Spinal cord mechanisms mediating behavioral hyperalgesia induced by neurokinin-1 tachykinin receptor activation in the rostral ventromedial medulla

doi:10.1016/j.neuroscience.2010.09.040

Neuroscience

Volume 171, Issue 4, 29 December 2010, Pages 1341-1356

https://doi.org/10.1016/j.neuroscience.2010.09.040 Get rights and content

Abstract

Hyperalgesia in animal injury models is linked to activation of descending raphespinal modulatory circuits originating in the rostral ventromedial medulla (RVM). A neurokinin-1 (NK-1) receptor antagonist microinjected into the RVM before or after inflammation produced by complete Freund's adjuvant (CFA) resulted in an attenuation of thermal hyperalgesia. A transient (acute) or a continuous infusion of Substance P (SP) microinjected into the RVM of non-inflamed animals led to similar pain hypersensitivity. Intrathecal pretreatment or post-treatment of a 5-HT3 receptor antagonist (Y-25130 or ondansetron) blocked the SP-induced hyperalgesia. The SP-induced hyperalgesia was both GABA_A and NMDA receptor-dependent after pre- and post-treatment with selective antagonists at the spinal level. A microinjection of SP into the RVM also led to increased NMDA NR1 receptor subunit phosphorylation in spinal cord tissue. The GABA_A receptor-mediated hyperalgesia involved a shift in the anionic gradient in dorsal horn nociceptive neurons and an increase in phosphorylated NKCC1 protein (isoform of the Na-K-Cl cotransporter). Following a low dose of SP infused into the RVM, intrathecal muscimol (GABA_A agonist) increased SP-induced thermal hyperalgesia, phosphorylated NKCC1 protein expression, and NMDA NR1 subunit phosphorylation in the spinal cord. The thermal hyperalgesia was blocked by intrathecal gabazine, the GABA_A receptor antagonist, and MK-801, the NMDA receptor channel blocker. These findings indicate that NK-1 receptors in the RVM are involved in SP-induced thermal hyperalgesia, this hyperalgesia is 5-HT3-receptor dependent at the spinal level, and involves the functional interaction of spinal GABA_A and NMDA receptors.

Research Highlights

▶RVM NK-1 receptors contribute to behavioral hyperalgesia after inflammation. ▶RVM SP microinjection induces and maintains hyperalgesia. ▶SP-induced hyperalgesia involves descending facilitatory mechanisms linked to 5HT-3, NMDA, and GABA receptor spinal circuitry.

Section snippets

Animals

Male Sprague–Dawley rats (80–300 g; Harlan, Indianapolis, IN, USA) were used for the behavioral, pharmacological and western blot experiments. Male Sprague–Dawley (80–100 g) rats were used for the electrophysiology experiments. All animals were housed and maintained on a 12:12 light:dark cycle with free access to food and water throughout the study. The animals were maintained and cared for in accordance to the guidelines outlined by the International Association for the Study of Pain (

Role of NK-1 receptors in the RVM in the initiation and maintenance of inflammation-induced behavioral hyperalgesia

We first tested the hypothesis that NK-1 receptors are involved in descending facilitation of behavioral hyperalgesia after inflammation. Using paw withdrawal latency as a measure of behavioral hyperalgesia, we examined the response to thermal stimuli in CFA-treated animals that received a microinjection of one of two NK-1 receptor antagonists, L-733,060 or L-732,138, or vehicle microinjection, into the RVM 10 min prior to the induction of inflammation (Fig. 1A, B). The microinjection of

Discussion

The present experiments provide evidence that RVM NK-1 receptors contribute to behavioral hyperalgesia after inflammation and that RVM SP microinjection induces and maintains hyperalgesia involving descending facilitatory mechanisms linked to 5HT-3, NMDA and GABA receptor spinal circuitry. We found that: (1) antagonism of NK-1 receptors in the RVM attenuated CFA-induced hyperalgesia, (2) there was increased RVM NK-1 expression at 2 h to 3 d following the onset of inflammation, (3) the effect of

Acknowledgments

This work was supported by NIHNS060735, NS059028, DE018573, and T32DE007309. The authors would like to thank Dr. Forbush at Yale University for providing us the anti-phospho-NKCC1 antibody R5.

