Stellate ganglion block ameliorated central post-stroke pain with comorbid anxiety and depression through inhibiting HIF-1α/NLRP3 signaling following thalamic hemorrhagic stroke.

BACKGROUND: Central post-stroke pain (CPSP) is an intractable and disabling central neuropathic pain that severely affects patients' lives, well-being, and socialization abilities. However, CPSP has been poorly studied mechanistically and its treatment remains challenging. Here, we used a rat model of CPSP induced by thalamic hemorrhage to investigate its underlying mechanisms and the effect of stellate ganglion block (SGB) on CPSP and emotional comorbidities. METHODS: Thalamic hemorrhage was produced by injecting collagenase IV into the ventral-posterolateral nucleus (VPL) of the right thalamus. The up-and-down method with von Frey hairs was used to measure the mechanical allodynia. Behavioral tests were carried out to examine depressive and anxiety-like behaviors including the open field test (OFT), elevated plus maze test (EPMT), novelty-suppressed feeding test (NSFT), and forced swim test (FST). The peri-thalamic lesion tissues were collected for immunofluorescence, western blotting, and enzyme-linked immunosorbent assay (ELISA). Genetic knockdown of thalamic hypoxia-inducible factor-1α (HIF-1α) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) with microinjection of HIF-1α siRNA and NLRP3 siRNA into the VPL of thalamus were performed 3 days before collagenase injection into the same regions. Microinjection of lificiguat (YC-1) and MCC950 into the VPL of thalamus were administrated 30 min before the collagenase injection in order to inhibited HIF-1α and NLRP3 pharmacologically. Repetitive right SGB was performed daily for 5 days and laser speckle contrast imaging (LSCI) was conducted to examine cerebral blood flow. RESULTS: Thalamic hemorrhage caused persistent mechanical allodynia and anxiety- and depression-like behaviors. Accompanying the persistent mechanical allodynia, the expression of HIF-1α and NLRP3, as well as the activities of microglia and astrocytes in the peri-thalamic lesion sites, were significantly increased. Genetic knockdown of thalamic HIF-1α and NLRP3 significantly attenuated mechanical allodynia and anxiety- and depression-like behaviors following thalamic hemorrhage. Further studies revealed that intra-thalamic injection of YC-1, or MCC950 significantly suppressed the activation of microglia and astrocytes, the release of pro-inflammatory cytokines, the upregulation of malondialdehyde (MDA), and the downregulation of superoxide dismutase (SOD), as well as mechanical allodynia and anxiety- and depression-like behaviors following thalamic hemorrhage. In addition, repetitive ipsilateral SGB significantly restored the upregulated HIF-1α/NLRP3 signaling and the hyperactivated microglia and astrocytes following thalamic hemorrhage. The enhanced expression of pro-inflammatory cytokines and the oxidative stress in the peri-thalamic lesion sites were also reversed by SGB. Moreover, LSCI showed that repetitive SGB significantly increased cerebral blood flow following thalamic hemorrhage. Most strikingly, SGB not only prevented, but also reversed the development of mechanical allodynia and anxiety- and depression-like behaviors induced by thalamic hemorrhage. However, pharmacological activation of thalamic HIF-1α and NLRP3 with specific agonists significantly eliminated the therapeutic effects of SGB on mechanical allodynia and anxiety- and depression-like behaviors following thalamic hemorrhage. CONCLUSION: This study demonstrated for the first time that SGB could improve CPSP with comorbid anxiety and depression by increasing cerebral blood flow and inhibiting HIF-1α/NLRP3 inflammatory signaling.

Spinal MCP-1 Contributes to Central Post-stroke Pain by Inducing Central Sensitization in Rats.

