 purinoceptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), virtually abolished I(Ca) inhibition. DPCPX alone partially antagonized I(Ca) inhibition. 5. Suramin antagonized the UTP-induced inhibition of I(Ca), while DPCPX had no effect. 6. Extracellular application of adenosine (ADO) also inhibited I(Ca) in a voltage-dependent manner via G(i/o)-protein activation. 7. Mainly N- and P/Q-type VDCCs were inhibited by both ATP and ADO via G(i/o)-protein betagamma subunits in seemingly convergence pathways.
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pacap induced depolarizations in hamster Submandibular Ganglion neurons
The Bulletin of Tokyo Dental College, 2003Co-Authors: Takashi Suzuki, Hirohito Ono, Hideaki IkegamiAbstract:In this study, we have investigated the effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on in vitro hamster Submandibular Ganglion neurons using the conventional intracellular recording technique. PACAP (10 microM) induced slow depolarizations in approximately 70% of tested cells. PACAP-induced depolarizations were approximately 10 mV in the peak amplitude, and their durations were approximately 10 min. The slow depolarizations were accompanied by a decrease in membrane conductance (gm) at the initial phase and an increase in gm at the peak phase. Membrane input resistance increased by 14.8 +/- 2.2% (mean +/- S.E., max.) of the resting value at the initial phase and decreased by 30.8 +/- 4.3% (max.) at the peak phase. Anodal break spikes were elicited at the initial phase during PACAP-induced depolarization. In one neuron, anodal break spikes were elicited at the peak. Spikes which followed the anodal break spike were also elicited at 4 Hz in the initial phase during the slow depolarizations. The decrease in gm was probably produced by an inhibition of calcium conductance and an inhibition of slow Ca(2+)-activated K+ channels, while the increase in gm might have been produced by an activation of nonselective cation channels. The slow depolarizations by PACAP might be mediated by a membrane-delimited signal transduction cascade involving G protein in the Submandibular Ganglion neurons.
Takayuki Endoh - One of the best experts on this subject based on the ideXlab platform.
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neuropeptide y modulates calcium channels in hamster Submandibular Ganglion neurons
Neuroscience Research, 2012Co-Authors: Takayuki Endoh, Hiromi Nobushima, Masakazu TazakiAbstract:Abstract It is established that neuropeptide Y (NPY) is a transmitter of parasympathetic secretory impulses in Submandibular gland. The neuropeptides substance P, vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) are likely mediators of secretory parasympathetic responses of the gland. Previously, we have shown that substance P, VIP and CGRP modulate voltage-dependent Ca 2+ channels (VDCCs) in hamster Submandibular Ganglion (SMG) neurons. In this study, we attempt to characterize the effect of NPY on VDCCs current using Ba 2+ ( I Ba ) in SMG neurons. Application of NPY caused both facilitation and inhibition of L-type and N/P/Q-type I Ba , respectively. Intracellular dialysis of the Gα s -protein antibody attenuated the NPY-induced facilitation of I Ba . The adenylate cyclase (AC) inhibitor, as well as protein kinase A (PKA) inhibitor attenuated the NPY-induced facilitation of I Ba . Intracellular dialysis of the Gα i -protein antibody attenuated the NPY-induced inhibition of I Ba . Application of a strong depolarizing voltage prepulse attenuated the NPY-induced inhibition of I Ba . These results indicate that NPY facilitates L-type VDCCs via Gα s -protein involving AC and PKA. On the other hand, NPY also inhibits N/P/Q-type VDCCs via Gα i -protein βγ subunits in the SMG neurons.
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Calcitonin gene-related peptide- and adrenomedullin-induced facilitation of calcium current in Submandibular Ganglion.
