Downregulation of Sp1 Inhibits the Expression of HDAC1/SOX10 to Alleviate Neuropathic Pain-like Behaviors after Spinal Nerve Ligation in Mice.

Specific protein 1 (Sp1) is a member of the Sp/Kruppel-like factor family, which regulates cellular processes of neurons in the nervous system. This study was performed to examine the regulatory role and the underlying mechanism of transcription factor Sp1 in neuropathic pain (NP)-like behaviors after spinal nerve ligation (SNL). Sp1 and histone deacetylase 1(HDAC1) expressions were determined in the C57BL6 mouse model with NP-like behaviors after SNL, which demonstrated that Sp1 and HDAC1 elevation occurred in neurons in the spinal dorsal horn of SNL mice. The chromatin immunoprecipitation assay verified that Sp1 was bound to the HDAC1 promoter region and HDAC1 to the SRY-box-containing gene 10 (SOX10) promoter region in the spinal dorsal horn. Immunofluorescence was performed to determine Sp1, HDAC1, and SOX10 in the spinal dorsal horn neurons as well as the neuronal marker (NeuN), microglial marker (Iba-1), and astrocyte marker (GFAP). The nociceptive test was performed to characterize the hindlimb paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) of mice 0-10 days after model establishment. Loss- and gain-of-function assays revealed that Sp1 promoted HDAC1 expression, and HDAC1 in turn promoted SOX10 expression. HDAC1 elevation reversed the effects of Sp1 silencing, and the increased PWT and PWL of SNL mice were negated after SOX10 overexpression. Meanwhile, SOX10 also restored the results by Sp1 knockdown. Collectively, downregulating Sp1 alleviates NP-like behaviors after SNL via the HDAC1/SOX10 axis.

CCR1 enhances SUMOylation of DGCR8 by up-regulating ERK phosphorylation to promote spinal nerve ligation-induced neuropathic pain.

Neuropathic pain is a somatosensory nervous system dysfunction that remains a threatening health problem globally. Recent studies have highlighted the involvement of C-C motif chemokine receptor 1 (CCR1) in neuropathic pain. Herein, the current study set out to explore the modulatory role of CCR1 in spinal nerve ligation (SNL)-induced neuropathic pain and its underlying molecular mechanism. First, it was found that CCR1 was highly expressed in spinal cord tissues and microglial cells of SNL rats. On the other hand, CCR1 knockdown attenuated nerve pain in SNL rats and repressed microglial cell activation in SNL rats and also in the LPS-induced microglial cell model of nerve injury, as evidenced by elevated microglial cell markers OX-42 and IL-1ß, IL-6 and TNF-α. Mechanistically, CCR1 enhanced small ubiquitin-like modifier 1 (SUMO1) modification of DiGeorge syndrome critical region gene 8 (DGCR8) in LPS-treated microglial cells by phosphorylating ERK. Moreover, CCR1 silencing brought about elevations in mechanical withdrawal threshold and thermal withdrawal latency. To conclude, our findings indicated that CCR1 enhanced the modification of DGCR8 by SUMO1 through phosphorylation of ERK, thereby promoting the activation and inflammatory response of spinal cord microglial cells and increasing the sensitivity of SNL rats to pain. Thus, this study offers a promising therapeutic target for the management of neuropathic pain.

Corrigendum: Lipoxin A4 Inhibits NLRP3 Inflammasome Activation in Rats With Non-compressive Disc Herniation Through the JNK1/Beclin-1/PI3KC3 Pathway.

[This corrects the article DOI: 10.3389/fnins.2020.00799.].

Lipoxin A4 Inhibits NLRP3 Inflammasome Activation in Rats With Non-compressive Disc Herniation Through the JNK1/Beclin-1/PI3KC3 Pathway.

