ABSTRACT
OBJECTIVE@#To investigate the inhibitory effect of ANA-12 that blocks brain-derived neurotrophic factor (BDNF)/ tropomyosin receptor kinase B (TrkB) signaling on inflammatory pain in rats and explore the underlying mechanism.@*METHODS@#Forty-two adult SD rats were randomized into BDNF-induced acute pain group (n=24) and CFA-induced chronic pain group. The former group were randomly divided into 4 subgroups, including a control group, ANA-12 treatment group, BDNF treatment group, and BDNF+ANA-12 treatment group; the latter group were subgrouped into control group, CFA treatment group (CFA) and CFA + ANA-12 treatment group. The effects of ANA-12 treatment on pain behaviors of the rats with BDNF-induced acute pain and CFA-induced chronic inflammatory pain were observed. Western blotting was used to examine TrkB signaling and expressions of microglia marker protein Iba1 and TNF-α in the spinal cord of the rats.@*RESULTS@#BDNF injection into the subarachnoid space significantly increased the number of spontaneous paw withdrawal of the rats (P < 0.05), which was obviously reduced by ANA-12 treatment (P < 0.05). The rats with intraplantar injection of CFA, showed significantly increased ipsilateral mechanical stimulation sensitivity (P < 0.05), and ANA-12 treatment obviously increased the ipsilateral foot withdrawal threshold (P < 0.05). Treatment with either BDNF or CFA significantly increased the phosphorylation level of TrkB (Y705) in the spinal cord of the rats (P < 0.05), which was significantly lowered by ANA-12 treatment (P < 0.05). Treatment with BDNF and CFA both significantly up-regulated the expressions of Iba1 and TNF-α in the spinal cord (P < 0.05), but ANA-12 significantly reduced their expression levels (P < 0.05).@*CONCLUSION@#ANA-12 can reduce spinal cord inflammation and relieve acute and chronic pain in rats by targeted blocking of BDNF/TrkB signaling.
Subject(s)
Animals , Rats , Brain-Derived Neurotrophic Factor/metabolism , Chronic Pain/drug therapy , Inflammation , Rats, Sprague-Dawley , Receptor, trkB/metabolismABSTRACT
As the most common symptomatic reason to seek medical consultation, pain is a complex experience that has been classified into different categories and stages. In pain processing, noxious stimuli may activate the anterior cingulate cortex (ACC). But the function of ACC in the different pain conditions is not well discussed. In this review, we elaborate the commonalities and differences from accumulated evidence by a variety of pain assays for physiological pain and pathological pain including inflammatory pain, neuropathic pain, and cancer pain in the ACC, and discuss the cellular receptors and signaling molecules from animal studies. We further summarize the ACC as a new central neuromodulation target for invasive and non-invasive stimulation techniques in clinical pain management. The comprehensive understanding of pain processing in the ACC may lead to bridging the gap in translational research between basic and clinical studies and to develop new therapies.
ABSTRACT
Pathological pain refers to the pain that caused by the tissue injury due to trauma, infection, tumor, etc. It may turn into chronic pain if it lasts for more than one month or remains when the tissue injury is healed. Patients with chronic pain often suffer insomnia. anxiety, depression and other mental disorders. which may seriously impair their physical function and quality of life, subsequently leading to many social and economic problems. Recent studies have found that epigenetic regulation may explain, at molecular levei, the pathogenesis of pathological pain, including inflammation pain, neuropathic pain and psychological pain, which may lead to the devclopment of its thcrapcutic means. In this article, we reviewed the latest research progress of epigenetic regulation of chronic pathological pain. including DNA methylation, histone acetylation and miRNA activity.
ABSTRACT
AIM:To investigate the effects of P2X4 receptor on peri-sciatic administration of recombinant rat TNF-α(rrTNF)-induced mechanical allodynia.METHODS:Male Sprague-Dawley rats (180~200 g) were used in the experiments.The levels of P2X4 receptor on day 3, day 7 and day 14 after peri-sciatic administration of rrTNF were exam-ined by Western blot, and the location of P2X4 receptor in the spinal dorsal horn was observed by double immunofluores-cence staining.The changes of 50%paw-withdrawal thresholds of the rat were detected by behavioral test, and the level of TNF-αin the spinal dorsal horn was also examined by Western blot when TNP-ATP was intrathecally injected before the ad-ministration of rrTNF.RESULTS:Compared with control group, the expression of P2X4 receptor in the spinal dorsal horn on the ipsilateral side significantly increased on day 3, day 7 and day 14 (P<0.01) after rrTNF (100 ng/L) administra-tion.P2X4 receptor was co-localized only with microglia, but not with neurons or astrocytes.Intrathecal injection of TNP-ATP before rrTNF administration prevented mechanical allodynia induced by rrTNF and inhibited the upregulation of TNF-αin the spinal dorsal horn.CONCLUSION:P2X4 receptors in microglia may be involved in rrTNF-induced mechanical allodynia by the upregulation of TNF-αin the spinal dorsal horn.
ABSTRACT
Lipocalin-2 (LCN2) is an acute-phase protein induced by injury, infection, or other inflammatory stimuli. LCN2 binds small hydrophobic ligands and interacts with cell surface receptor to regulate diverse cellular processes. The role of LCN2 as a chemokine inducer in the central nervous system (CNS) has been previously reported. Based on the previous participation of LCN2 in neuroinflammation, we investigated the role of LCN2 in formalin-induced nociception and pathological pain. Formalin-induced nociceptive behaviors (licking/biting) and spinal microglial activation were significantly reduced in the second or late phase of the formalin test in Lcn2 knockout mice. Likewise, antibody-mediated neutralization of spinal LCN2 attenuated the mechanical hypersensitivity induced by peripheral nerve injury in mice. Taken together, our results suggest that LCN2 can be therapeutically targeted, presumably for both prevention and reversal of acute inflammatory pain as well as pathological pain.
Subject(s)
Animals , Mice , Acute-Phase Proteins , Central Nervous System , Hypersensitivity , Ligands , Mice, Knockout , Microglia , Nociception , Pain Measurement , Peripheral Nerve Injuries , Spinal CordABSTRACT
Pathological pain or clinical pain is caused by tissue and nerve injuries, and is usually chronic and mainly divided into inflammatory pain and neuropathic pain. Pathological pain is typically characterized by hyperalgesia (increased responsiveness to noxious stimuli) and allodynia (painful responses to normally innocuous stimuli). The mitogen-activated proteins kinases (MAPKs) are a family of evolutionally conserved molecules that play a critical role in cell signaling, consisting of extracellular signal regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK), which play an important role in neural plasticity of pathological pain. Inhibition of MAPKs alleviates inflammatory pain and neuropathic pain in different animal models. It is very important to study the inhibition of MAPKs as a therapeutic approach to treat pathological pain.
ABSTRACT
Pathological pain or clinical pain is caused by tissue and nerve injuries,and is usually chronic and mainly divided into inflammatory pain and neuropathic pain. Pathological pain is typically characterized by hyperalgesia (increased responsiveness to noxious stimuli) and allodynia (painful responses to normally innocuous stimuli). The MAPKs are a family of evolutionally conserved molecules that play a critical role in cell signaling,consisting of extracellular signal-regulated kinase (ERK),p38,and c-Jun N-terminal kinase (JNK),which play an important role in neural plasticity of pathological pain. Inhibition of MAPKs alleviates inflammatory pain and neuropathic pain in different animal models. It is very important to study the inhibition of MAPKs as a therapeutic approach to treating pathological pain. All the studies suggest that MAPKs is a promising therapeutic target for pathological pain.