Distribution of receptors for acetylcholine and 5‐hydroxytryptamine on identified leech neurones growing in culture.

Pellegrino, Mario; Simonneau, Michel

doi:10.1113/jphysiol.1984.sp015316

Cited by 29 publications

(17 citation statements)

References 29 publications

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“…Because of the poor signal-to-noise ratio in the records from the growth cone, we cannot put very tight limits on this electrical equality. Nevertheless, our determination is consistent both with the cable theory predictions (I. Pamas and I. Segev, unpublished calculations) and the reversal potential measurements for iontophoretically applied ACh (Pellegrino and Simonneau, 1984). In an earlier paper (Fuchs et al,198 1) evidence was presented that action potentials might fail to propagate at branch points in some cultured N cells when conducted from fine processes towards the cell body.…”

Section: Measurements Of Potential and Channel Distributionsupporting

confidence: 78%

“…For example, the high input impedance of these cultured cells was used by I. Parnas and I. Segev (unpublished observations) to calculate that the potential decrement along even l-pm-diameter processes would be insignificant. Also, Pellegrino and Simonneau (1984) showed that with an intracellular electrode in the soma, the reversal potential for ionophoretically applied ACh was the same whether the neurotransmitter was applied to the soma or to the tip of a growing process. Using voltage-sensitive dyes, we could test this conclusion directly.…”

Section: Retzius Cell mentioning

confidence: 99%

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Optical recording of calcium and voltage transients following impulses in cell bodies and processes of identified leech neurons in culture

1987

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Optical methods were used to examine the spread of electrical potentials and the distribution and time course of calcium transients in individual identified nerve cells isolated from the leech. A photodiode array detected voltage transients by measuring absorbance changes of cells stained with the voltage-sensitive dye RH155 added to the bath. Calcium transients were recorded by measuring absorbance changes of the dye arsenazo III, which had been injected into the cells. In addition, Lucifer yellow was injected to outline the some and processes. Calcium changes resulting from individual action potentials were recorded from N, P, and Retzius cells without averaging. Signals from T cells and anterior pagoda (AP) cells were weaker but could be detected with averaging. These results are in accord with previous studies on calcium contributions to action potentials in these cells. For all cells, larger or wider action potentials gave bigger signals. Calcium changes from each of a train of action potentials were of equal amplitude, showing no sign of facilitation. Calcium transients from Retzius cells that had formed chemical synapses with P cells had properties similar to those of isolated cells. We were also able to detect responses from prolonged subthreshold depolarizations to -40 mV from a hyperpolarized membrane potential (-65 mV). These signals rose throughout the duration of the pulse (1–2 sec). With the photodiode array we mapped the distribution of the calcium signals. The amplitudes from each pixel are proportional to the amount of calcium entering that element in response to the stimulating pulse, if the simplifying assumption is made that the calcium buffering of the cytoplasm is uniform throughout the cell. The largest signals were detected over the axon stump left from the cell isolation procedure. Large signals were also detected from the soma. Weak signals were detected from the processes of some cells. From many Retzius cells, no signals at all were detected from the newly formed processes. Using the photodiode array, we also recorded voltage transients from the cells. Signals were recorded from all over the arborization of the neuron, with no obvious variation in time course, showing that the entire cell, including fine slender processes and broad growth cones, was essentially isopotential. Combining these observations with the measured distribution of calcium transients in the same cell suggests that the density of calcium channels in most cells is less in the outgrowing processes than in the soma or axon stump.

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Section: Measurements Of Potential and Channel Distributionsupporting

confidence: 78%

Section: Retzius Cell mentioning

confidence: 99%

Optical recording of calcium and voltage transients following impulses in cell bodies and processes of identified leech neurons in culture

1987

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“…The occurrence of extrasynaptic receptors has been widely documented for a number of possible neurotransmitters including GABA (e.g. Alger & Nicoll, 1982;Pellegrino & Simonneau, 1984 …”

Section: Gaba Receptors In the Embryo Spinal Cordmentioning

confidence: 99%

Ionic and pharmacological properties of reciprocal inhibition in Xenopus embryo motoneurones.

Soffe¹

1987

The Journal of Physiology

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SUMMARY1. Properties of rhythmic, compound mid-cycle inhibitory post-synaptic potentials (i.p.s.p.s), which constitute one of the three main synaptic drives to motoneurones during fictive swiming in Xenopus embryos, have been examined using ionic and pharmacological manipulation.2. Mid-cycle i.p.s.p.s are Cl-dependent. They are reversed by intracellular Clinjection and attenuated by lowered extracellular Cl-concentration.3. In response to bath application of 100 /iM-glycine or 100 /uM-y-aminobutyric acid (GABA), motoneurones show a decrease in cell input resistance of 24+ 2-9 MQ (mean + S.E. of mean) or 16 + 3-7 % and 26 + 6-0 MQ or 14 + 2-0% respectively. This is associated with a weak hyperpolarization or depolarization of 0 + 1-5 mV and -3+1-4 mV respectively. Both responses can be made strongly depolarizing by intracellular Cl-injection.4. The response to glycine is blocked by 1 Lm-strychnine but is largely unaffected by bicuculline below 50 /M. The response to GABA is largely blocked by 10 fMbicuculline but is unaffected by 1 /m-strychnine. Both strychnine and bicuculline are therefore specific antagonists in the amphibian embryo preparation. Glycine and GABA are both partially antagonized by 10 /LM-picrotoxin. 5. Mid-cycle i.p.s.p.s recorded in motoneurones during fictive swimming are reduced in amplitude by 05-t1 /M-strychnine but are largely unaffected by 40 #tM-bicuculline. In embryos immobilized by ventral root transaction, 100 /Mtubocurarine, a likely GABA antagonist in the embryo, has no effect on mid-cycle inhibition. Glycine is suggested to be the probable transmitter released by commissural interneurones and mediating mid-cycle inhibition during fictive swimming, acting to increase conductance of Cl-.

