scholarly journals Gene Knockdown of the N -Methyl-d-Aspartate Receptor NR1 Subunit with Subcutaneous Small Interfering RNA Reduces Inflammation-induced Nociception in Rats

2010 ◽  
Vol 112 (6) ◽  
pp. 1482-1493 ◽  
Author(s):  
Ping-Heng Tan ◽  
Yuan-Yi Chia ◽  
Lok-Hi Chow ◽  
Jieh-Jie Chen ◽  
Lin-Cheng Yang ◽  
...  
Keyword(s):  
Nervous System ◽  
Dorsal Root Ganglion ◽  
Subcutaneous Injection ◽  
Messenger Rna ◽  
Dorsal Root ◽  
Complete Freund’S Adjuvant ◽  
Aspartate Receptor ◽  
Freund’S Adjuvant ◽  
Complete Freund's Adjuvant ◽  
Freund's Adjuvant

Background Spinal N-methyl-D-aspartate receptors have been demonstrated to play an important role in the facilitation and maintenance of nociception. To avoid adverse effects of blocking N-methyl-D-aspartate receptors in the central nervous system, blocking N-methyl-D-aspartate receptor in peripheral nervous system is an ideal alternative. Transfection of small interfering RNAs (siRNAs) into cells has been revealed to provide potent silencing of specific genes. In this study, the authors examined the effect of subcutaneous injection of siRNA targeting the NR1 subunit of the N-methyl-D-aspartate receptor on silencing NR1 gene expression and subsequently abolishing inflammatory nociception in rats. Methods Male Sprague-Dawley rats received intradermal injection of NR1 siRNA and underwent injection of formalin or complete Freund's adjuvant. The flinch response and mechanical hypersensitivity by von Frey filaments were assessed. Then the messenger RNA and protein of NR1 in skin and dorsal root ganglion were analyzed. Results The results revealed that subcutaneous injection of 1 nmol NR1 siRNA effectively diminished the nociception induced by formalin and complete Freund's adjuvant stimuli and attenuated the level of NR1 messenger RNA and protein in skin and ipsilateral dorsal root ganglion. The antinociception effect and the inhibition of NR1 expression persisted for about 7 days after administration of NR1 siRNA. Conclusions The data of this study suggest that NR1 siRNA has potential therapeutic value in the treatment of inflammatory pain induced or maintained by peripheral nociceptor activity and support the potential application of this method to the study of nociceptive processes and target the validation of pain-associated genes.

scholarly journals Combination of a δ-opioid Receptor Agonist and Loperamide Produces Peripherally-mediated Analgesic Synergy in Mice

2019 ◽  
Vol 131 (3) ◽  
pp. 649-663 ◽  
Author(s):  
Daniel J. Bruce ◽  
Cristina D. Peterson ◽  
Kelley F. Kitto ◽  
Eyup Akgün ◽  
Sophia Lazzaroni ◽  
...  
Keyword(s):  
Nervous System ◽  
Opioid Receptor ◽  
Receptor Agonist ◽  
Complete Freund’S Adjuvant ◽  
Opioid Receptor Agonist ◽  
The Central Nervous System ◽  
Freund’S Adjuvant ◽  
Complete Freund's Adjuvant ◽  
Freund's Adjuvant ◽  
Δ Opioid Receptor

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background The long-term use of opioids for analgesia carries significant risk for tolerance, addiction, and diversion. These adverse effects are largely mediated by μ-opioid receptors in the central nervous system. Based on the authors’ previous observation that morphine and δ-opioid receptor agonists synergize in spinal cord in a protein kinase Cε–dependent manner, they predicted that this μ-opioid receptor–δ-opioid receptor synergy would take place in the central terminals of nociceptive afferent fibers and generalize to their peripheral terminals. Therefore, the authors hypothesized that loperamide, a highly efficacious μ-opioid receptor agonist that is excluded from the central nervous system, and oxymorphindole, a δ-opioid receptor agonist that was shown to synergize with morphine spinally, would synergistically reverse complete Freund’s adjuvant–induced hyperalgesia. Methods Using the Hargreaves assay for thermal nociception, the von Frey assay for mechanical nociception and the complete Freund’s adjuvant–induced model of inflammatory pain, we tested the antinociceptive and antihyperalgesic effect of loperamide, oxymorphindole, or the loperamide–oxymorphindole combination. Animals (Institute for Cancer Research [ICR] CD1 strain mice; n = 511) received drug by systemic injection, intraplantar injection to the injured paw, or a transdermal solution on the injured paw. Dose–response curves for each route of administration and each nociceptive test were generated, and analgesic synergy was assessed by isobolographic analysis. Results In naïve animals, the loperamide–oxymorphindole combination ED50 value was 10 times lower than the theoretical additive ED50 value whether given systemically or locally. In inflamed animals, the combination was 150 times more potent systemically, and 84 times more potent locally. All combinations showed statistically significant synergy when compared to the theoretical additive values, as verified by isobolographic analysis. The antihyperalgesia was ablated by a peripherally-restricted opioid antagonist. Conclusions From these data we conclude that the loperamide–oxymorphindole combination synergistically reverses complete Freund’s adjuvant–induced inflammatory hyperalgesia. The authors also conclude that this interaction is mediated by opioid receptors located in the peripheral nervous system.