BACKGROUND: Non-compressive disc herniation is induced by an inflammatory response from the nucleus pulposus tissue and nerve roots. Lipoxins (LXs) are important endogenous anti-inflammatory mediators in the body, helping to inhibit neutrophil recruitment and stimulate autophagy in monocytes and macrophages. Here, we investigated the molecular mechanisms underlying the effects of exogenous lipoxin administration on rats with non-compressive disc herniation. METHOD: A non-compressive disc herniation model was established in rats. Fifty rats were randomly divided into: sham group, model group, PI3K inhibitor (LY294002) group, lipoxin A4 group (LXA4), and PI3K inhibitor and lipoxin A4 group (LY294002 + LXA4). Similar groupings were established for rat spinal neurons. Changes in the mechanical pain threshold and thermal pain threshold were monitored at different times. The expression of proinflammatory and anti-inflammatory mediators was assessed by ELISA, while immunohistochemistry was employed to measure the expression levels of NLRP3 and p-JNK1. The expression levels of autophagy-related proteins were measured by western blot. RESULTS: In vivo, the pain threshold was markedly decreased in the model group at each time point examined compared with that in sham group. LY294002 treatment further reduced the pain threshold. After LXA4 injection, the pain threshold was significantly increased, and the effect of LY294002 was significantly weakened (p < 0.05). The levels of proinflammatory cytokines were increased in rats with non-compressive disc herniation, and these levels were further increased by LY294002 treatment (p < 0.05). However, treatment with LXA4 significantly reduced the levels of these proinflammatory cytokines in the model group (p < 0.05). The opposite effect was observed for anti-inflammatory mediators. The expression of NLRP3 was largely increased in the model group compared with that in the sham group (p < 0.05). Treatment with LY294002 also increased the NLRP3 expression level, while the administration of LXA4 elicited the opposite effect. Furthermore, western blot analysis showed that the expression of autophagy-related proteins was greatly decreased in the model group, whereas it was significantly increased in the LXA4 group (p < 0.05). The in vitro results were consistent with the outcomes observed in vivo. CONCLUSIONS: These data suggested that LXA4 inhibited NLRP3 activation in rats with non-compressive disc herniation by regulating the JNK1/beclin-1/PI3KC3 pathway.

MicroRNA-22 exerts its neuroprotective and angiogenic functions via regulating PI3K/Akt signaling pathway in cerebral ischemia-reperfusion rats.

The aims of this study were to study the effects of miR-2 on cerebral ischemia-reperfusion rats and to explore its further mechanism. Rats were assigned into sham, model, miR-22 control and miR-22 groups. Observation of neurological behaviors at 24 h after operation found that neurological functions were severely damaged in the model and miR-22 control groups and these damages were improved by miR-22. RT-PCR indicated that miR-22 mRNA level in the brain tissue was significantly decreased in the model and miR-22 control groups, but increased in the miR-22 group. TTC staining showed increased percentage of cerebral infarction volume in the model and miR-22 control groups and this increase was reduced by miR-22. Immunohistochemistry showed increased densities of CD34+ and VEGF+ microvessels in the cortex in the model and miR-22 control groups, which were further increased in the miR-22 group. ELISA showed increased serum VEGF and Ang-1 levels in the model and miR-22 control groups, which were also further increased in the miR-22 group. Western blot analysis showed increased phosphorylation level of PI3K and Akt in brain tissue in the model and miR-22 control groups, which were further increased in the miR-22 group. Administration of LY294002, a specific PI3K pathway inhibitor, significantly reversed all the effects of miR-22 on rats in the model group. miR-22 exerts its neuroprotective and angiogenic functions via the PI3K/Akt signaling pathway, at least partly, in rats under cerebral ischemia-reperfusion.

Sevoflurane attenuates brain damage through inhibiting autophagy and apoptosis in cerebral ischemia­reperfusion rats.

The present study aimed to investigate the effects of sevoflurane post­conditioning in a rat brain cerebral ischemia­reperfusion (I/R) model and examine its possible mechanism. Rats were randomly divided into six groups: Sham control group (Sham), I/R group, sevoflurane group (Se), Toll­like receptor­4 (TLR4) inhibitor group (Tak­242), nuclear factor (NF)­κB inhibitor group (QNZ) and Sevoflurane post­conditioning combined with TLR4­NF­κB signaling pathway inhibitor group (Se + Tak­242). Morris water maze test and tetrazolium chloride staining were used to investigate the I/R injury. The nerve cell apoptosis and autophagy in cortical tissue were detected by TUNEL and transmission electron microscopy, respectively. The expression of TLR4 protein in cortical tissue was observed by immunohistochemical staining. The expression of autophagy and apoptotic associated proteins in cortical tissues and the activity of TLR4­NF­κB signaling pathway were assayed by western blot analysis. Sevoflurane post­conditioning improved the learning and memory dysfunction caused by cerebral I/R injury. The cerebral infarction area, nerve cell apoptosis and formation of autophagic vacuoles were reduced after sevoflurane administration. The expression of light chain 3II/I, Beclin­1, Bad and Cleaved­Caspase­3 proteins were inhibited and the expression of Bcl­2 protein was upregulated after sevoflurane administration. Sevoflurane post­conditioning also inhibited the TLR4 protein and NF­κB phosphorylation, and increased inhibitor of kBα phosphorylation. The treatment effect of Tak­242 and QNZ groups were not significantly different compared with the Se group (P>0.05), and the Se + Tak­242 group had the best results. The present study demonstrated that sevoflurane post­conditioning could protect middle cerebral artery occlusion­induced brain injury rats by inhibiting autophagy and apoptosis, and that its mechanism is related to the TLR4­NF­κB signaling pathway.

