FUNCTIONAL DIFFERENTIATION IN sB AND sC NEURONS OF TOAD SYMPATHETIC GANGLIA

Honma, Shinji

doi:10.2170/jjphysiol.20.281

Cited by 26 publications

(17 citation statements)

References 16 publications

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“…Thus, the subthreshold EPSPs may have another functional role; perhaps they generate APs during the development of the peptidergic late-slow EPSP in B-cells as has been demonstrated in vitro (Schulman & Weight, 1976). The list of probable targets in the skin that can be innervated by B-cells includes mucous and granular glands (Honma, 1970), cold receptors (Spray, 1974) and mechanoreceptors (Loewenstein, 1956;Lang et al 1975). Although these targets receive a low-frequency sympathetic discharge without any baroreceptor modulation (about 40% of B-cells had a frequency of APs lower than 0 1 s-1), these lowdischarge frequencies are unlikely to result from selective depression of sympathetic transmission to B-cells as a result of urethane anaesthesia because the frequency of APs ranged widely in different cells in the same animal (from 0 01 to 0'4 s-').…”

Section: Characteristics Of B-sympathetic Pathwaysmentioning

confidence: 92%

“…The amplitude and duration of the slow depolarization ranged from 3 to 7 mV and from 20 to 60 s. Preganglionic B-fibre and C-fibre inputs were left intact in all preparations which exhibited these responses. Activation of B-cells by stimulation of the skin Honma (1970) and showed that B-cells innervate targets in the skin. Since targets of sympathetic nerves often give rise to sensory fibres which participate in reflex activation of the sympathetic system (Janig, 1988;Janig & McLachlan, 1992), we tested whether a reflex response could be evoked in B-cells following tactile stimulation of the skin of the hindlimb.…”

Section: Methods Preparationmentioning

confidence: 99%

“…Characteristics of C-sympathetic pathways In vitro and in vivo experiments have shown that the stimulation of preganglionic C-fibres produces cutaneous and muscular vasoconstriction in the toad (Honma, 1970) and bullfrog (Yoshimura, 1979;Stofer et at. 1990).…”

Section: Characteristics Of B-sympathetic Pathwaysmentioning

confidence: 99%

“…There are two major divisions of the peripheral sympathetic nervous system of amphibians; the B-fibre system and the C-fibre system (Nishi, Soeda & Koketsu, 1965;Honma, 1970;Dodd & Horn 1983a;Smith, 1994). Peripheral targets for neurones in paravertebral sympathetic ganglia of the bullfrog (BFSG) include the bladder, mucous and granular glands, as well as blood vessels in the skin and in striated muscles.…”

mentioning

confidence: 99%

“…Peripheral targets for neurones in paravertebral sympathetic ganglia of the bullfrog (BFSG) include the bladder, mucous and granular glands, as well as blood vessels in the skin and in striated muscles. Stimulation of the preganglionic C-fibres causes vasoconstriction in the skin and muscle (Honma, 1970;Yoshimura, 1979;Horn, Fatherazi & Stofer, 1988;Stofer, Fatherazi & Horn, 1990), whereas stimulation of B-fibres produces secretion from cutaneous glands (Honma, 1970;Lang, Sjoberg & Skoglund, 1975), modulation of the sensitivity of cutaneous mechanoreceptors (Loewenstein, 1956) and a shortening of the recovery of arterioles which had been previously constricted following C-fibre stimulation (Yoshimura, 1979). The B-fibre and C-fibre systems originate from separate groups of neurones in the spinal cord and remain anatomically separate as they pass through the paravertebral ganglia (Nishi & Koketsu, 1960;Dodd & Horn 1983a;; but see also Smith & Weight, 1986).…”

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confidence: 99%

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In vivo activity of B‐ and C‐neurones in the paravertebral sympathetic ganglia of the bullfrog.

