On the mechanism of a long-lasting neuromuscular depression in crayfish

Czternasty, G.; Bruner, J.

doi:10.1016/0306-4492(80)90115-x

Cited by 7 publications

(5 citation statements)

References 32 publications

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“…EJP amplitude decreases when deep abdominal extensor muscles are cooled below the temperature at which crayfish are maintained (15°C, Friedrich et al, 1994). A similar effect is seen in deep abdominal flexor muscles, which are also phasic in nature (Czternasty and Bruner, 1980). Concomitant changes in EJP shape suggest that muscle fiber input resistance increases with decreasing temperature, as has been shown for other crayfish muscles (Fischer and Florey, 1981;Stephens, 1990).…”

Section: Exoskeletal Musclesmentioning

confidence: 72%

Physiological functions of FMRFamide‐like peptides (FLPs) in crustaceans

Mercier

Friedrich

Boldt

2003

Microscopy Res & Technique

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Section: Exoskeletal Musclesmentioning

confidence: 72%

Physiological functions of FMRFamide‐like peptides (FLPs) in crustaceans

Mercier

Friedrich

Boldt

2003

Microscopy Res & Technique

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“…Increases in intracellular Ca2' have also been suggested to reduce synaptic depression at the crayfish neuromuscular junction (17). A particularly interesting observation at this synapse is that a brief high-frequency burst of action potentials in the giant motor neuron leads to rapid recovery from depression (18).…”

Section: Recovery From Synaptic Depressionmentioning

confidence: 99%

Analysis of synaptic depression contributing to habituation of gill-withdrawal reflex in Aplysia californica

Byrne¹

1982

Journal of Neurophysiology

106

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1. Repeated stimulation of the siphon skin results in short-term habituation of the reflex contractions of the gill (38). The habituation, in turn, is correlated with a depression of the excitatory postsynaptic potentials (EPSPs) in motor neurons from mechanoreceptor sensory neurons (SN) (7, 16). The present study was undertaken to examine the parametric features of the synaptic depression and gain insights into the mechanisms underlying the reduced transmitter release. 2. Single sensory neuron action potentials were repeatedly elicited with depolarizing current pulses while the amplitude of the resultant EPSPs in the motor neuron was monitored. Synaptic depression varies as a complex function of interstimulus interval (ISI). At an ISI of 1 s, depression is rapid and reaches a plateau at 36% of control. In contrast, the depression at an ISI of 100 s is less pronounced, showing a gradual decay to 65% of control with the 10th EPSP. Surprisingly, there are no significant differences in time course or magnitude of depression across a broad range of intermediate ISIs (3, 10, and 30 s), although depression at these ISIs is intermediate between the 1 and 100 s ISIs. 3. There is also a complex relationship between spike interval and the depression of the second of two EPSPs. Thus, depression of the second of two EPSPs or depression of a train of EPSPs is not a monotonic function of spike interval. Indeed, the data suggest that there may be a slight underlying facilitatory process with short spike intervals. 4. The results also indicate that the recovery of synaptic depression following a train of 10 stimuli is not constant. Shorter spike intervals produce more rapid recovery. 5. These data are inconsistent with a classical depletion model (33) for synaptic depression and indicate that either a single complex function of time and ISI or multiple functions underlie synaptic depression and its recovery at the sensory neuron synapse.

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“…The Q 10 value associated with changes in input resistance was Ϫ1.82 Ϯ 0.25; the negative value indicates that input resistance increased with decreasing temperature. Czternasty and Bruner (1980) also reported that input resistance of crayfish muscle fibers increased when temperature was lowered from 19 to 9°C, and they obtained a Q 10 value equivalent to Ϫ2.1. The increase in input resistance with decreasing temperature probably helps to compensate somewhat for the reduction in quantal content and explains why the Q 10 value for the effect on EJP amplitude is lower than that for quantal content.…”

Section: R E S U L T Smentioning

confidence: 91%

“…The functional significance of this temperature dependence and the mechanisms that underlie it are not known. As temperature drops, EJP amplitude decreases in the DEMs (Friedrich et al 1994) and in the deep abdominal flexor muscles (Czternasty and Bruner 1980). The enhanced capacity for DF 2 to increase EJP amplitude might help to compensate for reduced synaptic transmission at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Synaptic Modulation by a Neuropeptide Depends on Temperature and Extracellular Calcium

Dunn

Mercier

2003

Journal of Neurophysiology

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The crayfish neuropeptide DRNFLRFamide increases transmitter release from synaptic terminals onto muscle cells. As temperature decreases from 20 to 8 degrees C, the size of excitatory junctional potentials (EJPs) decreases, and the peptide becomes more effective at increasing EJP amplitude. The goal of the present study was to determine whether the enhanced effectiveness of the peptide is strictly a temperature-related effect, or whether it is related to the fact that the EJPs are smaller at low temperature, allowing a greater range for EJP amplitude to increase. Decreasing temperature reduced the number of quanta of transmitter released per nerve impulse (assessed by recording synaptic currents) and increased input resistance in muscle fibers. As in earlier work, the ability of the peptide to increase EJP amplitude was enhanced by decreasing temperature. However, the peptide was also more effective at increasing EJP amplitude when transmitter output was lowered by reducing the ratio of calcium to magnesium ions in the bath. Thus the effectiveness of the peptide may be related to the level of output from the synaptic terminals.

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On the mechanism of a long-lasting neuromuscular depression in crayfish

Cited by 7 publications

References 32 publications

Physiological functions of FMRFamide‐like peptides (FLPs) in crustaceans

Physiological functions of FMRFamide‐like peptides (FLPs) in crustaceans

Analysis of synaptic depression contributing to habituation of gill-withdrawal reflex in Aplysia californica

Synaptic Modulation by a Neuropeptide Depends on Temperature and Extracellular Calcium

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