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“…Even if one assumed that the processes were leaky, with a specific membrane resistance of only half that of the soma, the attenuation of a pulse applied to the cell body would be negligible for a cell with 100 processes, each 50 jum in length and 1 ,um in diameter -an over-estimate of branching on polylysine. Moreover, when transmitter is pipetted onto the tip of a long process, the reversal potential is not detectably different from that seen with application to the soma (Pellegrino & Simmoneau, 1984). Nevertheless, non-homogeneity of the voltage clamp of the Retzius cell and its processes may turn out to be an important factor when the ionic currents are analysed.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, the release of 5-HT from the Retzius cells has been shown to be quantal (Henderson, Kuffler, Nicholls & Zhang, 1983), and release sites containing synaptic vesicles have been identified by electron microscopy (Drapeau, Kuffler & Nicholls, 1983). Because cultured leech neurones have high input resistances (100-150 MQ) and grow only short neurites, calculations and experimental observations suggest that the tips of the neurites are isopotential with the cell bodies (Fuchs et al 1982;Pellegrino & Simmoneau, 1984).…”

mentioning

confidence: 99%

Voltage dependence of 5‐hydroxytryptamine release at a synapse between identified leech neurones in culture.

Dietzel¹,

Drapeau²,

Nicholls³

1986

The Journal of Physiology

136

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SUMMARY1. The release of 5-hydroxytryptamine (5-HT) from presynaptic terminals has been studied by the voltage-clamp technique at synapses made by isolated Retzius and pressure (P) sensory neurones dissected from the leech C.N.s. and maintained in tissue culture. At these synapses facilitation, depression and modulation of release occur with action potentials and with voltage-clamp pulses.2. Depolarization of Retzius cells from a constant holding potential by steps of varying amplitude (5 ms in duration) caused graded release of 5-HT. The steep transfer function for release using these short test pulses resembled that seen at the giant synapse of the squid: synaptic potentials increased markedly with presynaptic depolarizations beyond -25 mV and decreased with large depolarizing pulses beyond +40 mV.3. When the steady holding potential of voltage-clamped Retzius cells was suddenly displaced to a new value within the range of -40 mV to -85 mV, there followed a slow but smaller change of the post-synaptic P-cell membrane potential in the same direction. After an initial delay of about 40 ms, the post-synaptic potential reached its new level with an exponential time course and a time constant of 0 7 s. Since Retzius and P cells are not electrically coupled, these effects can be accounted for by alterations in tonic release of transmitter.4. Changes of presynaptic holding potential to a more depolarized level resulted in an increase in voltage noise recorded in the P cell. Conversely, hyperpolarization from a depolarized level reduced noise. Noise analysis showed that these changes could be accounted for by quantal events with a mean amplitude of about 0-15 mV. This value is similar to that for spontaneous miniature potentials and quantal fluctuations observed at synapses between Retzius and P cells. I. D. DIETZEL, P. DRAPEA U AND J. G. NICHOLLS responses evoked by depolarizations to 0 mV with pulses of 5 ms duration were reduced in amplitude as the holding potential of the Retzius cell was increased from the resting value of -45 to -75 mV. For example, depolarization to 0 mV starting from -45 mV evoked synaptic potentials as much as ten times larger than those evoked by depolarizations to 0 mV starting from -75 mV. With step depolarizations or hyperpolarizations of the holding potential, the effect on release evoked by brief pulses to 0 mV built up over an exponential time course similar to that found for the effect of holding potential on tonic release (r = 0 7 s).6. Frequency-dependent facilitation of transmission occurred with paired stimuli applied to Retzius cells. The time constant of decay of facilitation was similar (approximately 100 ms) with impulses and under voltage-clamp conditions. The time course of the decay of facilitation was independent of the holding potential. It is concluded that two-shock facilitation and modulation of release by changes in the resting potential depend on different presynaptic mechanisms.

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Distribution of receptors for acetylcholine and 5‐hydroxytryptamine on identified leech neurones growing in culture.

Cited by 29 publications

References 29 publications

Optical recording of calcium and voltage transients following impulses in cell bodies and processes of identified leech neurons in culture

Optical recording of calcium and voltage transients following impulses in cell bodies and processes of identified leech neurons in culture

Ionic and pharmacological properties of reciprocal inhibition in Xenopus embryo motoneurones.

Voltage dependence of 5‐hydroxytryptamine release at a synapse between identified leech neurones in culture.

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