Archives of oral biology, 2010Co-Authors: Takayuki Endoh, Yoshiyuki Shibukawa, Maki Tsumura, Hideki Ichikawa, Masakazu Tazaki, Takashi InoueAbstract:Abstract Objective The control of saliva secretion is mainly under parasympathetic control. The Submandibular Ganglion (SMG) is a parasympathetic Ganglion which receives inputs from preGanglionic cholinergic neurons, and innervates the Submandibular salivary gland to control saliva secretion. The aim of this study was to investigate if adrenomedullin (ADM) and/or calcitonin gene-related peptide (CGRP) modulate voltage-dependent calcium channel (VDCCs) current ( I Ca ) in SMG. Design The profile of CGRP and ADM actions in SMG was studied using the whole-cell configuration of the patch-clamp technique. Results Both ADM and CGRP facilitated I Ca . These facilitations were attenuated by intracellular dialysis of the anti-Gα s -protein and pretreatment of SQ22536 (an adenylate cyclase inhibitor). Conclusions ADM and CGRP facilitates VDCCs mediated by Gα s -protein and adenylate cyclase in SMG.
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modulation of voltage dependent calcium channels by neurotransmitters and neuropeptides in parasympathetic Submandibular Ganglion neurons
Archives of Oral Biology, 2004Co-Authors: Takayuki EndohAbstract:The control of saliva secretion is mainly under parasympathetic control, although there also could be a sympathetic component. Sympathetic nerves are held to have a limited action in secretion in Submandibular glands because, on electrical stimulation, only a very small increase to the normal background, basal secretion occurs. Parasympathetic stimulation, on the other hand, caused a good flow of saliva with moderate secretion of acinar mucin, plus an extensive secretion of granules from the granular tubules. The Submandibular Ganglion (SMG) is a parasympathetic Ganglion which receives inputs from preGanglionic cholinergic neurons, and innervates the Submandibular salivary gland to control saliva secretion. Neurotransmitters and neuropeptides acting via G-protein coupled receptors (GPCRs) change the electrical excitability of neurons. In these neurons, many neurotransmitters and neuropeptides modulate voltage-dependent calcium channels (VDCCs). The modulation is mediated by a family of GPCRs acting either directly through the membrane delimited G-proteins or through second messengers. However, the mechanism of modulation and the signal transduction pathway linked to an individual GPCRs depend on the animal species. This review reports how neurotransmitters and neuropeptides modulate VDCCs and how these modulatory actions are integrated in SMG systems. The action of neurotransmitters and neuropeptides on VDCCs may provide a mechanism for regulating SMG excitability and also provide a cellular mechanism of a variety of neuronal Ca(2+)-dependent processes.
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multiple signal pathways coupling vip and pacap receptors to calcium channels in hamster Submandibular Ganglion neurons
Autonomic Neuroscience: Basic and Clinical, 2004Co-Authors: Hideaki Kamaishi, Takayuki Endoh, Takashi SuzukiAbstract:Abstract The Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are two novel neuropeptides which produce particular biological effects caused by interaction with G-protein-coupled receptors. We have shown in a previous study where VIP and PACAP 38 inhibit voltage-dependent calcium channel (VDCC) currents (I Ca ) via G-proteins in hamster Submandibular Ganglion (SMG) neurons. In this study, we attempt to further characterize the signal transduction pathways of VIP-and PACAP 38-induced modulation of I Ca . Application of 1 μM VIP and PACAP 38 inhibited I Ca by 33.0±3.1% and 36.8±2.6%, respectively (mean±S.E.M., n =8). Application of strong voltage prepulse attenuated PACAP 38-induced inhibition of I Ca . Pretreatment of cAMP dependent protein kinase (PKA) activator attenuated VIP-induced inhibition, but not the PACAP 38-induced inhibition. Intracellular dialysis of the PKA inhibitor attenuated the VIP-induced inhibition, but not the PACAP 38-induced inhibition. Pretreatment of protein kinase C (PKC) activator and inhibitor attenuated VIP-induced inhibition, but not the PACAP 38-induced inhibition. Pretreatment of cholera toxin (CTX) attenuated PACAP 38-induced inhibition of I Ca . These findings indicate that there are multiple signaling pathways in VIP and PACAP 38-induced inhibitions of I Ca : one pathway would be the VPAC 1 /VPAC 2 receptors-induced inhibition involving both the PKA and PKC, and another one concerns the PAC 1 receptor-induced inhibition via G s -protein βγ subunits. The VIP-and PACAP 38-induced facilitation of I Ca can be observed in the SMG neurons in addition to inhibiting of I Ca .