Effect of perioperative administration of dexmedetomidine on delirium after cardiac surgery in elderly patients: a double-blinded, multi-center, randomized study.

OBJECTIVE: Postoperative delirium (POD) is a serious complication in elderly patients undergoing cardiac surgery. This study was aimed at investigating the effect of perioperative administration of dexmedetomidine for general anesthesia maintenance on occurrence and duration of POD in elderly patients after cardiac surgery. METHODS: One hundred and sixty-four patients were enrolled after cardiac surgery between June 2009 and December 2016. Patients were assigned by a computer-generated randomization sequence in a 1:1 ratio to receive dexmedetomidine general anesthesia maintenance or propofol general anesthesia maintenance. POD was assessed every day with confusion assessment method for intensive care units (ICU) during the first 5 postoperative days. RESULTS: There was no significance in incidence of POD between the dexmedetomidine group and the propofol group (P=0.0758). In patients treated with dexmedetomidine, the median onset time of delirium was delayed (second day vs first day) and the duration of delirium reduced (2 days vs 3 days) when compared with propofol-treated patients. The dexmedetomidine-treated patients also displayed a lower VAS score and less opiate analgesic consumption. No difference was observed in respect to other postoperative outcomes. CONCLUSION: For elderly patients, perioperative administration of dexmedetomidine reduced incidence, delayed onset and shortened duration of POD after cardiac surgery.

Intraoperative and postoperative infusion of dexmedetomidine combined with intravenous butorphanol patient-controlled analgesia following total hysterectomy under laparoscopy.

The present prospective, randomized, double-blinded, controlled study aimed to investigate the efficacy and safety of dexmedetomidine (DEX) combined with butorphanol for patient-controlled intravenous analgesia (PCIA) following total laparoscopic hysterectomy. A total of 88 patients undergoing total laparoscopic hysterectomy and receiving postoperative PCIA were divided into two groups following surgery. Patients received DEX 0.5 µg/kg intravenously in the DEX group or 0.9% normal saline in the control (CON) group following anesthesia induction. Postoperatively, the PCIA (10 mg butorphanol with 300 µg dexmedetomidine in the DEX group or without DEX in the CON group) was delivered as a 0.5 ml bolus (lockout interval of 15 min) with a continuous background infusion of 2 ml/h. Cardiovascular and respiratory variables, cumulative butorphanol consumption, pain scores, level of sedation, concerning adverse events and the degree of patient satisfaction were recorded for 24 h post-surgery. A total of 81 patients completed the study. Blood pressure and heart rate exhibited no significant difference between the two groups during surgery and for 24 h post-surgery. Compared with the CON group, patients in the DEX group required ~19% less butorphanol (P<0.05). During the first 24 h post-surgery, patients from the DEX group had a significantly lower visual analogue scale score at rest and movement states compared with the CON group (P<0.05). There was no significant difference in sedation score between the groups. The satisfaction scores were significantly higher in the DEX group compared with those in the CON group (P<0.05). Compared with the CON group, the DEX group exhibited a lower rate of postoperative nausea and vomiting (P<0.05). There was no occurrence of serious adverse events, including respiratory depression, hypotension, bradycardia and somnolence. In conclusion, following total laparoscopic hysterectomy, the loading dose of DEX (0.5 µg/kg) followed by a continuous infusion as an adjunct to butorphanol PCIA resulted in effective analgesia, significant butorphanol sparing and less butorphanol-induced nausea and vomiting without excessive sedation or adverse effects. The trial registration number was ChiCTR1800015675 at the Chinese Clinical Trial Registry (chictr.org.cn) and the date of registration was 4th April 2018.