Central post-stroke pain (CPSP) is a highly refractory form of central neuropathic pain that has been poorly studied mechanistically. Recent observations have emphasized the critical role of the spinal dorsal horn in CPSP. However, the underlying mechanisms remain unclear. In this study, rats were subjected to thalamic hemorrhage to investigate the role of spinal monocyte chemoattractant protein-1 (MCP-1) and C-C motif chemokine receptor 2 (CCR2) in the development of CPSP. Immunohistochemical staining and ELISA were used to assess the expression changes of c-Fos, Iba-1, GFAP, MCP-1, and CCR2 in the dorsal horn of the lumbar spinal cord following thalamic hemorrhage, and the involvement of spinal MCP-1 in CPSP was examined by performing intrathecal anti-MCP-1 mAb injection to neutralize the spinal extracellular MCP-1. We demonstrated that intra-thalamic collagenase microinjection induced persistent bilateral mechanical pain hypersensitivity and facilitated the spontaneous pain behaviors evoked by intraplantar bee venom injection. Accompanying CPSP, the expression of c-Fos, Iba-1, and GFAP in the lumbar spinal dorsal horn was significantly increased up to 28 days post-intra-thalamic collagenase microinjection. Intrathecal injection of minocycline and fluorocitrate dramatically reverses the bilateral mechanical pain hypersensitivity. Moreover, intra-thalamic collagenase microinjection dramatically induced the up-regulation of MCP-1 but had no effect on the expression of CCR2 in the bilateral lumbar spinal dorsal horn, and MCP-1 was primarily localized in the neuron. Intrathecal injection of anti-MCP-1 mAb was also able to reverse CPSP and reduce the expression of c-Fos, Iba-1, and GFAP in the lumbar spinal dorsal horn. These findings indicated that spinal MCP-1 contributes to CPSP by mediating the activation of spinal neurons and glial cells following thalamic hemorrhage stroke, which may provide insights into pharmacologic treatment for CPSP.

Intervertebral foramen injection of plerixafor attenuates neuropathic pain after chronic compression of the dorsal root ganglion: Possible involvement of the down-regulation of Nav1.8 and Nav1.9.

Neuropathic pain is a common chronic pain condition with major impact on quality of life. However, its physiopathologic mechanism remains unknown and pain management is still a challenge. Accumulating evidence indicated that C-X-C chemokine receptor type 4 (CXCR4) played a critical role in the process of pain. Thus, the present study aimed to investigate whether intervertebral foramen injection of CXCR4 antagonist, plerixafor, was able to relieve neuropathic pain and explore the possible underlying mechanism. Chronic compression of the dorsal root ganglion (CCD) was established as a typical model of neuropathic pain. The results indicated that CCD induced multiple pain-related behaviors and the expression of CXCR4, Nav1.8 and Nav1.9 was significantly increased in compressed dorsal root ganglion (DRG) neurons. Knocking down CXCR4 expression could significantly reduce neuropathic pain and intervertebral foramen plerixafor injection (IVFP) dramatically decreased the up-regulation of Nav1.8 and Nav1.9 and attenuated neuropathic pain. The analgesic duration of IVFP was maintained at least for 24 h which was much longer than intervertebral foramen injection of Nav1.8 blocker and local anesthetics. Therefore, our study provided evidence that IVFP could reduce the expression of Nav1.8 and Nav1.9 in DRG neurons which might contribute to, at least in part, the analgesic effect of plerixafor on CCD-induced neuropathic pain. It is concluded that IVFP was an effective and applicable treatment approach for neuropathic pain.

The analgesic effects of ulinastatin either as a single agent or in combination with sufentanil: A novel therapeutic potential for postoperative pain.

Ulinastatin is a broad-spectrum protease inhibitor widely used for the treatment of various inflammation-related diseases owing to its recognized excellent anti-inflammatory and cytoprotective properties. However, whether ulinastatin can relieve postoperative pain remains unclear. In this study, we evaluated the analgesic effects of ulinastatin administered either as a single agent or in combination with sufentanil in a validated preclinical rat model of postoperative pain induced by plantar incision. We found that incisional surgery on the hind paw of these rats induced sustained ipsilateral mechanical pain hypersensitivity that lasted for at least 10 days. A single intraperitoneal (i.p.) injection of ulinastatin prevented the development and reversed the maintenance of incision-induced mechanical pain hypersensitivity in a dose-dependent manner. However, ulinastatin had no effect on the baseline nociceptive threshold. Moreover, repeated i.p. injections of ulinastatin persistently attenuated incision-induced mechanical pain hypersensitivity and promoted recovery from the surgery. The rats did not develop any analgesic tolerance over the course of repeated injections of ulinastatin. A single i.p. injection of ulinastatin was also sufficient to inhibit the initiation and maintenance of incision-induced hyperalgesic priming when the rats were subsequently challenged with an ipsilateral intraplantar prostaglandin E2 injection. Furthermore, the combined administration of ulinastatin and sufentanil significantly enhanced the analgesic effect of sufentanil on postoperative pain, which involved mechanisms other than a direct influence on opioid receptors. These findings demonstrated that ulinastatin had a significant analgesic effect on postoperative pain and might be a novel pharmacotherapeutic agent for managing postoperative pain either alone or as an adjuvant.

