Tachykinin induced regulation of excitatory amino acid responses in the rat spinal cord in vitro

Urbán, László; Naeem, Sami; Patel, I.A.; Dray, A.

doi:10.1016/0304-3940(94)90446-4

“…Our ultrastructural results in the NST revealed that some NK1-immunoreactive dendrites are contacted by giant axon terminals exhibiting morphological features of primary afferent terminals. Our data support the idea that the activation of NK1 receptors by SP may modulate glutamatergic neurotransmission in the cat and rat NST, as has been suggested is the case in the spinal cord (Randic et al, 1990;Rusin et al, 1993;Urban et al, 1994;Chizh et al, 1995).…”

Section: Cellular Distribution Of Nk1 Receptors In Rat and Cat Dvcsupporting

confidence: 90%

Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study

Baude

¹

,

Shigemoto

²

1998

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Immunoreactivity for the substance P receptor (NK1 receptor) has been investigated by light and electron microscopy in the dorsal vagal complexes of adult rats and cats. The general pattern of NK1 immunoreactivity was similar for both rat and cat. Numerous NK1-immunoreactive neurons were present in the area postrema, the nucleus of the solitary tract, and the dorsal motor nucleus of the vagus nerve. The density of labelled neurons differed between the subnuclei of the nucleus of the solitary tract. Overall, the efferent neurons of the dorsal motor nucleus of the vagus nerve highly expressed NK1 when compared to neurons in the nucleus of the solitary tract. The results are discussed with reference to the viscerotopic organisation of the dorsal vagal complex. Ultrastructural analysis demonstrated that NK1 immunoreactivity was present only at the membrane surface of somatic and dendritic profiles of neurons. No labelling was found in axon terminals, axons, or glial processes. NK1 immunoreactivity, as revealed by a preembedding immunogold technique in serial ultrathin sections, was preferentially located at nonsynaptic sites. A semiquantitative study suggested that the density of NK1 receptors is statistically higher at membrane sites free of any contact (synaptic or not) with axon terminals. The subcellular localisation of NK1 immunoreactivity was similar for neurons of both rat and cat. These results suggest that in the dorsal vagal complex, substance P might act on NK1 receptors through a process of volume transmission.

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“…Most of the axon terminals contacting NK1-immunoreactive profiles have similar anatomical features (see Results). Our data support the idea that the activation of NK1 receptors by SP may modulate glutamatergic neurotransmission in the cat and rat NST, as has been suggested is the case in the spinal cord (Randic et al, 1990;Rusin et al, 1993;Urban et al, 1994;Chizh et al, 1995). Our ultrastructural results in the NST revealed that some NK1-immunoreactive dendrites are contacted by giant axon terminals exhibiting morphological features of primary afferent terminals.…”

Section: Cellular Distribution Of Nk1 Receptors In Rat and Cat Dvcsupporting

confidence: 90%

Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study

Baude¹,

Shigemoto

²

1998

View full text Add to dashboard Cite

Immunoreactivity for the substance P receptor (NK1 receptor) has been investigated by light and electron microscopy in the dorsal vagal complexes of adult rats and cats. The general pattern of NK1 immunoreactivity was similar for both rat and cat. Numerous NK1-immunoreactive neurons were present in the area postrema, the nucleus of the solitary tract, and the dorsal motor nucleus of the vagus nerve. The density of labelled neurons differed between the subnuclei of the nucleus of the solitary tract. Overall, the efferent neurons of the dorsal motor nucleus of the vagus nerve highly expressed NK1 when compared to neurons in the nucleus of the solitary tract. The results are discussed with reference to the viscerotopic organisation of the dorsal vagal complex. Ultrastructural analysis demonstrated that NK1 immunoreactivity was present only at the membrane surface of somatic and dendritic profiles of neurons. No labelling was found in axon terminals, axons, or glial processes. NK1 immunoreactivity, as revealed by a preembedding immunogold technique in serial ultrathin sections, was preferentially located at nonsynaptic sites. A semiquantitative study suggested that the density of NK1 receptors is statistically higher at membrane sites free of any contact (synaptic or not) with axon terminals. The subcellular localisation of NK1 immunoreactivity was similar for neurons of both rat and cat. These results suggest that in the dorsal vagal complex, substance P might act on NK1 receptors through a process of volume transmission.