References (69)

V.C. Anseloni et al.
Inflammation-induced shift in the valence of spinal GABA-A receptor-mediated modulation of nociception in the adult rat
J Pain
(2008)
M. Antal et al.
Direct evidence of an extensive GABAergic innervations of the spinal dorsal horn by fibres descending from the rostral ventromedial medulla
Neuroscience
(1996)
L.A. Bee et al.
Rostral ventromedial medulla control of spinal sensory processing in normal and pathophysiological states
Neuroscience
(2007)
A.J. Beitz
The nuclei of origin of brain stem enkephalin and substance P projection to the rodent nucleus raphe magnus
Neuroscience
(1982)
D. Conte et al.
Transmitter content, origins and connections of axons in the spinal cord that possess the serotonin (5-hydroxytryptamine) 3 receptor
Neuroscience
(2005)
R. Dubner et al.
Activity-dependent neuronal plasticity following tissue injury and inflammation
Trends Neurosci
(1992)
A.W. Flemmer et al.
Activation of the Na-K-Cl cotransporter NKCC1 detected with a phosphor-specific antibody
J Biol Chem
(2002)
G. Green et al.
An excitatory role for 5-HT in spinal inflammatory nociceptive transmission; state-dependent actions via dorsal horn 5-HT3 receptors in the anaesthetized rat
Pain
(2000)
Y. Guan et al.
Changes in AMPA receptor phosphorylation in the rostral ventromedial medulla after inflammatory hyperalgesia in rats
Neurosci Lett
(2004)
Y. Guan et al.
Inflammation-induced upregulation of AMPA receptor subunit expression in brain stem pain modulatory circuitry
Pain
(2003)

M.V. Hamity et al.

Effects of neurokinin-1 receptor agonism and antagonism in the rostral ventromedial medulla of rats with acute or persistent inflammatory nociception

Neuroscience

(2010)

K. Hargreaves et al.

A new and sensitive method for measuring thermal nociception in cutaneous hyperalgesia

Pain

(1988)

J.L.K. Hylden et al.

Intrathecal morphine in mice: a new technique

Eur J Pharmacol

(1980)

C.C. LaMotte

Lamina X of primate spinal cord: distribution of five neuropeptides and serotonin

Neuroscience

(1988)

L. Leger et al.

Neurokinin NK1- and NK3-immunoreactive neurons in serotonergic cell groups in the rat brain

Neurosci Lett

(2002)

H. Maeno et al.

Distribution of the substance P receptor (NK-1 receptor) in the central nervous system

Brain Res Mol Brain Res

(1993)

M.K. McGowan et al.

Antinociception produced by microinjection of L-glutamate into the ventromedial medulla of the rat: mediation by spinal GABA_A] receptors

Brain Res

(1993)

M.J. Millan

Descending control of pain

Prog Neurobiol

(2002)

B.M. Morales-Aza et al.

Inflammation alters cation chloride cotransporter expression in sensory neurons

Neurobiol Dis

(2004)

C. Pacharinsak et al.

NK-1 receptors in the rostral ventromedial medulla contribute to hyperalgesia produced by intraplantar injection of capsaicin

Pain

(2008)

F. Porreca et al.

Chronic pain and medullary descending facilitation

Trends Neurosci

(2002)

K. Ren et al.

Descending modulation in persistent pain: an update

Pain

(2002)

K. Ren et al.

The effects of a non-competitive NMDA receptor antagonist, MK-801, on behavioral hyperalgesia and dorsal horn neuronal activity in rats with unilateral inflammation

Pain

(1992)

