scholarly journals Role of Ih in differentiating the dynamics of the gastric and pyloric neurons in the stomatogastric ganglion of the lobster, Homarus americanus

2016 ◽  
Vol 115 (5) ◽  
pp. 2434-2445 ◽  
Author(s):  
Lin Zhu ◽  
Allen I. Selverston ◽  
Joseph Ayers
Keyword(s):  
Rhythmic Activity ◽  
Homarus Americanus ◽  
Stomatogastric Ganglion ◽  
Phase Plane Analysis ◽  
Heart Cells ◽  
Gastric Mill ◽  
Slow Oscillations ◽  
Cationic Current ◽  
Burst Period

The hyperpolarization-activated inward cationic current ( Ih) is known to regulate the rhythmicity, excitability, and synaptic transmission in heart cells and many types of neurons across a variety of species, including some pyloric and gastric mill neurons in the stomatogastric ganglion (STG) in Cancer borealis and Panulirus interruptus. However, little is known about the role of Ih in regulating the gastric mill dynamics and its contribution to the dynamical bifurcation of the gastric mill and pyloric networks. We investigated the role of Ih in the rhythmic activity and cellular excitability of both the gastric mill neurons (medial gastric, gastric mill) and pyloric neurons (pyloric dilator, lateral pyloric) in Homarus americanus. Through testing the burst period between 5 and 50 mM CsCl, and elimination of postinhibitory rebound and voltage sag, we found that 30 mM CsCl can sufficiently block Ih in both the pyloric and gastric mill neurons. Our results show that Ih maintains the excitability of both the pyloric and gastric mill neurons. However, Ih regulates slow oscillations of the pyloric and gastric mill neurons differently. Specifically, blocking Ih diminishes the difference between the pyloric and gastric mill burst periods by increasing the pyloric burst period and decreasing the gastric mill burst period. Moreover, the phase-plane analysis shows that blocking Ih causes the trajectory of slow oscillations of the gastric mill neurons to change toward the pyloric sinusoidal-like trajectories. In addition to regulating the pyloric rhythm, we found that Ih is also essential for the gastric mill rhythms and differentially regulates these two dynamics.

Maturation of Lobster Stomatogastric Ganglion Rhythmic Activity

1999 ◽  
Vol 82 (4) ◽  
pp. 2006-2009 ◽  
Author(s):  
Kathryn S. Richards ◽  
William L. Miller ◽  
Eve Marder
Keyword(s):  
Power Spectrum ◽  
Larval Stage ◽  
Rhythmic Activity ◽  
Homarus Americanus ◽  
Stomatogastric Ganglion ◽  
Neuron Activity ◽  
Cycle Frequency ◽  
Conventional Analysis ◽  
Occurrence Times ◽  
Embryonic And Larval Development

The stomatogastric ganglion of the adult lobster, Homarus americanus generates extremely regular pyloric rhythms with a characteristic period of 0.5–1.5 Hz. To study the changes in the pyloric rhythm during embryonic and larval development, we recorded excitatory junctional potentials evoked by lateral pyloric (LP) neuron activity. Early in development the motor discharge of the LP neuron was often irregular, preventing use of conventional analysis methods that rely on extracting burst times to calculate cycle frequency and its variability. Instead, cycle frequency was determined for the LP neuron from the peak of the power spectrum obtained from the occurrence times of excitatory junctional potentials in the p1 muscle. The ratio of the power in the peak to the power from 0 to 3 Hz was used as a relative measure of the regularity of the rhythm. Throughout embryonic and the first larval stage, LP neuron activity is slow, irregular, and only weakly periodic. The regularity of the rhythm increased during midlarval stages, and both the frequency and regularity increased considerably by the postlarval stage LIV.

Spectral Analyses Reveal the Presence of Adult-Like Activity in the Embryonic Stomatogastric Motor Patterns of the Lobster, Homarus americanus

2008 ◽  
Vol 99 (6) ◽  
pp. 3104-3122 ◽  
Author(s):  
Kristina J. Rehm ◽  
Adam L. Taylor ◽  
Stefan R. Pulver ◽  
Eve Marder
Keyword(s):  
Nervous System ◽  
Rhythmic Activity ◽  
Homarus Americanus ◽  
Gastric Mill ◽  
Stomatogastric Nervous System ◽  
Cancer Borealis ◽  
Motor Patterns ◽  
Similar Frequency ◽  
Rhythmic Behavior ◽  
Slow Activity