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angiotensin ii induced ionic currents and signalling pathways in Submandibular Ganglion neurons
Archives of Oral Biology, 2003Co-Authors: Minako Abe, Takayuki Endoh, Takashi SuzukiAbstract:Abstract Angiotensin II (Ang II) is one of the most important vasoconstrictive hormones but is also known to act as a neuromodulator and a neurotransmitter in the central and peripheral nervous system. The Submandibular Ganglion (SMG) neuron is a parasympathetic Ganglion which receives inputs from preGanglionic cholinergic neurons, and innervates the Submandibular salivary gland to control saliva secretion. In this study, the effects of Ang II on SMG neurons were investigated using the whole-cell patch clamp technique. Membrane currents evoked by a ramp pulse from +50 to −100 mV (−150 mV/500 ms) were compared in both the absence and presence of Ang II. In eight neurons tested, 1 μM Ang II increased inward currents by 42.0±8.2%. The reversal potentials of the Ang II-induced current were 0.2±0.6 mV. These increase of inward currents by Ang II were antagonized by losartan, a selective antagonist of AT 1 receptors. Intracellular dialysis with 0.1 mM guanosin 5′- O -(2-thiodiphosphate) (GDP-β-S), a G-proteins blocker, and anti-G q/11 antibody attenuated Ang II-induced ionic current. In addition, pretreatment of neurons with 10 μM staurosporine (stauro), a protein kinase C (PKC) inhibitor, 0.5 μM PMA, a PKC activator, and 10 μM KN-93, a Ca 2+ /calmodulin-dependent protein kinase II (CaM K II) inhibitor, attenuated Ang II-induced ionic current in SMG neurons. The data presented here demonstrated that Ang II-induced ionic current via G q/11 -proteins involving both PKC and CaM K II pathways in SMG neurons.
W. C. Wong - One of the best experts on this subject based on the ideXlab platform.
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a study of the structure and functions of the Submandibular Ganglion
Annals Academy of Medicine Singapore, 1995Co-Authors: W. C. Wong, Engang LingAbstract:The Submandibular Ganglion (SMG) of both the rat and monkey is composed of a collection of small ganglia distributed mainly at the hilum of the Submandibular gland. Ultrastructurally, its constituent neurons have a prominent nucleus and numerous randomly distributed cytoplasmic organelles. In the rat SMG a variable number of its neurons are immunoreactivities for [Met5]enkephalin-Arg6-Gly7-Leu8, neuropeptide Y (NPY), substance P (SP), tyrosine hydroxylase (TH) and vasoactive intestinal polypeptide (VIP). In the monkey, however, the SMG neurons only react for NPY and SP. Following sectioning of the lingual nerve, SMG neurons of both the rat and monkey showed structural alterations; a marked change was also observed in the immunoreactivities of the rat neurons. There were signs of recovery in the structural features and immunoreactivities in the SMG neurons in animals with longer survival periods of up to 2 months. This suggests that the changes in the neurons after denervation are acute but reversible in nature. After fluorogold injections into the Submandibular and sublingual glands of the rat, a variable number of neurons in the superior salivatory nucleus (SSN), superior cervical Ganglion (SCG) and trigeminal Ganglion (TG) were labelled. A hypothetical model depicting the possible interactions between the parasympathetic SMG and the preGanglionic nucleus, that is, the SSN, as well as the sympathetic SCG and the sensory TG is presented. It is proposed that the SMG functions as a relay as well as a modulatory centre for salivatory activity.
