5-Hydroxytryptamine Type 3 Receptor Modulates Opioid-induced Hyperalgesia and Tolerance in Mice

Background Opioid-induced hyperalgesia (OIH) and tolerance are challenging maladaptations associated with opioids in managing pain. Recent genetic studies and the existing literature suggest the 5-hydroxytryptamine type 3 (5-HT3) receptor participates in these phenomena. The location of the relevant receptor populations and the interactions between the 5-HT3 system and other systems controlling OIH and tolerance have not been explored, however. We hypothesized that 5-HT3 receptors modulate OIH and tolerance, and that this modulation involves the control of expression of multiple neurotransmitter and receptor systems. Methods C57BL/6 mice were exposed to a standardized 4-day morphine administration protocol. The 5-HT3 antagonist ondansetron was administered either during or after the conclusion of morphine administration. Mechanical testing was used to quantify OIH, and thermal tail-flick responses were used to measure morphine tolerance. In other experiments spinal cord and dorsal root ganglion tissues were harvested for analysis of messenger RNA concentrations by real-time polymerase chain reaction or immunochemistry analysis. Results The results showed that (1) systemic or intrathecal injection of ondansetron significantly prevented and reversed OIH, but not local intraplantar injection; (2) systemic or intrathecal injection of ondansetron prevented and reversed tolerance; and (3) ondansetron blocked morphine-induced increases of multiple genes relevant to OIH and tolerance in dorsal root ganglion and spinal cord. Conclusions Morphine acts via a 5-HT3-dependent mechanism to support multiple maladaptations to the chronic administration of morphine. Furthermore, the use of 5-HT3 receptor antagonists may provide a new avenue to prevent or reverse OIH and tolerance associated with chronic opioid use.

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Microglial BDNF, PI3K, and p-ERK in the Spinal Cord Are Suppressed by Pulsed Radiofrequency on Dorsal Root Ganglion to Ease SNI-Induced Neuropathic Pain in Rats

Pain Research and Management ◽

10.1155/2019/5948686 ◽

2019 ◽

Vol 2019 ◽

pp. 1-15 ◽

Cited By ~ 3

Author(s):

Xueru Xu ◽

Shaoxiong Fu ◽

Xiaomei Shi ◽

Rongguo Liu

Keyword(s):

Spinal Cord ◽

Neuropathic Pain ◽

Dorsal Root Ganglion ◽

Nerve Injury ◽

Calcium Binding ◽

Dorsal Root ◽

Intrathecal Injection ◽

Pulsed Radiofrequency ◽

Erk Phosphorylation ◽

Extracellular Signal

Background. Pulsed radiofrequency (PRF) on the dorsal root ganglion (DRG) has been applied to alleviate neuropathic pain effectively, yet the mechanisms underlying pain reduction owing to this treatment are not clarified completely. The activated microglia, brain-derived neurotrophic factor (BDNF), phosphatidylinositol 3-kinase (PI3K), and phosphorylated extracellular signal-regulated kinase (p-ERK) in the spinal cord were demonstrated to be involved in developing neuropathic pain. Also, it has been just known that PRF on DRG inhibits the microglial activation in nerve injury rats. Here, we aim to investigate whether PRF treatment could regulate the levels of BDNF, PI3K, and p-ERK in the spinal cord of rats with spared nerve injury (SNI) via suppressing the spinal microglia activation to ease neuropathic pain. Methods. The rats with SNI were intrathecally treated with minocycline (specific microglia inhibitor) or same volume of dimethyl sulfoxide once daily, beginning from 1 h before nerve transection to 7 days. PRF was applied adjacent to the L4-L5 DRG of rats with SNI at 45 V for 6 min on the seventh postoperative day, whereas the free-PRF rats were treated without PRF. The withdrawal thresholds were studied, and the spinal levels of ionized calcium-binding adapter molecule 1 (Iba1), BDNF, PI3K, and p-ERK were calculated by western blot analysis, reverse transcription-polymerase chain reaction, and immunofluorescence. Results. The paw withdrawal mechanical threshold and paw withdrawal thermal latency decreased in the ipsilateral hind paws after SNI, and the spinal levels of Iba1, BDNF, PI3K, and p-ERK increased on day 21 after SNI compared with baseline (P<0.01). An intrathecal injection of minocycline led to the reversal of SNI-induced allodynia and increase in levels of Iba1, BDNF, PI3K, and p-ERK. Withdrawal thresholds recovered partially after a single PRF treatment for 14 days, and SNI-induced microglia hyperactivity, BDNF upregulation, and PI3K and ERK phosphorylation in the spinal cord reduced on D14 due to the PRF procedure. Conclusion. Microglial BDNF, PI3K, and p-ERK in the spinal cord are suppressed by the therapy of PRF on DRG to ease SNI-induced neuropathic pain in rats.

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Intrathecal injection of bone marrow stromal cells attenuates neuropathic pain via inhibition of P2X4R in spinal cord microglia

Journal of Neuroinflammation ◽

10.1186/s12974-019-1631-0 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 7

Author(s):

Yongbo Teng ◽

Yang Zhang ◽

Shouwei Yue ◽

Huanwen Chen ◽

Yujuan Qu ◽

...

