Profiling of neuropeptides released at the stomatogastric ganglion of the crab, Cancer borealis with mass spectrometry

This work reports on a capillary electrophoresis (CE) separation method coupled to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) imaging for improved neuropeptide coverage in the model organism Cancer borealis.

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Episodic Bouts of Activity Accompany Recovery of Rhythmic Output By a Neuromodulator- and Activity-Deprived Adult Neural Network

Journal of Neurophysiology ◽

10.1152/jn.00370.2003 ◽

2003 ◽

Vol 90 (4) ◽

pp. 2720-2730 ◽

Cited By ~ 36

Author(s):

Jason A. Luther ◽

Alice A. Robie ◽

John Yarotsky ◽

Christopher Reina ◽

Eve Marder ◽

...

Keyword(s):

Neural Network ◽

Neuronal Network ◽

Recovery Process ◽

Stomatogastric Ganglion ◽

Cancer Borealis ◽

Pyloric Network ◽

Underlying Mechanisms ◽

Over Time ◽

Phase Relationships ◽

Pyloric Rhythm

The pyloric rhythm of the stomatogastric ganglion of the crab, Cancer borealis, slows or stops when descending modulatory inputs are acutely removed. However, the rhythm spontaneously resumes after one or more days in the absence of neuromodulatory input. We recorded continuously for days to characterize quantitatively this recovery process. Activity bouts lasting 40–900 s began several hours after removal of neuromodulatory input and were followed by stable rhythm recovery after 1–4 days. Bout duration was not related to the intervals (0.3–800 min) between bouts. During an individual bout, the frequency rapidly increased and then decreased more slowly. Photoablation of back-filled neuromodulatory terminals in the stomatogastric ganglion (STG) neuropil had no effect on activity bouts or recovery, suggesting that these processes are intrinsic to the STG neuronal network. After removal of neuromodulatory input, the phase relationships of the components of the triphasic pyloric rhythm were altered, and then over time the phase relationships moved toward their control values. Although at low pyloric rhythm frequency the phase relationships among pyloric network neurons depended on frequency, the changes in frequency during recovery did not completely account for the change in phase seen after rhythm recovery. We suggest that activity bouts represent underlying mechanisms controlling the restructuring of the pyloric network to allow resumption of an appropriate output after removal of neuromodulatory input.

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Electrical coupling and innexin expression in the stomatogastric ganglion of the crabCancer borealis

Journal of Neurophysiology ◽

10.1152/jn.00536.2014 ◽

2014 ◽

Vol 112 (11) ◽

pp. 2946-2958 ◽

Cited By ~ 22

Author(s):

Sonal Shruti ◽

David J. Schulz ◽

Kawasi M. Lett ◽

Eve Marder

Keyword(s):

Sequence Similarity ◽

Electrical Coupling ◽

Homarus Americanus ◽

Stomatogastric Ganglion ◽

Electrical Synapse ◽

Coupling Coefficients ◽

Cancer Borealis ◽

Electrophysiological Recordings ◽

Pyloric Dilator ◽

Lateral Posterior

Gap junctions are intercellular channels that allow for the movement of small molecules and ions between the cytoplasm of adjacent cells and form electrical synapses between neurons. In invertebrates, the gap junction proteins are coded for by the innexin family of genes. The stomatogastric ganglion (STG) in the crab Cancer borealis contains a small number of identified and electrically coupled neurons. We identified Innexin 1 ( Inx1), Innexin 2 (Inx2), Innexin 3 (Inx3), Innexin 4 ( Inx4), Innexin 5 (Inx5), and Innexin 6 ( Inx6) members of the C. borealis innexin family. We also identified six members of the innexin family from the lobster Homarus americanus transcriptome. These innexins show significant sequence similarity to other arthropod innexins. Using in situ hybridization and reverse transcriptase-quantitative PCR (RT-qPCR), we determined that all the cells in the crab STG express multiple innexin genes. Electrophysiological recordings of coupling coefficients between identified pairs of pyloric dilator (PD) cells and PD-lateral posterior gastric (LPG) neurons show that the PD-PD electrical synapse is nonrectifying while the PD-LPG synapse is apparently strongly rectifying.

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Calcium-dependent plateau potentials in a crab stomatogastric ganglion motor neuron. I. Calcium current and its modulation by serotonin

Journal of Neurophysiology ◽

10.1152/jn.1995.74.5.1929 ◽

1995 ◽

Vol 74 (5) ◽

pp. 1929-1937 ◽

Cited By ~ 34

Author(s):

B. Zhang ◽

R. M. Harris-Warrick

Keyword(s):

