scholarly journals Peptidergic and Aminergic Modulation of Insect Skeletal Muscle

1986 ◽  
Vol 124 (1) ◽  
pp. 143-176 ◽  
Author(s):  
PETER D. EVANS ◽  
CAMILLA M. MYERS
Keyword(s):  
Biogenic Amines ◽  
Neuromuscular Transmission ◽  
Muscular Contraction ◽  
Model Systems ◽  
Muscle Fibres ◽  
Adenosine Analogues ◽  
Modes Of Action ◽  
Motor Neurones ◽  
Insect Skeletal Muscle ◽  
Contraction And Relaxation

Insect skeletal muscles are frequently innervated by small numbers of motor neurones, all of which can be uniquely identified physiologically. They therefore present excellent model systems in which to study the basic principles of neuromuscular transmission and the modulation of these effects by biogenic amines and peptides. The extensor-tibiae muscle of the hind leg of the locust is a much studied, large muscle that is innervated by three identified motor neurones and one identified modulatory neurone. Much attention has recently been focused on the modulation of neuromuscular transmission and muscular contraction in this muscle by biogenic amines and peptides. One proximal bundle of muscle fibres in the extensor-tibiae muscle exhibits a myogenic rhythm of contraction and relaxation. The rhythm is stimulated by a variety of peptides including proctolin, the AKH-related peptides M1 and M2, and by small cardioactive peptide (SCPB). In addition, it is activated by 5-hydroxytryptamine and by oneclass of adenosine analogues. The rhythm is inhibited by octopamine and by a second class of adenosine analogues. The actions of these various modulatory compounds will be discussed in terms of the likely numbers of pharmacologically distinct receptors in this preparation and their modes of action. Neuromuscular transmission and muscular contraction in the extensor-tibiae muscle is modulated by the biogenic amine octopamine and by the peptides, proctolin and FMRFamide. The actions of these modulators are discussed in relation differences in the responsiveness of various regions of the muscle, to the frequency dependence of their effects on motor neurone activityand to their modes of action. The cellular locations and mode of transmission to the muscle of some of these modulators will be considered. Octopamine and proctolin are contained within neurones which innervate the muscle, whilst FMRFamide- and SCPB-like peptides appear to be released into the locust haemolymph as neurohormones.

An Arthropod Muscle Innervated by Nine Excitatory Motor Neurones

1980 ◽  
Vol 88 (1) ◽  
pp. 249-258
Author(s):  
CHRISTINE E. PHILLIPS
Keyword(s):  
Action Potentials ◽  
Motor Neurone ◽  
Muscle Fibres ◽  
Relaxation Rates ◽  
Motor Neurones ◽  
The Individual ◽  
Contraction And Relaxation ◽  
High Degree ◽  
Individual Motor ◽  
Indirect Stimulation

The anatomical and physiological organization of the locust metathoracic flexor tibiae was examined by a combination of intracellular recording and electron microscopy. Nine excitatory motor neurones, three fast, three intermediate and three slow innervate the muscle; each is uniquely identifiable using a combination of physiological response and soma location. A simple spatial distribution of inputs to the muscle from the individual motor neurones was not found. Individual muscle fibres responded to as many as seven of the motor neurones in various combinations. The muscle fibres are heterogeneous, ranging from slow (tonic) to fast (phasic) in a continuum from predominantly phasic proximally to tonicdistally. This is demonstrated by contraction and relaxation rates to directand indirect stimulation, as well as contraction elicited by action potentials in a single flexor motor neurone. The fast and slow contractile properties of the muscle fibres are matched by appropriate ultrastructures. Such a high degree of complexity of neuromuscular innervation as that found in the metathoracic flexor tibiae has not previously been described for an arthropod muscle.

scholarly journals Muscular Movements in Man, and their Evolution in the Infant: a Study of Movement in Man, and its Evolution, together with Inferences as to the Properties of Nerve-Centres and their Modes of Action in expressing Thought

1889 ◽  
Vol 35 (149) ◽  
pp. 23-44 ◽  
Author(s):  
Francis Warner
Keyword(s):  
Brain Area ◽  
Muscular Contraction ◽  
The Body ◽  
Brain Areas ◽  
Modes Of Action ◽  
Central Nerve System ◽  
Nerve System ◽  
The Brain ◽  
Compound Series ◽  
Stimulation Of

(1) Movement in mau has long been a subject of profitable study. Visible movement in the body is produced by muscular contraction following upon stimulation of the muscles by efferent currents passing from the central nerve-system. Modern physiological experiments have demonstrated that when a special brain-area discharges nerve-currents, these are followed by certain visible movements or contraction of certain muscles corresponding. So exact are such reactions, as obtained by experiment upon the brain-areas, that movements similar to those produced by experimental excitation of a certain brain-area may be taken as evidence of action in that area, or as commencing in discharge from that area (see Reinforcement of Movements, 35; Compound Series of Movements, 34).