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“…Thus, ventral root responses in the rat isolated spinal cord preparation evoked by stimulation of afferent nerve fibres were hardly affected by antagonists of NMDA or tachykinin receptors alone, but there was a pronounced inhibition when both types of antagonists were used together (Thompson et al, 1993). Activation of NKI or NK2 receptors enhanced NMDA-and quisqualate-evoked ventral root depolarization (Urban et al, 1994a). The co-operation between neurokinin and excitatory amino acid transmitters has recently been reviewed by Urban et al (1994b).…”

Section: Capsaicin-induced Heat Dissipationmentioning

confidence: 99%

Evidence for the participation of glutamate in reflexes involving afferent, substance P‐containing nerve fibres in the rat

Juránek

¹

,

Lembeck

²

1996

British J Pharmacology

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Responses mediated, either peripherally or centrally, by substance P‐containing primary afferent C‐fibres were investigated in the rat following impairment of axonal transport by colchicine (120 μg kg−1 i.p., daily for 3 days), and after treatment with the tachykinin antagonist SR‐140333 (10–100 μg kg−1, i.v.) or the N‐methyl‐D‐aspartate (NMDA) antagonist MK‐801 (100 μg kg−1). Peripheral effects mediated by afferent C‐fibres were measured by plasma protein extravasation (Evans blue method), following antidromic stimulation of the sciatic nerve, topical application of mustard oil and, as control, i.v. injection of substance P. SR‐140333 (100 μg kg−1) reduced the effects by 86%, 75% and 74%, respectively. Colchicine reduced the effects of the first two stimuli by 31% and 33% and, as expected not the effect of substance P. The increase of paw skin temperature following capsaicin i.v. was inhibited by SR‐140333, but not by colchicine. MK‐801 had no effect on the plasma protein extravasation following antidromic sciatic nerve stimulation or on the rise of paw skin temperature induced by capsaicin i.v., thus excluding an effect of MK‐801 on peripheral terminals of afferent neurones. Depressor reflexes, which are known to be mediated by capsaicin‐sensitive afferent neuones, such as those elicited (A) by a stimulating dose of 30 ng capsaicin i.a., (B) by distension of the ascending colon or (C) by afferent sciatic nerve stimulation were studied. Colchicine significantly reduced depressor reflexes A and B, but had no effect on reflex C. None of the reflexes was affected by SR‐140333. MK‐801 significantly inhibited all three reflexes. Capsaicin, injected either i.v. (200 μg kg−1) or into the nucleus caudatus/putamen (i.c., 30 μg), induced an increase in paw skin temperature and a decrease in colon temperature. The rise in fore paw skin temperature (Δt = 2.3 ± 0.4°C) evoked by capsaicin i.v. was almost completeley blocked by SR‐140333 (100 μg kg−1, i.v.), but no inhibition was observed with MK‐801, indicating that capsaicin had brought about a release of substance P from peripheral nerve terminals. Colchicine did not influence heat dissipation induced by i.v. capsaicin. When capsaicin was injected i.c., the rise in paw skin temperature in colchicine‐ and SR‐140333‐pretreated groups did not differ from that of the control group. MK‐801 totally prevented the heat loss reaction to i.c. capsaicin administration. Colchicine did not change the effects of i.v. or i.c. injected capsaicin: this excludes the involvement of a mechanism dependent on axonal transport of neurotransmitters. The reduction of axonal transport by colchicine reduced plasma extravasation induced by mustard oil and antidromic sciatic nerve stimulation (peripheral functions) and depressor reflexes evoked by i.a. capsaicin and colon distension (central functions). It can be argued that afferent stimulation of the sciatic nerve includes the stimulation of A‐fibres, which might be less sensitive to colchicine. SR‐140333 was effective only on peripherally mediated ...

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Tachykinin induced regulation of excitatory amino acid responses in the rat spinal cord in vitro

Cited by 28 publications

References 16 publications

Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study

Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study

Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study

Evidence for the participation of glutamate in reflexes involving afferent, substance P‐containing nerve fibres in the rat

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