Consciousness inhibition of intravenous dexmedetomidine in patients undergoing lower limb surgery with epidural anesthesia: A dose-response study by age group.

Dexmedetomidine (DEX) induces a dose dependent sedation and has been widely used as an adjuvant sedative during regional anesthesia recently. We aimed to investigate the effective dose of intravenous single-dose DEX to induce consciousness inhibition in patients of different ages undergoing lower limb surgery with epidural anesthesia. Ninety-two patients were divided into three groups according to their ages. Patients aged 18-45 years, 46-64 years and 65-85 years in group Y, group M and group O, respectively. With the accomplishment of epidural anesthesia, a pre-calculated dose of DEX was infused for more than 10 minutes and the sedative state was assessed by Observer's Assessment of Alertness/Sedation (OAA/S) scale 30 minutes after the infusion. A modified Dixon's up-and-down method was applied to decided the dose of DEX for each sequential patient. The 50% effective dose (ED50) of DEX in the three groups were 0.40, 0.76 and 1.03 µg/kg, respectively. The 95% effective dose (ED95) in group O (0.54 µg/kg) was 45% of group Y (1.21µg/kg) and 64% of group M (0.84µg/kg). Besides, the incidence of bradycardia was more frequent with the increase of age. The present study indicated that the appropriate single-dose of DEX to induce consciousness inhibition should reduce with the increase of age in patients undering lower limb surgery with epidural anesthesia, especially in patients over 64 years old. This result may protect the old patients from excessive sedation and dose-dependent adverse reactions.

Intraoperative use of dexmedetomidine promotes postoperative sleep and recovery following radical mastectomy under general anesthesia.

Postoperative sleep disturbance and fatigue following radical mastectomy were high risks for prolonged convalescence in patients with breast cancer. The present study was designed to observe the effect of intraoperative use of dexmedetomidine on postoperative sleep, fatigue and recovery following radical mastectomy under general anesthesia. Forty-seven patients were randomized into two groups that were maintained with propofol/remifentanil/Ringer's solution (Control group), or propofol/remifentanil/Dexmedetomidine (DEX group) for surgery under general anesthesia. During the first night following surgery, patients receiving dexmedetomine spent more time sleeping when compared with those form the Control group. During the first week following operation, when compared with the Control group, patients from the DEX group had a higher score of global 40-item recovery questionnaire on day 3 following operation, and lower 9-question fatigue severity scores on day 3 and day 7 following operation. In conclusion, intraoperative use of dexmedetomidine is sufficient to improve postoperative sleep disorder, promote postoperative recovery. The adverse effect of dexmedetomidine on sleep disturbance might be contributed to its recovery-promoting effect.

Effects of andrographolide on postoperative cognitive dysfunction and the association with NF-κB/MAPK pathway.

The present study investigated the effects of andrographolide on postoperative cognitive dysfunction (POCD) in aged rats to gain insight of the underlying mechanism, which may provide theoretical basis for the clinical application of andrographolide to prevent POCD in older patients. Thirty aged male rats were randomly assigned to 3 groups: Control, model and andrographolide groups. The Morris water maze test was used to examine the spatial memory and learning ability of the rats postoperatively. The histological alterations of neuronal cells in the hippocampus were visualized by H&E staining. The serum levels of neuron-specific enolase (NSE), human soluble protein-100ß (S-100ß) and the inflammation factors of interluekin (IL)-1ß, IL-6 and TNF-α involved in the nuclear factor κB (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathway were detected by ELISA. The NF-κB/MAPK signaling pathway-associated proteins in rat serum were detected by western blotting. Following andrographolide treatment, the rats significantly gained learning ability after surgery. Is it ameliorated hippocampal neuronal injury in rats following surgery. Andrographolide decreased NSE, S-100ß, and the inflammation factors, IL-6, IL-1ß and TNF-α in serum. Andrographolide reduced NF-κB/MAPK pathway-associated protein expression. Andrographolide ameliorated POCD in aged rats following surgery. The underlying mechanism may be associated with the downregulation the inflammatory factors and NF-κB/MAPK-associated protein expression.