Muscarinic cholinergic receptors in the human spinal cord: differential localization of [3H]pirenzepine and [3H]quinuclidinylbenzilate binding sites

doi:10.1016/0006-8993(85)90854-6

Brain Research

Volume 345, Issue 1, 14 October 1985, Pages 196-199

https://doi.org/10.1016/0006-8993(85)90854-6 Get rights and content

Abstract

The localization of muscarinic cholinergic receptor subtypes was studied in the human spinal cord using in vitro labelling of cryostat sections with [³H]quinuclidinylbenzilate (QNB) and [³H]pirenzepine (PZ) followed by autoradiography. The highest densities of [³H]QNB binding were localized in laminae II (substantia gelatinosa) and IX (motor neurons); in contrast, the highest density of [³H]PZ binding was localized to lamina II where the binding density was 22—32% higher than in lamina IX. These results suggest that the M₁ and M₂ muscarinic cholinergic receptor subtypes may be differentially localized in sensory and motor regions of the human spinal cord.

Reference (13)

AquiloniusS.-M. et al.
Topographical localization of choline acetyltransferase within the human spinal cord and comparison with some other species
Brain Research
(1981)
GillbergP.-G. et al.
Muscarinic binding sites in small homogenates and in autoradiographic sections of rat and human spinal cord
Brain Research
(1984)
NagataY. et al.
Regional distribution of cholinergic neurons in human spinal cord transections in the patients with and without motor neuron disease
Brain Research
(1982)
RexedB.
Some aspects of the cytoarchitectonics and synaptology of the spinal cord
Prog. Brain Res.
(1964)
ScattonB. et al.
Autoradiographic localization of muscarinic cholinergic receptors at various segmental levels of the human spinal cord
Neurosci. Lett.
(1984)
WatsonM. et al.
[³H]Pirenzepine selectively identifies a high-affinity population of muscarinic cholinergic receptors in the rat cerebral cortex
Life Sci.
(1982)

There are more references available in the full text version of this article.

Cited by (54)

