Dermorphin D-Arg2, Lys4 (1-4) amide inhibits below-level heat hypersensitivity in mice after contusive thoracic spinal cord injury

We examined whether activating mu-opioid receptors (MORs) in the peripheral nervous system attenuates spinal cord injury (SCI) pain-like behavior in mice. We produced a contusive SCI at the T10 vertebral level and examined motor and sensory dysfunction for 6 weeks. At 6 weeks, we tested the effect of subcutaneous (s.c.) injection of dermorphin [D-Arg2, Lys4] (1-4) amide (DALDA), a peripherally acting MOR-preferring agonist, on mechanical and heat hypersensitivity. Basso mouse scale score was significantly decreased after SCI, and mice showed hypersensitivity to mechanical and heat stimulation at the hind paw beginning at 2 weeks, as indicated by increased paw withdrawal frequency to mechanical stimulation and decreased paw withdrawal latency to heat stimulation. In wild-type SCI mice, DALDA (1 mg/kg, s.c.) attenuated heat but not mechanical hypersensitivity. The effect was blocked by pretreatment with an intraperitoneal injection of methylnaltrexone (5 mg/kg), a peripherally restricted opioid receptor antagonist, and was also diminished in Pirt-MOR conditional knockout mice. DALDA did not adversely affect exploratory activity or induced preference to drug treatment in SCI mice. In vivo calcium imaging showed that DALDA (1, 10 mg/kg, s.c.) inhibited responses of small dorsal root ganglion neurons to noxious heat stimulation in Pirt-GCaMP6s mice after SCI. Western blot analysis showed upregulation of MOR in the lumbar spinal cord and sciatic nerves at 6 weeks after SCI. Our fin...
Source: Pain - Category: Anesthesiology Tags: Research Paper Source Type: research

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In this study, the biological effects and mechanisms of RACK1 contributes to the pathogenesis of chronic constriction injury (CCI)-induced neuropathic pain were investigated. By western blot and staining, we found that RACK1 protein changed in dorsal root ganglion (DRG) neurons and spinal cord (SC) neurons except glial cells after CCI. Especially, RACK1 was co-located with IB4-, CGRP-positive neurons, suggesting it was related to integrate nociceptive information from the primary afferents in DRG. The successful establishment of CCI models also directly led to mechanical allodynia and heat hyperalgesia, which could be rev...
Source: Neuroscience Letters - Category: Neuroscience Source Type: research
Conclusion and Future Aspects This review summarizes available NTF expression data, compiles existing evidence on the effects of glial NTF signaling in healthy conditions and in disease models (Figure 1), and highlights the importance of this topic for future studies. The relationship between NTFs and glia is crucial for both the developing and adult brain. While some of these factors, such as NT-3 and CNTF, have highly potent effects on gliogenesis, others like BDNF and GDNF, are important for glia-mediated synapse formation. Neurotrophic factors play significant roles during neurodegenerative disorders. In many cases, ...
Source: Frontiers in Physiology - Category: Physiology Source Type: research
We examined the expression of TRPV1 in peripheral tissue and DRG neurons of CPIP model rats and we studied whether CPIP model could induce peripheral sensitization of TRPV1 channel and enhance DRG neuron excitability. Then we examined the therapeutic effects of locally applied TRPV1 specific antagonist AMG9810 on pain responses of CPIP model rats. Lastly, we explored the effects of AMG9810 on DRG neuron hyperexcitability and spinal glial activation induced by CPIP. Our results demonstrate that TRPV1 plays an important role in mediating the behavioral hypersensitivity of CPIP model rats via promoting peripheral nociceptor a...
Source: Frontiers in Pharmacology - Category: Drugs & Pharmacology Source Type: research
In this study we established a chronic constrictive injury (CCI) model and used western blot, quantitative real-time PCR, immunostaining, intrathecal injection, and siRNA methods to explore which HDAC subunit is involved in regulating Kv1.2 expression to mediate NPP. Our results demonstrated that nerve injury led to upregulation of HDAC1 expression in the DRG, and of HDAC2 in the DRG and spinal cord. Double-labeling immunofluorescence histochemistry showed that Kv1.2 principally co-localized with HDAC2, but not HDAC1, in NF200-positive large neurons of the DRG. Intrathecal injection with the HDAC inhibitor, suberoylanilide...