Motor Neuron ◽

Voltage Clamp ◽

Physiological Role ◽

Input Resistance ◽

Stomatogastric Ganglion ◽

Channel Blockers ◽

Plateau Potentials ◽

Cancer Borealis ◽

Calcium Dependent ◽

Voltage Dependent

1. Using current- and voltage-clamp techniques, we examined the biophysical properties of a voltage-dependent Ca2+ current and its physiological role in plateau potential generation in the dorsal gastric (DG) motor neuron of the stomatogastric ganglion in the crab, Cancer borealis. 2. Stimulation of one of a set of identified serotonergic/cholinergic mechanosensory cells, the gastropyloric receptor (GPR) cells, induced plateau potentials in DG. A brief pressure application of serotonin (5-HT) closely mimicked the effect of the GPR cells. The 5-HT-evoked plateau in DG was not blocked by the sodium channel blocker, tetrodotoxin (TTX), or a combination of TTX with potassium channel blockers, including tetraethylammonium (TEA) and 4-aminopyridine (4-AP), and the Ih blocker, CsCl. The 5-HT-evoked plateau was eliminated by the Ca2+ channel blockers Co2+ and Cd2+, suggesting that Ca2+ entry is essential for plateau potentials in DG. During the plateau, we observed a 30% decrease in input resistance. 3. When sodium and potassium currents were blocked pharmacologically, injection of suprathreshold depolarizing current evoked all-or-none plateau-like responses lasting several seconds, even in the absence of 5-HT. This response was blocked by Ca2+ channel blockers, further supporting a role for Ca2+ in plateau generation. 5-HT significantly prolonged the duration of this plateau. 4. We isolated a voltage-dependent Ca2+ current in voltage-clamped DG neurons. This current was analyzed with the use of either Ca2+ or Ba2+ as the charge carrier after other currents had been maximally blocked with extracellular TTX, TEA, 4-AP, and CsCl and intracellular loading with Cs+ and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). The Ca2+ current was detectable at -45 mV, peaked at -15 mV, and was estimated to reverse at +45 mV. Co2+ and Cd2+ effectively blocked the Ca2+ current. 5. The voltage dependence of activation of the Ca2+ current was quantantitively analyzed by fitting the voltage-conductance relation with a third power Boltzmann relation. The maximum conductance (gA), half-activation voltage (VA) for individual gating steps, and the slope steepness (k) were 0.19 +/- 0.02 (SE) microS, -36.5 +/- 2.0 mV, and 4.4 +/- 1.4 mV/e-fold, respectively. 6. 5-HT significantly potentiated the gA by approximately 42% without affecting VA and k. 7. We conclude from our current- and voltage-clamp results that a voltage-dependent Ca2+ current plays an important role in generating plateau potentials in the DG neuron. Enhancement of the voltage-dependent Ca2+ current by 5-HT is one of the mechanisms for 5-HT-evoked plateau potentials.

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Rapid adaptation to elevated extracellular potassium in the pyloric circuit of the crab, Cancer borealis

Journal of Neurophysiology ◽

10.1152/jn.00135.2020 ◽

2020 ◽

Vol 123 (5) ◽

pp. 2075-2089 ◽

Cited By ~ 1

Author(s):

Lily S. He ◽

Mara C.P. Rue ◽

Ekaterina O. Morozova ◽

Daniel J. Powell ◽

Eric J. James ◽

...

Keyword(s):

Potassium Concentration ◽

Fold Increase ◽

Stomatogastric Ganglion ◽

Extracellular Potassium ◽

Rapid Adaptation ◽

Cancer Borealis ◽

High Potassium ◽

Transient Loss ◽

High Potassium Concentration ◽

Nonstationary Effects

Solutions with elevated extracellular potassium are commonly used as a depolarizing stimulus. We studied the effects of high potassium concentration ([K+]) on the pyloric circuit of the crab stomatogastric ganglion. A 2.5-fold increase in extracellular [K+] caused a transient loss of activity that was not due to depolarization block, followed by a rapid increase in excitability and recovery of spiking within minutes. This suggests that changing extracellular potassium can have complex and nonstationary effects on neuronal circuits.

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Restoration of descending inputs fails to rescue activity following deafferentation of a motor network

Journal of Neurophysiology ◽

10.1152/jn.00183.2012 ◽

2012 ◽

Vol 108 (3) ◽

pp. 871-881 ◽

Cited By ~ 7

Author(s):

Jebun Nahar ◽

Kawasi M. Lett ◽

David J. Schulz

Keyword(s):

Time Course ◽

Critical Role ◽

Stomatogastric Ganglion ◽

Homeostatic Plasticity ◽

Projection Neurons ◽

Cancer Borealis ◽

Compensatory Response ◽

Pyloric Network ◽

Motor Network ◽

Network Output

Motor networks such as the pyloric network of the stomatogastric ganglion often require descending neuromodulatory inputs to initiate, regulate, and modulate their activity and their synaptic connectivity to manifest physiologically appropriate output. Prolonged removal of these descending inputs often results in a compensatory response that alters the inputs themselves, their targets, or both. Using the pyloric network of the crab, Cancer borealis, we investigated whether isolation of motor networks would result in alterations that change the responses of these networks to restored modulatory input. We used a reversible block with isotonic sucrose to transiently alter descending inputs into the pyloric network of the crab stomatogastric ganglion. Using this method, we found that blocking neuromodulatory inputs caused a reduced ability for subsequently restored modulatory projections to appropriately generate network output. Our results suggest that this could be due to changes in activity of descending projection neurons as well as changes in sensitivity to neuromodulators of the target neurons that develop over the time course of the blockade. These findings suggest that although homeostatic plasticity may play a critical role in recovery of functional output in a deafferented motor network, the results of these compensatory changes may alter the network such that restored inputs no longer function appropriately.