Stimulating muscarinic M<inf>1</inf> receptors in the anterior cingulate cortex reduces mechanical hypersensitivity via GABAergic transmission in nerve injury rats
2019, Brain Research
Citation Excerpt :
Our previous immunohistochemistry study showed that muscarinic M1 receptors are clearly expressed in the rat ACC (Koga et al., 2017). Consistently, autoradiography studies in both humans and rats have shown the existence of muscarinic M1 receptors in the ACC (Villiger and Faull, 1985; Wamsley et al., 1984). In the current study, the nerve injury induced by PNSL at 7 days post-ligation did not change the protein expression of muscarinic M1 receptors in the contralateral and ipsilateral sides of the ACC.
Cholinergic systems modulate synaptic transmission across the neuraxis and play an important role in higher brain function including cognition, arousal and nociception. The anterior cingulate cortex (ACC) is a fundamental brain region for nociception and chronic pain, and receives cholinergic projections mainly from basal forebrain. Recently, we found that the activation of muscarinic M₁ receptors in the ACC produced antinociceptive behavior in response to mechanical stimulation. However, it has not been tested whether stimulating muscarinic receptors in the ACC can reduce mechanical hypersensitivity in animal models of chronic pain.
Here, we tested whether the activation of muscarinic M₁ receptors in the ACC can alleviate mechanical hypersensitivity in a nerve injury model. The activation of muscarinic M₁/M₄ receptors by McN-A-343 injected into the contralateral side of the ACC, but not into the ventral posterolateral nucleus, was found to dose-dependently reduce mechanical hypersensitivity 7 days following partial sciatic nerve ligation in rats. The reduction of mechanical hypersensitivity by McN-A-343, was blocked by a selective muscarinic M₁ antagonist, but not a M₄ receptor antagonist. Importantly, the nerve injury model did not change the protein expression of muscarinic M₁ receptors in the ACC. Additionally, a type A γ-aminobutyric acid (GABA_A) receptor agonist injected into the ACC reduced the mechanical hypersensitivity in this injury model. Finally, a GABA_A receptor antagonist blocked the reduction of mechanical hypersensitivity by McN-A-343 in the injury model. Collectively, these results suggest that activations of muscarinic M₁ receptors in the ACC reduce nerve injury-induced mechanical hypersensitivity through GABAergic transmission via GABA_A receptors.
Differential regulation of primary afferent input to spinal cord by muscarinic receptor subtypes delineated using knockout mice
2014, Journal of Biological Chemistry
Citation Excerpt :
On the other hand, stimulation of even-numbered mAChRs (M2 and M4) typically inhibits adenylyl cyclase activity and voltage-activated calcium channels through activation of Gi/o proteins (7–9). In both rats and humans, mAChRs in the spinal cord are densest in the superficial dorsal horn (10–12). M2 is the major mAChR subtype expressed in the spinal cord, whereas M3 and M4 subtypes represent only a fraction of the total mAChRs in the spinal cord (5, 13–15).
Stimulation of muscarinic acetylcholine receptors (mAChRs) inhibits nociceptive transmission at the spinal level. However, it is unclear how each mAChR subtype regulates excitatory synaptic input from primary afferents. Here we examined excitatory postsynaptic currents (EPSCs) of dorsal horn neurons evoked by dorsal root stimulation in spinal cord slices from wild-type and mAChR subtype knock-out (KO) mice. In wild-type mice, mAChR activation with oxotremorine-M decreased the amplitude of monosynaptic EPSCs in ∼67% of neurons but increased it in ∼10% of neurons. The inhibitory effect of oxotremorine-M was attenuated by the M₂/M₄ antagonist himbacine in the majority of neurons, and the remaining inhibition was abolished by group II/III metabotropic glutamate receptor (mGluR) antagonists in wild-type mice. In M₂/M₄ double-KO mice, oxotremorine-M inhibited monosynaptic EPSCs in significantly fewer neurons (∼26%) and increased EPSCs in significantly more neurons (33%) compared with wild-type mice. Blocking group II/III mGluRs eliminated the inhibitory effect of oxotremorine-M in M₂/M₄ double-KO mice. In M₂ single-KO and M₄ single-KO mice, himbacine still significantly reduced the inhibitory effect of oxotremorine-M. However, the inhibitory and potentiating effects of oxotremorine-M on EPSCs in M₃ single-KO and M₁/M₃ double-KO mice were similar to those in wild-type mice. In M₅ single-KO mice, oxotremorine-M failed to potentiate evoked EPSCs, and its inhibitory effect was abolished by himbacine. These findings indicate that activation of presynaptic M₂ and M₄ subtypes reduces glutamate release from primary afferents. Activation of the M₅ subtype either directly increases primary afferent input or inhibits it through indirectly stimulating group II/III mGluRs.
Spinal Cord: Regional Anatomy, Cytoarchitecture and Chemoarchitecture
2012, The Human Nervous System, Third Edition
Receptors involved in the antinociception of intrathecal melatonin in formalin test of rats
2011, Neuroscience Letters