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a light and electron microscopical localisation of the superior salivatory nucleus of the rat
Journal für Hirnforschung, 1994Co-Authors: W. C. Wong, Engang LingAbstract:The present study localised the superior salivatory nucleus (SSNc) in the reticular formation in rats using the retrograde axonal transport of fluorogold (FG). An ultrastructural study using the retrograde transport of horseradish peroxidase (HRP) was also carried out. After FG or cholera toxin conjugated-HRP (CT-HRP) injections into the lingual nerve, the labelling of SSNc in both the experiments was comparable. The retrogradely labelled cells were located in the ipsilateral parvocellular reticular formation (PCRt), dorsolateral to the facial nucleus and medial to the nucleus of the spinal tract of the trigeminal nerve. The rostrocaudal extent of the nucleus was about 0.9-1.05 mm, between the levels of the ascending facial nerve fibres caudally and the root of the facial nerve rostrally. The number of cells labelled was between 300-360, most of them being small to medium sized (14 x 22 mm) and appeared fusiform or polygonal. In rats receiving intraglandular injections of the tracers, the localisation and the rostrocaudal extent of the SSNc were similar, but the number of its containing labelled cells was only about 1/2 of the above. The SSNc cells that supplied the intra-glandular Submandibular Ganglion were not topographically arranged. On electron microscopy, the SSNc cells showed the typical features of preGanglionic autonomic neurons. The cells contained a prominent round or oval nucleus. Their cytoplasm was rich in organelles especially conspicuous was the aggregations of the cisternae of rough endoplasmic reticulum in distinct clumps. In the neuropil between the SSNc cells were present numerous dendrites, axons, axon terminals and neuroglial cells. Most of the axon terminals contained predominantly round agranular vesicles with a few dense-cored or flattened agranular vesicles. The majority of the synapses associated with the HRP-labelled SSNc cells were on the dendrites with occasional axosomatic or axoaxonal synaptic contacts. A remarkable feature was the occurrence of synaptic contacts between HRP-labelled axons and some labelled soma.
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a study on the Submandibular Ganglion of the monkey with special reference to ultrastructural changes after lingual nerve sectioning
Archives of Histology and Cytology, 1993Co-Authors: W. C. Wong, Engang LingAbstract:This study describes normal light and electron microscopic features of the monkey Submandibular Ganglion. The intraglandular Ganglion is composed of a collection of smaller ganglia distributed mainly at the hilum of the Submandibular gland: one or two large ganglia were often found along with the main duct, while the smaller ones were located at the periphery. All Ganglion cells were covered by satellite cells. Ultrastructurally, the Ganglion cells showed the usual features of autonomic neurons, being round to oval with a prominent nucleus and nucleolus. Their cytoplasm contained numerous randomly distributed organelles. Occasional Ganglion cells showed darkened dendrites. The majority of the synapses observed were of the axo-dendritic type, although the axo-somatic type was not uncommon. In the latter, the axon terminals were sometimes seen to deeply invaginate the soma of the Ganglion cells forming synaptic contacts. Non-synaptic desmosome-like junctional complexes were common between the Ganglion cells. Following the severance of the lingual nerve, the Ganglion showed structural alterations beginning 1 day after the operation. The earliest sign of change was the increase in the number of macrophages surrounding the Ganglion. Three and five days after the lingual nerve sectioning, the number of darkened dendrites considerably increased. Associated with this change were neuronal nuclei displaying irregular outlines. Other changes involved the disintegration of the preGanglionic fibres and their axon terminals. The latter were observed to be engulfed by the infiltrated macrophages and Schwann cells. By 7 days after the preGanglionic parasympathectomy, the Ganglion cells resumed normal features, suggesting the acute and reversible nature of the transneuronal degeneration of the monkey Submandibular Ganglion cells. This is further supported by the absence of cell death during the period examined.
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The intraglandular Submandibular Ganglion of postnatal and adult rats. II. A morphometric and quantitative study.
Journal of anatomy, 1992Co-Authors: Y K Ng, W. C. Wong, E A LingAbstract:A morphometric study was undertaken on the Submandibular Ganglion cells in rats of different ages. This showed a direct proportional increase with age in all the variables measured. Mean cross-sectional cell area showed the most dramatic growth, an increase of more than 5-fold between birth and young adulthood. Mean cell diameter and cell perimeter doubled over the same period. The growth of the nucleus, expressed as diameter, was slower when compared with that of the Ganglion cells as a whole. The number of intraglandular Ganglion cells remained relatively unchanged from birth to young adulthood, ranging from about 3000 to 5000 cells. They were mainly distributed at the hilar region of the Submandibular salivary gland, contributing 1/2 to 2/3 of the total Ganglion cell population. The second largest cell population was in the intralobular region, which made up about one-third of the population. The least populated region was in the connective tissue of the sublingual salivary gland, which contained only about 5-7% of the total cell number. Cell counts based on the fluorogold labelling method were generally lower than those made after haematoxylin and eosin staining. In the 2-d-old animals, counts of fluorogold-labelled cells were only about half the H & E counts. The discrepancy may be due to the thicker sections used in the fluorogold method, superimposition of cells leading to an underestimation of cell numbers. Nevertheless, the fluorogold labelling method provided rapid and reproducible results. Its main advantage is that the labelled Ganglion cells emit a bright yellow fluorescence which is readily identified; the other is the simplicity of the procedure, as labelling of Ganglion cells can be achieved by the intraperitoneal route.