Ivanoff

Smith

1995

The Journal of Physiology

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1. Spontaneous, in vivo synaptic activity was recorded from 146 B‐cells and 60 C‐cells in the IXth and Xth paravertebral sympathetic ganglia of the urethane‐anaesthetized bullfrog. Sympathetic outflow to the blood vessels, which are innervated by C‐cells, is different from that received by targets in the skin, which are innervated by B‐cells. 2. B‐cells were divided into three groups: the first (61 cells) exhibited only action potentials (APs) at 0.01‐0.3 s‐1; the second (59 cells) exhibited APs and EPSPs and the third (26 cells) were silent. In addition to their usual suprathreshold input from the ipsilateral sympathetic chain, 53% of B‐cells received subthreshold input which probably arose from fibres in the contralateral chain. ‘Slow’ B‐cells exhibited less subthreshold activity and a slightly higher AP frequency than ‘fast’ B‐cells. All B‐cells are involved in a sympathetic reflex which is activated by tactile stimulation of the skin of the hindlimb. Activation of this reflex increased AP frequency without promoting long‐lasting depolarization. 3. Sixty‐seven per cent of C‐cells exhibited rhythmic bursting activity with or without small intraburst EPSPs. Bursts tended to correlate with electrocardiographic (ECG) activity. The remainder exhibited an irregular pattern of activity which was not correlated with ECG activity and which included one to three APs and EPSPs interspersed between the bursts. Activity of both types of C‐cell was inhibited following stimulation of the skin. 4. An average of twenty‐three B‐cells and twenty‐one C‐cells discharge simultaneously in vivo. This reflects branching of preganglionic fibres and results in synchrony of discharge in both postganglionic B‐ and C‐fibres.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Characteristics Of B-sympathetic Pathwaysmentioning

confidence: 92%

Section: Methods Preparationmentioning

confidence: 99%

Section: Characteristics Of B-sympathetic Pathwaysmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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In vivo activity of B‐ and C‐neurones in the paravertebral sympathetic ganglia of the bullfrog.

Ivanoff

Smith

1995

The Journal of Physiology

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Synaptic organization of amphibian sympathetic ganglia

Lascar

Eugène

Taxi

1996

Microsc. Res. Tech.

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The synaptic organization of the amphibian sympathetic ganglia was studied, especially in the last two abdominal paravertebral ganglia of the frog. These ganglia appear to form a monosynaptic relay, not containing interneurons. They consist of two systems working in parallel: the principal neurons, by far the most numerous, and a small number of chromaffin (i.e., SIF) cells, usually arranged in clusters. Each principal neuron is innervated by a preganglionic branch forming a set of cholinergic synapses which exhibit classical ultrastucture. The only peculiarity is the presence of a subsynaptic apparatus in a variable percentage of synaptic complexes. Electro‐physiological studies have demonstrated that synaptic transmission is due to ACh release and involves several postsynaptic potentials. Moreover, the principal neurons are of two types, B and C, whose preganglionic axons and their own axons have different conduction velocities. C neurons tend to be small in diameter, and B neurons are larger, but the size distribution of the two populations overlaps. More recently, it was demonstrated that these two neuronal systems have different immunocytochemical features. The C preganglionic fibers contain an LHRH‐like peptide, which is responsible for late synaptic events. The B preganglionic fibers contain CGRP, whose role has not yet been established. The principal neurons all contain adrenaline, but neuropeptide Y is also present in C neurons and could be a second transmitter at peripheral junctions. SP‐containing fibers also pass through the ganglia, but give rise to intraganglionic synapses only rarely, except in the celiac plexus. Galanin can coexist with neuropeptide Y in certain C neurons. Numerous principal neurons are immunoreactive for VIP. Chromaffin cells contain noradrenaline and metenkephalin, and some contain SP or LHRH; they are endocrine cells controlled by preganglionic fibers and can have a modulatory effect on principal neurons endowed with appropriate receptors. The accessibility of frog abdominal ganglia and the anatomical separation of B and C preganglionic fiber pathways provide interesting systems in which to carry out experimentation on the stability and specificity of synaptic contacts. After postganglionic axotomy, the majority of synapses disappear by disruption of synaptic contacts. There is a certain discrepancy between the recovery of synaptic transmission and the reappearance of morphologically identifiable synapses, suggesting that a certain amount of transmission is possible at contacts devoid of synaptic complexes. The selective deafferentation of B or C neurons showed that the subsynaptic apparati are mainly found at B neuron synapses. The course of reinnervation following selective deafferentation reveals the existence of different specificities at B and C synapses: C neurons are easily reinnervated by B preganglionic fibers, whereas C fibers appear fairly ineffective at reinnervating B neurons, even after a long interval. Attempts were made to reinnervate ganglionic neurons...