M.A. Ruda

Spinal dorsal horn circuitry involved in the brain stem control of nociception

Prog Brain Res

(1988)

M. Saffroy et al.

Autoradiographic distribution of tachykinin NK₂ binding sites in the rat brain: comparison with NK₁ and NK₃ binding sites

Neuroscience

(2003)

R. Suzuki et al.

Descending facilitatory control of mechanically evoked responses is enhanced in deep dorsal horn neurons following peripheral nerve injury

Brain Res

(2004)

R. Suzuki et al.

Bad news from the brain: descending 5-HT pathways that control spinal pain processing

Trends Pharmacol Sci

(2004)

A.J. Todd et al.

GABA-immunoreactive neurons in the dorsal horn of the rat spinal cord

Neuroscience

(1989)

M.O. Urban et al.

The glutamate synapse: a target in the pharmacological management of hyperalgesic pain states

Prog Brain Res

(1998)

H. Vanegas et al.

Descending control of persistent pain: inhibitory or facilitatory?

Brain Res Rev

(2004)

C.J. Woolf et al.

The induction and maintenance of central sensitization is dependent on N-methyl-d-aspartic acid receptor activation; implications for the treatment of post-injury pain hypersensitivity states

Pain

(1991)

K. Yang et al.

Voltage-clamp recordings of postsynaptic currents in substantia gelatinosa in vitro] and its applications to assess synaptic transmission

Brain Res Protoc

(2001)

D. Budai et al.

NK-1 receptors modulate the excitability of ON cells in the rostral ventromedial medulla

J Neurophysiol

(2007)

S.E. Burgess et al.

Time-dependent descending facilitation from the rostral ventromedial medulla maintains, but does not initiate, neuropathic pain

J Neurosci

(2002)