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the intraglandular Submandibular Ganglion of postnatal and adult rats i a light and electron microscope study
Journal of Anatomy, 1992Co-Authors: W. C. Wong, Engang LingAbstract:The structure of the intraglandular Submandibular Ganglion is described in both postnatal and adult rats. The Ganglion is localised mainly at the hilum where the majority of the cell bodies are observed. Ganglia are also present in the intralobular septa of both the Submandibular and the sublingual glands. Often they are found along the main salivary ducts with the larger ganglia being encapsulated by connective tissue. On electron microscopy, the Submandibular Ganglion cells show the usual features of autonomic neurons. The cells contain a prominent round nucleus. Numerous short processes project from the soma together with a few long dendrites. The organelles are randomly distributed throughout the soma. Most of the synapses observed were on the short processes with occasional axosomatic synapses. Nonsynaptic desmosome-like contacts are a common feature among the Ganglion cells. Especially noteworthy are contacts made by the dendrites which deeply invaginate the soma of an adjacent nerve cell. The Ganglion cells of the postnatal and adult Submandibular ganglia show minor differences. Ultrastructurally, the postnatal cells show signs of immaturity such as abundant free ribosomes, well developed Golgi complexes and disorganised rough endoplasmic reticulum. Mitotic satellite cells were observed associated with the postnatal Ganglion cells. The study has confirmed that all the Submandibular Ganglion cells show a positive reaction for acetylcholinesterase. Enzyme activity is localised in the cisternae of rough endoplasmic reticulum, the Golgi complex, plasma membrane and nuclear envelope.
Engang Ling - One of the best experts on this subject based on the ideXlab platform.
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a study of the structure and functions of the Submandibular Ganglion
Annals Academy of Medicine Singapore, 1995Co-Authors: W. C. Wong, Engang LingAbstract:The Submandibular Ganglion (SMG) of both the rat and monkey is composed of a collection of small ganglia distributed mainly at the hilum of the Submandibular gland. Ultrastructurally, its constituent neurons have a prominent nucleus and numerous randomly distributed cytoplasmic organelles. In the rat SMG a variable number of its neurons are immunoreactivities for [Met5]enkephalin-Arg6-Gly7-Leu8, neuropeptide Y (NPY), substance P (SP), tyrosine hydroxylase (TH) and vasoactive intestinal polypeptide (VIP). In the monkey, however, the SMG neurons only react for NPY and SP. Following sectioning of the lingual nerve, SMG neurons of both the rat and monkey showed structural alterations; a marked change was also observed in the immunoreactivities of the rat neurons. There were signs of recovery in the structural features and immunoreactivities in the SMG neurons in animals with longer survival periods of up to 2 months. This suggests that the changes in the neurons after denervation are acute but reversible in nature. After fluorogold injections into the Submandibular and sublingual glands of the rat, a variable number of neurons in the superior salivatory nucleus (SSN), superior cervical Ganglion (SCG) and trigeminal Ganglion (TG) were labelled. A hypothetical model depicting the possible interactions between the parasympathetic SMG and the preGanglionic nucleus, that is, the SSN, as well as the sympathetic SCG and the sensory TG is presented. It is proposed that the SMG functions as a relay as well as a modulatory centre for salivatory activity.