The stomatogastric nervous system (STNS) of the embryonic lobster is rhythmically active prior to hatching, before the network is needed for feeding. In the adult lobster, two rhythms are typically observed: the slow gastric mill rhythm and the more rapid pyloric rhythm. In the embryo, rhythmic activity in both embryonic gastric mill and pyloric neurons occurs at a similar frequency, which is slightly slower than the adult pyloric frequency. However, embryonic motor patterns are highly irregular, making traditional burst quantification difficult. Consequently, we used spectral analysis to analyze long stretches of simultaneous recordings from muscles innervated by gastric and pyloric neurons in the embryo. This analysis revealed that embryonic gastric mill neurons intermittently produced pauses and periods of slower activity not seen in the recordings of the output from embryonic pyloric neurons. The slow activity in the embryonic gastric mill neurons increased in response to the exogenous application of Cancer borealis tachykinin-related peptide 1a (CabTRP), a modulatory peptide that appears in the inputs to the stomatogastric ganglion (STG) late in larval development. These results suggest that the STG network can express adult-like rhythmic behavior before fully differentiated adult motor patterns are observed, and that the maturation of the neuromodulatory inputs is likely to play a role in the eventual establishment of the adult motor patterns.

Contribution of individual ionic currents to activity of a model stomatogastric ganglion neuron

1992 ◽  
Vol 67 (2) ◽  
pp. 341-349 ◽  
Author(s):  
J. Golowasch ◽  
F. Buchholtz ◽  
I. R. Epstein ◽  
E. Marder
Keyword(s):  
Action Potential ◽  
Model Neuron ◽  
Outward Current ◽  
Rhythmic Activity ◽  
Stomatogastric Ganglion ◽  
Delayed Rectifier ◽  
Maximal Conductance ◽  
Action Potential Frequency ◽  
Potential Frequency

1. The behavior of the mathematical model for the lateral pyloric (LP) neuron of the crustacean stomatogastric ganglion (STG) developed in the previous paper was further studied. 2. The action of proctolin, a neuromodulatory peptide that acts directly on the LP neuron, was modeled. The effect of the proctolin-activated current (iproc) on the model neuron mimics the effects of proctolin on the isolated biological LP neuron. The depolarization and increased frequency of firing seen when iproc is activated are associated with changes in the relative contributions of the delayed rectifier (id) and the Ca(2+)-activated outward current (io(Ca] to the repolarization phase of the action potential. 3. The effects of turning off the A-current (iA) in the model were compared with those obtained by pharmacologically blocking iA in the biological neuron. iA appears to regulate action-potential frequency as well as postinhibitory rebound activity. 4. The role of iA on the rhythmic activity of the cell was studied by modifying several of its parameters while periodically activating a simulated synaptically activated conductance, isyn. 5. The effects of manipulations of the maximal conductances (g) for id and io(Ca) were studied. id strongly influences action-potential frequency, whereas io(Ca) strongly influences action-potential duration. 6. Modifications of the maximal conductance of the inward Ca2+ current (iCa) were compared with the effects of blocking iCa in the real cell. 7. The role of the hyperpolarization-activated inward current (ih) during ongoing rhythmic activity was assessed by periodically activating isyn while modifying ih.

Synaptic regulation of cellular properties and burst oscillations of neurons in gastric mill system of spiny lobsters, Panulirus interruptus

1984 ◽  
Vol 52 (1) ◽  
pp. 54-73 ◽  
Author(s):  
D. F. Russell ◽  
D. K. Hartline
Keyword(s):  
Motor Neurons ◽  
Pattern Generator ◽  
Stomatogastric Ganglion ◽  
Gastric Mill ◽  
Panulirus Interruptus ◽  
Synaptic Regulation ◽  
Gastric Cells ◽  
Current Pulses ◽  
Regenerative Property ◽  
Stimulation Of