Address of the President Sir Alan Hodgkin, O. M. at the Anniversary Meeting, 30 November 1973

1974 ◽  
Vol 185 (1078) ◽  
Keyword(s):  
Surface Membrane ◽  
Muscular Activity ◽  
Nerve Impulse ◽  
Muscular Contraction ◽  
Single Fibre ◽  
Muscle Fibres ◽  
Constant Length ◽  
Axon Membrane ◽  
Ultrastructural Studies ◽  
Mathematical Skill

The Copley Medal is awarded to Professor A. F. Huxley, F. R. S. A. F. Huxley has made outstanding contributions to our knowledge of the nerve impulse and of the mechanism by which muscle fibres are caused to contract. Jointly with Hodgkin, he introduced the powerful method of intracellular recording from nerve cells and showed that during the propagation of an impulse the mem­brane potential reverses its sign, and does not simply fall towards zero as had been widely believed. This work - interrupted by the 1939-45 war, but later resumed - led to the proposal that the impulse arises from a transient influx of sodium ions through the axon membrane. The ‘ionic theory’ of nervous conduction was then established by a series of convincing experiments and calculations for which Huxley later shared the Nobel Prize. Huxley next turned his attention to the mechanism of muscular contraction. He equipped himself for this purpose by inventing a new type of interference microscope. In experiments on living isolated muscle fibres, Huxley showed that contraction is accompanied by a shortening of the isotropic band of each sarco­mere, while the remaining portion (the anisotropic band) retains approximately constant length. His findings complemented the important ultrastructural studies of H. E. Huxley and led them both to propose a ‘sliding filament’ mechanism as the basis of muscular motion. During further microscopic observations on the living muscle fibre, A. F. Huxley produced most striking evidence on the way in which an excitatory potential change of the surface membrane is communicated, through local tubular channels, to the interior of the fibre where it activates the contractile elements. In his most recent work, A. F. Huxley has continued to develop his single-fibre technique to resolve even finer details of the dynamic changes which occur during muscular activity. His work is characterized by a rare combination of profound theoretical insight, mathematical skill and superb technical mastery, all of which has enabled him to select problems of first-rate importance and to pursue them with outstanding success.

Temperature Effects on Neuromuscular Transmission (Opener Muscle of Crayfish, Astacus Leptodactylus)

1981 ◽  
Vol 94 (1) ◽  
pp. 251-268
Author(s):  
LUDWIG FISCHER ◽  
ERNST FLOREY
Keyword(s):  
Decay Time ◽  
Neuromuscular Transmission ◽  
Membrane Conductance ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Astacus Leptodactylus ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Temperature Range ◽  
Parallel Change

In experiments on the opener muscle of the third walking legs of crayfish (Astacus leptodactylus) it was found that the mechanical tension developed in response to repetitive stimulation of the single motor axon increases over the entire temperature range from 30 down to 0°C. In contrast to this, the tension elicited by depolarizing single muscle fibres decreases with decreasing temperature; the threshold for excitation-contraction coupling is not significantly altered. With decreasing temperature the resting potential decreases (up to 2 mV/°C) but the amplitude and decay time of the e.p.s.p.'s increase. The time constant, λ, of e.p.s.p. decay has a Q10 of less than −2 in the range above 15 °C but reaches a value of −7 between 10 and 0°C. This pattern of temperature dependence is fully accounted for by a parallel change of membrane resistance and its reciprocal, the membrane conductance. The corresponding activation energies computed from λ-values approximate 3 kcal/mol at high temperature and 46 kcal/mol in the low temperature range. The combined effects of a lowered resting potential, an increased amplitude, and especially an increased decay time of e.p.s.p.s result in a drastic enhancement of the depolarization reached during summation of e.p.s.p.s as the temperature is decreased. These effects overcompensate the declining effectiveness of excitation-contraction coupling so that the entire process of neuromuscular transmission becomes more and more effective as the temperature declines. In order to reach the same tension lower frequencies of nerve stimulation are needed at lower temperatures.

