SIRT6 suppresses mitochondrial defects and cell death via the NF-κB pathway in myocardial hypoxia/reoxygenation induced injury.

The present study explored changes of the SIRT6/NF-κB pathway in myocardial hypoxia/reoxygenation induced injury and the effects on mitochondrial damage and myocardial damage by regulating SIRT6. SIRT6 expression decreased and NF-κB expression increased in H9c2 cells during hypoxic injury. Cell death and mitochondrial defects paralleled mPTP opening, and a decrease in ΔΨm occurred in hypoxic myocytes compared with normoxic control cells in annexin V and propidium iodide staining and TUNEL results. These effects were suppressed in cells overexpressing SIRT6, but reemerged in cells expressing the SIRT6 mutant. We also found that NF-κB p65 increased in both the cytoplasm and nuclei, which could be repressed by SIRT6 overexpression. The expression level of NF-κB was significantly and negatively correlated with the SIRT6 mRNA level. Our data demonstrated that SIRT6/NF-κB changed during hypoxic injury and SIRT6 overexpression averted mitochondrial defects through inhibition of NF-κB in hypoxic H9c2 cells. Activation of SIRT6 may be a potential method for hypoxia/reoxygenation injury therapy.

Spinal NF-κB and chemokine ligand 5 expression during spinal glial cell activation in a neuropathic pain model.

BACKGROUND: The NF-κB pathway and chemokine (C-C motif) ligand 5 (CCL5) are involved in pain modulation; however, the precise mechanisms of their interactions in chronic neuropathic pain have yet to be established. METHODS: The present study examined the roles of spinal NF-κB and CCL5 in a neuropathic pain model after chronic constriction injury (CCI) surgery. CCI-induced pain facilitation was evaluated using the Plantar and von Frey tests. The changes in NF-κB and CCL5 expression were analyzed by immunohistochemistry and Western blot analyses. RESULTS: Spinal NF-κB and CCL5 expression increased after CCI surgery. Repeated intrathecal infusions of pyrrolidine dithiocarbamate (PDTC, a NF-κB inhibitor) decreased CCL5 expression, inhibited the activation of microglia and astrocytes, and attenuated CCI-induced allodynia and hyperalgesia. Intrathecal injection of a CCL5-neutralizing antibody attenuated CCI-induced pain facilitation and also suppressed spinal glial cell activation after CCI surgery. However, the CCL5-neutralizing antibody did not affect NF-κB expression. Furthermore, selective glial inhibitors, minocycline and fluorocitrate, attenuated the hyperalgesia induced by intrathecal CCL5. CONCLUSIONS: The inhibition of spinal CCL5 expression may provide a new method to prevent and treat nerve injury-induced neuropathic pain.

Resveratrol facilitates pain attenuation in a rat model of neuropathic pain through the activation of spinal Sirt1.

BACKGROUND: Little research has been conducted regarding the implications of Sirt1 (a classic III HDAC) in neuropathic pain. The aim of this study was to investigate the variation in the expressions of spinal Sirt1 and acetyl-histone H3 in a rat model of chronic constriction injury. METHODS: A neuropathic pain model of chronic constriction injury (CCI) was established in a unilateral hind limb in Sprague-Dawley rats. RESULTS: Western blot analysis and immunohistochemistry revealed that Sirt1 (silent information regulator) expression decreased, whereas acetyl-histone H3 increased in the spinal cord following CCI surgery. The intrathecal administration of resveratrol, an activator of Sirt1, attenuated CCI-induced mechanical allodynia and thermal hyperalgesia, increased Sirt1 expression, and decreased acetyl-histone H3 in the spine. Resveratrol induced no obvious histopathological changes in the spinal cord. CONCLUSIONS: Our data provide new evidence for the contribution of spinal Sirt1 to the initiation and maintenance of neuropathic pain. The antinociceptive effects of resveratrol may be mediated through the activation of spinal Sirt1 in CCI rats.

Intrathecal injection of anti-CX3CR1 neutralizing antibody delayed and attenuated pain facilitation in rat tibial bone cancer pain model.

This study was designed to investigate the effect of intrathecal injection of anti-CX3CR1 neutralizing antibody on pain behaviors in the rat tibial bone cancer pain model. Syngeneic Walker 256 mammary gland carcinoma cells were injected into the tibia medullary cavity to establish the rat model of bone cancer pain. Ambulatory pain, mechanical hindpaw withdrawal threshold, and latency of paw withdrawal to a thermal stimulus were observed. Haematoxylin/eosin staining was used to observe the bone damage on day 21. Intrathecal injection of anti-CX3CR1 neutralizing antibody both delayed the development of ambulatory pain and hyperalgesia and attenuated established pain facilitation, but had no effects on destruction of bone. Our results suggest that intrathecal injection of anti-CX3CR1 neutralizing antibody delayed and attenuated pain facilitation in the rat tibial bone cancer pain model.

Intracerebroventricular or intrathecal injection of glycine produces analgesia in thermal nociception and chemical nociception via glycine receptors.

The present study was designed to investigate the role of glycine receptors in analgesia induced by injection of glycine in vivo. Glycine was injected intracerebroventricularly or intrathecally and strychnine, a glycine receptor antagonist, was injected intracerebroventricularly or intrathecally before glycine injection. The effects on the pain threshold index in hot-plate test and the writhing times in acetic acid-induced writhing test were observed. The locomotor activity and motor performance (rotarod test) were also observed. The dosages of glycine and strychnine we choose had no effect on locomotor activity or motor performance in conscious mice. Glycine increased the pain threshold index in hot-plate test and decreased the writhing times of the mice. Strychnine antagonized the effects induced by glycine above. These results demonstrated that intracerebroventricular or intrathecal injection of glycine can produce analgesia in thermal nociception and chemical nociception in vivo, which is mediated by glycine receptors.