scholarly journals Direct Evidence for the Ongoing Brain Activation by Enhanced Dynorphinergic System in the Spinal Cord under Inflammatory Noxious Stimuli

2010 ◽  
Vol 112 (2) ◽  
pp. 418-431 ◽  
Author(s):  
Yasuko Taketa ◽  
Keiichi Niikura ◽  
Yasuhisa Kobayashi ◽  
Masaharu Furuya ◽  
Toshikazu Shimizu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Messenger Rna ◽  
Intrathecal Injection ◽  
Complete Freund’S Adjuvant ◽  
Dynorphin A ◽  
Intraplantar Injection ◽  
Freund’S Adjuvant ◽  
Complete Freund's Adjuvant ◽  
Freund's Adjuvant ◽  
Noxious Stimuli

Background Dynorphin A in the spinal cord is considered to contribute to nociceptive stimuli. However, it has not yet been determined whether activation of the spinal dynorphinergic system under nociceptive stimuli plays a role in direct acceleration of the ascending nociceptive pathway. In this study, the authors investigated the role of spinal dynorphinergic transmission in ongoing brain activation under noxious stimuli in mice. Methods The changes in prodynorphin messenger RNA expression and dynorphin A (1-17)-like immunoreactivity in the mouse spinal cord were determined after the intraplantar injection of complete Freund's adjuvant in mice. The signal intensity in different brain regions after the intraplantar injection of complete Freund's adjuvant or intrathecal injection of dynorphin A (1-17) was measured by a pharmacological functional magnetic resonance imaging analysis. Results Complete Freund's adjuvant injection produced pain-associated behaviors and induced a dramatic increase in signal intensity in the mouse cingulate cortex, somatosensory cortex, insular cortex, and thalamic nuclei. These effects were not seen in prodynorphin knockout mice. Prodynorphin messenger RNA expression and dynorphin A (1-17)-like immunoreactivity on the ipsilateral side of the spinal cord were markedly increased in complete Freund's adjuvant-injected mice. Furthermore, intrathecal injection of dynorphin A (1-17) at relatively high doses caused pain-associated behaviors and a remarkable increase in the activities of the cingulate cortex, somatosensory cortex, insular cortex, and medial and lateral thalamic nuclei in mice. Conclusions These findings indicate that spinally released dynorphin A (1-17) by noxious stimuli leads to the direct activation of ascending pain transmission.

Bromodomain-containing Protein 4 Activates Voltage-gated Sodium Channel 1.7 Transcription in Dorsal Root Ganglia Neurons to Mediate Thermal Hyperalgesia in Rats

2017 ◽  
Vol 127 (5) ◽  
pp. 862-877 ◽  
Author(s):  
Ming-Chun Hsieh ◽  
Yu-Cheng Ho ◽  
Cheng-Yuan Lai ◽  
Hsueh-Hsiao Wang ◽  
An-Sheng Lee ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Dorsal Root Ganglia ◽  
Dorsal Root ◽  
Thermal Hyperalgesia ◽  
Complete Freund’S Adjuvant ◽  
Voltage Gated Sodium Channel ◽  
Voltage Gated ◽  
Freund’S Adjuvant ◽  
Complete Freund's Adjuvant ◽  
Freund's Adjuvant

Abstract Background Bromodomain-containing protein 4 binds acetylated promoter histones and promotes transcription; however, the role of bromodomain-containing protein 4 in inflammatory hyperalgesia remains unclear. Methods Male Sprague–Dawley rats received hind paw injections of complete Freund’s adjuvant to induce hyperalgesia. The dorsal root ganglia were examined to detect changes in bromodomain-containing protein 4 expression and the activation of genes involved in the expression of voltage-gated sodium channel 1.7, which is a key pain-related ion channel. Results The intraplantar complete Freund’s adjuvant injections resulted in thermal hyperalgesia (4.0 ± 1.5 s; n = 7). The immunohistochemistry and immunoblotting results demonstrated an increase in the bromodomain-containing protein 4–expressing dorsal root ganglia neurons (3.78 ± 0.38 fold; n = 7) and bromodomain-containing protein 4 protein levels (2.62 ± 0.39 fold; n = 6). After the complete Freund’s adjuvant injection, histone H3 protein acetylation was enhanced in the voltage-gated sodium channel 1.7 promoter, and cyclin-dependent kinase 9 and phosphorylation of RNA polymerase II were recruited to this area. Furthermore, the voltage-gated sodium channel 1.7–mediated currents were enhanced in neurons of the complete Freund’s adjuvant rats (55 ± 11 vs. 19 ± 9 pA/pF; n = 4 to 6 neurons). Using bromodomain-containing protein 4–targeted antisense small interfering RNA to the complete Freund’s adjuvant–treated rats, the authors demonstrated a reduction in the expression of bromodomain-containing protein 4 (0.68 ± 0.16 fold; n = 7), a reduction in thermal hyperalgesia (7.5 ± 1.5 s; n = 7), and a reduction in the increased voltage-gated sodium channel 1.7 currents (21 ± 4 pA/pF; n = 4 to 6 neurons). Conclusions Complete Freund’s adjuvant triggers enhanced bromodomain-containing protein 4 expression, ultimately leading to the enhanced excitability of nociceptive neurons and thermal hyperalgesia. This effect is likely mediated by the enhanced expression of voltage-gated sodium channel 1.7.

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