Keyword(s):

Spinal Cord ◽

Bone Marrow ◽

Neuropathic Pain ◽

Dorsal Root Ganglion ◽

Dorsal Root ◽

Purinergic Receptor ◽

Intrathecal Injection ◽

Transient Receptor Potential Vanilloid ◽

Drg Neurons ◽

Analgesic Effects

Abstract Background Neuropathic pain is one of the most debilitating of all chronic pain syndromes. Intrathecal (i.t.) bone marrow stromal cell (BMSC) injections have a favorable safety profile; however, results have been inconsistent, and complete understanding of how BMSCs affect neuropathic pain remains elusive. Methods We evaluated the analgesic effect of BMSCs on neuropathic pain in a chronic compression of the dorsal root ganglion (CCD) model. We analyzed the effect of BMSCs on microglia reactivity and expression of purinergic receptor P2X4 (P2X4R). Furthermore, we assessed the effect of BMSCs on the expression of transient receptor potential vanilloid 4 (TRPV4), a key molecule in the pathogenesis of neuropathic pain, in dorsal root ganglion (DRG) neurons. Results I.t. BMSC transiently but significantly ameliorated neuropathic pain behavior (37.6% reduction for 2 days). We found no evidence of BMSC infiltration into the spinal cord parenchyma or DRGs, and we also demonstrated that intrathecal injection of BMSC-lysates provides similar relief. These findings suggest that the analgesic effects of i.t. BMSC were largely due to the release of BMSC-derived factors into the intrathecal space. Mechanistically, we found that while i.t. BMSCs did not change TRPV4 expression in DRG neurons, there was a significant reduction of P2X4R expression in the spinal cord microglia. BMSC-lysate also reduced P2X4R expression in activated microglia in vitro. Coadministration of additional pharmacological interventions targeting P2X4R confirmed that modulation of P2X4R might be a key mechanism for the analgesic effects of i.t. BMSC. Conclusion Altogether, our results suggest that i.t. BMSC is an effective and safe treatment of neuropathic pain and provides novel evidence that BMSC’s analgesic effects are largely mediated by the release of BMSC-derived factors resulting in microglial P2X4R downregulation.

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

Anesthesiology ◽

10.1097/aln.0b013e3181ca31d9 ◽

2010 ◽

Vol 112 (2) ◽

pp. 418-431 ◽

Cited By ~ 6

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.

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Glycine receptors expression in rat spinal cord and dorsal root ganglion in prostaglandin E2 intrathecal injection models

BMC Neuroscience ◽

10.1186/s12868-018-0470-8 ◽

2018 ◽

Vol 19 (1) ◽

Cited By ~ 2

Author(s):

Hung-Chen Wang ◽

Kuang-I Cheng ◽

Pei-Ru Chen ◽

Kuang-Yi Tseng ◽

Aij-Lie Kwan ◽

...

Keyword(s):

Spinal Cord ◽

Dorsal Root Ganglion ◽

Prostaglandin E2 ◽

Dorsal Root ◽

Intrathecal Injection ◽

Glycine Receptors ◽

Rat Spinal Cord

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Down-regulation of NOX4 expression in dorsal root ganglion of spinal cord could alleviate cancer induced bone pain in rats by reducing oxidative stress response

10.21203/rs.2.24002/v1 ◽

2020 ◽

Author(s):

Hao Long ◽

Hui Zheng ◽

Long Ai ◽

Kamil Osman ◽

Zhigang Liu

Keyword(s):

Oxidative Stress ◽

Spinal Cord ◽

Dorsal Root Ganglion ◽

Dorsal Root ◽

Bone Pain ◽

Malignant Tumors ◽

Intrathecal Injection ◽

Down Regulation ◽

Downstream Effects

Abstract Background Cancer-induced bone pain (CIBP) is a common complication in many patients with malignant tumors, and seriously affects their quality of life. Recent studies have implicated reactive oxygen species (ROS) in the perception and regulation of pain through the spinal cord, indicating their possible involvement in CIBP as well. NADPH oxidases (NOX) generate ROS such as H2O2, superoxide anion, nitric oxide etc. as byproducts of oxidative phosphorylation. In this study, we will analyze the expression levels of NOX4 and its mechanism of action in CIBP. Material and Methods A CIBP model was established in rats and NOX4 was knocked down in the dorsal root ganglia via intrathecal injection of specific lentivirus. The downstream effects of NOX4 knockdown were analyzed by RT-PCR, immunofluorescence and Western blotting. Results NOX4 was significantly upregulated in the rats with CIBP, and mainly localized in the microglia of the dorsal root ganglion of spinal cord. However, NOX4 knockdown alleviated CIBP by reducing oxidative stress and weakening spinal cord sensitization to pain. Conclusion Down-regulation of NOX4 in the dorsal root ganglion of spinal cord can alleviate CIBP by reducing oxidative stress.

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