CENTRALLY GENERATED RHYTHMIC ACTIVITY AND MODULATORY FUNCTION OF THE OVIDUCTAL DORSAL UNPAIRED MEDIAN (DUM) NEURONES IN TWO ORTHOPTERAN SPECIES (CALLIPTAMUS SP. AND DECTICUS ALBIFRONS)

1993 ◽  
Vol 174 (1) ◽  
pp. 123-138 ◽  
Author(s):  
E. Kalogianni ◽  
G. Theophilidis
Keyword(s):  
Firing Rate ◽  
Firing Pattern ◽  
Anterior Part ◽  
Motor Pattern ◽  
Egg Laying ◽  
Abdominal Ganglion ◽  
Muscle Fibres ◽  
Motor Neurones ◽  
Rhythmic Firing ◽  
Dorsal Unpaired Median

The rhythmic firing pattern of the putatively octopaminergic dorsal unpaired median (DUM) neurones supplying the oviductal system of female orthopterans, Calliptamus sp. and Decticus albifrons, was examined. Our data provide evidence that the oviductal DUM neurones in the seventh abdominal ganglion modulate the oviductal motor pattern, both peripherally and centrally, during the inhibition of egg-laying behaviour. In a minimally dissected animal, rhythmic activation of the oviductal DUM and motor neurones can be readily elicited by isolation of the seventh abdominal ganglion from the anterior part of the nerve cord. The bursting activity of the DUM neurones is temporally correlated with the oviductal motor rhythm. Both populations of oviductal neurones retain their rhythmic firing pattern after total isolation of the genital ganglia, indicating the presence of an oviductal central pattern generator. The effects of stimulation of oviductal DUM neurones on the oviductal motor activity were monitored by recording intracellularly from oviductal muscle fibres and extracellularly from motor axons. These effects consist of a reduction in the amplitude and frequency of excitatory postsynaptic potentials (EPSPs) in the muscle fibre and in the firing rate in oviductal motor neurones. We suggest that the change in EPSP amplitude results from peripheral release of octopamine by DUM neurones. The decreased firing rate of motor neurones, however, appears to be a central effect, possibly caused by central release of octopamine by DUM neurones.

Modulatory effects of nitric oxide on synaptic depression in the crayfish neuromuscular system

2000 ◽  
Vol 203 (23) ◽  
pp. 3595-3602 ◽  
Author(s):  
H. Aonuma ◽  
T. Nagayama ◽  
M. Takahata
Keyword(s):  
Nitric Oxide ◽  
Neuromuscular Transmission ◽  
Procambarus Clarkii ◽  
Synaptic Depression ◽  
Physiological Property ◽  
Muscle Fibres ◽  
Flexor Muscle ◽  
Bath Application ◽  
Flexor Muscles ◽  
Stimulation Of

A characteristic physiological property of the neuromuscular junction between giant motor neurones (MoGs) and fast flexor muscles in crayfish is synaptic depression, in which repetitive electrical stimulation of the MoG results in a progressive decrease in excitatory junction potential (EJP) amplitude in flexor muscle fibres. Previous studies have demonstrated that l-arginine (l-Arg) modulates neuromuscular transmission. Since l-Arg is a precursor of nitric oxide (NO), we examined the possibility that NO may be involved in modulating neuromuscular transmission from MoGs to abdominal fast flexor muscles. The effect of a NO-generating compound, NOC7, was similar to that of l-Arg, reversibly decreasing the EJP amplitude mediated by the MoG. While NOC7 reduced the amplitude of the EJP, it induced no significant change in synaptic depression. In contrast, a scavenger of free radical NO, carboxy-PTIO, and an inhibitor of nitric oxide synthase, l-NAME, reversibly increased the EJP amplitude mediated by MoGs. Synaptic depression mediated by repetitive stimulation of MoGs at 1 Hz was partially blocked by bath application of l-NAME. Bath application of a NO scavenger, a NOS inhibitor and NO-generating compounds had no significant effects on the depolarisation of the muscle fibres evoked by local application of l-glutamate. The opposing effects on EJP amplitude of NOC7 and of carboxy-PTIO and l-NAME suggest that endogenous NO presynaptically modulates neuromuscular transmission and that it could play a prominent role at nerve terminals in eliciting MoG-mediated synaptic depression in the crayfish Procambarus clarkii.