Source: Neuroscience - Category: Neuroscience Source Type: research
Conclusion: The present study suggests that the extract of LMZ attenuates CFA-induced inflammatory pain by suppressing the ERK1/2 and NF-κB signaling pathway at both peripheral and central level. Introduction Pain is one of the most common symptoms in clinical practice, and inflammatory pain is the most important type of pain (Patapoutian et al., 2009). Inflammatory pain is a growing global health problem. In generally, there is a common course of progression in inflammation and pain share. When patients experience inflammation, they may develop hyperalgesia or allodynia to various mechanical, thermal, or che...
Source: Frontiers in Pharmacology - Category: Drugs & Pharmacology Source Type: research
Tomoya Nakamachi1*, Ayano Tanigawa1, Norifumi Konno1, Seiji Shioda2 and Kouhei Matsuda1 1Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, Toyama, Japan 2Innovative Drug Discovery, Global Research Center for Innovative Life Science, Hoshi University, Tokyo, Japan Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with potent suppressive effects on feeding behavior in rodents, chicken, and goldfish. Teleost fish express two PACAPs (PACAP1, encoded by the adcyap1a gene, and PACAP2, encoded by the adcyap1b gene) and two PACAP receptors (PAC...
Source: Frontiers in Endocrinology - Category: Endocrinology Source Type: research
CONCLUSIONS: CREB1 involved in the regulation of NP and nerve repair process, suggesting that CREB1 has potential as a new target for the treatment of chronic NP. PMID: 30964189 [PubMed - in process]
Source: European Review for Medical and Pharmacological Sciences - Category: Drugs & Pharmacology Tags: Eur Rev Med Pharmacol Sci Source Type: research
Conclusion and Perspectives Since their cloning 20 years ago, the physiological importance of TREK-1 channels has continued to grow (Figure 3). Today, TREK-1 channels have been shown to be important and their presence is essential in a number of physiopathological processes. Their involvement in these different processes demonstrate the necessity to design pharmacological modulators, activators or inhibitors, of these channels to correct any TREK-1-related dysfunctions. Despites a number of studies and many molecule screenings, only few putative new drugs were identified. The activators belonging to the ML and BL series ...
Source: Frontiers in Pharmacology - Category: Drugs & Pharmacology Source Type: research
This study not only provides biological evidence to support the use of duloxetine as the first standard CIPN drug but will also lead to potential new targets for CIPN drug development. Introduction A major dose-limiting complication of chemotherapy is chemotherapy-induced peripheral neuropathy (CIPN). The greatest contributors to CIPN are taxanes (e.g., paclitaxel) and platinum-based (e.g., oxaliplatin) treatments (Krukowski et al., 2015). Paclitaxel (PTX) can effectively treat several of the most common cancers including breast cancer, lung cancer, and ovarian cancer (Ewertz et al., 2015; Cetinkaya-Fisgin et al., ...
Source: Frontiers in Pharmacology - Category: Drugs & Pharmacology Source Type: research
Abstract Neuropathic pain (NP) has complicated pathogenesis as it mainly involves a lesion or dysfunction of the somatosensory nervous system and its clinical treatment remains challenging. Chronic constriction injury (CCI) model is a widely used neuropathic pain model and involved in mechanisms including both nerve inflammatory and injury. Cytokines and their receptors play essential roles in the occurrence and persistence of neuropathic pain, but the underlying mechanisms have not well been understood. Therefore, Interleukin-1 receptor-associated kinase 1 (IRAK1) is chosen to explore the possible mechanisms of N...
Source: Neurochemical Research - Category: Neuroscience Authors: Tags: Neurochem Res Source Type: research
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