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a light and electron microscopical localisation of the superior salivatory nucleus of the rat
Journal für Hirnforschung, 1994Co-Authors: W. C. Wong, Engang LingAbstract:The present study localised the superior salivatory nucleus (SSNc) in the reticular formation in rats using the retrograde axonal transport of fluorogold (FG). An ultrastructural study using the retrograde transport of horseradish peroxidase (HRP) was also carried out. After FG or cholera toxin conjugated-HRP (CT-HRP) injections into the lingual nerve, the labelling of SSNc in both the experiments was comparable. The retrogradely labelled cells were located in the ipsilateral parvocellular reticular formation (PCRt), dorsolateral to the facial nucleus and medial to the nucleus of the spinal tract of the trigeminal nerve. The rostrocaudal extent of the nucleus was about 0.9-1.05 mm, between the levels of the ascending facial nerve fibres caudally and the root of the facial nerve rostrally. The number of cells labelled was between 300-360, most of them being small to medium sized (14 x 22 mm) and appeared fusiform or polygonal. In rats receiving intraglandular injections of the tracers, the localisation and the rostrocaudal extent of the SSNc were similar, but the number of its containing labelled cells was only about 1/2 of the above. The SSNc cells that supplied the intra-glandular Submandibular Ganglion were not topographically arranged. On electron microscopy, the SSNc cells showed the typical features of preGanglionic autonomic neurons. The cells contained a prominent round or oval nucleus. Their cytoplasm was rich in organelles especially conspicuous was the aggregations of the cisternae of rough endoplasmic reticulum in distinct clumps. In the neuropil between the SSNc cells were present numerous dendrites, axons, axon terminals and neuroglial cells. Most of the axon terminals contained predominantly round agranular vesicles with a few dense-cored or flattened agranular vesicles. The majority of the synapses associated with the HRP-labelled SSNc cells were on the dendrites with occasional axosomatic or axoaxonal synaptic contacts. A remarkable feature was the occurrence of synaptic contacts between HRP-labelled axons and some labelled soma.
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a study on the Submandibular Ganglion of the monkey with special reference to ultrastructural changes after lingual nerve sectioning
Archives of Histology and Cytology, 1993Co-Authors: W. C. Wong, Engang LingAbstract:This study describes normal light and electron microscopic features of the monkey Submandibular Ganglion. The intraglandular Ganglion is composed of a collection of smaller ganglia distributed mainly at the hilum of the Submandibular gland: one or two large ganglia were often found along with the main duct, while the smaller ones were located at the periphery. All Ganglion cells were covered by satellite cells. Ultrastructurally, the Ganglion cells showed the usual features of autonomic neurons, being round to oval with a prominent nucleus and nucleolus. Their cytoplasm contained numerous randomly distributed organelles. Occasional Ganglion cells showed darkened dendrites. The majority of the synapses observed were of the axo-dendritic type, although the axo-somatic type was not uncommon. In the latter, the axon terminals were sometimes seen to deeply invaginate the soma of the Ganglion cells forming synaptic contacts. Non-synaptic desmosome-like junctional complexes were common between the Ganglion cells. Following the severance of the lingual nerve, the Ganglion showed structural alterations beginning 1 day after the operation. The earliest sign of change was the increase in the number of macrophages surrounding the Ganglion. Three and five days after the lingual nerve sectioning, the number of darkened dendrites considerably increased. Associated with this change were neuronal nuclei displaying irregular outlines. Other changes involved the disintegration of the preGanglionic fibres and their axon terminals. The latter were observed to be engulfed by the infiltrated macrophages and Schwann cells. By 7 days after the preGanglionic parasympathectomy, the Ganglion cells resumed normal features, suggesting the acute and reversible nature of the transneuronal degeneration of the monkey Submandibular Ganglion cells. This is further supported by the absence of cell death during the period examined.
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the intraglandular Submandibular Ganglion of postnatal and adult rats i a light and electron microscope study
Journal of Anatomy, 1992Co-Authors: W. C. Wong, Engang LingAbstract:The structure of the intraglandular Submandibular Ganglion is described in both postnatal and adult rats. The Ganglion is localised mainly at the hilum where the majority of the cell bodies are observed. Ganglia are also present in the intralobular septa of both the Submandibular and the sublingual glands. Often they are found along the main salivary ducts with the larger ganglia being encapsulated by connective tissue. On electron microscopy, the Submandibular Ganglion cells show the usual features of autonomic neurons. The cells contain a prominent round nucleus. Numerous short processes project from the soma together with a few long dendrites. The organelles are randomly distributed throughout the soma. Most of the synapses observed were on the short processes with occasional axosomatic synapses. Nonsynaptic desmosome-like contacts are a common feature among the Ganglion cells. Especially noteworthy are contacts made by the dendrites which deeply invaginate the soma of an adjacent nerve cell. The Ganglion cells of the postnatal and adult Submandibular ganglia show minor differences. Ultrastructurally, the postnatal cells show signs of immaturity such as abundant free ribosomes, well developed Golgi complexes and disorganised rough endoplasmic reticulum. Mitotic satellite cells were observed associated with the postnatal Ganglion cells. The study has confirmed that all the Submandibular Ganglion cells show a positive reaction for acetylcholinesterase. Enzyme activity is localised in the cisternae of rough endoplasmic reticulum, the Golgi complex, plasma membrane and nuclear envelope.
