Recording ionic events from cultured, DiI-labelled myenteric neurons in the guinea-pig proximal colon

Vogalis, Fivos; Hillsley, Kirk; Smith, Terence K.

doi:10.1016/s0165-0270(99)00180-6

Cited by 17 publications

(12 citation statements)

References 47 publications

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“…The retrograde neuronal tracer DiI was used to map the projection lengths of individual CM motor neurones along the length of mouse colon (see Vogalis et al 2000; Brookes, 2001). This was performed to determine whether a single CM motor neurone could project (and hence possibly release) acetylcholine over 15 mm of colon simultaneously, to account for the temporally synchronized EJPs we have recorded above.…”

Section: Resultsmentioning

confidence: 99%

Synchronization of enteric neuronal firing during the murine colonic MMC

Spencer

Hennig

Dickson

et al. 2005

The Journal of Physiology

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DiI (1,1 didodecyl-3,3,3 ,3 -tetramethylindocarbecyanine perchlorate) retrograde labelling and intracellular electrophysiological techniques were used to investigate the mechanisms underlying the generation of spontaneously occurring colonic migrating myoelectric complexes (colonic MMCs) in mice. In isolated, intact, whole colonic preparations, simultaneous intracellular electrical recordings were made from pairs of circular muscle (CM) cells during colonic MMC activity in the presence of nifedipine (1-2 µM). During the intervals between colonic MMCs, spontaneous inhibitory junction potentials (IJPs) were always present. The amplitudes of spontaneous IJPs were highly variable (range 1-20 mV) and occurred asynchronously in the two CM cells, when separated by 1 mm in the longitudinal axis. Colonic MMCs occurred every 151 ± 7 s in the CM and consisted of a repetitive discharge of cholinergic rapid oscillations in membrane potential (range: 1-20 mV) that were superimposed on a slow membrane depolarization (mean amplitude: 9.6 ± 0.5 mV; half-duration: 25.9 ± 0.7 s). During the rising (depolarizing) phase of each colonic MMC, cholinergic rapid oscillations occurred simultaneously in both CM cells, even when the two electrodes were separated by up to 15 mm along the longitudinal axis of the colon. Smaller amplitude oscillations (< 5 mV) showed poor temporal correlation between two CM cells, even at short electrode separation distances (i.e. < 1 mm in the longitudinal axis). When the two electrodes were separated by 20 mm, all cholinergic rapid oscillations and IJPs in the CM (regardless of amplitude) were rarely, if ever, coordinated in time during the colonic MMC. Cholinergic rapid oscillations were blocked by atropine (1 µM) or tetrodotoxin (1 µM). Slow waves were never recorded from any CM cells. DiI labelling showed that the maximum projection length of CM motor neurones and interneurones along the bowel was 2.8 mm and 13 mm, respectively. When recordings were made adjacent to either oral or anal cut ends of the colon, the inhibitory or excitatory phases of the colonic MMC were absent, respectively. In summary, during the colonic MMC, cholinergic rapid oscillations of similar amplitudes occur simultaneously in two CM cells separated by large distances (up to 15 mm). As this distance was found to be far greater than the projection length of any single CM motor neurone, we suggest that the generation of each discrete cholinergic rapid oscillation represents a discreet cholinergic excitatory junction potential (EJP) that involves the synaptic activation of many cholinergic motor neurones simultaneously, by synchronous firing in many myenteric interneurones. Our data also suggest that ascending excitatory and descending inhibitory nerve pathways interact and reinforce each other.

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Section: Resultsmentioning

confidence: 99%

Synchronization of enteric neuronal firing during the murine colonic MMC

Spencer

Hennig

Dickson

et al. 2005

The Journal of Physiology

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“…The methods for measuring intracellular Ca 2+ in myenteric neurons maintained in primary culture were similar to those published by others 28–31 . Myenteric neurons grown on glass coverslips were loaded for 45 min at 37 °C in Opti‐MEM (Invitrogen, Carlsbad, CA, USA) solution containing the calcium indicator dye, fluo‐4 AM (2 μ mol L −1 )(Molecular Probes, Inc., Eugene, OR, USA) and Pluronic F‐127 (1% v/v) (Molecular Probes).…”

Section: Methodsmentioning

confidence: 99%

“…The methods for measuring intracellular Ca 2+ in myenteric neurons maintained in primary culture were similar to those published by others. [28][29][30][31] Myenteric neurons grown on glass coverslips were loaded for 45 min at 37°C in Opti-MEM (Invitrogen, Carlsbad, CA, USA) solution containing the calcium indicator dye, fluo-4 AM (2 lmol L )1 )(Molecular Probes, Inc., Eugene, OR, USA) and Pluronic F-127 (1% v/v) (Molecular Probes). After fluo-4 loading, cover slips containing neurons were transferred to a cover glassbased chamber mounted on a microscope (Olympus, IX 70, Optical Analysis Corp, Nashua, NH, USA).…”

Section: Calcium Imagingmentioning

confidence: 99%

α₂‐Adrenoceptors couple to inhibition of R‐type calcium currents in myenteric neurons