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Outside of the brain, within the spinal dorsal horn, SP is involved in the transmission of nociceptive information and evokes inflammation when applied to peripheral tissues [23,24]. In addition, SP injection into the RVM, a principal source of serotoninergic neurons, evokes hypersensitivity via RVM expressing NK1 receptors and subsequent activation of the descending facilitation pathway [55]. Thus, SP has opposing effects on nociceptive modulation depending on brain region.
Previous studies have demonstrated that continuous substance P (SP) infusion into the rat striatum attenuated hind paw formalin-induced nociceptive behaviors and mechanical hypersensitivity via a neurokinin-1 (NK1) receptor dependent mechanism. However, whether there is a role of striatal infusion of SP on chronic, neuropathic pain has yet to be demonstrated. The present study investigated the effect of continuous SP infusion into the rat striatum using a reverse microdialysis method is antinociceptive in a rat model of chronic, mononeuropathic pain. Two weeks after partial sciatic nerve injury, the ipsilateral hind paw demonstrated mechanical hypersensitivity. Infusion of SP (0.2, 0.4, or 0.8 μg/mL, 1 μL/min) for 120 min into the contralateral striatum dose-dependently relieved mechanical hypersensitivity. The antinociceptive effect of SP infusion was inhibited by co-infusion with the NK1 receptor antagonist CP96345 (10 μM). Neither ipsilateral continuous infusion nor acute microinjection of SP (10 ng) into the contralateral striatum was antinociceptive. A role of striatal muscarinic cholinergic neurons is suggested since co-infusion of SP with atropine (10 μM), but not the nicotinic receptor mecamylamine (10 μM), blocked antinociception. The current study suggests that activation of striatal muscarinic receptors through NK1 receptors could be a novel approach to managing chronic pain.
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The descending pain modulatory circuit through the PAG and RVM modulates pain bidirectionally; increasing or dampening pain in response to internal and environmental stressors. This circuit also mediates the central analgesic actions of opioids. Neuroimaging studies confirm the involvement of the PAG and RVM as important in top-down modulation of pain in humans, including effects of placebo or changes in pain modulation with attention. This chapter includes an overview of the PAG and RVM, neurotransmitter systems that modulate activity of neurons within each area and the properties of pain-modulating neurons in acute and chronic pain.
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There is evidence to suggest that pronociceptive effects of spinal 5-HT3R involve activation of microglia and astrocytes in the dorsal horn (Guo et al., 2014) and play an important role in descending facilitation. For example, intrathecal 5-HT3R antagonists (Y25130 or ondansetron) inhibited hyperalgesia induced by substance P microinjection into the RVM (LaGraize et al., 2010). In inflammatory and neuropathic pain conditions pronociceptive effects of 5-HT3R prevail, although a 5-HT3R agonist (mCPBG) inhibited nociceptive behaviors in the formalin pain test (Jeong et al., 2004) and had antiallodynic effects in a neuropathic pain model (SNL) and this effect was reversed by GABAA or GABAB receptor blockade (Okazaki et al., 2008).
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Increase of histone acetylation in the GABAergic neurons in the rostral ventromedial medulla associated with mechanical hypersensitivity after repeated restraint stress
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Psychophysical stresses frequently increase sensitivity and response to pain, which is termed stress-induced hyperalgesia (SIH). However, the mechanism remains unknown. The rostral ventromedial medulla (RVM) and locus coeruleus (LC) are core elements of the descending pain modulatory system, which modulate nociceptive transmission in the spinal dorsal horn. In the present study we examined the acetylation of histone H3 in the RVM and LC after repeated restraint stress for 3 weeks to clarify changes in the descending pain modulatory system in the rat with SIH. The repeated restraint stress induced mechanical hypersensitivity in the hindpaw and an increase in acetylation of histone H3 in the RVM but not the LC. The number of acetylated histone H3-IR cells in the RVM was significantly higher in the repeated restraint group (282.9 ± 43.1) than that in the control group (134.7 ± 15.6, p < 0.05). Furthermore, the repeated restraint stress increased acetylation of histone H3 in the RVM GABAergic neurons but not the RVM serotonergic neurons. The GAD67 protein level in the RVM was significantly higher in repeated restraint group (144.9 ± 17.0%) than that in the control group (100.0 ± 8.9%, p < 0.05). These findings suggest the possibility that the stress-induced neuroplasticity in the RVM GABAergic neurons is involved in the mechanical hypersensitivity due to the dysfunction of the descending pain modulatory system.
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¹: Present address: University of Maryland School of Medicine, Department of Physiology, 655 W. Baltimore Street, Baltimore, MD 21201, USA.

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Pain Mechanisms and Sensory NeuroscienceResearch PaperSpinal cord mechanisms mediating behavioral hyperalgesia induced by neurokinin-1 tachykinin receptor activation in the rostral ventromedial medulla

Abstract

Research Highlights

Section snippets

Animals

Role of NK-1 receptors in the RVM in the initiation and maintenance of inflammation-induced behavioral hyperalgesia

Discussion

Acknowledgments

J Pain

Neuroscience

Neuroscience

Neuroscience

Neuroscience

Trends Neurosci

J Biol Chem

Pain

Neurosci Lett

Pain

Neuroscience

Pain

Eur J Pharmacol

Neuroscience

Neurosci Lett

Brain Res Mol Brain Res

Brain Res

Prog Neurobiol

Neurobiol Dis

Pain

Trends Neurosci

Pain

Pain

Prog Brain Res

Neuroscience

Brain Res

Trends Pharmacol Sci

Neuroscience

Prog Brain Res

Brain Res Rev

Pain

Brain Res Protoc

NK-1 receptors modulate the excitability of ON cells in the rostral ventromedial medulla

J Neurophysiol

Time-dependent descending facilitation from the rostral ventromedial medulla maintains, but does not initiate, neuropathic pain

J Neurosci

Pain Mechanisms and Sensory Neuroscience
Research Paper
Spinal cord mechanisms mediating behavioral hyperalgesia induced by neurokinin-1 tachykinin receptor activation in the rostral ventromedial medulla