Jeff W Lichtman - One of the best experts on this subject based on the ideXlab platform.
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rapid and modifiable neurotransmitter receptor dynamics at a neuronal synapse in vivo
Nature Neuroscience, 2008Co-Authors: Corey M. Mccann, John S. Coggan, Juan Carlos Tapia, Jeff W LichtmanAbstract:Synaptic plasticity underlies the adaptability of the mammalian brain, but has been difficult to study in living animals. Here we imaged the synapses between pre- and postGanglionic neurons in the mouse Submandibular Ganglion in vivo, focusing on the mechanisms that maintain and regulate neurotransmitter receptor density at postsynaptic sites. Normally, synaptic receptor densities were maintained by rapid exchange of receptors with nonsynaptic regions (over minutes) and by continual turnover of cell surface receptors (over hours). However, after Ganglion cell axons were crushed, synaptic receptors showed greater lateral mobility and there was a precipitous decline in insertion. These changes led to near-complete loss of synaptic receptors and synaptic depression. Disappearance of postsynaptic spines and presynaptic terminals followed this acute synaptic depression. Therefore, neurotransmitter receptor dynamism associated with rapid changes in synaptic efficacy precedes long-lasting structural changes in synaptic connectivity.
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in vivo imaging of presynaptic terminals and postsynaptic sites in the mouse Submandibular Ganglion
Developmental Neurobiology, 2008Co-Authors: Corey M. Mccann, Jeff W LichtmanAbstract:Much of what is currently known about the behavior of synapses in vivo has been learned at the mammalian neuromuscular junction, because it is large and accessible and also its postsynaptic acetylcholine receptors (AChRs) are readily labeled with a specific, high-affinity probe, alpha-bungarotoxin (BTX). Neuron-neuron synapses have thus far been much less accessible. We therefore developed techniques for imaging interneuronal synapses in an accessible Ganglion in the peripheral nervous system. In the Submandibular Ganglion, individual preGanglionic axons establish large numbers of axo-somatic synapses with postGanglionic neurons. To visualize these sites of synaptic contact, presynaptic axons were imaged by using transgenic mice that express fluorescent protein in preGanglionic neurons. The postsynaptic sites were visualized by labeling the acetylcholine receptor (AChR) alpha7 subunit with fluorescently tagged BTX. We developed in vivo methods to acquire three-dimensional image stacks of the axons and postsynaptic sites and then follow them over time. The Submandibular Ganglion is an ideal site to study the formation, elimination, and maintenance of synaptic connections between neurons in vivo.
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Synaptic dynamism measured over minutes to months: age-dependent decline in an autonomic Ganglion
Nature Neuroscience, 2003Co-Authors: Wen-biao Gan, Elaine Kwon, Guoping Feng, Joshua R Sanes, Jeff W LichtmanAbstract:Naturally occurring rearrangements of synaptic terminals are common in the nervous systems of young mammals, but little is known about their incidence in adults. Using transgenic mice that express yellow fluorescent protein (YFP) in axons, we repeatedly imaged nerve terminals in the parasympathetic Submandibular Ganglion. We found that the pattern of synaptic branches underwent significant rearrangements over several weeks in young adult mice. In older mice, rearrangements were less common, and synaptic patterns on individual neurons were recognizable for many months to years. Axonal branches frequently retracted or extended on a time scale of minutes in young adult mice, but seldom in mature animals. These results provide direct evidence for a decrease in plasticity of interneuronal connections as animals make the transition from young adulthood to middle age. The long-term stability of synaptic patterns could provide a structural basis for the persistence of memory in the adult nervous system.