The properties of neurons in the stomatogastric ganglion (STG) participating in the pattern generator for the gastric mill rhythm were studied by intracellular current injection under several conditions: during ongoing gastric rhythms, in the nonrhythmic isolated STG, after stimulation of the nerve carrying central nervous system (CNS) inputs to the STG, or under Ba2+ or Sr2+. Slow regenerative depolarizations during ongoing rhythms were demonstrated in the anterior median, cardiopyloric, lateral cardiac, gastropyloric, and continuous inhibitor (AM, CP, LC, GP, and CI) neurons according to criteria such as voltage dependency, burst triggering, and termination by brief current pulses, etc. Experiments showed that regenerative-like behavior was not due to synaptic network interactions. The slow regenerative responses were abolished by isolating the stomatogastric ganglion but could be reestablished by stimulating the input nerve. This indicates that certain CNS inputs synaptically induce the regenerative property in specific gastric neurons. Slow regenerative depolarizations were not demonstrable in gastric mill (GM) motor neurons. Their burst oscillations and firing rate were instead proportional to injected current. CNS inputs evoked a prolonged depolarization in GM motor neurons, apparently by a nonregenerative mechanism. All the gastric cells showed prolonged regenerative potentials under 0.5-1.5 mM Ba2+. We conclude that the gastric neurons of the STG can be divided into three types according to their properties: those with a regenerative capability, a repetitively firing type, and a nonregenerative "proportional" type. The cells are strongly influenced by several types of CNS inputs, including "gastric command fibers."

scholarly journals The Role of HCN Channels on Membrane Excitability in the Nervous System

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Daisuke Kase ◽  
Keiji Imoto
Keyword(s):  
Intracellular Signaling ◽  
Hcn Channels ◽  
Heart Cells ◽  
Hcn Channel ◽  
Membrane Excitability ◽  
Wide Range ◽  
Inward Currents ◽  
Range Of Functions ◽  
Channel Currents

Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels were first reported in heart cells and are recently known to be involved in a variety of neural functions in healthy and diseased brains. HCN channels generate inward currents when the membrane potential is hyperpolarized. Voltage dependence of HCN channels is regulated by intracellular signaling cascades, which contain cyclic AMP, PIP2, and TRIP8b. In addition, voltage-gated potassium channels have a strong influence on HCN channel activity. Because of these funny features, HCN channel currents, previously called funny currents, can have a wide range of functions that are determined by a delicate balance of modulatory factors. These multifaceted features also make it difficult to predict and elucidate the functional role of HCN channels in actual neurons. In this paper, we focus on the impacts of HCN channels on neural activity. The functions of HCN channels reported previously will be summarized, and their mechanisms will be explained by using numerical simulation of simplified model neurons.

scholarly journals Heat Shock Protein 90 as Therapeutic Target for CVDs and Heart Ageing

2022 ◽  
Vol 23 (2) ◽  
pp. 649
Author(s):  
Siarhei A. Dabravolski ◽  
Vasily N. Sukhorukov ◽  
Vladislav A. Kalmykov ◽  
Nikolay A. Orekhov ◽  
Andrey V. Grechko ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Molecular Chaperones ◽  
Heat Shock Protein 90 ◽  
Misfolded Proteins ◽  
Heart Cells ◽  
Metabolic Demand ◽  
Heart Protection ◽  
High Metabolic Demand

Cardiovascular diseases (CVDs) are the leading cause of death globally, representing approximately 32% of all deaths worldwide. Molecular chaperones are involved in heart protection against stresses and age-mediated accumulation of toxic misfolded proteins by regulation of the protein synthesis/degradation balance and refolding of misfolded proteins, thus supporting the high metabolic demand of the heart cells. Heat shock protein 90 (HSP90) is one of the main cardioprotective chaperones, represented by cytosolic HSP90a and HSP90b, mitochondrial TRAP1 and ER-localised Grp94 isoforms. Currently, the main way to study the functional role of HSPs is the application of HSP inhibitors, which could have a different way of action. In this review, we discussed the recently investigated role of HSP90 proteins in cardioprotection, atherosclerosis, CVDs development and the involvements of HSP90 clients in the activation of different molecular pathways and signalling mechanisms, related to heart ageing.

Intracellular motility of mitochondria: role of the inner compartment in migration and shape changes of mitochondria in XTH-cells

1978 ◽  
Vol 30 (1) ◽  
pp. 99-115
Author(s):  
J. Bereiter-Hahn
Keyword(s):  
Phase Contrast ◽  
Heart Cells ◽  
Underlying Principle ◽  
Good Accord ◽  
Contrast Microscopy ◽  
Mitochondrial Motility ◽  
Time Required ◽  
Shape Changes ◽  
Intracellular Motility