Bian

Galligan

2007

Neurogastroenterology Motil

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Abstractα 2 -adrenoceptors inhibit Ca 2+ influx through voltage-gated Ca 2+ channels throughout the nervous system and Ca 2+ channel function is modulated following activation of some G-protein coupled receptors. We studied the specific Ca 2+ channel inhibited following α 2 -adrenoceptor activation in guinea pig small intestinal myenteric neurons. Ca 2+ currents (I Ca 2+ ) were studied using whole-cell patch clamp techniques. Changes in intracellular Ca 2+ (Δ[Ca 2+ ] i ) in nerve cell bodies and varicosities were studied using digital imaging where Ca 2+ influx was evoked by KCl (60 mM) depolarization. The α 2 -adrenoceptor agonist, UK 14,304 (0.01 − 1 μM) inhibited I Ca 2+ and Δ[Ca 2+ ] i ; maximum inhibition of I Ca 2+ was 40%. UK 14,304 did not affect I Ca 2+ in the presence of SNX-482 or NiCl 2 (R-type Ca 2+ channel antagonists). UK 14,304 inhibited I Ca 2+ in the presence of nifedipine, ω-agatoxin IVA or ω-conotoxin, inhibitors of L-, P/Q-and N-type Ca 2+ channels. UK 14,304 induced Inhibition of I Ca 2+ was blocked by pertussis toxin pretreatment (1 μg/ml for 2 hr). α 2 -Adrenoceptors couple to inhibition of R-type Ca 2+ channels via a pertussis toxin-sensitive pathway in myenteric neurons. R-type channels may be a target for the inhibitory actions of norepinephrine released from sympathetic nerves on to myenteric neurons. Keywordsα1E; Ca v2.3 ; calcium imaging; enteric nervous system; presynaptic inhibitionGastrointestinal motility is controlled in part by the enteric nervous system (ENS) and by extrinsic sympathetic nerves. The ENS provides primary control over gut function while the sympathetic innervation modulates ENS activity (1). The myenteric plexus, a division of the ENS, is particularly important for control of gastrointestinal motility (2). Using electrophysiological criteria, myenteric neurons can be classified as S or AH neurons (3) and AH neurons may be intrinsic primary afferent neurons (4). In AH neurons the action potential has a Ca 2+ shoulder that is dependent on activation of N-type Ca 2+ channels (5). Ca 2+ entering during the action potential triggers calcium release from intracellular stores (6,7). The rise in intracellular Ca 2+ then activates a Ca 2+ -dependent K + channel, causing a long-lasting afterhyperpolarization (AHP) (4,8,9). S neurons are interneurons and motorneurons (10). Although action potentials in S neurons are blocked completely by tetrodotoxin (sodium channel antagonist), they are also associated with increases in intracellular calcium that are partly dependent on activation of N-type Ca 2+ channels (11).Guinea pig myenteric neurons express multiple Ca2+ subtypes (12). The total Ca 2+ current (I Ca 2+ ) in myenteric neurons is composed of contributions of Ca 2+ influx through L-N-P/Q- and R-type Ca 2+ channels (13-18). The R-type channels make the largest contribution to the total I Ca 2+ in myenteric neurons of guinea-pig small intestine maintained in the primary culture (13). R-type Ca 2+ channels are composed of the pore forming α 1E subunit (19,20). SNX 482 (2...

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“…In the guinea-pig small intestine, all Dogiel type II neurons have processes that project to the mucosa (Song et al 1991(Song et al , 1994 and many, perhaps all, Dogiel type II neurons in the large intestine project to the mucosa (Lomax and Furness 2000;Vogalis et al 2000). In pig and human, at least a proportion of the Dogiel type II neurons innervate the mucosa (Hens et al , 2001.…”

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confidence: 99%

Projections and chemistry of Dogiel type II neurons in the mouse colon

et al. 2004

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The physiological properties, shapes, projections and neurochemistries of Dogiel type II neurons have been thoroughly investigated in the guinea-pig intestine in which these neurons have been identified as intrinsic primary afferent neurons. Dogiel type II neurons in the myenteric ganglia of mice have similar physiological properties to those in guinea-pigs but whether other features of the neurons are similar is unknown. We have used intracellular dye-filling, retrograde tracing, immunohistochemistry and nerve lesions to determine salient features of Dogiel type II neurons of the mouse colon. Dye-filling showed that the neurons provide profuse terminal networks in the myenteric ganglia and also have axons that project towards the mucosa. Retrograde tracing and lesion studies showed that these axons provide direct innervation to the mucosa. High proportions of the neurons had immunoreactivity for calretinin, calbindin, choline acetyltransferase, the purine P2X2 receptor and calcitonin gene-related peptide (CGRP). CGRP was the most selective marker of the neurons. Following surgery to remove an area of myenteric plexus, the CGRP-immunoreactive nerve fibres in the mucosa degenerated. Thus, Dogiel type II neurons in mice have similar shapes and projections but some differences in chemistry from those in guinea-pigs. The close similarities between the two species in the shapes, projections and electrophysiology of these neurons suggest that they serve the same functions in both species.

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Recording ionic events from cultured, DiI-labelled myenteric neurons in the guinea-pig proximal colon

Cited by 17 publications

References 47 publications

Synchronization of enteric neuronal firing during the murine colonic MMC

Synchronization of enteric neuronal firing during the murine colonic MMC

α₂‐Adrenoceptors couple to inhibition of R‐type calcium currents in myenteric neurons

Projections and chemistry of Dogiel type II neurons in the mouse colon

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Recording ionic events from cultured, DiI-labelled myenteric neurons in the guinea-pig proximal colon

Cited by 17 publications

References 47 publications

Synchronization of enteric neuronal firing during the murine colonic MMC

Synchronization of enteric neuronal firing during the murine colonic MMC

α2‐Adrenoceptors couple to inhibition of R‐type calcium currents in myenteric neurons

Projections and chemistry of Dogiel type II neurons in the mouse colon

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α₂‐Adrenoceptors couple to inhibition of R‐type calcium currents in myenteric neurons