The authors examined the antinocicepotive effect of melatonin in a nociceptive state and investigated a possible interaction with adrenergic or cholinergic receptors underlying this effect at the spinal level. Nociception was induced by a subcutaneous injection of 50 μl of a 5% formalin solution to the hindpaw of male Sprague–Dawley rats. The reversal effects of alpha-1 adrenoceptor antagonist (prazosin), alpha-2 adrenoceptor antagonist (yohimbine), muscarinic receptor antagonist (atropine) and nicotinic receptor antagonist (mecamylamine) on the activity of melatonin were assessed. Intrathecal melatonin reduced the flinching response during phase 1 and phase 2 in the formalin test. Intrathecal prazosin, yohimbine, atropine and mecamylamine increased the attenuating flinching response in both phases observed by intrathecal melatonin. Collectively, the present data suggest that intrathecal melatonin attenuates the facilitated state and acute pain evoked by formalin injection. Furthermore, the antinociception of melatonin is mediated through the alpha-1 adrenoceptor, alpha-2 adrenoceptor, muscarinic and nicotinic receptors in the spinal cord.
Dynamic control of glutamatergic synaptic input in the spinal cord by muscarinic receptor subtypes defined using knockout mice
2010, Journal of Biological Chemistry
Citation Excerpt :
For example, neurons and nerve terminals expressing choline acetyltransferase and acetylcholinesterase (enzymes for acetylcholine synthesis and degradation, respectively) are located in the spinal dorsal horn (1, 2). The superficial laminae contain the highest density of mAChRs in the spinal dorsal horn (3–5). Stimulation of mAChRs attenuates the responses of dorsal horn neurons to noxious stimuli (6), whereas blocking spinal mAChRs with atropine causes a large increase in pain sensitivity (7).
Activation of muscarinic acetylcholine receptors (mAChRs) in the spinal cord inhibits pain transmission. At least three mAChR subtypes (M₂, M₃, and M₄) are present in the spinal dorsal horn. However, it is not clear how each mAChR subtype contributes to the regulation of glutamatergic input to dorsal horn neurons. We recorded spontaneous excitatory postsynaptic currents (sEPSCs) from lamina II neurons in spinal cord slices from wild-type (WT) and mAChR subtype knock-out (KO) mice. The mAChR agonist oxotremorine-M increased the frequency of glutamatergic sEPSCs in 68.2% neurons from WT mice and decreased the sEPSC frequency in 21.2% neurons. Oxotremorine-M also increased the sEPSC frequency in ∼50% neurons from M₃-single KO and M₁/M₃ double-KO mice. In addition, the M₃ antagonist J104129 did not block the stimulatory effect of oxotremorine-M in the majority of neurons from WT mice. Strikingly, in M₅-single KO mice, oxotremorine-M increased sEPSCs in only 26.3% neurons, and J104129 abolished this effect. In M₂/M₄ double-KO mice, but not M₂- or M₄-single KO mice, oxotremorine-M inhibited sEPSCs in significantly fewer neurons compared with WT mice, and blocking group II/III metabotropic glutamate receptors abolished this effect. The M₂/M₄ antagonist himbacine either attenuated the inhibitory effect of oxotremorine-M or potentiated the stimulatory effect of oxotremorine-M in WT mice. Our study demonstrates that activation of the M₂ and M₄ receptor subtypes inhibits synaptic glutamate release to dorsal horn neurons. M₅ is the predominant receptor subtype that potentiates glutamatergic synaptic transmission in the spinal cord.
Signaling mechanisms mediating muscarinic enhancement of GABAergic synaptic transmission in the spinal cord
2009, Neuroscience
Activation of muscarinic acetylcholine receptors (mAChRs) inhibits spinal nociceptive transmission by potentiation of GABAergic tone through M₂, M₃, and M₄ subtypes. To study the signaling mechanisms involved in this unique mAChR action, GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of lamina II neurons were recorded using whole-cell patch clamp techniques in rat spinal cord slices. The mAChR agonist oxotremorine-M caused a profound increase in the frequency of GABAergic sIPSCs, which was abolished in the Ca²⁺-free solution. Inhibition of voltage-gated Ca²⁺ channels with Cd²⁺ and Ni²⁺ largely reduced the effect of oxotremorine-M on sIPSCs. Blocking nonselective cation channels (NSCCs) with SKF96365 or 2-APB also largely attenuated the effect of oxotremorine-M. However, the KCNQ channel blocker XE991 and the adenylyl cyclase inhibitor MDL12330A had no significant effect on oxotremorine-M-induced increases in sIPSCs. Furthermore, the phosphoinositide-3-kinase (PI3K) inhibitor wortmannin or LY294002 significantly reduced the potentiating effect of oxotremorine-M on sIPSCs. In the spinal cord in which the M₃ subtype was specifically knocked down by intrathecal small interfering RNA (siRNA) treatment, SKF96365 and wortmannin still significantly attenuated the effect of oxotremorine-M. In contrast, SKF96365 and wortmannin both failed to alter the effect of oxotremorine-M on sIPSCs when the M₂/M₄ mAChRs were blocked. Therefore, our study provides new evidence that activation of mAChRs increases synaptic GABA release through Ca²⁺ influx and voltage-gated Ca²⁺ channels. The PI3K–NSCC signaling cascade is primarily involved in the excitation of GABAergic interneurons by the M₂/M₄ mAChRs in the spinal dorsal horn.

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: This research was supported by the New Zealand Medical Research Council, the New Zealand Neurological Foundation and the Auckland Medical Research Foundation.

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Muscarinic cholinergic receptors in the human spinal cord: differential localization of [3H]pirenzepine and [3H]quinuclidinylbenzilate binding sites

Abstract

Brain Research

Brain Research

Brain Research

Prog. Brain Res.

Neurosci. Lett.

Life Sci.

Muscarinic cholinergic receptors in the human spinal cord: differential localization of [³H]pirenzepine and [³H]quinuclidinylbenzilate binding sites