Mitochondrial movements have been followed by phase-contrast microscopy in living XTH-cells (Xenopus laevis tadpole-heart cells) in tissue culture. The same organelles have been viewed subsequently in electron micrographs. Locomotion of mitochondria proceeds at velocities up to 100 micrometer/min. Formation of branches of mitochondria and other shape changes may occur with the same speed. Mitochondrial motility can be classified into 4 types: (I) Alternating extension and contraction at the two ends of rod-shaped mitochondria. (2) Lateral branching. (3) Alternate stretching and contraction of arbitrary parts of a mitochondrion amounting to a kind of peristaltic action. (4) Transverse wave propagation along the organelle. Types I to 3 can be reduced to the same underlying principle; they cause locomotion. Formation of mitochondrial extensions is due to elongation of cristae. The observations are discussed in terms of 4 specific proposals. (I) Intracellular locomotion of mitochondria is caused by local enlargements and contractions of the organelles. (2) The shape changes are correlated with alterations in the arrangement of the cristae. (3) Such arrangements are not associated with overall swelling or shrinkage of the mitochondrion; they are local features. (4) Estimates of the time required for rearrangement of the inner compartment amount to less than 0.3 s for single crista arrangements during the fastest shape changes, and less than 1–3 s during slower alterations. This high velocity is in good accord with the hypothesis of energy conservation by conformational events during oxidative phosphorylation.

Mechanisms Underlying Type I mGluR-Induced Activation of Lobster Gastric Mill Neurons

2006 ◽  
Vol 96 (6) ◽  
pp. 3378-3388 ◽  
Author(s):  
Rafael Levi ◽  
Allen I. Selverston
Keyword(s):  
G Protein ◽  
Calcium Release ◽  
Metabotropic Glutamate Receptor ◽  
Cyclopiazonic Acid ◽  
Stomatogastric Ganglion ◽  
Type I ◽  
Gastric Mill ◽  
Concentration Increase ◽  
Cellular Mechanisms ◽  
Excitatory Effect

In addition to ionotropic effects, glutamate and acetylcholine have metabotropic modulatory effects on many neurons. Here we show that in the stomatogastric ganglion of the lobster, glutamate, one of the main ionotropic neurotransmitters, modulates the excitability of gastric mill neurons. The neurons in this well-studied system produce rhythmic output to a subset of lobster foregut muscles. Recently, metabotropic glutamate receptor (mGluR) agonists were suggested as modulators of the rhythmic output, in addition to the previously described muscarinic modulation by acetylcholine. However, the cellular mechanisms responsible for these effects on the pattern are not known. Using intracellular recording methods and calcium imaging, we show that glutamate has an excitatory effect on specific neurons in the stomatogastric ganglion, which is mediated by mGluRs. Responses to the application of mGluR type I agonists are transient oscillations in the system, probably arising from network interactions. We show that the excitatory effect is sensitive to phospholipase-C and IP3 and is G-protein dependent. The G-protein dependency was demonstrated by GDPβS and GTPγS injection into identified neurons. The depolarizations and oscillations were accompanied by an increase of intracellular Ca2+ levels and correlated Ca2+ oscillations. By using cyclopiazonic acid, an endoreticular Ca2+ uptake inhibitor, we show that some internal calcium release may augment the response, but is not crucial for its production. Interestingly, although Ca2+ concentration increase is typically associated with the phosphoinositide pathway, in the lobster, the Ca2+ concentration increase—either voltage dependent or independent—cannot account for the observed depolarization.

Injection of guanosine 5'-cyclic monophosphate into heart cells blocks calcium slow channels

1985 ◽  
Vol 248 (5) ◽  
pp. H745-H749 ◽  
Author(s):  
G. Bkaily ◽  
N. Sperelakis
Keyword(s):  
Cyclic Nucleotides ◽  
Action Potentials ◽  
Heart Cells ◽  
Myocardial Cells ◽  
Cyclic Monophosphate ◽  
Intracellular Injection ◽  
Ventricular Cells ◽  
Camp And Cgmp ◽  
Slow Action Potentials

The role of guanosine 5'-cyclic monophosphate (cGMP) in the regulation of the ionic slow channels in heart muscle is less well known than that of adenosine 3,'5'-cyclic monophosphate (cAMP). The effects of intracellular injection of cAMP and cGMP in cultured chick embryonic heart (ventricular) cells by the liposome method were studied. Injection of cAMP into the cells induced spontaneous slow action potentials that could be blocked by verapamil and nifedipine. Injection of cGMP blocked on-going slow action potentials, and this effect was reversed by increasing cAMP. Thus both cAMP and cGMP are involved in the regulation of the slow calcium channels in myocardial cells, and the two cyclic nucleotides are antagonistic.

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