Potentiation of Neuromuscular Transmission by an Octopaminergic Neurone in the Locust

1979 ◽  
Vol 79 (1) ◽  
pp. 169-190 ◽  
Author(s):  
MICHAEL O'SHEA ◽  
PETER D. EVANS
Keyword(s):  
Indirect Effects ◽  
Neuromuscular Transmission ◽  
Time Course ◽  
Muscle Tone ◽  
Muscle Tension ◽  
Presynaptic Receptors ◽  
Extensor Muscle ◽  
Muscle Membrane ◽  
Muscle Fibres ◽  
Central Synapses

1. Spikes in the octopaminergic dorsal unpaired median (DUM) neurone which innervates the extensor tibiae muscle of the locust metathoracic leg (DUMETi) produce direct and indirect effects on muscle tension. 2. Direct effects include a slowing of an intrinsic rhythm of contraction and relaxation, a relaxation of muscle tone and a small hyperpolarization of the muscle membrane potential. The latter two effects are weak and variable. All three effects are mimicked by superfusion of octopamine and are mediated by octopamine receptors on the muscle fibres. 3. Indirect effects are found when the DUMETi neurone is stimulated at the same time as the motoneurones innervating the extensor muscle. They include (a) potentiation of tension generated in the extensor muscle by spikes in the slow excitatory motoneurone (SETi), (b) reduction in duration of each twitch contraction generated by SETi due to an increase in the rate at which the muscle relaxes, (c) increase in the amplitude of the synaptic potential generated by SETi. These various effects have a time course of several minutes and far outlast the duration of DUMETi stimulation. They can be mimicked by superfusion of octopamine. 4. The effect of DUMETi on neuromuscular transmission is mediated by receptors with a high affinity for octopamine located both on the muscle and on the terminals of the slow motoneurone. The presence of the presynaptic receptors is revealed by the increase in the frequency of spontaneous miniature end plate potentials recorded in the muscle in the presence of octopamine. 5. DUMETi is a member of a group of similar aminergic neurones and it is suggested that they may share a role in modulating transmission at peripheral neuromuscular synapses, and possibly central synapses.

Platyhelminth FMRFamide-related peptides (FaRPs) contract Schistosoma mansoni (Trematoda: Digenea) muscle fibres in vitro

Parasitology ◽  
1994 ◽  
Vol 109 (4) ◽  
pp. 455-459 ◽  
Author(s):  
T. A. Day ◽  
A. G. Maule ◽  
C. Shaw ◽  
D. W. Halton ◽  
S. Moore ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Neuromuscular Transmission ◽  
Free Acid ◽  
Muscle Fibres ◽  
Channel Blockers ◽  
Excitatory Effect ◽  
Extracellular Medium ◽  
High K ◽  
Dose Dependent

SUMMARYMolluscan FMRFamide and two recently discovered platyhelminth FMRFamide-related peptides (FaRPs), GNFFRFamide from the cestode Moniezia expansa and RYIRFamide from the terrestrial turbellarian Artioposthia triangulata, cause dose-dependent contractions of individual muscle fibres from Schistosoma mansoni in vitro. The most potent FaRP tested was the turbellarian peptide RYIRFamide, which produced a concentration-dependent effect between 10−9 and 10−7 M. FMRFamide and GNFFRFamide were less potent, inducing contractions between 10−8–10−6 M and 10−7–10−5 M respectively. The contractile effect of each of these peptides was blocked by the presence of 1 µM FMR-DFamide. FMRF free acid did not elicit contraction of the muscle fibres. The FaRP-induced contractions did not occur if the Ca2+ was omitted and 0·5 µM EGTA was added to the extracellular medium. The FaRP-induced contractions were not blocked by the Ca2+ channel blockers nicardipine, verapamil or diltiazem, although high K+-induced contractions of these fibres were blocked by nicardipine. These data indicate the presence of FaRP receptors on schistosome muscle fibres and demonstrate their ability to mediate muscle contraction. The action of these endogenous flatworm peptides on schistosome muscle is the first demonstration of a direct excitatory effect of any putative neurotransmitter on the muscle of a flatworm, and establishes a role for FaRPs in neuromuscular transmission in trematodes. In addition, it provides the first evidence that the peptidergic nervous system is a rational target for chemotherapeutic attack in parasitic platyhelmiths.

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