show abstract

Synaptic organization of amphibian sympathetic ganglia

Lascar

Eugène

Taxi

1996

Microsc. Res. Tech.

View full text Add to dashboard Cite

The synaptic organization of the amphibian sympathetic ganglia was studied, especially in the last two abdominal paravertebral ganglia of the frog. These ganglia appear to form a monosynaptic relay, not containing interneurons. They consist of two systems working in parallel: the principal neurons, by far the most numerous, and a small number of chromaffin (i.e., SIF) cells, usually arranged in clusters. Each principal neuron is innervated by a preganglionic branch forming a set of cholinergic synapses which exhibit classical ultrastructure. The only peculiarity is the presence of a subsynaptic apparatus in a variable percentage of synaptic complexes. Electrophysiological studies have demonstrated that synaptic transmission is due to ACh release and involves several postsynaptic potentials. Moreover, the principal neurons are of two types, B and C, whose preganglionic axons and their own axons have different conduction velocities. C neurons tend to be small in diameter, and B neurons are larger, but the size distribution of the two populations overlaps. More recently, it was demonstrated that these two neuronal systems have different immunocytochemical features. The C preganglionic fibers contain an LHRH-like peptide, which is responsible for late synaptic events. The B preganglionic fibers contain CGRP, whose role has not yet been established. The principal neurons all contain adrenaline, but neuropeptide Y is also present in C neurons and could be a second transmitter at peripheral junctions. SP-containing fibers also pass through the ganglia, but give rise to intraganglionic synapses only rarely, except in the celiac plexus. Galanin can coexist with neuropeptide Y in certain C neurons. Numerous principal neurons are immunoreactive for VIP. Chromaffin cells contain noradrenaline and metenkephalin, and some contain SP or LHRH; they are endocrine cells controlled by preganglionic fibers and can have a modulatory effect on principal neurons endowed with appropriate receptors. The accessibility of frog abdominal ganglia and the anatomical separation of B and C preganglionic fiber pathways provide interesting systems in which to carry out experimentation on the stability and specificity of synaptic contacts. After postganglionic axotomy, the majority of synapses disappear by disruption of synaptic contacts. There is a certain discrepancy between the recovery of synaptic transmission and the reappearance of morphologically identifiable synapses, suggesting that a certain amount of transmission is possible at contacts devoid of synaptic complexes. The selective deafferentation of B or C neurons showed that the subsynaptic apparati are mainly found at B neuron synapses. The course of reinnervation following selective deafferentation reveals the existence of different specificities at B and C synapses: C neurons are easily reinnervated by B preganglionic fibers, whereas C fibers appear fairly ineffective at reinnervating B neurons, even after a long interval. Attempts were made to reinnervate ganglionic neurons with som...

show abstract

FUNCTIONAL DIFFERENTIATION IN sB AND sC NEURONS OF TOAD SYMPATHETIC GANGLIA

Cited by 26 publications

References 16 publications

In vivo activity of B‐ and C‐neurones in the paravertebral sympathetic ganglia of the bullfrog.

In vivo activity of B‐ and C‐neurones in the paravertebral sympathetic ganglia of the bullfrog.

Synaptic organization of amphibian sympathetic ganglia

Synaptic organization of amphibian sympathetic ganglia

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