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Matrix of neuromodulators in neurosecretory structures of the crab Cancer borealis.

Journal of Experimental Biology ◽

10.1242/jeb.198.12.2431 ◽

1995 ◽

Vol 198 (12) ◽

pp. 2431-2439 ◽

Cited By ~ 11

Author(s):

A E Christie ◽

P Skiebe ◽

E Marder

Keyword(s):

Ophthalmic Artery ◽

Neural Circuit ◽

Stomatogastric Ganglion ◽

Red Pigment ◽

Cancer Borealis ◽

Double Labeling ◽

Neuroactive Compounds ◽

Crustacean Cardioactive Peptide ◽

Other Substances ◽

Neurohemal Organs

The crustacean stomatogastric ganglion, which is situated in the ophthalmic artery, can be modulated by both intrinsically released molecules and hormones. In the crab Cancer borealis, over a dozen neuroactive compounds have been identified in the input axons that project into the stomatogastric neuropil. However, little is known about the modulator content of the two major neurohemal organs, the sinus glands and the pericardial organs, in this crab. We now report the results of a series of immunocytochemical experiments designed to identify putative neurohormones in these tissues. We find that the majority of modulators present in the input axons of the stomatogastric ganglion are also present in at least one of the neurohemal organs. Specifically, allatostatin-like, buccalin-like, cholecystokinin-like, FLRFamide-like, GABA-like, locustatachykinin-like, myomodulin-like, proctolin-like, red pigment concentrating hormone-like and serotonin-like immunoreactivities are all present in both the stomatogastric neuropil and at least one of the neurohemal organs. Thus, these substances are likely to serve a dual role as both local and hormonal modulators of the stomatogastric network. Two other substances, beta-pigment dispersing hormone and crustacean cardioactive peptide, are not present in the stomatogastric neuropil, but beta-pigment dispersing hormone immunoreactivity is present in the sinus glands and crustacean cardioactive peptide immunoreactivity is present in the pericardial organs. It is likely that crustacean cardioactive peptide exerts its influence on the stomatogastric neural circuit via hormonal pathways. Double-labeling experiments show that the patterns of modulator co-localization present in the stomatogastric neuropil are different from those in the neurosecretory organs, suggesting that few rules of colocalization hold across these tissues.

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GABA and responses to GABA in the stomatogastric ganglion of the crab Cancer borealis

Journal of Experimental Biology ◽

10.1242/jeb.203.14.2075 ◽

2000 ◽

Vol 203 (14) ◽

pp. 2075-2092 ◽

Cited By ~ 1

Author(s):

A.M. Swensen ◽

J. Golowasch ◽

A.E. Christie ◽

M.J. Coleman ◽

M.P. Nusbaum ◽

...

Keyword(s):

Nervous System ◽

Gaba Receptors ◽

Reversal Potential ◽

Stomatogastric Ganglion ◽

Projection Neurons ◽

Gamma Aminobutyric Acid ◽

Stomatogastric Nervous System ◽

Cancer Borealis ◽

Excitatory Response ◽

Commissural Neuron

The multifunctional neural circuits in the crustacean stomatogastric ganglion (STG) are influenced by many small-molecule transmitters and neuropeptides that are co-localized in identified projection neurons to the STG. We describe the pattern of gamma-aminobutyric acid (GABA) immunoreactivity in the stomatogastric nervous system of the crab Cancer borealis and demonstrate biochemically the presence of authentic GABA in C. borealis. No STG somata show GABA immunoreactivity but, within the stomatogastric nervous system, GABA immunoreactivity co-localizes with several neuropeptides in two identified projection neurons, the modulatory proctolin neuron (MPN) and modulatory commissural neuron 1 (MCN1). To determine which actions of these neurons are evoked by GABA, it is necessary to determine the physiological actions of GABA on STG neurons. We therefore characterized the response of each type of STG neuron to focally applied GABA. All STG neurons responded to GABA. In some neurons, GABA evoked a picrotoxin-sensitive depolarizing, excitatory response with a reversal potential of approximately −40 mV. This response was also activated by muscimol. In many STG neurons, GABA evoked inhibitory responses with both K(+)- and Cl(−)-dependent components. Muscimol and beta-guanidinopropionic acid weakly activated the inhibitory responses, but many other drugs, including bicuculline and phaclofen, that act on vertebrate GABA receptors were not effective. In summary, GABA is found in projection neurons to the crab STG and can evoke both excitatory and inhibitory actions on STG neurons.

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