Ulinastatin Exhibits Antinociception in Rat Models of Acute Somatic and Visceral Pain Through Inhibiting the Local and Central Inflammation.

INTRODUCTION: Ulinastatin, a broad-spectrum serine protease inhibitor, has been widely used to treat various diseases clinically. However, so far, the antinociceptive effect of ulinastatin remains less studied experimentally and the underlying mechanisms of ulinastatin for pain relief remain unclear. This study aimed to find evidence of the analgesic effect of ulinastatin on acute somatic and visceral pain. METHODS: The analgesic effect of ulinastatin on acute somatic and visceral pain was evaluated by using formalin and acetic acid-induced writhing test. The analgesic mechanism of ulinastatin was verified by detecting the peripheral inflammatory cell infiltration and spinal glial activation with hematoxylin-eosin (H&E) and immunohistochemistry staining. RESULTS: We found that both of intraperitoneal (i.p.) pre-administration and post-administration of ulinastatin could reduce the total number of flinching and the licking duration following intraplantar formalin injection in a dose-related manner. However, the inhibitory effect of ulinastatin existed only in the second phase (Phase 2) of formalin-induced spontaneous pain response, with no effect in the first phase (Phase 1). The formalin-induced edema and ulcer were also improved by i.p. administration of ulinastatin. Moreover, i.p. administration of ulinastatin was also able to delay the occurrence of acetic acid-induced writhing and reduced the total number of writhes dose-dependently. We further demonstrated that ulinastatin significantly decreased the local inflammatory cell infiltration in injured paw and peritoneum tissue under formalin and acetic acid test separately. The microglial and astrocytic activation in the spinal dorsal horn induced by intraplantar formalin and i.p. acetic acid injection were also dramatically inhibited by i.p. administration of ulinastatin. CONCLUSION: Our results for the first time provided a new line of evidence showing that ulinastatin could attenuate acute somatic and visceral pain by inhibiting the peripheral and spinal inflammatory reaction.

Impact of inhalational anesthetics on postoperative cognitive function: Study protocol of a systematic review and meta-analysis.

BACKGROUND: Conflict findings of the impact of inhalational anesthetics on postoperative cognitive function are reported. No systematic review has been performed to solve the problem. The aim of the study was to assess the effect of different inhalational anesthetics on postoperative cognitive function in a network meta-analysis. METHODS: We will search MEDLINE, EMBASE, the Central Register of Controlled Trials in the Cochrane library, and CINAHL for randomized controlled trials or cohort studies assessing the short-term or long-term cognitive function of elderly patients (over 60 years) receiving major surgeries and inhalational anesthetics (desflurane, isoflurane, sevoflurane, halothane, and nitrous oxide) during surgery. Two reviewers will independently screen study eligibility, extract information from eligible studies, and appraise study quality. The impact of inhalational anesthetics will be assessed through: incidence of postoperative cognitive dysfunction at 1 week, 3 months, 1 year, and over 1 year after surgery; incidence of post-operative delirium; test of postoperative cognitive function. RESULTS: The results of this systematic review and meta-analysis will be published in a peer-reviewed journal. CONCLUSION: To our knowledge, this systematic review will be the first to evaluate existing research on the incidence of postoperative cognitive function after inhalational anesthetics. Our study will assess the effect of different inhalational anesthetics on postoperative cognitive function. ETHICS AND DISSEMINATION: The review will be finished in December 2017, and the result will be published in a peer-reviewed journal or disseminated through conference posters or abstracts. REVIEW REGISTRATION NUMBER: CRD42017056675 (www.crd.york.ac.uk/PROSPERO).

[Effects of salidroside-pretreatment on neuroethology of rats after global cerebral ischemia-reperfusion].

OBJECTIVE: To study the effects of salidroside-pretreatment on changes of neuroethology in rats with global cerebral ischemia-reperfusion injury so as to investigate its probable mechanism. METHODS: Sixty SD male rats were randomly divided into sham-operated group, untreated group and salidroside-pretreated group. The rats in salidroside-pretreated group were intraperitoneally administered with salidroside for seven days. The dose of salidroside was 12 mg/(kg.d). Thirty minutes after the last administration, the acute global cerebral ischemia-reperfusion in rats of the untreated group and the salidroside-pretreated group was induced by using the modified Pulsinelli's 4-vessel occlusion method. Five rats in each group were killed to obtain their brains 24 hours after reperfusion. The water content in the right brain was measured by calculating the ratio of dry weight to wet weight of the right brain. Activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) in hippocampus of the rats were measured. Then neurological severity scores (NSSs) of the other 15 rats in each group were observed respectively before and 6, 12, 24, 48 and 96 h after reperfusion. At the fifth day after reperfusion, the test of Morris water maze was carried out to examine the memories and learning abilities of the rats. RESULTS: The content of MDA, the activity of SOD, the NSS, the mean incubation period and the ratio of time in the second quadrant in the untreated group were significant different from those in the sham-operated group (P<0.05). Compared with the untreated group, the brain water content, the content of MDA and the NSS degraded, and the mean incubation period shortened in salidroside-pretreated group. The activity of SOD and the ratio of residence time in the second quadrant increased in salidroside-pretreated group as compared with the untreated group (P<0.05). CONCLUSION: Salidroside can reduce the degree of cerebral edema of rats with global cerebral ischemia-reperfusion injury, relieve the metabolism abnormity of free radical and improve the function of cognition.

[Transcatheter pulmonary valve replacement in sheep: 6-month evaluation of self-expanding valved stents].

OBJECTIVE: The purpose of this study was to determine the feasibility of transcatheter pulmonary valve replacement in sheep up to 6 months post procedure. METHODS: Fresh sheep pericardium treated with a 0.6% glutaraldehyde solution for 36 hours was sutured to a valvular ring and then fixed onto a newly designed nitinol self-expandable stent. Thoracotomy was performed in sheep (23.5 +/- 3.1) kg under general anesthesia and the device was delivered into the native pulmonary valve of the sheep via the anterior wall of right ventricle by catheter and fooled for 6 months. RESULTS: One sheep died 4 months after the procedure due to in-stent thrombosis. Another 4 animals survived the 6-month observing period. Angiographic and hemodynamic measurements confirmed good positioning and function of the stents with a competent valve immediately post procedure and 6 months post the procedure in surviving animals. CONCLUSION: Implantation of the nitinol self-expandable stent in the pulmonary valve position by a transcatheter approach is feasible and good function of transcatheter implanted memory nitinol valved stents was shown after 6 months of implantation in sheep.

[Autologous sinoatrial node cells heterotopic transplantation for treating bradycardia: an experiment with dogs].

OBJECTIVE: To explore the feasibility of autografting sinoatrial nodal cells heterotopic transplantation to construct an ectopia pacemaker for treating bradycardia. METHODS: Sixteen healthy adult dogs were randomly divided into 2 equal groups: graft group and control group. The sinoatrial node (SAN) of the dogs in the graft group was harvested and digested into cell suspension in vitro, then injected to the autogenic right ventricular wall adjacent to heart apex. Commensurable culture medium was injected to the same position with the dogs in control group. Two week later, all dogs underwent transcatheter ablation of His bundle to create a complete heart block model and an electrophysiology study was carried out. In order to investigate the change of rhythm, isoproterenol and atropine was injected respectively to dogs of the graft group. Two weeks later the dogs were killed with their hearts taken out. Immunofluorescence histochemistry was used to investigate the survival of grafted cells and gap junction formed between grafted cells and ventricular myocytes. RESULTS The isolated cells from SAN retained active and beating. After ablation, the heart rate of the dogs of the graft group was (91 +/- 14) bpm, significantly higher than that of the control group, [(49 +/- 11) bpm, t = 6. 672, P < 0.01], and electrocardiography showed that these ventricular rhythms originated from the cell transplant sites. After the injection of isoproterenol the ventricular rate of the graft group was (118 +/- 15) bpm, significantly higher than that before the injection, (95 +/- 11) bpm, t = 3.491, P < 0.01), however, after the injection of atropine, the heart rate of the graft group was (101 +/- 17) bpm, not significantly different from that before the injection, [(95 +/- 11) bpm, t = 0.838, P > 0.05]. Immunofluorescence staining showed that the grafted autografting sinoatrial nodal cells all survived and that there was connexin-43 expression among the cells. CONCLUSION: Transplantation of autologous SAN cells into the right ventricular wall can boost the ventricular rhythm which is sensitive to isoproterenol but not to atropine. Grafted SAN cells can form gap junctions with adjacent myocytes.